DOCSLIB.ORG

Electrowinning of Tellurium by Means of PLS Modelling

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Electrowinning of Tellurium by Means of PLS Modelling 2009:056 MASTER'S THESIS Optimisation of Influential Factors in Electrowinning of Tellurium by Means of PLS Modelling Seyed Mohammad Khosh Khoo Sany Luleå University of Technology Master Thesis, Continuation Courses Minerals and Metallurgical Engineering Department of Chemical Engineering and Geosciences Division of Process Metallurgy 2009:056 - ISSN: 1653-0187 - ISRN: LTU-PB-EX--09/056--SE Optimisation of Influential Factors in Electrowinning of Tellurium by Means of PLS Modelling Master Thesis By: Seyed Mohammad Khoshkhoo Sany [email protected] Supervisors: Prof. Åke Sandström (Luleå University of Technology) Dr. Nils Johan Bolin (Boliden Mineral AB) Abstract Electrowinning of tellurium is a relatively simple process that can be carried out effectively by employing the existing technology. In order to obtain tellurium with the least amount of impurities, the effects of three main factors were studied, namely current density, free concentration of caustic soda and initial concentration of tellurium. Five elements were chosen as the main impurities: Ag, Bi, Cd, Ni and Pb. A series of 17 experiments arranged in a CCF (central composite faced-centred) design has been carried out and the results were fitted using PLS (partial least squares) method. The effect of free caustic concentration was found to be the most important of the three parameters studied. Current density was also important, yielding the least amount of impurities at high current densities. Tellurium concentration had the smallest effect of the three parameters studied. From the model, current densities of 330-350 A/m2, tellurium concentrations of 90-120 g/l and free sodium hydroxide concentration of around 120 g/l are suggested as optimal conditions for obtaining the purest tellurium. Table of Contents Abstract..................................................................................................................... 1 Acknowledgment ...................................................................................................... 3 Aim of the project ..................................................................................................... 4 Chapter 1 – Tellurium ............................................................................................... 5 1.1 Introduction ..................................................................................................... 5 1.2 Geochemistry .................................................................................................. 5 1.3 Resources ........................................................................................................ 6 1.4 Production ....................................................................................................... 6 1.5 Purification...................................................................................................... 9 1.5.1 Vacuum Distillation.................................................................................. 9 1.5.2 Zone Refining........................................................................................... 9 1.6 Applications .................................................................................................. 10 1.7 Economy ....................................................................................................... 10 Chapter 2- Electrowinning........................................................................................12 2.1 Introduction to Electrowinning ...................................................................... 12 2.1.1 Introduction to electrometallurgy ............................................................ 12 2.1.2 Basic Facts.............................................................................................. 12 2.1.3 Faraday Law ........................................................................................... 14 2.1.4 Current Efficiency................................................................................... 14 2.1.5 Electrode Potential and Nernst’s Equation............................................... 14 2.1.6 Cell Voltage and energy consumption..................................................... 15 2.1.7 Metal Deposition..................................................................................... 15 2.2 Electrochemistry of Tellurium ....................................................................... 16 2.2.1 Cathodic Reduction of Tellurite .............................................................. 16 2.3 Electrowinning of Tellurium.......................................................................... 18 Chapter 3 - Experimental Part ..................................................................................21 3.1 Design of Experiments................................................................................... 21 3.1.1 Introduction ............................................................................................ 21 3.1.2 Definition of Factors ............................................................................... 21 3.1.3 Definition of Responses .......................................................................... 22 3.1.3 Design of Model ..................................................................................... 23 3.2 Experiments................................................................................................... 25 3.2.1 Investigating the Effect of Periodic Short-Circuited Current.................... 25 3.2.2 Running the Designed Experiments......................................................... 26 3.3 Analysing ...................................................................................................... 27 Chapter 4- Results and Discussion............................................................................29 4.1 Results........................................................................................................... 29 4.2 Fitting the Model and Evaluation of Fit.......................................................... 31 4.3 Using the Model (Optimisation)..................................................................... 35 4.4 Conclusion..................................................................................................... 40 4.5 Future Work .................................................................................................. 41 References................................................................................................................43 2 Acknowledgment I am grateful to the financial support given by Boliden Mineral AB which enabled me to carry out this project. Also, I wish to thank Prof. Åke Sandström for his guidance throughout my master studies at Luleå University of Technology and for giving me the opportunity to perform this thesis. Dr. Nils-Johan Bolin is greatly acknowledged for his help with the theoretical and experimental parts of the project. I am very thankful to Paul Kruger who always had time to answer my questions. In addition, I appreciate all the assistance I received from Rolf Danielsson, Amang Saleh, Mikael Widman, Mikael Eriksson and Carina Andersson during the laboratory work. Lars Eric Carlsson is sincerely thanked for analysing my samples and teaching me how to play badminton (you have been very patient). Boliden’s musical band, Anders Nyström, Conny Jacobsson, Gösta Pettersson and his lovely wife, Per Ivar Marklund, Mehran Mousavipour, Ulrika Holmgren and Daniel Holmgren, is appreciated for inviting me to their group and for their open mindedness attitude towards my music. There is no enough space to name all other nice friends that I have found in Boliden. They made a nice and joyful stay for me during the time I was working on the thesis. I am grateful to all of you. If it wasn’t for my friend Sepehr, I would have never been able to come so far in my education. He was the one who gave me his invaluable consults helping me finding the right path. A considerable part of my success is because of him. Thank you Sepehr. Above all, I can’t find suitable words to express thanks to my family for all they have done for me. I am indebted to my dad for his never-ending care and support, and to my mum for her unconditional love. My lovely sisters have been emotionally supporting me during all these times. I love you all! 3 Aim of the project Tellurium is a rare metal with a very promising market. Demand for highly pure tellurium to be used in strategic applications is increasing day by day. Boliden AB possesses considerable resources of tellurium both in its gold bearing minerals and in the copper anode slimes. Recovery and purification of this tellurium indeed is a promising business in a near future. This thesis work focuses on a single stage of every tellurium processing line; electrowinning. Electrowinning is an important stage to produce commercial grade tellurium of higher value. Interaction between important factors and their influence on the purity of electrowon tellurium have been investigated in this project. In order to obtain tellurium with a minimum content of impurities, optimum values are suggested by modelling the process, using the partial least square (PLS) method. 4 Chapter 1 – Tellurium 1.1 Introduction Tellurium with atomic number of 52 is one of the rarest elements in the earth crust with an abundancy of only 10 ppb. It was first discovered by a Hungarian mineralogist Franz-Joseph Müller von Reichenstein in 1782. The route of the word comes from Tellus which means earth in Latin.
Load more

Recommended publications
  • Membraneless Electrolyzers for Solar Fuels Production
    Membraneless Electrolyzers for Solar Fuels Production Jonathan T. Davis Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Graduate School of Arts and Sciences Columbia University 2019 © 2019 Jonathan T. Davis All rights reserved ABSTRACT Membraneless electrolyzers for solar fuels production Jonathan “Jack” Davis Solar energy has the potential to meet all of society’s energy demands, but challenges remain in storing it for times when the sun is not shining. Electrolysis is a promising means of energy storage which applies solar-derived electricity to drive the production of chemical fuels. These so-called solar fuels, such as hydrogen gas produced from water electrolysis, can be fed back to the grid for electricity generation or used directly as a fuel in the transportation sector. Solar fuels can be generated by coupling a photovoltaic (PV) cell to an electrolyzer, or by directly converting light to chemical energy using a photoelectrochemical cell (PEC). Presently, both PV- electrolyzers and PECs have prohibitively high capital costs which prevent them from generating hydrogen at competitive prices. This dissertation explores the design of membraneless electrolyzers and PECs in order to simplify their design and decrease their overall capital costs. A membraneless water electrolyzer can operate with as few as three components: A cathode for the hydrogen evolution reaction, an anode for the oxygen evolution reaction, and a chassis for managing the flows of a liquid electrolyte and the product gas streams. Absent from this device is an ionically conducting membrane, a key component in a conventional polymer electrolyte membrane (PEM) electrolyzer that typically serves as a physical barrier for separating product gases generated at the anode and cathode.
    [Show full text]
  • Recommendation for Use Hofmann Voltameter for Educational Purposes
    Glaswarenfabrik Tel. +49 (0) 9779 808 0 Karl Hecht Fax +49 (0) 9779 808 88 GmbH & Co KG Email: [email protected] Stettener Straße 22-24 Internet: www.assistent.eu 97647 Sondheim/Rhön VAT No. DE132198535 Germany Recommendation for use Hofmann voltameter for educational purposes Product number: 44285010 and 44286010 A water decomposition apparatus is used for the demonstration of electrolysis, i. e. for the decomposition of water into hydrogen and oxygen by means of electric current. The apparatus is consisting of a glass tube with pear-shaped funnel and two lateral measuring tubes 60 ml : 0.2 ml with glass stopcocks. There are two versions available: Product number 44285010 Spare parts Glass part No. 44287010 Metal tripod 2 Clamps No. 40870010 2 Platinum electrodes No. 44288010 Product number 44286010 Spare parts Glass part No. 44287010 Metal tripod 2 Clamps No. 40870010 2 Carbon electrodes No. 44289010 Experimental setup and test procedure Attach the voltameter with two clamps to the support. Insert the carbon or platinum electrodes into the measuring tubes. The stoppers have to be firmly in position in order to avoid leakage of liquid. For safety reasons place the apparatus into a glass tray. Pour in the electrolyte through the funnel while stopcocks are both open to let the air escape. Close the stopcocks as soon as the electrolyte has reached the level of stopcock bores. Connect the electrodes and the pole terminals at the tripod by means of two short connecting cables. Connect a DC voltage source and supply with electrical energy. The required direct voltage is about 10 V to 20 V at max.
    [Show full text]
  • 3B Scientific® Physics
    3B SCIENTIFIC® PHYSICS Hofmann's Voltameter, S U58010 Instruction Sheet 11/08 ALF 1 Stand base with rod 2 Sockets 3 Gold leaf electrodes 4 Gas collection tube 5 Stop cock 6 Water reservoir 1. Safety instructions Since the conductivity of distilled water is too low electrolysis is carried out using dilute sulphuric acid The apparatus is made of glass. There is a risk of (c = 1 mol/l approx.). Students should always be breakage and resulting injury. informed of the dangers of the chemicals needed for • Handle the apparatus with care when carrying it the experiment. and make sure it is stable on the desk. • Carefully add the sulphuric acid to the water • Do not subject the glass components to while stirring. Never do this the other way round. mechanical stress. • Wear protective goggles when mixing the solution Hydrogen and oxygen form an explosive mixture. and when releasing the gases. • Never re-combine the gases in a test tube. Caution! Any acid that escapes can cause irreparable stains and holes in clothing. 1 2. Description 5. Example experiments Hofmann's voltameter is used for the electrolysis of 5.1 Investigation of the conductivity and composition water (converting electrical energy into chemical of water energy), quantitative determination of the resulting • Pour distilled water into the water reservoir with gases and confirmation of Faraday’s laws. both stopcocks open until both tubes are full. The apparatus consists of three vertical glass tubes Then close the stopcocks. connected to each other at the bottom. Taps at the • Turn on the power supply and observe the top ends of the outside tubes are closed whilst the electrodes.
    [Show full text]
  • Chemistry Unit: 4CH0 Paper: 2CR
    Write your name here Surname Other names Centre Number Candidate Number Pearson Edexcel International GCSE Chemistry Unit: 4CH0 Paper: 2CR Wednesday 13 June 2018 – Morning Paper Reference Time: 1 hour 4CH0/2CR You must have: Total Marks Ruler, calculator Instructions • Use black ink or ball-point pen. • Fill in the boxes at the top of this page with your name, centre number and candidate number. • Answer all questions. • Answer the questions in the spaces provided – there may be more space than you need. • Show all the steps in any calculations and state the units. • Some questions must be answered with a cross in a box . If you change your mind about an answer, put a line through the box and then mark your new answer with a cross . Information • The total mark for this paper is 60. • The marks for each question are shown in brackets – use this as a guide as to how much time to spend on each question. Advice • Read each question carefully before you start to answer it. • Write your answers neatly and in good English. • Try to answer every question. • Check your answers if you have time at the end. Turn over P53147A ©2018 Pearson Education Ltd. *P53147A0120* 1/1/1/1/1/1/ DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA *P53147A0220* 2 Answer ALL questions. 1 The table shows some information about five gases. Formula Boiling point Gas of molecule in °C chlorine Cl2 –35 oxygen O2 –183 carbon monoxide CO –191 nitrogen N2 –196 DO NOT WRITE IN THIS AREA WRITE IN DO NOT hydrogen H2 –253 Choose gases from the table to answer this question.
    [Show full text]
  • Understanding Impurities in Copper Electrometallurgy
    Scholars' Mine Masters Theses Student Theses and Dissertations 2015 Understanding Impurities in copper electrometallurgy Paul Laforest Follow this and additional works at: https://scholarsmine.mst.edu/masters_theses Part of the Metallurgy Commons Department: Recommended Citation Laforest, Paul, "Understanding Impurities in copper electrometallurgy" (2015). Masters Theses. 7704. https://scholarsmine.mst.edu/masters_theses/7704 This thesis is brought to you by Scholars' Mine, a service of the Missouri S&T Library and Learning Resources. This work is protected by U. S. Copyright Law. Unauthorized use including reproduction for redistribution requires the permission of the copyright holder. For more information, please contact [email protected]. UNDERSTANDING IMPURITIES IN COPPER ELECTROMETALLURGICAL PROCESSES By PAUL LAFOREST A THESIS Presented to the Faculty of the Graduate School of the MISSOURI UNIVERSITY OF SCIENCE AND TECHNOLOGY In Partial Fulfillment of the Requirements for the Degree MASTER OF SCIENCE IN METALLURGICAL ENGINEERING 2015 Approved by Michael S. Moats, Advisor F. Scott Miller Matthew J. O’Keefe © 2015 Paul Laforest All Rights Reserved iii PUBLICATION THESIS OPTION Paper I (14-25) in this thesis was prepared in a format to be submitted to Hydroprocess 2015. Paper II (26-46) was prepared in a format to be submitted to Copper 2016. iv ABSTRACT This work involves examining two industrial reports of methods to handle impurities in copper electrowinning and electrorefining. The first part evaluates the addition of Hydrostar, Cyquest N-900, DXG-F7, and Guartec EW to copper electrowinning electrolyte to affect MnO2 deposition on coated titanium anodes (CTAs). The second part examines the effects of anode chemistry and thiourea addition on the ductility of electrorefined copper starter sheet.
    [Show full text]
  • Electrolysis of Water - Wikipedia 1 of 15
    Electrolysis of water - Wikipedia 1 of 15 Electrolysis of water Electrolysis of water is the decomposition of water into oxygen and hydrogen gas due to the passage of an electric current. This technique can be used to make hydrogen gas, a main component of hydrogen fuel, and breathable oxygen gas, or can mix the two into oxyhydrogen, which is also usable as fuel, though more volatile and dangerous. It is also called water splitting. It ideally requires a potential difference of 1.23 volts to split water. Simple setup for demonstration of Contents electrolysis of water at home History Principle Equations Thermodynamics Electrolyte selection Electrolyte for water electrolysis Pure water electrolysis Techniques Fundamental demonstration Hofmann voltameter Industrial High-pressure High-temperature An AA battery in a glass of tap water Alkaline water with salt showing hydrogen Polymer electrolyte membrane produced at the negative terminal Nickel/iron Nanogap electrochemical cells Applications Efficiency Industrial output Overpotential Thermodynamics https://en.wikipedia.org/wiki/Electrolysis_of_water Electrolysis of water - Wikipedia 2 of 15 See also References External links History Jan Rudolph Deiman and Adriaan Paets van Troostwijk used, in 1789, an electrostatic machine to make electricity which was discharged on gold electrodes in a Leyden jar with water.[1] In 1800 Alessandro Volta invented the voltaic pile, and a few weeks later the English scientists William Nicholson and Anthony Carlisle used it for the electrolysis of water. In 1806
    [Show full text]
  • We Would Like to Thank WSGC and Dr. William Farrow for Making This Project Possible 2015 WSGC Elijah High-Altitude Balloon Paylo
    2015 WSGC Elijah High-Altitude Balloon Payload Project Final Report September 14, 2015 Ben Jensen1, Nate Klassen2, Woodrow Walker1, Scott Frazier3, Kai Swanson1, Taylor Davitz1 1Milwaukee School of Engineering, 2University of Wisconsin-Whitewater, 3University of Wisconsin- Milwaukee Abstract The purpose of this report is to discuss the research, development, and findings of several experiments performed on a high-altitude balloon payload platform. The team decided of the following five experiments to be performed during the flight: Oxygen Generation, Internal Heating, Speed of Sound Properties, Ozone Levels, and a new payload structure concept. The entire team was required to research and develop new skills to effectively design our experiments, including: Arduino programming, 3-D modeling/printing, soldering, launch equipment handling, and construction techniques. While the launch was successful, we did fall short of our overall goal in terms of data acquisition. The internship proved to be a rewarding introductory experience to real-world engineering. The project help us learn how to implement the entirety of the engineering process, using each person’s strengths to achieve an objective. Introduction The goal for the internship team was to research, design, and execute experiments aboard a high- altitude balloon platform. The team would collect and analyze data from each experiment. There were several constraints for the project, including budget, weight, and size. The team was given full control over what we wanted to research, and decided five upon concepts: Oxygen Generation, Internal Heating, Speed of Sound Properties, Ozone Levels, and a new payload structure concept. Oxygen Generation As the altitude increases, we see a corresponding decrease in air pressure.
    [Show full text]
  • Electrochemistry SECTION
    Electrochemistry SECTION – 1 : STRAIGHT OBJECTIVE TYPE 1.1 The E° in the given diagram is, (A) 0.5 (B) 0.6 (C) 0.7 (D) 0.8 1.2 What is cell entropy change of the following cell? Pt(s) | H2(g) | CH3COOH, HCl || KCl (aq) |Hg2Cl2| (s) | Hg P = 1 atm 0.1M 0.1M Emf of the cell is found to be 0.045 V at 298 K and temperature coefficient is 3.4 10 – 4 V K – 1 – 5 Given Ka (CH3COOH) = 10 M (A) 60 (B) 65.2 (C) 69.2 (D) 63.5 1.3 Following cell has EMF 0.7995 V. Pt | H2 (1 atm) | HNO3 (1M) || AgNO3 (1M) | Ag If we add enough KCl to the Ag cell so that the final Cl- is 1M. Now the measured emf of the cell is 0.222 V. The Ksp of AgCl would be : (A) 1 10 – 9.8 (B) 110 – 19.6 (C) 210– 10 (D) 2.6410–14 1.4 Zn Amalgam is prepared by electrolysis is aqueous ZnCl2 using Hg cathode (9gm). How much current is to be passed through ZnCl2 solution for 1000 seconds to prepare a Zn Amalgam with 25% Zn by wt. (Zn = 65.4) (A) 5.6 amp (B) 7.2 amp (C) 8.85 amp (D) 11.2 amp 1.5 The solubility of [Co(NH3)4Cl2] CIO4_________ if the λ = 50, λ = Co(NH3 ) 4 Cl 2 CIO4 70, and the measured resistance was 33.5 in a cell with cell constant of 0.20 is ____.
    [Show full text]
  • Biology • Environment • Chemistry MEMORABLE TEACHING MADE EASY!
    3bscientific.com Biology • Environment • ChemistryBiology • Environment NATURAL SCIENCES NATURAL 3B SCIENTIFIC® NATURAL SCIENCES 3bscientific.com 9000953 EN MEMORABLE TEACHING MADE EASY! Dear customer, Discover the variety of possibilities for making your teaching even more memorable and exciting. We have assembled a wide range of products and experiments for you for teaching various course content in biology. We can offer you detailed models, high-quality preparations and realis- tic replicas that illustrate the structures of plants, animals, humans and the earth as well as numerous experiment sets to aid independent study, practicing and learning. From page 104 onwards, you can browse through the selection of products relating to the earth sciences, ecology and chemistry. These include models of the structure of the earth, rock collections, measuring equipment for water and soil analysis, molecule construction kits and chemical measuring instruments. New and worthy of particular mention are the powerful and comprehensive Coach 7 measuring and analysis software, the VinciLab data logger and the €lab lab interface, as well as the numerous sensors for the measurement of biological and chemical para- meters (page 152 onwards). Representing a further innovation in our range are the devices for neurophysiological studies on intact earthworms. You can find these on page 94 onwards. Let yourself be inspired by our wide range. It’s well worth a look! Our competent team will be happy to advise you personally and is looking forward to receiving your suggestions and orders! We look forward to hearing from you! The 3B Scientific team ›NEW IN ZOOLOGY Limbs of various mammals The dissected real limbs enable scientific comparison of the anatomy of the front or rear legs of selected mammals and allow conclusions to be drawn about their walking and running behavior.
    [Show full text]
  • Answers Neatly and in Good English
    Write your name here (Surname Other names ] Centre Number Candidate Number Pearson Edexcel International GCSE Chemistry Unit:4CHO Paper: 2CR Wednesday 13 June 201 8 - Morning Paper Reference Time: 1 hour 4CHO/2CR You must have: Total Marks Ruler, calculator ] Instructions • Use black ink or ball-point pen. • Fill in the boxes at the top of this page with your name, centre number and candidate number. • Answer all questions. • Answer the questions in the spaces provided - there may be more space than you need. • Show all the steps in any calculations and state the units. • Some questions must be answered with a cross in a box Kl. If you change your mind about an answer, put a line through the box N and then mark your new answer with a cross IX]. Information • The total mark for this paper is 60. • The marks for each question are shown in brackets - use this as a guide as to how much time to spend on each question. Advice • Read each question carefully before you start to answer it. • Write your answers neatly and in good English. • Try to answer every question. • Check your answers if you have time at the end. Turnover > P53147A ©2018 Pearson Education Ltd. 1/1/1/1/1/1/ P 5 3 1 A 1 2 0 Pearson 0 -?!"'1 s ® 0 s<|" s ^|s "51 s ^p 1^ £ x g 0 I .1 r~ s, -Is 0 °' u. §<» ^y SffllS C*J 5|s § s: m I <0 £ o|niS cn|i° ^4 s ^| s m 0 & ^1» g4 s ? ,'^ x in •V '[>.
    [Show full text]
  • The Anode Process in Cobalt Electrowinning Torjus Åkre 1, Geir
    The Anode Process in Cobalt Electrowinning 1. R.R. Moskalyk, A.M. Alfantazi, Review of Present Cobalt Recovery Practice, Minerals & Metallurgical Torjus Åkre 1, Geir Martin Haarberg 1, Processing, vol. 17, 4, 2000, pp. 205-216. Sarbjyot Haarberg 2, Jomar Thonstad 1, 2. O. Forsén, J. Aromaa, Possibilities to Lower Energy Ole Morten Dotterud 3 Use in Electrowinning by Modification of Lead Anodes, Aqueous Electrotechnologies: Progress in 1 Norwegian University of Science and Technology, Theory and Practice, D.B. Dreisinger, ed., The Department of Materials Technology, Minerals, Metals & Materials Society, 1997, pp. 333- NO-7491 Trondheim, Norway 346. 3. T. Robinson et al., Copper Electrowinning – 2003 2 SINTEF Materials and Chemistry, World Tankhouse Operating Data, Copper 2003- NO-7465 Trondheim, Norway Cobre 2003, Copper Electrorefining and Electrowinning, J.E. Dutrizac, C.G. Clement, eds., 3 Falconbridge Nikkelverk A/S, vol. V, CIM, 2003, pp. 421-472. Service box 604, NO-4606 Kristiansand S, Norway 4. F. Grøntoft, Electrowinning Metal from Chloride Solution, U.S. Pat. 4,155,821, 1979. Industrial cobalt electrowinning is performed in sulphate or chloride based aqueous solutions /1/. The main anode reactions are oxygen and chlorine evolution respectively. Along with the gas formation, divalent cobalt ions are oxidized in both solutions, forming a cobalt(III) oxyhydroxide anode scale (CoOOH) by hydrolytic precipitation. In sulphate media, which is most widely used, alloyed lead is the predominant anode material. When using lead anodes, CoOOH deposition is advantageous, since the cobalt layer acts as a collector for lead corrosion particles, which will otherwise contaminate the cobalt product. Cobalt also shows a depolarizing effect on the Fig.
    [Show full text]
  • METALS PRODUCTION Theodore R. Beck Electrochemical Technology
    METALS PRODUCTION F- /J Theodore R. Beck Electrochemical Technology Corp. Abstract Existing procedures for design of electrochemical plants can be used for design of lunar processes taking into consideration the differences in environmental conditions. These differences include: 1/6 Earth gravity, high vacuum, solar electrical and heat source, space radiation heat sink, long days and nights, and different availabilityand economics of materials, energy, and labor. Techniques have already been developed for operation of relatively small scale hydrogen-oxygen fuel cell systems used in the U.S. lunar landing program. Design and operation of lunar aqueous electrolytic process plants appears to be within the state-of-the-art. Finding or developing compatible materials for construction and designing of fused-magma metal winning cells will present a real engineering challenge. 111-41 Introduction Electrochemical processes are candidates for exploiting lunar rocks to obtain oxygen, metals of construction, and by-product glasses and ceramic materials. Since the Apollo landings, NASA has supported some preliminary studies on electrochemical processing of lunar rocks. One of the first was a laboratory investigation at the Bureau of Mines by Kesterke on electrowinning of oxygen from • o 1 sthcate rocks. Electrolyses were performed with volcanic scoria, fluxed with fluorides to obtain operating temperatures in the range of 1050° to 1250°C, and a current of about 50 amperes. Oxygen was obtained at a current efficiency of about 55%. Solid cathode deposits were formed consisting of metal dendrites of iron, aluminum, silicon, etc., in an electrolyte matrix. Waldron. Ersffeld, and Criswell reviewed the role of chemical engineering in space manufacturing in 1979.
    [Show full text]