FEASIBILITY OF UTILIZING OIL-SANDS FLUID COKE AS A SECONDARY SOURCE OF by

Jing Feng

A thesis submitted in conformity with the requirements for the degree of Master of Applied Science

Department of Chemical Engineering and Applied Chemistry University of Toronto

© Copyright by Jing Feng 2017

Feasibility of Utilizing Oil-Sands Fluid Coke as A Secondary Source of Vanadium

Jing Feng

Master of Applied Science

Department of Chemical Engineering and Applied Chemistry

University of Toronto

2017

ABSTRACT

Oil-sands fluid coke (OSFC) is a major byproduct of upgrading Athabasca bitumen, which has a particularly high vanadium concentration (0.15 wt% and predominantly vanadyl porphyrins). This study explores the feasibility of extracting vanadium from OSFC. Chemical activation with KOH or NaOH converts organic vanadium in OSFC into water-soluble inorganic species. After chemical activation, water washing alone is able to dissolve over 98% of total vanadium in OSFC given enough time. Sequential washing enhances vanadium dissolution, shortens the washing process, and reduces the water usage by removing other elements (Ca, Ni,

Fe, Al and Si) in the first stage. Overall, it is technically feasible to recover over 90% of vanadium in OSFC as calcium vanadate via alkali metal hydroxide chemical activation, sequential water washing and calcium precipitation of vanadium. This process would allow the recycle, reuse of alkali metal hydroxide, and produce highly porous activated carbon.

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ACKNOWLEDGEMENTS

Firstly, I would like to express my greatest appreciation to my supervisor, Professor Charles Q. Jia, for his support, encouragement, and guidance in my research over the past years. I am very grateful for everything he has done for me and for my development. I would also like to thank Professor Donald W. Kirk for his kind advice throughout my entire research. They have always made time for me and they have always been there for me when I struggled.

Next, I must thank Jocelyn Zuliani for the training in lab work. Along with all the members in Green Technology, Celine, Leyan, Randeep, Johnathon, and Daniel. I am sure without any of you, the time I have spent in the department would have been less enjoyable. I am very glad that I have met and worked with all these wonderful people.

I am also very grateful to Dan Mathers and Jared Mudrik from ANALEST at Department of Chemistry, University of Toronto. They are always patient with my questions and concerns on analytical instruments, and thanks to their excellent training, I manage to learn a lot about instrument troubleshooting.

Last but not least, I would like to acknowledge my dearest family. I want to thank them for unconditional support regardless of my path in academia. Their support and their understanding literally have helped me to go through any difficult times and to conquer any challenges.

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TABLE OF CONTENT

ABSTRACT ...... ii

ACKNOWLEDGEMENTS ...... iii

TABLE OF CONTENT ...... iv

LIST OF TABLES ...... vii

LIST OF FIGURES ...... ix

CHAPTER 1. OVERVIEW ...... 1 1.1. INTRODUCTION ...... 1 1.2. RESEARCH OBJECTIVES ...... 2

CHAPTER 2. LITERATURE REVIEW ...... 3 2.1. VANADIUM ...... 3 2.1.1. General Background ...... 3 2.1.2. Commercial Recovery Processes ...... 4 2.2. CHARACTERIZATION OF OIL-SANDS FLUID COKE ...... 4 2.3. CHEMICAL ACTIVATION ON FLUID COKE...... 13

CHAPTER 3. MATERIALS AND METHODS ...... 17 3.1. DETERMINATION OF TOTAL VANADIUM CONTENT IN OIL-SANDS FLUID COKE ...... 17 3.1.1. Direct Acid Leaching Using Various Acids ...... 19 3.1.2. Direct Caustic Leaching Using 1M KOH Solution ...... 19 3.1.3. Dissolution of Ashed OSFC Using Aqua Regia ...... 19 3.1.4. X-Ray Fluorescence (XRF) on Ashed OSFC ...... 20 3.2. VANADIUM RECOVERY USING CHEMICAL ACTIVATION ...... 20 3.2.1. Chemical Activation of OSFC ...... 22 3.2.2. Washing Process of Activation Product ...... 23 3.3. VANADIUM SEPARATION AND STREAM PURIFICATION ...... 25 3.3.1. Solvent Extraction ...... 27

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3.3.2. Sequential Washing Using Water ...... 29

CHAPTER 4. RESULTS AND DISCUSSIONS ...... 30 4.1. DETERMINATION OF TOTAL VANADIUM CONTENT IN OIL-SANDS FLUID COKE 30 4.1.1. Direct Leaching of Raw Fluid Coke ...... 30 4.1.2. Acid Dissolution of Ashed OSFC Using Aqua Regia ...... 31 4.1.3. XRF Analysis on Ashed OSFC ...... 32 4.2. VANADIUM RECOVERY USING CHEMICAL ACTIVATION ...... 34 4.2.1. Activation Yield and Characteristics of Activated Coke ...... 34 4.2.2. Fate of Vanadium During Chemical Activation and Subsequent Washing ...... 36 4.3. VANADIUM SEPARATION AND STREAM PURIFICATION ...... 38 4.3.1. Solvent Extraction with Aliquat® 336...... 38 4.3.2. Sequential Washing Using Water ...... 40

CHAPTER 5. PROPOSED PROCESS OF VANADIUM RECOVERY VIA CHEMICAL ACTIVATION ON OSFC ...... 44

CHAPTER 6. CONCLUSIONS AND FUTURE RESEARCH ...... 46

CHAPTER 7. REFERENCES ...... 48

CHAPTER 8. APPENDICES ...... 53 APPENDIX 1 CALIBRATION CURVES ...... 53 Single-element ICP Standard Vanadium Calibration ...... 53 Multi-element ICP Standard Vanadium Calibration ...... 54 APPENDIX 2 XRF RAW DATA ...... 63 APPENDIX 3 SAMPLE PELLETS OF ASHED OSFC FOR XPF ANALYSIS ...... 66 APPENDIX 4 CORRECTED XRF RESULTS ...... 67 APPENDIX 6 DETERMINATION OF KOH AND NAOH PELLET PURITY ...... 68 APPENDIX 7 CALCULATION OF SOLVENT PREPARATION ...... 69 APPENDIX 8 DETERMINATION OF PARTITION COEFFICIENT AND MIXING TIME IN SOLVENT EXTRACTION ...... 70 Methodology ...... 70 Results and Discussions ...... 72 APPENDIX 9 OTHER ELEMENT CONCENTRATION IN SEQUENTIAL WASHING .... 73 v

APPENDIX 10 OLI SIMULATION ON VANADIUM PRECIPITATION ...... 74

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LIST OF TABLES

TABLE 1 VANADIUM WORLD ANNUAL PRODUCTION BY COUNTRY (HTTP://MINERALS.USGS.GOV) ...... 3 TABLE 2 PROPERTY PROXIMATE ANALYSIS OF FLUID COKE FROM SYNCRUDE, WT% (FUIMSKY,1998) ...... 9 TABLE 3 ULTIMATE ANALYSIS OF FLUID COKE FROM SYNCRUDE, WT% (FUIMSKY,1998) ...... 9 TABLE 4 ANALYSIS OF FLUID COKE ASH COMPOSITION FROM SYNCRUDE, WT% (FUIMSKY,1998) ...... 10 TABLE 5 THE ICP-AES OPERATING CONDITIONS ...... 18 TABLE 6 CHEMICALS INVOLVED IN CHEMICAL ACTIVATION PROCESS ...... 21 TABLE 7 THE INFORMATION OF MATERIALS INVOLVED IN SECTION 3.3 ...... 26 TABLE 8 CHEMICAL COMPOSITION OF 0.5 M ALIQUAT® 336 SOLVENT (500 ML) ... 27 TABLE 9 ASH CONTENT OF FLUID COKE PARTICLES OF DIFFERENT PARTICLE SIZES ...... 32 TABLE 10 YIELD OF CHEMICAL ACTIVATION AND ASH CONTENT OF ACTIVATED COKE AFTER WASHING WITH WATER ...... 34 TABLE 11 FATE OF VANADIUM AFTER CHEMICAL ACTIVATION AND DURING WATER AND DILUTED HCL WASHING (BASED ON 25 G OF DRIED OSFC) ...... 36 TABLE 12 VANADIUM DISTRIBUTION IN EACH ACTIVATED PRODUCT CATEGORY IN A PERCENTAGE BASIS ...... 37 TABLE 13 VANADIUM CONCENTRATIONS IN THE AQUEOUS PHASE UPON COMPLETION OF SOLVENT EXTRACTION WITH PRETREATED AND NON- PRETREATED SOVLENTS (0.5M, A/O=1) ...... 39 TABLE 14 CONCENTRATION AND EXTRACTION EFFICIENCY OF 0.5 M ALIQUAT® 336 IN KEROSENE WITH DIFFERENT A/O RATIOS ...... 40 TABLE 15 CONCENTRATION AND EXTRACTION EFFICIENCY OF 0.1 M ALIQUAT® 336 IN KEROSENE WITH DIFFERENT A/O RATIOS ...... 40 TABLE 16 VANADIUM CONCENTRATION AND RECOVERY PERCENTAGE IN 4- HOUR PER STAGE ...... 41

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TABLE 17 VANADIUM CONCENTRATION AND RECOVERY PERCENTAGE IN 1- HOUR PER STAGE ...... 41 TABLE 18 COMPOSITIONS OF WASHING SOLUTION AND RECOVERY PERCENTAGE DURING FIRST TWO WASHING STAGES (1 HOUR PER STAGE) ...... 42 TABLE 19 A SAMPLE OF CALIBRATION FOR VANADIUM ON ICP-AES ...... 53 TABLE 20 A SAMPLE OF CALIBRATION FOR VANADIUM ON ICP-AES ...... 54 TABLE 21 A SAMPLE OF CALIBRATION FOR ALUMINUM ON ICP-AES ...... 55 TABLE 22 A SAMPLE OF CALIBRATION FOR CALCIUM ON ICP-AES ...... 56 TABLE 23 A SAMPLE OF CALIBRATION FOR IRON ON ICP-AES ...... 57 TABLE 24 A SAMPLE OF CALIBRATION FOR POTASSIUM ON ICP-AES ...... 58 TABLE 25 A SAMPLE OF CALIBRATION FOR NICKEL ON ICP-AES ...... 59 TABLE 26 A SAMPLE OF CALIBRATION FOR SILICON ON ICP-AES ...... 60 TABLE 27 XRF ANALYSIS RESULTS FOR ASHED 53-106 µM FLUID COKE ...... 63 TABLE 28 XRF ANALYSIS RESULTS FOR ASHED 106-150 µM FLUID COKE ...... 64 TABLE 29 XRF ANALYSIS RESULTS FOR ASHED 150-212 µM FLUID COKE ...... 65 TABLE 30 AN ESTIMATION OF OTHER ELEMENTS USING VANADIUM CONTENT TO CORRECT XRF RESULTS ...... 67 TABLE 31 PURITY OF KOH PELLET TITRATION RESULTS ...... 68 TABLE 32 PURITY OF NAOH PELLET TITRATION RESULTS ...... 68 TABLE 33 DETERMINATION OF THE PARTITION COEFFICIENT OF SYNTHETIC SYSTEM AND MIXING TIME (0.5 M, A/O=2, PRETREATED 7 TIMES)...... 72 TABLE 34 OTHER ELEMENT CONCENTRATION IN SEQUENTIAL WASHING (1HR, 5- STAGE) ...... 73

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LIST OF FIGURES

FIGURE 1 SIMPLIFIED FLUID COKE PRODUCING SCHEMATICS (FURIMSKY, 2000). . 5 FIGURE 2 SEM SURFACE IMAGE OF FLUID COKE PARTICLES (CHEN, 2002) ...... 6 FIGURE 3 SEM IMAGE OF A CONTROLLED CHEMICALLY ACTIVATED FLUID COKE (SSA= 340 M2/G) (CHEN, 2002) ...... 7 FIGURE 4 TYPICAL STRUCTURES OF VANADYL PORPHYRINS ...... 8 FIGURE 5 SOLUBILITY OF VANADYL PORPHYRINS AT 23±2 °C AS A FUNCTION OF SOLUBILITY PARAMETER OF SOLVENT (FREEMAN ET AL., 1990) ...... 12 FIGURE 6 APPARATUS FOR CHEMICAL ACTIVATION PROCESS ...... 22 FIGURE 7 THE WASHING PROCESS OF ACTIVATED PRODUCT FOR THE 50HOURS WASHING ...... 25 FIGURE 8 COMPARISON OF LEACHING EFFECT OF VARIOUS AGENTS OVER 48 HOURS ...... 30 FIGURE 9 AQUA REGIA DISSOLUTION OF VANADIUM IN ASHED OSFC WITH DIFFERENT SOLID-LIQUID RATIOS AND DURATIONS ...... 31 FIGURE 10 VANADIUM CONTENTS OF FLUID COKE PARTICLES OF DIFFERENT SIZES ...... 33 FIGURE 11 PORE SIZE DISTRIBUTION OF KOH- AND NAOH ACTIVATED COKE ...... 35 FIGURE 12 CUMULATIVE SPECIFIC SURFACE AREA OF KOH AND NAOH ACTIVATED COKE ...... 35 FIGURE 13 DEPENDENCE OF CHLORIDE REMOVAL FROM RAFFINATE ON NUMBER OF PRETREATMENT STAGES ...... 38 FIGURE 14 PROPOSED PROCESS OF VANADIUM RECOVERY FROM OSFC VIA CHEMICAL ACTIVATION, SEQUENTIAL WATER WASHING AND CALCIUM PRECIPITATION ...... 45 FIGURE 15 A SAMPLE OF CALIBRATION FOR VANADIUM ON ICP-AES ...... 54 FIGURE 16 A SAMPLE OF CALIBRATION FOR VANADIUM ON ICP-AES ...... 55 FIGURE 17 A SAMPLE OF CALIBRATION FOR ALUMINUM ON ICP-AES ...... 56 FIGURE 18 A SAMPLE OF CALIBRATION FOR CALCIUM ON ICP-AES ...... 57 FIGURE 19 A SAMPLE OF CALIBRATION FOR IRON ON ICP-AES ...... 58 FIGURE 20 A SAMPLE OF CALIBRATION FOR POTASSIUM ON ICP-AES ...... 59

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FIGURE 21 A SAMPLE OF CALIBRATION FOR NICKEL ON ICP-AES ...... 60 FIGURE 22 A SAMPLE OF CALIBRATION FOR SILICON ON ICP-AES ...... 61 FIGURE 23 CALIBRATION CURVE FOR MULTIELEMENT STANDARDS ON ICP-AES 62 FIGURE 24 BRIQUETTED XRF SAMPLES ...... 66 FIGURE 25 . RELATION BETWEEN THE CONCENTRATION OF VANADIUM TRANSFERRED TO THE ORGANIC PHASE TO THAT REMAINED IN THE AQUEOUS PHASE THROUGH THE EXTRACTION BY 0.5 M ALIQUAT® 336 DISSOLVED IN KEROSENE FROM 0.1 M NAOH OR 3 M HCL MEDIA AT 25 °C (EL- NADI AND ET AL., 2009) ...... 70 FIGURE 26 INTERFACE OF OLI STUDIO ON WATER ANALYSIS AND INPUT OF SPECIES AND CONCENTRATIONS (NAOH-ACTIVATED OSFC) ...... 75 FIGURE 27 SIMULATION RESULTS OF VANADIUM PRECIPITATION BY ADDITION OF CALCIUM ION (NAOH-ACTIVATED OSFC) ...... 76

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CHAPTER 1. OVERVIEW

1.1. INTRODUCTION

Oil-sands fluid coke (OSFC) is an upgrading byproduct from Athabasca oil-sands bitumen. It is named after fluid coke because of the fluidized-bed reactor used in cracking process, in which long-chain bitumen molecules are continuously fed into the coker and simultaneously transferred between the reactor and burner vessels to gain energy for thermal cracking. Upon the completion of cracking, short chain hydrocarbon streams are achieved and transferred for future refineries, whereas fluid coke was produced as the waste of this process. Vanadium, which is a valuable and often used in a wide range of industries and applications, is found in crude oils and bitumens with a concentration ranging from 0.04 to 600 ppm in western Canada (Hodgson,1954; Bensebaa, 2000). The form of vanadium present in crude oils and bitumens is mainly vanadyl porphyrins (Dechaine & Gray, 2010; Zhao et al., 2013). Initially, it was hypothesized that vanadium would be captured and retained in the same chemical state after thermal cracking (Li & Le, 2007). Another study discovered crystalline clusters associated with vanadium, silicon, oxygen, sulfur, and iron were found within the carbon structure by Transmission Electron Microscopy (TEM) analysis (Zuliani et al., 2016). The elemental speciation of vanadium in OSFC remains unclear due to complex matrix effects.

Chemical activation is one of the most popular methods to prepare active carbon. By introducing chemicals into the activation process, a lower activation temperature is required and a superior grade of activated carbons with high specific surface areas is achieved. Hence, chemical activation is widely used in the applications such as water and gas purifications. Chemical activation is essentially an oxidation process that occurs on carbonaceous precursors with the assistance of the activating agent. Among different activating agents, alkaline hydroxides have shown their outstanding capability in chemical activation due to their strong corrosive and stable nature. It is hypothesized that the chemical activation process can oxidize vanadium within the porphyrin structure and convert it into an inorganic form. On the other hand, due to the dense structure of fluid coke, it is difficult for chelating agents to penetrate through the surface of fluid coke to recover vanadium from its organometallic form. With the help of a developed porous structure, inorganic vanadium becomes more accessible for recovery. 1

OSFC is viable as an alternative source of vanadium as the content of vanadium present in fluid coke has exceeded the ones in certain lean vanadium ores. With the massive daily production of fluid coke in bitumen refinery, vanadium can become as an extremely value-added byproduct.

1.2. RESEARCH OBJECTIVES

The overall objective of this research was to study the technical feasibility of recovering vanadium from OSFC, while converting the coke to porous carbon. To achieve this objective, following listed tasks have been carried out:

1. Develop a comprehensive method for quantifying vanadium content in oil sands fluid coke; 2. Determine the fate of vanadium during KOH chemical activation to recover vanadium from OSFC; 3. Determine the feasibility of using NaOH - a cheaper activating agent to recover vanadium from fluid coke; 4. And explore the options for separating vanadium from other elements in leaching solutions.

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CHAPTER 2. LITERATURE REVIEW

2.1. VANADIUM

2.1.1. General Background

Vanadium is a transition metal that was firstly discovered by Manuel Del Rio in 1801 within a Mexican lead vanadate ore. It is the 22nd abundant element in the crust of Earth (Moskalyk & Alfantazi, 2003). Vanadium is widely distributed in various forms; there are more than 50 vanadium-containing minerals such as carnotite, roscoelite, vanadinite, mottramite, and partonite (Perron, 2001). Other main sources of vanadium except ores and rock are metallurgical slags, spent catalysts, petroleum residues (Reese, 2001; Das et al., 2007). Vanadium is well known for its high tensile strength, fatigue resistance, and hardness; it has a broad range of applications in metal alloys. Due to the four oxidation states that vanadium possess, vanadium redox flow battery is another application that utilizes its unique characters. Currently, vanadium is massively produced by Japan, United States, China, South Africa, and Russia. The detailed annual production from 2008 to 2012 is tabulated in Table 1.

Table 1 Vanadium World Annual Production by Country (http://minerals.usgs.gov)

Production (thousand tonnes)

Country 2008 2009 2010 2011 2012

China 26 29 32 36 39

United States 0.52 0.23 1.06 0.59 0.272

Russia 14.5 14.5 15 15 15

South Africa 23.3 22.6 23.5 2.5 20

Japan 0.56 0.56 0.56 0.56 0.56

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2.1.2. Commercial Recovery Processes

It is quite difficult to produce metallic vanadium as it often combines with other elements in its sources. The salt roasting process that converts vanadium into water-soluble vanadates followed by leaching is a well-known way of vanadium extraction. Alkali metal salts such as sodium chloride, sodium carbonate, and sodium sulfate are commonly used for roasting, while leaching agents can be aqueous solutions of acids and bases or simply water.

In general, salt roasting can take place at temperature between 600 °C and 1250 °C within a fluidized bed reactor or a multiple hearth furnaces (Chen et al., 2006; Mahdavian et al., 2006) The proposed reaction of roasting is shown in Equations 1-3 (Gupta, 1992; Geyrhofer et al., 2003; Hukkanen and Walden, 1985)

Equation 1 or

Equation 2 or

Equation 3

2.2. CHARACTERIZATION OF OIL-SANDS FLUID COKE

Fluid coke, flexi coke, and delayed coke are the main three types of coke. Physical properties and chemical compositions of the different cokes vary due to their unique coking processes. In the fluid-coking process, the feedstock is evenly dispersed and injected into the fluidized bed reactor after preheating to 300°C. The reactor vessel (fluid coker) is operated at a temperature range of 480°C to 550°C. While the feed vapors are cracked within the temperature range, a liquid film is forming on the coke particles. Hence, the coke particles grow by layer as they flow back and forth between the reactor vessel and the heater. During the coking process,

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some of the coke (15-25%) is burned with air to provide sufficient heat for the coking process and to eliminate the requirement for external energy supplies. Hot coke nuclei are obtained and then circulated back to the reactor vessel with unburned hot coke to sustain the cracking reactions and maintain the reactor temperature. A simplified version of fluid-coking process scheme is shown in Figure 1 (Furimsky, 2000).

Figure 1 Simplified Fluid Coke Producing Schematics (Furimsky, 2000).

While the coke is circulating between the reactor vessel and the heater, non-volatile materials are attaching to the surface of the coke, thereby forming a non-porous smooth surface

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morphology with an “onion-like” internal structure. The Scanning Electron Microscope (SEM) image of fluid coke particles (100 – 200 µm) is shown in Figure 2. Once the carbon structure gets damaged via a controlled chemical activation, the internal layered structure is exposed and captured by SEM analysis as shown in Figure 3.

Figure 2 SEM Surface Image of Fluid Coke Particles (Chen, 2002)

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Figure 3 SEM Image of a Controlled Physically Activated Fluid Coke (SSA= 340 m2/g) (Chen, 2002)

Vanadium in coke originates from crude oil or other petroleum feedstock. It has been reported that vanadium is contained within the highly aromatic, highly polar asphaltene fraction (Biggs et al., 1985). The asphaltene fraction refers to the fraction of toluene soluble and n- alkane-insoluble (e.g., n-heptane) species present in a petroleum feed (Dechaine & Gray, 2010). Previous studies have shown that in crude oils and bitumens, vanadium presents predominantly in the form of vanadyl porphyrins which is vanadyl ion (VO2+) complexed with porphyrins (Amorim et al., 2007). In the porphyrin macrocycle, vanadium is bonded with one oxygen atom and the four nitrogen atoms from the porphyrin structure. Some typical vanadyl porphyrin structures are shown in Figure 4. Other studies have indicated that the vanadyl porphyrin compounds contribute to 50% - 80% of the total vanadium present in crude oil (Amorim et al., 2007). The most common forms of vanadyl porphyrins identified in petroleum deposits are the

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Etio form (Figure 4b) and the DPEP form (Figure 4d) (Dechaine & Gray, 2010; Qian et al., 2008). The majority of vanadium compounds exist as vanadyl ion (VO2+) in the form of vanadyl porphyrins with porous structures frozen in solid (Amorim et al., 2007). The primary chemical environment of vanadium is unchanged through the coking process, in which vanadium is almost quantitatively captured in the coking byproduct (Dechaine & Gray, 2010; Kelemen et al., 2007).

Figure 4 Typical Structures of Vanadyl Porphyrins

The chemical composition of fluid coke was studied by Furimsky over the years. The proximate, ultimate and ash composition analyses over fluid coke produced from 1979 to 1995 are shown in Table 2, Table 3, and Table 4.

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Table 2 Property Proximate Analysis of Fluid Coke from Syncrude, wt% (Fuimsky,1998)

Years 1979-1980 1980-1982 1982-1983 1983-1985 1985-1995

Property

Proximate

Moisture 0.44 0.60 0.50 0.69 0.25

Ash 5.40 7.21 5.18 7.52 4.83

Volatiles 4.85 5.11 6.23 6.10 4.99

Fixed Carbon 89.31 87.08 88.09 85.69 89.95

Table 3 Ultimate Analysis of Fluid Coke from Syncrude, wt% (Fuimsky,1998)

Years 1979-1980 1980-1982 1982-1983 1983-1985 1985-1995

Ultimate

Carbon 82.73 80.73 81.80 80.94 83.73

Hydrogen 1.72 1.63 1.66 1.56 1.77

H/C 0.25 0.24 0.24 0.23 0.25

Nitrogen 1.75 1.70 1.98 1.73 2.03

Sulfur 6.78 6.63 6.84 6.15 6.52

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Years 1979-1980 1980-1982 1982-1983 1983-1985 1985-1995

Oxygen 1.18 1.50 2.04 1.41 0.88

Table 4 Analysis of Fluid Coke Ash Composition from Syncrude, wt% (Fuimsky,1998)

Years 1979-1980 1980-1982 1982-1983 1983-1985 1985-1995

Ash content 5.4 7.21 5.18 7.52 4.83

V2O5 4.46 3.2 4.86 3.21 4.94

Al2O3 24.4 20.9 24.2 24.9 24.3

Fe2O3 9.72 8.18 9.26 12.1 11.4

TiO2 3.64 2.86 3.25 4.84 4.63

CaO 4.26 2.58 4.2 1.63 2.94

MgO 1.62 1.29 1.44 1.4 1.46

Na2O 1.51 1.17 1.57 1.16 1.67

K2O 1.83 1.78 1.83 1.93 1.72

BaO 0.2 0.15 0.07 0.14 0.09

SrO 0.11 0.06 0.09 0.06 0.11

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Years 1979-1980 1980-1982 1982-1983 1983-1985 1985-1995

MnO 0.26 0.21 0.25 0.29 0.27

Cr2O3 0.08 0.05 0.08 0.08 0.09

Total metal 52.0 42.5 51.1 51.8 53.7

SiO2 38.8 50.1 41.6 41.3 37.6

P2O5 0.25 0.21 0.23 0.35 0.04

SO3 3.59 2.73 2.65 1.87 2.88

Loss on fusion 2.9 2.3 1.82 2.5 2.62

Total 97.6 97.8 97.4 97.8 96.9

It is illustrated that the ash contents and the contents in Table 4 exhibit relatively large variations over the years. However, the weight fractions of major elements with respect to fluid coke, which are calculated from the ash contents, oxide contents in ash, and the elemental fractions in their corresponding , remain relatively constant. Therefore, the vanadium content present in the OFSC produced from 1979 to 1995 is 0.135 wt%± 0.004 wt% (1998).

There have been numerous studies attempting to identify the form of vanadium present in crude oil and petroleum (Zhao et al., 2013). To quantify vanadium in crude oil and its derivatives, several researchers have used solvent precipitation and extraction schemes to enrich vanadium compounds in a single fraction. As mentioned previously, much of the vanadyl porphyrins in crude oil are concentrated in asphaltene fraction. Asphaltenes can adopt a colloidal character in solution, the tendency to aggregate and precipitate in n-alkane solvents (primarily n- pentane or n-heptane) (Dechaine & Gray, 2010). This partitioning of vanadyl compounds in the asphaltene fraction could be attributed to their low solubility (in the order of 10-5 M) in most

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solvents (Freeman et al., 1990), as shown in Figure 5 below. Chlorinated solvents (e.g., chloroform and dichloromethane) showed the highest solubility, while all other solvents showed very little solvent power for the vanadyl porphyrins. Several studies have examined the efficacy of chemical extraction methods for vanadyl porphyrins within asphaltene samples. As observed with the solvent-based extraction methods, these methods are not likely to completely (the highest recovery was 57% of the free porphyrins initially present) extract all of the metalloporphyrins present in petroleum samples (Yin et al., 2009). This chemical limitation is further compounded by the fact that asphaltenes form aggregated colloidal structures in most organic solvents, which could further deter the extraction of the metalloporphyrins from the asphaltene phase.

Figure 5 Solubility of Vanadyl Porphyrins at 23±2 °C as A Function of Solubility Parameter of Solvent (Freeman et al., 1990)

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2.3. CHEMICAL ACTIVATION ON FLUID COKE

Activated carbon is often produced using an activation process from carbonaceous materials such as biomass (e.g. wood, nutshells, and peat) and petroleum pitch (e.g. coal and coke). There are two main types of activation methods: chemical activation and physical activation. Physical activation is also called thermal activation as it uses steam, carbon dioxide, air, or a mixture of any of these to perform a partial gasification/ oxidation process at a relatively high temperature that is required by chemical activation. Prior to physical activation, an additional process called carbonation is required, in which a thermal process carried out in an inert environment is performed. On the other hand, chemical activation requires assistance of chemicals – activating agents. Common activating agents include zinc chloride (ZnCl2), phosphoric acid (H3PO4), and potassium hydroxide (KOH). With the help of an activating agent, it often requires lower temperatures for a chemical activation achieve an equal and often greater degree of activation. The degree of activation is typically measured by specific surface area (SSA) in m2/g. The SSA of chemically activated carbon can exceed 2000 m2/g, while that of physically activated carbon is typically below 1000 m2/g. Also, chemical activation can be carried out in one step, combining carbonization and oxidation processes. It also results in a higher yield. (Lillo-Ródenas et al., 2003). However, there are some drawbacks associated with chemical activation such as a highly corrosive environment and the need of a washing step that requires a large quantity of water (Teng & Lin, 1998).

Both physical and chemical activations have been conducted on fluid coke previously. A two-step physical activation was carried out using steam on oil-sands fluid coke produced in Alberta (DiPanfilo & Egiebor, 1996). After 6 hours of activation at 850°C and atmospheric pressure, the BET-SSA of activated fluid coke was 318 m2/g with a yield below 50%. The BET surface area of the coke-based activated carbon is substantially smaller than most of commercial activated carbon that have an SSA 800 m2/g. Applying chemical activation on fluid coke using KOH, Zuliani et al. demonstrated that at 850°C and atmospheric pressure for 2 hours, they were able to produce an SSA of 1957 m2/g with a yield of 56%. The weight ratio of KOH to coke was 2.5:1. Hence, chemical activation is more effective to activate oil-sands fluid coke and create a better porous structure (Zuliani et al., 2014).

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Alkali metal hydroxides, particularly KOH, are well known chemical activating agents. The activated carbon produced with alkali metal hydroxides possesses some unique features such as low ash content, high adsorption capacity, and narrow pore size distribution (Lillo-Ródenas et al., 2003).

There are a series of chemical reactions in literature describing chemical activation with alkali metal hydroxides at 600 -900 °C for various precursors similar to fluid coke (petroleum cokes or coals). It was suggested that with KOH at 600 - 700°C, K2CO3 and hydrogen were the main products, whereas only a small portion of CO2 was detected (Otowa et al., 1993) as shown by Equation 4-6.

Equation 4

Equation 5

Equation 6

Once the activation temperature raised to more than 700°C, metallic potassium is produced due to the reduction of K2O by reducing agent (carbon or hydrogen) at high temperature. The reaction mechanism is represented in the equations below:

Equation 7

Equation 8

The author also emphasized that the metallic potassium was in a mobile phase at the higher activation temperatures, which provided an opportunity for metallic potassium to intercalate to the carbon matrix and to create pores. The reaction mechanism was further defined and described in equations below for KOH activation temperature at 600 - 900°C (Yuan et al., 2012). 14

Equation 9

At temperature over 900°C, following reaction was suggested:

Equation 10

This study confirmed that potassium ion was reduced into metallic potassium at high temperature chemical activations and established the feasibility of recovering and reusing KOH in the activation process, as metallic potassium can be readily converted into KOH when reacting with water.

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NaOH is a common alkali metal hydroxide widely used in industry, and it is significantly less expensive than KOH. NaOH-based chemical activation has been studied and compared with KOH-based activation. It was concluded that the activation mechanisms were the same. However, KOH was able to start activation at a lower temperature (400 °C) than NaOH (570°C) (Lillo-Ródenas et al., 2003). It was suggested that metallic sodium can be produced but NaOH- based activation doesn’t induce intercalations that separate and enlarge graphene layers in graphitic carbon (Raymundo-Pin ̃ero et al., 2005).

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CHAPTER 3. MATERIALS AND METHODS

3.1. DETERMINATION OF TOTAL VANADIUM CONTENT IN OIL- SANDS FLUID COKE

Previous studies have shown that there is approximately 0.135% of vanadium present in oil-sands fluid coke. To study the recovery of vanadium from fluid coke, it is essential to accurately determine the total vanadium content and better understand the chemical form of vanadium in raw fluid coke.

The fluid coke used in the experiments was produced by Syncrude Ltd.Canada. Fluid coke with a particle size range between 150 and 212 µm was used throughout the study described in this chapter. Some properties and the typical composition of fluid coke were obtained from previous studies (Cai & Jia, 2010; Furimsky, 1989).

The leaching agents included concentrated hydrochloric acid (HCl), concentrated nitric acid (HNO3), Aqua Regia, and 1M potassium hydroxide (KOH) solution. Solid KOH pellets were purchased from Sigma-Aldrich Canada (Oakville, ON), and KOH content is above 85% as per the manufacturer; the rest is mainly crystalline water. 1 M KOH solution was freshly made prior to each caustic leaching experiments, due to its high reactivity towards carbon dioxide.

Both concentrated HCl and concentrated HNO3 was purchased from Caledon Laboratories Ltd (Halton Hills, ON). Aqua Regia was freshly prepared by slowly mixing one volume of concentrated HNO3 with four volumes of concentrated HCl to meet a molar ratio of 1:3.

Other reagents involved Milli-Q water (Millipore, Etobicoke, ON) and vanadium standard for ICP (Fluka Analytical, Sigma-Aldrich Co. LLC., Oakville, ON). All solutions were prepared using Milli-Q water with a resistivity of 18.2 MΩ.cm at 25 °C. The purity of vanadium standard is 1000 ± 2 mg/L with a 5 vol% HNO3 background. The standard solutions for ICP calibration were prepared by diluting the stock standard with 5% HNO3 into 0 mg/L, 0.5 mg/L, 1 mg/L, 5 mg/L, 10 mg/L, and 20 mg/L.

Qualification of elemental composition of aqueous samples containing vanadium was carried out by ICP-AES housed and maintained by ANALEST in University of Toronto’s 17

Chemistry department. Specifically, vanadium concentrations were determined mostly from the wavelength of 292.464 nm due to its high sensitivity and less interferences with other elements that present in the aqueous sample. In limited cases, two other wavelengths (290.881 and 311.837 nm) were used as references. The operating conditions for ICP-AES are tabulated in Table 5.

Table 5 The ICP-AES Operating Conditions

Parameter

Analytical wavelengths for V (nm) 290.881, 292.464, 311.837

RF Power 1300 W

Plasma gas flow rate 15 µL/min

Auxiliary gas flow rate 0.2 µL/min

Nebulizer gas flow rate 0.8 µL/min

Sample flow rate 1.5 µL/min

View mode Axial

Read Peak area

Reading delay time 45 s

Replicates 3

Gas Argon

18

Trace metal concentrations were determined by dilution using a 5-level calibration curve.

Calibration standards were prepared using 5 vol% HNO3 solution. Along with every batch of tests, two additional check standards with concentrations of 0 and 1 mg/L were included in sample analysis to monitor the instrument’s working condition during ICP analysis. Calibration data and curves are provided in Appendix 1.

3.1.1. Direct Acid Leaching Using Various Acids

The direct leaching process was modified based on the method created by former students in Green Technology Lab. In their procedure, 1 g of fluid coke was leached using 16 mL fresh Aqua Regia at 100 rpm and 50 °C. Due to the large dilution factor for ICP sample preparation, the vanadium concentration was below detection limit. In this study, the solid-liquid ratio was modified to 1 g of fluid coke to 4 mL of Aqua Regia. Upon completion of the leaching process, all leachate was filtered via a 0.45 µm pore size syringe filter and 2.5 mL of the leachate was transferred to a 10-mL volumetric flask and Mill-Q water was added to the mark to make up a 10 mL aqueous solution with an approximate 5 vol% HNO3 background.

A comparison experiment of direct leaching using HNO3 and HCl was also conducted, where the solid to liquid ratio was kept at 1 g of fluid coke to 4 mL of acid.

3.1.2. Direct Caustic Leaching Using 1M KOH Solution

Caustic leaching is a common method used to dissolve vanadium from vanadium bearing solid such as spent catalyst (Chen et al., 2006; Zeng & Yong Cheng, 2009). Since fluid coke contains alumina and silica which are stable in acidic conditions, caustic leaching process was expected to dissolve alumina and silica compounds that might have locked vanadium. Milli-Q water was boiled for 15 min to expel carbon dioxide (CO2) present in the water, then it was used to prepare the 1 M KOH solution. Same solid to liquid ratio was used in direct caustic leaching Same solid to liquid ratio was used in direct caustic leaching.

3.1.3. Dissolution of Ashed OSFC Using Aqua Regia

The OSFC ashing procedure was adapted from the ASTM (D4422-13) ash-forming procedure for petroleum coke. 1.5 g of fluid coke with a particle size of 150-212 µm were dried in an oven at 105 °C overnight and placed in a desiccator. Prior to use, chemical-porcelain 19

crucibles were placed in a muffle furnace at 750 °C for one hour for decontamination. Cleaned crucibles were stored in a desiccator and weighed before use for leaching experiments.

To ash the OSFC, 1 g of dried coke sample was placed in a cleaned crucible, left the sample with the crucible in the muffle furnace at 700 °C for 6 hours. Subsequently, the OSFC ash was transferred into a centrifuge tube that contained 0.8 mL of HNO3 and 3.2 mL of HCl. Dissolution of OSFC ash was performed in triplicate at 50 °C, 150 rpm for 24 and 48 hours. Upon the completion of dissolution, the solution was transferred using a syringe filter (pore size: 0.45 µm) to a 10- mL volumetric flask. The syringe was cleaned with Mill-Q water twice. Finally, make up the mixture of leaching and rinsing solution were made up to a fixed 10 mL then further diluted by a factor of 6 for ICP analysis.

3.1.4. X-Ray Fluorescence (XRF) on Ashed OSFC

To determine the possible variations of vanadium content with particle size of fluid coke, fluid coke samples from three different particle size ranges (53-106, 106-150, 150-212 micron) were ashed and subjected to XRF analysis. XRF was not used directly to fluid coke, due to its low concentration of vanadium. Moreover, a direct analysis of coke needs a carbon-based reference material such as various certified coals (Shlewit & Alibrahim, 2006). On the other hand, XRF has been widely used in identifying and quantifying species in ash samples (Furimsky, 1989).

Approximately 10 g of fluid coke in each particle size range was sampled and further grounded to be less than 38 µm then followed by an ashing process to produce ash for XRF analysis. The ashing procedure followed the same ASTM (D4422-13) method stated in the previous section. Ashing of fluid coke in each size range and subsequent XRF analysis were performed in triplicate.

3.2. VANADIUM RECOVERY USING CHEMICAL ACTIVATION

High-temperature chemical activation is able to develop porous structure in coke. There are many activating agents that are commonly used depending on the precursor, such as KOH,

NaOH, ZnCl and H3PO4. Both the amount and the type of activating agents affect to the yield and SSA of activated coke products. For the same activating agent, a higher activating agent to 20

coke ratio results in a lower activated coke yield and normally a greater SSA (Otowa et al., 1997; Sudaryanto et al., 2006). Although the technical feasibility of chemical activation of petroleum coke has been established in the Green Technology Lab at the University of Toronto, the fate of vanadium in the coke during chemical activation has not been studied. Understanding the change of chemical states of vanadium during chemical activation is essential to the recovery of vanadium. In this chapter, the fate of vanadium during chemical activation as well as subsequent water washing stage is studied. Following a procedure developed at the Green Technology Lab, chemical activation was carried out with KOH or NaOH at a hydroxide-to-carbon molar ratio of 0.5. Other details of chemical activation and subsequent water-washing procedures can be found in the work of Zuliani et al. (2014).

Majority of the materials involved in this section was used in the previous section. Table 6 includes their properties and suppliers.

Table 6 Chemicals Involved in Chemical Activation Process

The State of Chemicals at Room Material Purity Supplier Temperature

Potassium Hydroxide Pellet ≥85% Sigma-Aldrich Canada

Solid Sodium Hydroxide Pellet ≥97% Caledon Laboratories Ltd

Fluid Coke (150-212 µm) N/A Syncrude

Hydrochloric Acid 36.5%-38% Caledon Laboratories Ltd

Liquid Methanol 99.8% Sigma-Aldrich Canada

Milli-Q Water 18.2 MΩ•cm Millipore

21

Gas N2 99.99% Peaks Scientific

3.2.1. Chemical Activation of OSFC

The experimental apparatus consisted of a stainless steel tube reactor (48 mm ID, 50 mm OD× 200 mm Length) which was placed in a vertical tubular furnace, a gas supply system which consisted of a mass flow rate controller attached to a nitrogen gas cylinder and a programmable temperature controller. The flue gas created from the activation process first passes through a condenser after exiting the reaction system, then entered a CO scrubber, and finally entered a

CO2 scrubber. The detailed set-up is shown in Figure 6.

Figure 6 Apparatus for Chemical Activation Process

Prior to the chemical activation process, the activating agent and fluid coke were thoroughly mixed along with an addition of 0.2 mL of methanol and 5 mL of Mill-Q water for 19.5 hours in the holder. To keep a hydroxide-to-carbon molar ratio of 0.5, the amount of KOH was 57.5 g and 36.5 g of NaOH for 25.0 g of fluid coke.

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After soaking was completed, the holder was placed at the centre of the tubular furnace. The system was purged with nitrogen to remove the air in it. The flow rate of nitrogen was 350 mL/min during the activation process. Before an activation started, the system was purged with nitrogen for 20 minutes. The temperature was raised to the pre-set level at the melting point of the activating agent. The temperature ramping rate was 5 ˚C/min. Once the temperature reached the pre-set melting point, the temperature was held for 2 hours in order to allow metal hydroxide to dehydrate, which stopped coke from being directly attacked by the steam from metal hydroxide and allowed a fully penetration of coke by molten metal hydroxide (Otowa et al., 1997). After holding for two hours, the temperature was raised again to reach 850 ˚C activation temperature with the same ramping rate and held for 2 hours for the activation process to complete. Within the activation, the system was protected by nitrogen purging. Upon the completion of activation, the reactor was allowed to cool down, and the product was removed from the furnace. The solid product was transferred to a beaker and the washing step proceeded.

3.2.2. Washing Process of Activation Product

The washing processes for KOH and NaOH chemical activated products were identical. The washing consisted of two parts: the first part is water washing as only Milli-Q water was introduced into the washing system. During water washing, the solid product in the beaker was washed with 800 mL Milli-Q water with agitation for 2 hours, followed by a vacuum filtration to separate solid and liquid phases. Eight 2-hour washings were done after the first one to reduce alkalinity, and 600 mL of fresh Milli-Q water was used each time.

The last water washing lasted for 14 hours (overnight) to ensure a maximum dissolution of vanadium into the washing solution. After combing all the aqueous samples in the first washing part, the aqueous body was concentrated using a hot plate into approximately 4 L. In the second part of the washing process, 400 mL of 20 vol% hydrochloric acid (HCl) solution was added, and the mixture was agitated overnight to ensure the complete consumption of the alkaline species present in the solution and all possible oxides on activated coke. After overnight acid washing, vacuum filtration was used, and 800 ml of Milli-Q water was added and mixed for 2 hours. The procedure was repeated two more times to bring the pH value back to neutral. After the final filtration, the solid product was collected from the filter paper and dried overnight in an

23

oven at 110 ˚C. After combing all the aqueous samples in the acidic washing part, the aqueous body was concentrated using a hot plate into approximately 2 L. The steps in the washing process are shown in Figure 7 below. The purpose of adding acidic washing steps was to dissolve oxides that can possibly prevent vanadium from leaching into the aqueous phase.

While the duration of acidic washing was kept constant, the duration of each washing stage in the water washing was then extended for 1 and 2 more hours to study the distribution of vanadium among different activation products. The three water washing processes made the total washing time to be 52 hours, 61 hours, and 70 hours.

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Figure 7 The Washing Process of Activated Product for the 50Hours Washing

3.3. VANADIUM SEPARATION AND STREAM PURIFICATION

In this section, solvent extraction process was used for concentrating and purifying the vanadium-containing stream obtained from Section 3.2. Sequential washing process was used as 25

an alternative washing process with less water consumption to achieve the goal of concentrating vanadium in washing streams.

Many studies had used an organic solvent to extract vanadium from various sources. Depending on the working conditions, different solvents could be applied at various pH levels. Quaternary ammonium salts are commonly used for extracting vanadium from a basic condition. Due to the high alkalinity of the vanadium-rich stream obtained from the water washing step after chemical activation, a commercialized organic solvent, Aliquat® 336, which is a mixture of C8 and C10 long-chain quaternary ammonium salts (Trioctylmethylammonium chloride and Tridecylmethylammonium chloride), was selected to concentrate vanadium under an alkaline condition (pH=13). The information of materials involved in this chapter is tabulated and shown in Table 7.

Table 7 The Information of Materials Involved in Section 3.3

The State of Chemicals at Room Material Purity Supplier Temperature

Potassium Hydroxide Pellet ≥85% Sigma-Aldrich Canada

Solid Silver Nitrate ≥99% Sigma-Aldrich Canada

Potassium Orthovanadate 99.9% metals basis Alfa Aesar

Aliquat® 336 75% Sigma-Aldrich Canada

Kerosene 99.8% VWR Canada Liquid

70%, ≥99.99% Nitric Acid Sigma-Aldrich Canada trace metal basis

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1-Octanol 98% VWR Canada

Milli-Q Water 18.2 MΩ•cm Millipore

In El-Nadi, Awwad and Nayi’s study, the author also stated the importance of performing pretreatment using 1 M KOH solution. Also, some of the experimental parameters such as mixing time were not examined by experiments. Potassium orthovanadate salt was purchased to perform a primary research.

3.3.1. Solvent Extraction

According to the study conducted by El-Nadi, Awwad, and Nayi for extracting vanadium aqueous lechant obtained from spent catalyst, due to the high viscosity of Aliquat® 336, kerosene and 1-octanol were added to obtain a 0.5 M Aliquat® 336 solvent with 10 vol% of 1- octanol was used as phase modifier (2009). The composition of a 500 mL designated solvent is listed in Table 8 and its calculation is present in Appendix 5.

Table 8 Chemical Composition of 0.5 M Aliquat® 336 Solvent (500 mL)

Chemical Species Volume (mL) Volume Fraction

Aliquat® 336 280 56%

Kerosene 170 34%

1-Octanol 50 10%

Another key point mentioned by El-Nadi, Awwad, and Nayi indicated that the chloride ions present in the organic solvent would reduce the effectiveness of the solvent during extraction. The author suggested a pretreatment process prior to extraction performed with an alkaline solution. In the pretreatment, an equal volume of freshly prepared 1 M KOH was mixed with the solvent and shaken for five minutes. The pretreatment was repeated several times “till

27

free of chloride ions” (2009). In this case, alkaline pretreatment was carried out 7 times. Then, solvents with and without pretreatment were used to identify the effect of chloride ion on vanadium extraction. The chloride ion concentration in the pretreatment raffinate was determined by 0.1 M silver nitrate titration addressed by ASTM method (D512-12).

Solvent extraction was carried out using separation funnels; the total fluid volume was ensured to be less than 2/3 of the total volume of the separation funnel. The solvent extraction procedure was also modified from El-Nadi’s article. As the author stated, 15 minutes of mixing time were sufficient. The mixing time was confirmed using synthetic feed solution of 1.1×10-2 M

K3VO4 with 0.1 M NaOH for one extraction stage with 10, 15, and 30 minutes which is shown in Appendix 5.

As the author presented, the partition coefficient for extracting vanadium in an alkaline medium is around 5.25 (the calculation of partition coefficient is in Appendix 6). Therefore, after one extraction stage with an organic to aqueous ratio of 2, more than 98% of the total vanadium in feed solution was extracted into the organic phase. The 50-hour water washing solution from Section 3.2.2. was used to study the effect associated with the chloride ion on the separation of vanadium (detailed results are shown in Appendix 6). Due to the low concentration of non- hydroxide anions in the real washing solution, 0.5 M Aliquat® 336 solvent was capable of providing more than enough positive ion sites at a 1 to 1 organic to aqueous volume ratio for a complete extraction of vanadium anions. Therefore, the increase of organic to aqueous volume ratio of 1 to 4 was studied. The samples of the raffinate obtained from solvent extraction with different parameters were acidified into 5 vol% HNO3 solutions for ICP-AES analysis. Due to the reaction of metallic alkali metal with water, alkali metal hydroxide was formed in the washing process. The pH value of the real washing solution was about 13, which mimics the ideal alkaline condition concluded by El-Nadi and et al for the extraction (0.1 M NaOH solution background). However, under the high alkalinity, other elements from fluid coke that were leached along with vanadium are likely to participate in the solvent extraction as well. Therefore, when preparing samples for ICP analysis, trace metal basis HNO3 was used to prevent the introduction of contaminants.

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3.3.2. Sequential Washing Using Water

Optimization of the water usage in the washing process mentioned in section 3.2.2. was another method used to concentrate the vanadium-containing stream. To achieve the maximal vanadium leaching with the use of minimal amount of water, a twelve-stage sequential washing with each stage lasting for 4 hours was conducted to ensure washing duration was identical to the procedure presented in section 3.2.2. The washing was also carried out by another twelve stages of 1-hour washing to determine the limiting parameter of the direct leaching. In each washing stage, 400 mL fresh Milli-Q water was added to the activation product. Upon a completion of one stage of washing, the solid portion was collected by vacuum filtration. The 400 mL washing solution was transferred to a 500-mL volumetric flask. The container was then rinsed with approximately 20 mL Milli-Q water for three times. The rinsing solutions were transferred to the same volumetric flask. Followed by adding Milli-Q water to reach the mark of 500 mL and stored for ICP sample preparation. The soild was then put into fresh 400-mL Milli-Q for the next stage washing. The sequential washing was carried out at room temperature and atmospheric pressure with a magnetic stirring bar stirring at 350 rpm. Sequential washings with different washing durations were performed on the activation products obtained by a 0.5 sodium hydroxide-to-carbon molar ratio.

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CHAPTER 4. RESULTS AND DISCUSSIONS

4.1. DETERMINATION OF TOTAL VANADIUM CONTENT IN OIL-SANDS FLUID COKE

4.1.1. Direct Leaching of Raw Fluid Coke

The direct leaching results on 150-212 µm oil-sands fluid coke using various leaching agents are shown in Figure 8.

Figure 8 Comparison of Leaching Effect of Various Agents over 48 hours

Figure 8 shows the extracted amount of vanadium with three acids and one base. The percentage vanadium extracted was calculated based on the assumption that total vanadium content in the coke was 0.135 wt%. Among all the leaching agents, Aqua Regia was the most effective in dissolving vanadium in fluid coke. However, only 0.0081 wt% of vanadium (6% of

Vtotal) was extracted even with Aqua Regia. Overall, this limited dissolution is consistent with the existing knowledge that vanadium in coke is predominantly in the form of vanadyl porphyrins which is a complex of vanadyl ion (VO2+) and porphyrins. In porphyrins, organic vanadium is locked in carbon structure and unlikely to be extractable by inorganic acids.

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The vanadium content extracted using 1 M KOH was 0.0005 wt% (0.4% of Vtotal). The result suggests that among the inorganic fraction of vanadium, 0.0005wt% (6% of inorganic vanadium) is associated with Si and Al. Crystals consisting of V, S, Si and Fe were discovered in fluid coke recently (Zuliani et al, 2016). Even though there were significant amounts of Si and Al in fluid coke, they were not the reason behind the limited dissolution of vanadium in inorganic acid. It is interesting that both HCl and HNO3 alone were able to dissolved about 2% of vanadium in the coke, suggesting the possibility of multiple oxidation states of inorganic vanadium. Aqua Regia has the highest oxidation power and dissolved the greatest amount of vanadium. In summary, vanadium in OSFC was mainly in organic forms that were not extractable with Aqua Regia. The fraction of inorganic vanadium that was exacted via Aqua Regia is about 6% of the total vanadium. Less than 10% of inorganic fraction was associated with Si and Al.

4.1.2. Acid Dissolution of Ashed OSFC Using Aqua Regia

This set of experiments was carried out to determine the total vanadium content in fluid coke. The results for Aqua Regia dissolution of ashed oil-sands fluid coke with different solid to liquid ratios and durations are plotted in Figure 9; the error bars represent one standard deviation.

Effect of Leching Time and Solid

0.160 Liquid Ratio 0.140 0.131 0.120 0.121 0.126 0.120 0.100 2ml-24hr 0.080 4ml-24hr 0.060 2ml-48hr 0.040 4ml-48hr

0.020 Vanadium Content[wt%] 0.000 150-212 µm

Figure 9 Aqua Regia Dissolution of Vanadium in Ashed OSFC with Different Solid-Liquid Ratios and Durations

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The highest amount of vanadium was found with 4ml of Aqua Regia after 48 hours - 0.131 wt%. Even after 48 hours with 4 ml of Aqua Regia, there was still some un-dissolved ash, most likely silicon compounds. It is possible that some vanadium was trapped in the residual. Therefore, it is concluded that fluid coke contained at least 0.13 wt% of vanadium. Given the uncertainties indicated by error bars, the effects of solid/liquid ratio and duration seemed insignificant, which was further confirmed by a T-test on 2ml-48h and 4ml-48h experiments.

4.1.3. XRF Analysis on Ashed OSFC

XRF analysis was carried out to determine the distribution of vanadium in coke particles of different sizes. To do so, the ash content was determined following ASTM standard (D4422- 13). As shown in Table 9, the finest particles (53-106 µm) contained slightly more ash, while the ash content of coke particles between (106 – 150 µm) and (150 - 212 µm) was insignificant.

Table 9 Ash Content of Fluid Coke Particles of Different Particle Sizes

Ash Content Particle Size Range (µm)

53-106 106-150 150-212

Avg. 3.975% 3.870% 3.850%

Std. 0.028% 0.022% 0.006%

R.Std. 0.704% 0.568% 0.156%

Figure 10 gives vanadium contents of fluid coke particles of different sizes. The vanadium content values were calculated based on ash contents shown in Table 9 and ash vanadium content obtained using XRF (Appendix 2).

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Figure 10 Vanadium Contents of Fluid Coke Particles of Different Sizes

As shown in Figure 10, there seems an increasing trend in vanadium content with coke particle size. T-test confirmed that the difference in vanadium content between 53-106 µm and 150-212 µm was statistically significant. It was noted that vanadium content values obtained using XRF (~ 0.17 wt%) were significantly greater than those determined using ICP-AES (at least 0.13 wt%). The discrepancy can be explained with the differences between two instruments. XRF is a surface technique; any uneven distribution of vanadium in ash particle would result in systematic bias. Most of the vanadium in coke is in organic form as porphyrins. During ashing when carbon is removed by combustion, vanadium in porphyrins would likely condense or nucleate on the surface of inorganic mineral particles. Consequently, surface vanadium concentration would be higher than that of the bulk. This theory is consistent with the observation that the finest particles had the greatest ash content and the lowest vanadium content obtained with XRF. More work is needed to verify this theory. It has been reported that nucleation, particles growth, coagulation and agglomeration could cause element enrichment on solid sample surface (Lind, 1999).

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4.2. VANADIUM RECOVERY USING CHEMICAL ACTIVATION

4.2.1. Activation Yield and Characteristics of Activated Coke

As shown in Table 10, yields of KOH and NaOH activation were similar. The average yield of three KOH activations was 59%, whereas the average yield of three NaOH activations was 61%.

Table 10 Yield of Chemical Activation and Ash Content of Activated Coke after Washing with Water

Activating Batch Yield Avg. Yield R.S.D. Ash Content Avg. Ash RSD Agent Number (%) (%) (%) (%) Content (%) (%)

1st 61 59 2.1 0.60 0.60 20.60

KOH 2nd 59 0.73

3rd 58 0.46

st 1 61 61 0.0 2.12 1.74 18.48

nd NaOH 2 61 1.85

rd 3 61 1.26

The specific surface area and pore size distribution of both KOH-activated and NaOH- activated coke were determined and shown in Figure 11 and Figure 12. The pore size distribution results (Figure 11) show that KOH-activated coke had more micropores than NaOH-activated coke, suggesting a stronger intercalation effect of K. Consequently, despite of the similar yield, the SSA of KOH-activated fluid coke (1610 m²/g) was much greater than that of NaOH-activated

34

fluid coke (890 m²/g), which is consistent with the work conducted by Linares-Solano and Lillo- Ródenas (2005).

Figure 11 Pore Size Distribution of KOH- and NaOH Activated Coke

Figure 12 Cumulative Specific Surface Area of KOH and NaOH Activated Coke

Ash contents of activated coke after washing were determined. More ash was found with NaOH-activated coke (1.74 wt%) than KOH-activated coke (0.60 wt%), substantially lower than 35

that in the raw coke (~ 6 wt%). The low ash content in KOH-activated, water-washed coke may be due to a greater solubility of potassium compounds in water or a deeper penetration of K that could result in a more complete reaction with inorganic components in the raw coke.

4.2.2. Fate of Vanadium During Chemical Activation and Subsequent Washing

OSFC was activated with KOH or NaOH and subsequently washed with Milli-Q water for 32 to 50 hours and 20 vol% diluted HCl for 20 hours afterwards. After chemical activation followed by water and acid washing, vanadium in coke was distributed among the four categories: 1. washed activated coke, 2. fine particles collected in washing solution, 3. water- washing solution: water-washable, 4. acid-washing solution: acid-extractable. The sum of parts 2 to 4 was termed “extractable vanadium content”. The sum of parts 1 to 4 is the total vanadium recovered. The total V content (in wt%) was the total recovered vanadium amount divided by the amount of raw coke (25 g). To determine V in washed activated coke and insoluble fines, the washed activated coke samples were ashed, and then the ash was dissolved in Aqua Regia. All the aqueous solutions were analyzed using ICP-AES. Table 11 and Table 12 summarizes the amount of vanadium recovered under different activation and washing conditions.

Table 11 Fate of Vanadium after Chemical Activation and during Water and Diluted HCl Washing (based on 25 g of Dried OSFC)

(1) (2) (3) (4)

V in V in V in Total Duration V in Insoluble Total Water- Acid- Recovered Activating of Water Washed Fines in Extractable Recove Washing Washing Vanadium Agent Washing Activated Washing V(g) red Solution Solution Content (hr) Coke (g) Solution V(g) (g) (g) (wt%) (g)

32 0.018 0.0022 0.0062 0.0041 0.013 0.031 0.12 NaOH 41 0.0084 0.00042 0.027 0.0011 0.029 0.037 0.15 50 0.00061 5.1E-05 0.036 0.000 0.036 0.037 0.15 32 0.0025 0.00013 0.011 0.023 0.034 0.037 0.15 KOH 41 0.00023 0.00016 0.022 0.015 0.037 0.037 0.15 50 5.0E-05 4.1E-05 0.036 0.000 0.036 0.036 0.14

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Table 12 Vanadium Distribution in Each Activated Product Category in a Percentage Basis

(1) (2) (3) (4) (2)+ (3)+ (4)

V in V in Duration V in Insoluble V in Water- Acid- Activating of Water Washed Fines in Extractable Washing Washing Agent Washing Activated Washing V (%) Solution (%) Solution (hr) Coke (%) Solution (%) (%)

32 59.0 7.2 20.3 13.4 41.0

NaOH 41 22.8 1.1 73.1 3.0 77.2

50 1.7 0.1 98.2 0.0 98.3

32 6.8 0.4 30.0 62.8 93.2

KOH 41 0.6 0.4 58.8 40.1 99.4

50 0.1 0.1 99.7 0.0 99.9

Data in Table 11 is presented as percentages in Table 12. The data above shows that chemical activation was able to convert organic vanadium into water dissoluble inorganic species –likely as alkali metal vanadate. At a 0.5 hydroxide-to-carbon molar ratio, NaOH and KOH were equally capable of converting organic vanadium into inorganic vanadium. Total vanadium extracted from OSFC was up to 0.15 wt% of OSFC. As indicated earlier, OSFC contains at least 0.13 wt% of vanadium. It is concluded that OSFC contains 0.15 wt% of vanadium. After chemical activation, water washing alone was able to extract over 98% of vanadium in OSFC. However, water washing was a slow process; 50 hours were needed to completely (>98%) dissolve vanadium.

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4.3. VANADIUM SEPARATION AND STREAM PURIFICATION

4.3.1. Solvent Extraction with Aliquat® 336

Effectiveness of the solvent is adversely affected by its chloride content. To lower the chloride content, the solvent was pretreated with 1 M KOH up to 7 times. The raffinates produced within the 7 pretreatments were titrated with 0.1 M silver nitrate (AgNO3) solution. Chloride content in the solvent was determined from the cumulative amount of chloride ion in the aqueous raffinate. The dependence of chloride removal on the number of pretreatment stages was plotted in Figure 13.

Figure 13 Dependence of Chloride Removal from Raffinate on Number of Pretreatment Stages

As shown in Figure 13, the cumulative amount of chloride removed increased with the number of stages increased. After pretreating the solvent for 7 times, over 77% of total chloride was removed from the 500 mL solvent, resulting a 0.115 M of chloride left in the solvent. Effect of chloride content on solvent extraction efficiency was studied.

Solvent extractions were performed on the 50-hour water washing solution with pretreated and raw solvents. The A/O volume ratio varied from 1 to 4. The result tabulated in

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Table 13 showed that the solvent was effective in extracting vanadate from the aqueous solution (> 90%), and less Cl- did enhance the extraction efficiency on vanadium. However, comparing the pretreated solvent with the raw solvent, the improvement in vanadium extraction efficiency of the pretreated solvent was rather limited, from 91% to 95%. It should be noted that lower chloride content in the solvent is desirable in order to minimize the amount of chloride that enters the aqueous solution during solvent extraction. As the aqueous solution after solvent extraction needs to be recycled and reused for subsequent activation.

Table 13 Vanadium Concentrations in the Aqueous Phase upon Completion of Solvent Extraction with Pretreated and Non-pretreated Sovlents (0.5M, A/O=1) V Concentration Extraction Efficiency Samples (ppm) (%) Combined Water Washing Solution 0.58 - After Extraction with Pretreated Solvent (7 0.03 95 times) After extraction with Non-treated Solvent 0.05 91

Effects of solvent strength and A/O on the extraction efficiency were also studied. Solvents used were 0.5 M Aliqua®t 336 in kerosene and 0.1 M Aliquat® 336 in kerosene. Both included 10 vol% of 1-octanol and were pretreated with 1 M KOH for 7 stages. A/O volume ratio was changed from 1 to 4. The results are shown in Table 14 and Table 15 below. As expected, vanadium extraction efficiency decreased with the increase of A/O ratio, regardless of solvent strength. And 0.5 M Aliquat® 336 was more effective than 0.1 M Aliquat® 336. Interestingly, both Fe and Ni species had a greater affinity towards the organic solvent. Anions such as vanadate and ferrate in the aqueous solution exchange with OH- in the organic solvent. With 0.5 M Aliquat® 336 and an A/O of 1, over 90% of V, Fe and Ni was extracted into the organic solvent. Solvent extraction with 0.1M Aliquat® 336 and an A/O ratio of 4 would retain the bulk amount of V (94%) in the aqueous phase with 100% of Fe and 100% of Ni extracted in the organic phase, thereby completely separating V from Fe and Ni.

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Table 14 Concentration and Extraction Efficiency of 0.5 M Aliquat® 336 in Kerosene with Different A/O Ratios

Concentration (ppm) Extraction Efficiency (%) Samples V Al Ca Fe Ni Si V Al Ca Fe Ni Si Combined Water Washing 0.58 1.21 0.09 3.85 0.13 3.32 ------Solution 0.5M, A/O=1 0.03 0.78 0.06 0.00 0.00 0.72 94 36 25 100 100 78 0.5M, A/O=2 0.13 0.88 0.04 0.00 0.00 1.12 77 27 50 100 100 66 0.5M, A/O=3 0.23 0.88 0.08 0.00 0.00 1.19 59 28 2 100 100 64

0.5M, A/O=4 0.30 0.89 0.05 0.00 0.00 1.25 48 26 38 100 100 62

Table 15 Concentration and Extraction Efficiency of 0.1 M Aliquat® 336 in Kerosene with Different A/O Ratios

Concentration (ppm) Extraction Efficiency (%) Samples V Al Ca Fe Ni Si V Al Ca Fe Ni Si Combined Water Washing 0.58 1.21 0.09 3.85 0.13 3.32 ------Solution 0.1M, A/O=1 0.41 1.05 0.03 0.00 0.00 1.30 29 13 64 100 100 61 0.1M, A/O=2 0.48 0.99 0.07 0.01 0.00 1.30 17 18 24 100 100 61 0.1M, A/O=3 0.53 1.08 0.08 0.02 0.00 1.38 8 11 7 100 100 58 0.1M, A/O=4 0.55 1.07 0.06 0.00 0.00 1.45 6 11 29 100 100 56

4.3.2. Sequential Washing Using Water

12-stage sequential water washing of activated OSFC was carried out with two different durations per stage (4 hours and 1 hour). The purpose of this study was to determine the feasibility of increasing vanadium concentration and reducing water usage. Vanadium concentrations in washing water and recovery percentages were tabulated in Table 16 and Table 17, respectively. In the tables, BDL means “below detection limit”. The recovery percentage was calculated based on 0.15 wt% vanadium in OSFC which is equivalent to 37.5 mg of vanadium in 25 g of OSFC. The amount of water used in each washing stage was 16 mL per gram of OSFC.

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Table 16 Vanadium Concentration and Recovery Percentage in 4-hour per Stage Sample Concentration Mass in each stage Recovery (ppm) (mg) percentage (%) Stage 1 25.29 12.65 38.9 Stage 2 38.41 19.20 59.1 Stage 3 1.00 0.50 1.5 Stage 4 0.15 0.08 0.2 Stage 5 BDL BDL BDL Stage 6 BDL BDL BDL Stage 7 BDL BDL BDL Stage 8 BDL BDL BDL Stage 9 BDL BDL BDL Stage 10 BDL BDL BDL Stage 11 BDL BDL BDL Stage 12 BDL BDL BDL Total 32.43 99.8

Table 17 Vanadium Concentration and Recovery Percentage in 1-hour per Stage Sample Concentration Mass in each Recovery (ppm) stage (mg) Percentage (%) Stage 1 9.70 4.95 13.2 Stage 2 58.09 29.64 79.0 Stage 3 1.13 0.58 1.5 Stage 4 0.21 0.11 0.3 Stage 5 0.12 0.06 0.2 Stage 6 BDL BDL BDL Stage 7 BDL BDL BDL Stage 8 BDL BDL BDL Stage 9 BDL BDL BDL Stage 10 BDL BDL BDL Stage 11 BDL BDL BDL Stage 12 BDL BDL BDL Total 35.33 94.2

The results showed that with 4 stages of 4-hour water washing, over 99 % of total vanadium was extracted into the aqueous phase. When the washing duration was shortened to 1 hour, the first 5 stages was able to extract over 94 % of vanadium from activated OSFC. In both cases, most vanadium was extracted in the first two stages: 98% for 4-hour per stage and 92% for 1-hour per stage. The total amount of water used in the first two stages was 32 mL per gram of

41

raw fluid coke, whereas the water amount in previous section was 224 mL per gram of raw fluid coke. This suggests that both the washing duration (50 hours) and the water amount (224 mL per gram of OSFC) in previous section were excessive. The results also confirmed that acid washing is not needed for vanadium extraction. When the washing duration per stage was shortened to 1 hour, the first five stages were able to extract over 94 % of the total vanadium from activated OSFC. It is important to note that the first stages extracted less vanadium than the second stages, 38.9% versus 59.1% in the first two 4-hour stages and 13.2% versus 79.0% in the first two 1- hour stages. This unusual observation might be caused by the dissolution of larger quantities of other elements. Table 18 shows compositions of washing solutions and recovery percentage of multiple elements during the first two washing stages (1 hour per stage). The recovery percentage was calculated based on the corrected XRF results (Appendix 4). The results show that the first washing stage extracted more Al, Ca, Fe, Ni and Si than the second stage, unlike V. In the first stage, 96% of Al, 91% of Si, 76% of Ni, 42% of Fe, and 16% of Ca were found in the aqueous solution. It is hypothesized that the lower concentration of vanadium in the first stage washing water is due to the high Ca2+ concentration. Calcium vanadate is rather insoluble in water and has a Ksp = 4.9 × 10−4 at 80 °C (Li, et al., 2010). Using OLI – a thermodynamic software package, it is confirmed that calcium vanadate is the least soluble vanadium compound and would precipitate from the washing solution if enough calcium is introduced into the aqueous phase. Another factor that could limit the dissolution of vanadium in the first washing stage is high concentrations of anionic species of Al, Si, Fe and Ni. The removal of other elements in the first stage may have accelerated vanadium dissolution in the second stage and shortened the overall washing process. More work is needed to verify this hypothesis.

Table 18 Compositions of Washing Solution and Recovery Percentage during First Two Washing Stages (1 Hour per Stage)

1st Stage Element Recovery Mass Corrected Total Amount of Element from XRF Recovery Percentage

(mg) (mg) (%) V 4.95 37.50 13.20 Al 90.02 94.21 95.55 Ca 4.52 28.88 15.65 Fe 23.62 56.76 41.61

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Ni 10.23 13.39 76.40 Si 127.38 140.03 90.97

2nd Stage Element Recovery Mass Corrected Total Amount of Element from XRF Recovery Percentage

(mg) (mg) (%) V 29.64 37.50 79.04 Al BDL 94.21 0.00 Ca 1.53 28.88 5.30 Fe 8.37 56.76 14.75 Ni 0.67 13.39 5.00 Si 2.14 140.03 1.53

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CHAPTER 5. PROPOSED PROCESS OF VANADIUM RECOVERY VIA CHEMICAL ACTIVATION ON OSFC

Based on the knowledge described in the previous chapters and the on-going work on vanadium precipitation with Ca(OH)2 which was carried by other members of the Green Technology Lab (Ellen Li, personal communication, Jan 4, 2017), a process of vanadium recovery from OSFC was proposed. As shown in Figure 14, the proposed process consisted of three main steps – 1. chemical activation with KOH or NaOH, 2. sequential water washing, and 3. calcium precipitation of dissolved vanadium.

The condition for chemical activation was described previously. After chemical activation, all vanadium in OSFC became water soluble. Sequential water washing at ambient temperature and atmospheric pressure would be able extract all vanadium into aqueous solution. Over 92 % of vanadium exists in aqueous solution from first two stages of water washing. Additional stages (the third and subsequent) might be required to further lower the impurity in the activated OSFC. The aqueous solution from the third and subsequent stages could be recycled for the subsequent first two stages.

In calcium precipitation step, Ca(OH)2 slurry was added into the aqueous solution from first two stages of water washing. Upon the addition of Ca(OH)2, anionic vanadate combined with cationic calcium to form calcium vanadate precipitates. Sufficient addition of Ca(OH)2 would allow precipitation of other anionic species of Ni, Fe, Al and Si (Ellen Li, personal communication, Jan 4, 2017). Calcium ion addition also precipitated out carbonate and sulphate in water washing solution. Consequently, KOH or NaOH was regenerated and reused for chemical activation of OSFC.

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Figure 14 Proposed Process of Vanadium Recovery from OSFC via Chemical Activation, Sequential Water Washing and Calcium Precipitation

More work is clearly needed to determine the process conditions for vanadium separation from the solid mixture of various calcium salts such as carbonate and sulfate. Calcium carbonate, once purified, can be thermally converted into calcium oxide – a precursor of Ca(OH)2.

With the current production of oil-sands fluid coke (7.3 M ton per year), vanadium from oil-sand fluid coke can be produced in 10 K ton annually, which is equivalent to an annual 0.7 M USD value-added byproduct in bitumen refinery.

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CHAPTER 6. CONCLUSIONS AND FUTURE RESEARCH

Conclusions drawn from this study are listed below:

1. Oil sands fluid coke (OSFC) studied contained 0.15 wt% of vanadium is predominantly in the form of organic vanadyl porphyrins. Aqua Regia extractable, inorganic fraction of vanadium is about 6% of the total vanadium amount. Less than 10% of the inorganic fraction is likely associated with Si and Al.

2. During chemical activation, NaOH and KOH are equally capable of converting un-leachable organic vanadium into water-dissoluble inorganic species-likely alkali metal vanadate. After chemical activation, water washing alone is able to dissolve over 98% of vanadium in OSFC.

3. Sequential washing is able to shorten the duration of washing process and reduce the water usage. First two stages of washing extracted over 92 % of vanadium in activated OSPC. Unlike other elements (Fe, Ni, Al, Si, Ca), vanadium extraction in the first washing stage is less than that in the second stage. This unusual behavior is tentatively attributed to the effective extraction of Ca, Al, Si, Fe and Ni in the first stage. The dissolution of those other elements in the first stage had limited vanadium dissolution in the first stage but enhanced vanadium dissolution in the second stage, hence shortened the overall washing process.

4. Aliquat® 336-based organic solvent is capable of extracting vanadium from aqueous solution. Solvent extraction efficiency increased with the strength of organic solvent and the solvent/aqueous solution ratio. Removal of chloride from Aliquat® 336-based solvent resulted in a small increase in extraction efficiency. Anionic species of Fe and Ni have a greater affinity towards Aliquat® 336-based solvent. Consequently, Fe and Ni can be extracted completely from the aqueous solution prior to the complete extraction of vanadium.

5. It is technically feasible to recover vanadium from OSFC as calcium vanadate via a multi-step process that consists of alkali metal hydroxide chemical activation, sequential water washing and calcium precipitation of vanadium. This process allows the recycle and reuse of KOH or NaOH for chemical activation and produce an activated OSFC product that is highly porous (> 1500 m2/g SSA with KOH and > 850 m2/g SSA with NaOH). 46

Following recommendations are made for future research:

1. The role of solvent extraction in vanadium recovery needs to be better understood by investigating the conditions for vanadium recovery from the spent solvent and for solvent regeneration.

2. More work is needed to better understand the dissolution kinetics of vanadium from activated OSFC as well as the solution chemistry. This information is needed for verifying the hypothesis that the presence of other elements such as Ca hinders vanadium dissolution. This work could be carried out experimentally and using thermodynamic software packages such as OLI.

3. Although an alkali metal hydroxide/carbon molar ratio of 0.5 iss able to result in a complete vanadium recovery, a lower ratio shall be tested. A lower ratio will lead to a lower activating agent usage and a higher yield of activated OSFC.

4. There is a need for better understanding of the formation of calcium vanadate during calcium precipitation, for exploring options of source of calcium ions, and calcium vanadate separation from precipitation products.

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CHAPTER 8. APPENDICES

APPENDIX 1 CALIBRATION CURVES

There were two vanadium-containing ICP standard stock solutions used throughout the study. In Chapter 3 and Chapter 4, a single-element ICP standard solution was used for the generation of the calibration curve. In Chapter 5, a customized multi-element ICP stock solution was used to generate the calibration curves. The information of the calibrations are tabulated below and the calibration curves are plotted as well.

Single-element ICP Standard Vanadium Calibration

Table 19 A Sample of Calibration for Vanadium on ICP-AES

Wavelength (nm) Concentrati Labels on (mg/L) 290.88 309.31 311.837 Blank 0 14563 2099 5015.9 Standard 1 0.5 17445.5 36919 85607.9 Standard 2 1 24587 69036 161000 Standard 3 5 66001 345472 840936 Standard 4 10 117239 654642 1636856 Standard 5 20 214699 1346982 3267696

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Figure 15 A Sample of Calibration for Vanadium on ICP-AES

Multi-element ICP Standard Vanadium Calibration

Table 20 A Sample of Calibration for Vanadium on ICP-AES

Wavelength (nm) Labels Concentration (mg/L) 290.88 309.31 311.837 Blank 0 1940.04 3148.52 13367.8 Standard 1 0.496 32748.1 20449.9 84101.8 Standard 2 0.992 66024.5 29137.6 162145 Standard 3 2.976 194763 60682.9 487340 Standard 4 9.92 646483 149251 1625358

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Figure 16 A Sample of Calibration for Vanadium on ICP-AES

Table 21 A Sample of Calibration for Aluminum on ICP-AES Wavelength (nm) Labels Concentration (mg/L) 308.215 394.401 396.153 Blank 0 1498.05 418.072 478.227 Standard 1 0.497 5488.85 16455.3 38335.7 Standard 2 0.994 11984.2 35799.6 79147.7 Standard 3 2.982 33856.1 102836 222406 Standard 4 9.94 107343 329581 686760

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Figure 17 A Sample of Calibration for Aluminum on ICP-AES

Table 22 A Sample of Calibration for Calcium on ICP-AES Wavelength (nm) Labels Concentration (mg/L) 315.887 317.933 393.366 Blank 0 -12536 4199.42 261791 Standard 1 0.505 35780.1 100706 6005296 Standard 2 1.01 81125.3 223993 1.3E+07 Standard 3 3.03 218185 608515 3.4E+07 Standard 4 10.1 677423 1895595 Sat'd

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Figure 18 A Sample of Calibration for Calcium on ICP-AES

Table 23 A Sample of Calibration for Iron on ICP-AES Wavelength (nm) Labels Concentration (mg/L) 238.204 239.562 259.939 Blank 0 870.437 891.843 1104.49 Standard 1 0.501 39590.9 46972 42462 Standard 2 1.002 79484.1 94314.6 84724.4 Standard 3 3.006 232140 275289 246779 Standard 4 10.02 750863 885466 799435

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Figure 19 A Sample of Calibration for Iron on ICP-AES

Table 24 A Sample of Calibration for Potassium on ICP-AES Wavelength (nm) Labels Concentration (mg/L) 766.49 Blank 0 10099.2 Standard 1 0.501 225920 Standard 2 1.002 608117 Standard 3 3.006 1487620 Standard 4 10.02 5311219

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Figure 20 A Sample of Calibration for Potassium on ICP-AES

Table 25 A Sample of Calibration for Nickel on ICP-AES Wavelength (nm) Labels Concentration (mg/L) 221.648 231.604 232.003 Blank 0 -57.36 -41.151 -434.22 Standard 1 0.4983 14224.2 17313.6 7336.16 Standard 2 0.9966 28603.9 34560.2 14659.4 Standard 3 2.9898 83288.6 99940.4 42900.9 Standard 4 9.966 268490 321870 140129

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Figure 21 A Sample of Calibration for Nickel on ICP-AES

Table 26 A Sample of Calibration for Silicon on ICP-AES Wavelength (nm) Labels Concentration (mg/L) 212.412 251.611 288.158 Blank 0 437.358 265.047 1567.2 Standard 1 0.503 3687.92 11816.7 5495.68 Standard 2 1.006 7072.08 22712.6 10538.6 Standard 3 3.018 19780.6 63364.2 29279.7 Standard 4 10.06 69551.6 223173 103136

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Figure 22 A Sample of Calibration for Silicon on ICP-AES

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Figure 23 Calibration curve for multielement standards on ICP-AES

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APPENDIX 2 XRF RAW DATA

The XRF data is not suitable for calculating the sulfur content as sulfur can react with oxygen involved in the ashing process and escape as a gas phase.

Table 27 XRF Analysis Results for Ashed 53-106 µm Fluid Coke

Mass Fraction (wt%) Particle Sizes Compound Sample 1 Sample 2 Sample 3

53-106 µm SiO2 36.11% 33.47% 37.30%

Al2O3 21.25% 19.65% 21.95%

Fe2O3 9.70% 9.73% 9.78%

V2O5 7.50% 7.53% 7.75%

SO3 6.67% 6.39% 6.58%

CaO 4.84% 4.47% 4.75%

TiO2 4.72% 4.45% 4.72%

NiO 2.09% 1.90% 2.00%

Na2O 1.98% 1.79% 1.98%

K2O 1.76% 1.68% 1.76%

MgO 1.43% 1.34% 1.51%

P2O5 0.48% 0.41% 0.49%

MnO 0.23% 0.22% 0.21%

SrO 0.17% 0.17% 0.19%

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BaO 0.16% 0.17% 0.16%

Table 28 XRF Analysis Results for Ashed 106-150 µm Fluid Coke

Mass Fraction (wt%) Particle Sizes Compound Sample 1 Sample 2 Sample 3

106-150 µm SiO2 36.30% 36.80% 36.70%

Al2O3 21.41% 21.63% 21.61%

Fe2O3 9.92% 9.90% 9.95%

V2O5 7.97% 7.76% 8.00%

SO3 7.01% 7.23% 6.56%

CaO 4.81% 4.73% 4.99%

TiO2 4.69% 4.85% 4.91%

NiO 1.96% 2.03% 2.09%

Na2O 1.92% 1.87% 2.05%

K2O 1.87% 1.82% 1.78%

MgO 1.46% 1.40% 1.48%

P2O5 0.49% 0.48% 0.49%

MnO 0.21% 0.24% 0.22%

SrO 0.19% 0.21% 0.19%

BaO 0.16% 0.19% 0.14%

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Table 29 XRF Analysis Results for Ashed 150-212 µm Fluid Coke

Mass Fraction (wt%) Particle Sizes Compound Sample 1 Sample 2 Sample 3

150-212 µm SiO2 36.02% 35.81% 36.62%

Al2O3 21.42% 21.37% 21.62%

Fe2O3 9.62% 9.71% 10.04%

V2O5 7.94% 7.97% 8.31%

SO3 7.02% 6.43% 6.89%

CaO 4.82% 4.92% 4.87%

TiO2 4.75% 4.82% 4.85%

NiO 2.01% 2.11% 2.05%

Na2O 1.79% 1.97% 2.03%

K2O 1.76% 1.70% 1.78%

MgO 1.43% 1.43% 1.56%

P2O5 0.48% 0.49% 0.47%

MnO 0.24% 0.26% 0.25%

SrO 0.18% 0.19% 0.20%

BaO 0.16% 0.15% 0.19%

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APPENDIX 3 SAMPLE PELLETS OF ASHED OSFC FOR XPF ANALYSIS

Figure 24 Briquetted XRF Samples

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APPENDIX 4 CORRECTED XRF RESULTS

In Chapter 4, the vanadium content present in fluid coke was determined using chemical activation. The content of other elements was estimated using the factor between the vanadium content determined by XRF and the vanadium content determined by chemical activation. A sample calculation is shown below and the corrected contents are tabulated in Table 30.

Table 30 An Estimation of Other Elements Using Vanadium Content to Correct XRF Results

Element Content Averaged Element Modified Element Oxide Content by Weight Content Ash Obtained Vanadium Present in in Ash Content Element by XRF Content 25 g of Raw (%) (%) Fraction (%) (%) Coke (mg)

SiO2 36.15% 3.85% 0.47 0.65% 0.56% 140.03

Al2O3 21.47% 3.85% 0.53 0.44% 0.38% 94.21

Fe2O3 9.79% 3.85% 0.70 0.26% 0.23% 56.76 V O 8.07% 3.85% 0.56 0.17% 0.15% 37.50 150-212 µm 2 5 SO3 6.78% 3.85% 0.40 0.10% 0.09% 22.49 CaO 4.87% 3.85% 0.72 0.13% 0.12% 28.88 NiO 2.06% 3.85% 0.79 0.06% 0.05% 13.39

Na2O 1.93% 3.85% 0.74 0.05% 0.05% 11.85

K2O 1.75% 3.85% 0.83 0.06% 0.05% 12.02

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APPENDIX 6 DETERMINATION OF KOH AND NAOH PELLET PURITY

Prior to chemical activation, the purity of KOH and NaOH pellets were examined by acid-base titration. 0.1 M of HCl solution was used as the source of acid, and phenolphthalein was used as the color indicator in this acid-base titration. The Milli-Q water used to prepare KOH and NaOH solutions were boiled for 15 min to drive off the carbon dioxide present in the water and then put the water into a sealed bottle for cooling down to ambient temperature.

Table 31 Purity of KOH Pellet Titration Results Total Pellet Mass Mass of KOH Calculated from HCl Amount of Percentage of Total (g) Consumption (g) Impurities Impurity (%) (g) 0.0694 0.0560 0.0134 19.36% 0.1080 0.0866 0.0214 19.80% 0.0975 0.0805 0.0170 17.45% 0.0627 0.0506 0.0121 19.24% 0.0398 0.0325 0.0073 18.25% Average 18.82% Standard 0.85% Dev. Pellet 81.18% Purity

Table 32 Purity of NaOH Pellet Titration Results Total Pellet Mass Mass of NaOH Calculated from HCL Amount of Percentage of Total (g) Consumption (g) (g) Impurities Impurity (%) (g) 0.114133 0.1088 0.0053 4.67% 0.063429 0.0599 0.0035 5.56% 0.06039 0.0556 0.0048 7.93% 0.068176 0.0651 0.0031 4.51% 0.053933 0.0497 0.0042 7.85% Average 6.11% Standard 1.50% Dev Pellet 93.89% Purity

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APPENDIX 7 CALCULATION OF SOLVENT PREPARATION

In order to prepare 500 mL 0.5 M Aliquat® 336, the volume of Aliquat® 336 stock needed is:

The volume of 1-octanol is:

The volume of kerosene is:

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APPENDIX 8 DETERMINATION OF PARTITION COEFFICIENT AND MIXING TIME IN SOLVENT EXTRACTION

Methodology

El-Nadi and et al. has used 0.5 M Aliquat® 336 to extract 99% of a relatively high concentration (synthesized by 1g/L V2O5) vanadium from an alkaline aqueous (0.1 M NaOH solution). It is mentioned in their study that 15 min is sufficient for ion exchange between two phases. In order to confirm the mixing time, it was essential to calculate the partition coefficient for the synthetic vanadium-bearing.

Figure 26 is the published results from El-Nadi and et al. The plot demonstrates the correlation between the concentration of vanadium transferred to the organic phase and the concentration of vanadium in the aqueous phase during the solvent extraction using 0.5 M Aliquat® 336 from 0.1 M NaOH solution.

Figure 25 . Relation between the concentration of vanadium transferred to the organic phase to that remained in the aqueous phase through the extraction by 0.5 M Aliquat® 336 70

dissolved in kerosene from 0.1 M NaOH or 3 M HCl media at 25 °C (El-Nadi and et al., 2009)

Based on the information presented, the partition coefficient associated with their system is:

Based on the partition coefficient calculated, the fraction of vanadium (V) present in the organic phase after one extraction with an organic to aqueous ratio of 2 is:

Therefore, one complete extraction can reach the efficiency of 91.3%.

The mixing time was confirmed using synthetic feed solution of 0.638 g/L K3VO4 with 0.1 M NaOH for one extraction. The concentration of vanadium in synthetic feed solution was equivalent to the concentration El-Nadi used in his study with 1g/L V2O5. The synthetic feed stock was prepared by dissolving 0.31506 g of K3VO4 into a 50-mL volumetric flask and then diluted by 10 times, due to the difficulties involved in the precise measuring of the small amount of vanadate salt.

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Results and Discussions

Table 33 shows the result of a parallel experiments that keep the same of Aliquat® 336 molarity, the pretreatment time, and the organic to aqueous ratio. The result of synthetic V(V) After one extraction with mixing time of 10 min, 15 min, and 30 min, the aqueous phases were analyzed by ICP-AES to calculate the extraction efficiency.

Table 33 Determination of the Partition Coefficient of Synthetic System and Mixing Time (0.5 M, A/O=2, Pretreated 7 Times) Concentration of Mass of V Extraction Efficiency Sample ID V(V) (ppm) (mg) (%) Synthetic V(V) Solution 630.10 15.75

10min 2.17 0.054 99.43

15min 2.35 0.059 99.63

30min 2.35 0.059 99.63

Upon the completion of extractions, a quick pH measurement was conducted using pH paper. It was observed that the pH of all raffinate was higher than the synthetic stock solution. In 3- the synthetic solution, V(V) stayed in the form of VO4 as indicated in the Pourbaix diagram of 3- - vanadium. The VO4 ions were exchanged by OH in the organic phase, thereby increasing the concentration of OH- in the aqueous phase upon mixing. Also, it is proved that 15 min of mixing is sufficient for completing the ion exchange between two phases, because the extraction efficiency stayed the same with extending the mixing time, which hindered an equilibrium stage was reached. Moreover, the higher extraction efficiency of one extraction indicated there’s a larger partition coefficient associated with the system.

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APPENDIX 9 OTHER ELEMENT CONCENTRATION IN SEQUENTIAL WASHING

Table 34 Other Element Concentration in Sequential Washing (1hr, 5-stage)

Al Ca Concentratio Mass in each stage Concentration Mass in each stage

n (ppm) (mg) (ppm) (mg) Water Washing_Stage 1 180.03 90.02 9.03 4.52 Water Washing_Stage 2 BDL BDL 1.53 0.77 Water Washing_Stage 3 BDL BDL 1.31 0.66 Water Washing_Stage 4 BDL BDL 1.36 0.68 Water Washing_Stage 5 BDL BDL 1.43 0.72 Total 90.02 7.33 Fe Ni Concentratio Mass in each stage Concentration Mass in each stage

n (ppm) (mg) (ppm) (mg) Water Washing_Stage 1 47.23 23.62 20.47 10.23 Water Washing_Stage 2 16.75 8.37 1.33 0.67 Water Washing_Stage 3 18.63 9.32 0.35 0.18 Water Washing_Stage 4 23.20 11.60 0.23 0.12 Water Washing_Stage 5 8.41 4.20 BDL BDL Total 57.11 11.19 Si Concentratio Mass in each stage

n (ppm) (mg) Water Washing_Stage 1 254.77 127.38 Water Washing_Stage 2 4.28 2.14 Water Washing_Stage 3 0.88 0.44 Water Washing_Stage 4 0.49 0.25 Water Washing_Stage 5 BDL BDL Total 130.21

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APPENDIX 10 OLI SIMULATION ON VANADIUM PRECIPITATION

In order to validate vanadium precipitation with sequential washing solution, the software OLI Electrolyte Simulation (Build 9.3) was deployed to validate the feasibility and to simulate the precipitation reaction. OLI Studio is capable of predicting any water chemistry mixture with temperature -50 to 300 °C, pressure o to 1500 bar, and ionic strength 0-30 molal (OLI Systems, 2016).

In this section, both water analysis and stream were used to build the simulation models based on different assumptions. In water analysis model, species were input in form of ions, which assuming all input were soluble. Under this condition, the concentration obtained from ICP were converted into their corresponding cations and anions at pH=14 according to Pourbaix diagrams associated with each element. However, when considering activation product such as solid carbonate, the assumption was all the activation products were complete dissolved into aqueous phase. This assumption can be validate using the reconcile feature in water analysis. By reconciling the input of species at a given temperature and pressure, the simulation can validate components present in the aqueous phase. The reconciled results can be exported and used as a stream for further analysis such as survey and single point calculation (precipitation point, vapor point, boiling point, etc.).

The amount of carbonate produced within activation was calculated based on the chemical activation reaction (Equation 9). Using the amount of burn-off to estimate the amount of carbonate and metallic alkali metal produced within the activation process. In order to simulate the washing condition at time equals to 0, concentrations of each ICP-detectable element from first two washing stages were added as the input concentration in the simulation. Figure 27 shows the interface of reconciliation with input of concentrations of a post-NaOH activation sequential washing.

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Figure 26 Interface of OLI Studio on Water Analysis and Input of Species and Concentrations (NaOH-Activated OSFC)

As there was neither solid phase of Na2CO3 nor NaOH present in the reconciliation results, it illustrated that the amount of water in a washing stage was sufficient to completely react and dissolve produced metallic alkali metal and carbonate. The reconciled data was exported as a stream and used for a simulation of vanadium precipitation shown in Figure 28 below.

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Figure 27 Simulation Results of Vanadium Precipitation by Addition of Calcium Ion (NaOH-Activated OSFC)

As the result shows, once 0.56 mol/L of calcium ion was introduced, vanadium would start to precipitate as calcium vanadate.

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