Hydrometallurgy 150 (2014) 192–208
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Hydrometallurgy
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Review Extraction of lithium from primary and secondary sources by pre-treatment, leaching and separation: A comprehensive review
Pratima Meshram a,b, B.D. Pandey a,⁎,T.R.Mankhandb a CSIR—National Metallurgical Laboratory, Jamshedpur 831 007, India b Dept. of Metallurgical Engineering, IIT, BHU, Varanasi 221 005, India article info abstract
Article history: In this comprehensive review resources of lithium and status of different processes/technologies in vogue or Received 27 October 2013 being developed for extraction of lithium and associated metals from both primary and secondary resources Received in revised form 4 October 2014 are summarized. Lithium extraction from primary resources such as ores/minerals (spodumene, petalite and Accepted 12 October 2014 lepidolite) by acid, alkaline and chlorination processes and from brines by adsorption, precipitation and ion Available online 23 October 2014 exchange processes, is critically examined. Problems associated with the exploitation of other resources such
Keywords: as bitterns and seawater are highlighted. As regards the secondary resources, the industrial processes followed Lithium and the newer developments aiming at the recovery of lithium from lithium ion batteries (LIBs) are described Primary ores in detail. In particular pre-treatment of the spent LIBs, leaching of metals from the cathode material in different Brines acids and separation of lithium and other metals from the leach liquors, are discussed. Although spent LIBs are LIBs currently processed to recover cobalt and other base metals but not lithium, there is a good prospect for the Hydrometallurgical recovery recovery of lithium in the coming years. Varying compositions of batteries for different applications require development of a suitable recycling process to recover metals from all types of LIBs. © 2014 Elsevier B.V. All rights reserved.
Contents
1. Introduction...... 193 2. Resourcesoflithium...... 193 2.1. Primary resources — minerals/claysandbrines...... 193 2.2. Secondary resources — lithiumionbatteries...... 194 3. Extractionoflithiumfromprimaryresources...... 195 3.1. Lithiumextractionfromminerals/clays...... 195 3.1.1. Acidprocess...... 196 3.1.2. Alkalineprocess...... 197 3.1.3. Chlorinationprocess...... 197 3.1.4. Otherprocesses...... 197 3.2. Lithiumextractionfrombrines/seawater/bitterns...... 197 3.2.1. Adsorptionprocess...... 198 3.2.2. Precipitationprocess...... 199 3.2.3. Ionexchange/Solventextractionprocess...... 199 3.3. Extraction of lithium from secondary resources — lithiumionbatteries...... 200 3.3.1. Majorindustrialprocesses...... 200 3.3.2. Recentdevelopmentinrecyclingoflithiumionbatteries...... 202 4. Conclusions...... 206 Acknowledgements...... 206 References...... 206
⁎ Corresponding author. E-mail address: [email protected] (B.D. Pandey).
http://dx.doi.org/10.1016/j.hydromet.2014.10.012 0304-386X/© 2014 Elsevier B.V. All rights reserved. P. Meshram et al. / Hydrometallurgy 150 (2014) 192–208 193
1. Introduction Table 1 Principal commercial lithium minerals with compositiona.
Lithium is the 25th most abundant element (at 20 mg/kg) in the Mineral Formula % Lithium content earth's crust. Lithium finds an application in rechargeable lithium ion bat- Theoretical Range in commercial teries (LIBs) because of its very high energy density by weight and high minerals electrochemical potential (3.045 V). With a present consumption level Spodumene LiAlSi O or Li O·Al O ·4SiO 3.73 1.9–3.3 of ~22% of the total lithium produced in LIBs, it is expected to reach to 2 6 2 2 3 2 Lepidolite LiKAl2F2Si3O9 or 3.56 1.4–1.9
~40% by 2020 (Wang et al., 2012). Besides batteries, at present it has LiF·KF·Al2O3·3SiO2 – major applications in glass and ceramics (30%), greases (11%), metallurgi- Amblygonite LiAlFPO4 or 2LiF·Al2O3·P2O5 4.74 3.5 4.2 – cal (4%) industries and also in chemicals/pharmaceuticals, rubbers etc. Triphylite LiFePO4 or Li2O·2FeO·P2O5 4.40 2.5 3.8 Petalite LiAlSi O or Li O·Al O ·8SiO 2.27 1.6–2.21 (Garrett, 2004; Holdren, 1971). As per the Madrid Report of July 2010, 4 10 2 2 3 2 Bikitaite LiAlSi2O6·H2O 3.28 1.35–1.7 lithium falls in the border-line of low-to-medium in supply and demand, Eucryptite LiAlSiO4 5.53 2.34–3.3 primarily due to scanty resources (Tedjar, 2013). It is also understood that Montebrasite Li2O·Al2O3·2SiO2 3.93 0.9–1.8 – the demand for lithium is increasing further due to its application in nu- Jadarite LiNaSiB3O7(OH) 3.39 0.096 0.1 – clear and strategic areas. As per recent estimates of lithium reserves, out Zinnwaldite LiKFeAl2F2Si3O10 or 1.7 1.21 1.3 LiF·KF·FeO·Al O ·3SiO of 103 deposits with more than 1,00,000 t of lithium, each deposit has a 2 3 2 Hectorite Na0.3(Mg,Li)3Si4O10(F,OH)2 0.56 0.36 different mineralogical composition and therefore, requires the appropri- Zabuyelite Li2CO3 18.75 – ate technology to process (Gruber et al., 2011). In view of this, lithium is a Industrial Minerals and Rocks (2006), Norton and Schlegel (1955), Schaller (1937),and usually extracted from its mineral that is found in igneous rocks (chiefly Siame and Pascoe (2011). spodumene) and from lithium chloride salts found in brine pools, while ignoring other resources including the low-grade ores. The rising demand for lithium for various applications thus calls for policy about the fate of discarded lithium ion batteries in e-waste that prospecting and processing all viable resources. Lithium extraction is distributed internationally. Lithium batteries also contain potentially from ores/minerals utilizes roasting followed by leaching, while its toxic materials including metals, such as copper, nickel and lead, and extraction from brines includes evaporation, precipitation, adsorption organic chemicals, such as toxic and flammable electrolytes containing and ion exchange (Garrett, 2004). Lithium can be extracted from LIBs LiClO4,LiBF4,andLiPF6. Defunct Li-ion batteries are classified as hazard- by leaching followed by precipitation, ion exchange or solvent extrac- ous due to their lead (Pb) (6.29 mg/kg), cobalt (163,544 mg/kg), copper tion and electrolysis (Shuva and Kurny, 2013). It is estimated that 250 (98,694 mg/kg) and nickel (9525 mg/kg) contents with exceeded limits t of ore (spodumene) or 750 t of brine or 28 t of lithium ion batteries of chromium, lead, arsenic and thallium (Bernardes et al., 2004; Kang of mobile phones and laptops or 256 batteries of electric vehicles et al., 2013). Human and environmental exposures to these chemicals (EVs) are required to produce 1 t of lithium (Tedjar, 2013). Lithium con- are typically regulated during the manufacture of lithium batteries centrate obtained mainly by the flotation of pegmatites (ore), is pulver- through occupational health and safety laws, and potential fire hazards ized and leached in hot acid, and lithium is precipitated as lithium associated with their transportation. These findings support the need carbonate (Tahil, 2010). The processing of pegmatites is expensive as for stronger government policies at the local, national, and compared to that of the brines due to the heating and dissolution international levels to encourage recovery, recycling, and reuse of lithi- steps involved, but the higher metal concentration in pegmatites partly um battery materials. In view of the above, efforts must be made to compensates for the cost. Because of the cost factor in the lithium develop an environmentally benign and economically viable technology extraction from brine compared to the ores, many deposits of spodu- for recycling spent LIBs. mene are not currently being mined/processed. Lithium is also present This review focuses on the primary and secondary resources of in seawater, but the concentration is too low to be economical. As lithium available for exploitation and provides comprehensive details regards lithium metal, it can be produced by both carbothermic reduc- on the conventional/currently practiced lithium extraction methods tion and metallothermic reduction of oxide (at times hydroxide) and vis-a-vis the resource type. The resources that are covered include also by electrolysis of LiCl (Kipouros and Sadoway, 1998). In view ores/minerals/clays and brines/seawater and bitterns, and lithium ion of the scattered literature on the extraction of lithium from primary batteries for the hydrometallurgical recovery of lithium. resources viz., ores, minerals and the brines, it is considered worthwhile to review the details and discuss critically the merits and demerits of 2. Resources of lithium various processes in vogue or being developed. With the increasing use of LIBs in mobile phones, laptops, cam- 2.1. Primary resources — minerals/clays and brines corders, tracking systems, military and medical devices and in large energy storage systems including that of transportation applications Lithium is produced from a variety of natural sources, e.g., minerals (None million EVs expected by 2015), there will be a significant pressure such as spodumene, clays such as hectorite, salt lakes, underground on lithium resources and its supplies (Kuo, 2011). The disposal of spent brine reservoirs etc. Lithium is a minor component of igneous rocks, batteries may involve landfilling, stabilization, incineration or recycling. primarily granite. The most abundant lithium containing rocks/minerals In landfills, heavy metals have the potential to leach slowly into the soil, are pegmatites, spodumene and petalite. Other minerals are lepidolite, groundwater or surface water. amblygonite, zinnwaldite and eucryptite (Ferrell, 1985). Zinnwaldite The methods for recycling spent LIBs are based mainly on pyro-/ is the impure form of lepidolite with higher content of FeO (up to hydro-metallurgical processes (Li et al., 2009a). The disadvantage of all 11.5% Fe as FeO) and MnO (3.2%) (Paukov et al., 2010). Pegmatites con- pyro-recycling processes is that lithium is not recovered. The traditional tain recoverable amounts of lithium, tin, tantalum, niobium, beryllium pyrometallurgical processes can burn off all the organic electrolyte and and other elements. Table 1 lists the principal commercial lithium min- binder, and facilitate the leaching of valuable metals. In the hydrometal- erals found in pegmatites along with their composition. The theoretical lurgical processes, the dismantled electrodes are dissolved in concen- lithium content in these minerals is 3% to 5.53%, but most mineral de- trated acid and the metal rich leach solutions are treated to recover posits have around 0.5%–2% Li and the pegmatite-bearing ores that are the individual metal by the different methods mentioned above. These often exploited have b1% Li (Mohr et al., 2010). Spodumene is the pri- processes may produce wastewater containing fluoride which is difficult mary lithium mineral being mined. to treat, and can pollute the environment due to the incomplete Among the clay minerals, hectorite, a type of smectite is rich in lith- recycling of the organic binder and electrolyte. There is an inconsistent ium and magnesium, and generally contains 0.3 to 0.6% Li. The best 194 P. Meshram et al. / Hydrometallurgy 150 (2014) 192–208
Table 2 Geographical availability for various lithium resources and their lithium contents.
Resources Li content % (w/w) Location of the largest amount References
Pegmatites Spodumene 1.9–3.3 Australia Industrial Minerals and Rocks (2006), Legers (2008), Lepidolite 1.53–3.6 Zimbabwe Clarke (2013), AMRA (2013) Zabuyelite 17–18.75 China Petalite 1.6–2.1 Zimbabwe Amblygonite 3.5–4.2% Canada, Brazil, Surinam Eucryptite 2.34 Zimbabwe
Sedimentary rocks Smectite (hectorite) 0.27–0.7 Hector, California. and Nevada, US Industrial Minerals and Rocks (2006) Lacustrine evaporites 1.8% lithium oxide Jadar Valley, Serbia
Brine Continental b2700 mg/L (with K, B) Chile Evans (2008,2009), ~532 mg/L Bolivia Legers (2008), Geothermal b400 mg/L (with Mn and Zn) United States Clarke (2013), Oil field b700 mg/L (with Br) United States Mohr et al. (2012) Sea water 0.18 mg/L Chile, Argentina, China and Tibet
Secondary resource Spent LIBs 2–7% – Shuva and Kurny (2013)
known hectorite deposit with 0.7% Li is in Hector, California. Flint clays plant. Lithium carbonate is mostly produced from both ores and brines and other high-alumina clays contain b0.01 to 0.5% Li. Jadarite is a and the production figures are often expressed as lithium carbonate newly discovered lithium-boron containing mineral found in Serbia equivalent (LCE). Other chemicals such as lithium chloride and hydrox- (Mohr et al., 2012). These minerals are often concentrated to around ide are also produced in varying amounts. 2%–4% Li for use in the ceramics and glass industry (Garrett, 2004). In India small pocket deposits mostly comprising of lepidolite in Seawater contains about 0.1–0.2 mg/L Li (Bach and Wasson, 1981). pegmatites of mica fields are located. The maximum lithium content
Total amount of metallic lithium in seawater (globally) is estimated to (lepidolite with 2–6% Li2O) is found in Jharkhand followed by that of be ~230 Gt. Brine sources include lithium found in salt water deposits — Chhattisgarh (2.56% Li2O) and Rajasthan (2.25% Li2O as pegmatites in lakes, salars, oilfield brines, and geothermal brines. Oilfield brines are Udaipur, Bhilwara, Jodhpur and Ajmer, and zinnwaldite in Dagana). underground brine reservoirs that are located with oil. Geothermal brines Others include spodumene in Raichur, Karnataka (Banerjee et al., 1994), are underground brines naturally heated, e.g., in the Salton Sea California. amblygonite in granitic rocks of Paddar (Kashmir) and lepidolite at Brines containing lithium make up 66% of the world's lithium resources; Dhir-Bil (Goalpara), Assam. Lithium bearing bauxite has also been identi- pegmatites make up 26% and sedimentary rocks make up 8% (Gruber, fied in the Salal area, Jammu (Brown and Dey, 1955; Krishnaswamy, 2010; Kesler et al., 2012). 1979; Roonwal et al., 2005). Almost 70% of the global lithium deposits are concentrated in South America's ABC (Argentina, Bolivia and Chile) region. Table 2 details the geographical availability of various resources of lithium vis-a-vis lithium 2.2. Secondary resources — lithium ion batteries content and their locations. The lithium concentrations in the salars of Chile, Argentina, and Bolivia are in the range 0.04–0.16%. According to Out of the various secondary resources, spent LIBs are the most prom- Yaksic and Tilton (2009) the resource of lithium is estimated to be inent secondary source of lithium and other metals. To recycle these 64 Mt. Chile has the world's largest resource of brine (7.5 Mt, 1500– materials, it is desired to understand the construction/composition of 2700 mg/L Li) containing lithium, followed by Bolivia (resource: 9.0 Mt the cells in brief and how they transform during their use. with 532 mg/L Li) and Argentina (resource: 2.6 Mt, 400–700 mg/L Li) Lithium ion battery is a term generally used for a battery which has and these three countries account for almost 80% of the world's brine lithium metal, lithium alloy or material adsorbing lithium ions for its reserves (Mohr et al., 2012). Estimates of lithium resources are published negative active material. LIB uses carbon as an anode and lithium ions extensively (Clarke and Harben, 2009; Gruber et al., 2011; Ono, 2009; exist in the carbon material; there is no metallic lithium at any state of Evans, 2010a, 2010b; USGS, 1980, 1986, 2005, 2009, 2010, 2011, 2012, charge during normal usage. Depending on their technical construction 2013). and properties batteries are categorized as either primary or secondary. Lithium rock production began with lithium minerals (1899) in the From the legislative view point batteries are also categorized as portable USA (Garrett, 2004). Since the first lithium production from brines at (household) and vehicle or industrial batteries. Primary cells are con- Searles Lake, USA in 1936, brines are exploited largely in South America structed with metallic lithium. The metallic lithium in a non- and China. The largest producer of lithium in the world is Chile where rechargeable primary lithium battery is a combustible alkali metal that lithium is extracted from salar brine at the Atacama Salt Flat. Lithium self-ignites at 178 °C, and when exposed to water/seawater reacts exo- production from brines is also at salt lakes in Tibet and Qinghai in thermically and releases hydrogen. Primary batteries are single-use as China, besides at Nevada in the United States. Several newer installations irreversible discharge reactions occur in the cells and after use they (by 2013) are on various stages of exploration/operation for brine source are disposed off. Secondary battery cells have a chemistry that allows re- which are: one more in China, six in Argentina, three in Chile and one in versing the discharge reaction and are rechargeable. LIBs are of the re- Bolivia (Clarke, 2013). Currently 8% of lithium is obtained from salt lake chargeable secondary type. The functional parts of LIBs are the cathode, brines and sea by sedimentation. Significant quantities of lithium com- anode, electrolyte and separator, which are housed in a protective pounds and ore concentrates are also produced in Australia, Canada, metal casing. Portugal, Russia and Zimbabwe. Currently, Australia produces lithium The chemical reaction in the cell expressed below shows the forms concentrate from spodumene at the mines in Mt Catlin, Western in which lithium and cobalt can be present in the spent LIBs. Australia. The 160,000 t/annum concentrate produced in Western þ → þ : ð Þ Australia is processed to 16,000 t/annum lithium carbonate in its Chinese LiCoyOz 6C LixC6 Li1−xCoyOz 1 P. Meshram et al. / Hydrometallurgy 150 (2014) 192–208 195
Table 3 Various components of LIBs, materials used and their meritsa.
Component Wt.% of the total Material Structure Properties/Merits weight of the battery
Cathode 39.1 ± 1.1 LiCoO2 Layered High structural stability and can be cycled for N500 times with 80–90% capacity retention
LiMn2O4 Spinel Attractive for ecological and economic reasons; discharges ~3 V
LiNiO2 Layered Cheaper & possesses higher energy density (15% higher by volume, 20% higher
by weight), but less stable & less ordered as compared to LiCoO2
LiFePO4 Olivine Suitable for biomedical applications because of higher safety levels and
Li2FePO4F Olivine lower cost
LiCo1/3Ni1/3Mn1/3O Layered/spinel Possesses high capacity with structural and thermal stability, and safe to use
Li(LiaNixMnyCoz)O2 Layered/spinel Anode Carbon Graphite Low cost and availability. It has the ability to reversibly absorb and release large Hard carbon Microspheres quantity of Li (Li:C = 1:6)
Electrolyte Lithium salt like LiPF6, Li[PF3(C2F5)3] Withstands high temperature and possesses high mobility of Li ions
or LiBC4O8 in organic solvents Plastic case 22.9 ± 0.7 Polyethylene terephthalate layers, a polymer layer and a Hermetically sealed battery body which converts chemical energy to electrical polypropylene layer, layers of carbonized plastic energy in order to generate current Outer casing 10.5 ± 1.1 Stainless steel, aluminium Copper foil 8.9 ± 0.3 Copper ~14 μm thick Aluminium foil 6.1 ± 0.6 Aluminium ~20 μm thick Polymer foil & 5.2 ± 0.4 Polyethylene, polypropylene or composite Use of 3–8 μm layers (PP/PE/PP) with 50% porosity electrolyte polyethylene/polypropylene films Solvent 4.7 ± 0.2 Ethylene carbonate, dimethyl carbonate Non-aqueous &diethylcarbonate Electrical contact 2.0 ± 0.5 Aluminium and copper Conductive
a Wakihara and Yamamoto (1998), Gaines and Cuenca (2000), Nazri and Pistoia (2004) Paulino et al., (2008) and Fergus (2010).
The active mass (cathode, anode and electrolyte) of LIBs comprises of and Olson (1978) have reviewed methods and techniques for the almost 40% of the weight whereas ~30% (wt) of these components are extraction of lithium from ores, brines and clays. Processes followed carbon (anode). A number of chemical species in the cathode material for the extraction of lithium from different resources have also been within the lithium-ion family have been reported including the type, compiled in detail by Garrett (2004). structure of the materials used and their electrochemical properties In order to process ores/concentrates, acid digestion with H2SO4 may which are listed in Table 3. Generally LIBs have a short life of 2–3years be followed for decomposition of the silicate structure at 250–400 °C whether they are used or not. The spent batteries are a good source of which is suitable for the processing of lepidolite, amblygonite and several metals like Li, Co, Ni, Co, Mn etc. zinnwaldite (Kondás and Jandová, 2006). In the sulfate process lithium minerals such as lepidolite are decomposed at high temperature in the 3. Extraction of lithium from primary resources presence of potassium and/or sodium sulfate. Alkali digestion is suitable for the decomposition of spodumene and lepidolite largely by the treat- 3.1. Lithium extraction from minerals/clays ment of potassium carbonate to produce lithium hydroxide. In the alka- line/gypsum process the mineral is reacted with limestone or a mixture Lithium is extracted from its minerals by two processes — acid and of calcium sulfate with calcium oxide and/or hydroxide by heating to alkaline though chlorination is also attempted in some cases. Averill convert silicate to soluble lithium aluminate from which LiOH or Li2CO3
Table 4 Lithium extraction from its minerals/clays by acid process.
Raw material % Li Experimental conditions %Li Li2CO3 References Extraction purity Pre-treatment Roasting Time Water leaching (%) temp. (°C) (h) L/S ratio Temp. (°C) Time (h)
Lepidolite conc. 2.0 Sulfation roasting 850 0.5 2.5:1 Room temp. 0.5 91.6 – Yan et al. (RT) (2012a) Lepidolite conc. 2.0 Salt roasting with 880 0.5 0.8:1 RT 0.5 ~90 N99.5 Yan et al.
Na2SO4 + CaCl2 (2012b) Lepidolite conc. 2.55 Sulfation roasting 1000 0.5 15:1 85 3 90.4 – Luong et al.
Na2SO4:Li molar (2013) ratio = 2:1 Lepidolite conc. 1.79 Roasting with iron 850 1.5 1:1 RT 1 85 (open – Luong et al. sulfate system) (2014) 93 (closed system) Zinnwaldite conc. 0.96 Roasting with 850 1 10:1 RT 0.5 N90 N90 Siame and sodium sulfate Pascoe (2011) Petalite/Lepidolite 1.9 Calcination 1100 2 7.5/1 50 1 97.3 99 Sitando and
Roasting (H2SO4) 300 1 Crouse (2012) Spodumene 4.21 Calcination 1100 1 Leaching & ––90 – Mcketta (1988),
Roasting (H2SO4) 250 0.167 precipitation Tahil (2010)
Spodumene 2.81 Roasting & H2SO4 1050–1090 0.5 1:4 225 1 96 ~99.6 Chen et al. leaching (2011a, 2011b), Clarke (2013)
Montmorillonite clay 1.2% Li2O Without roasting ––5:1 (H2SO4 leach) 250 1.5 90 Li2SO4 Amer (2008) 196 P. Meshram et al. / Hydrometallurgy 150 (2014) 192–208
Table 5 Lithium extraction from its minerals/clays by alkali process.
Raw material % Li Pre-treatment Experimental conditions % Li Li2CO3 References extraction purity (%) Roasting temp. Water leaching (°C), time (h) Time (h) Temp. (°C) (L/S ratio)
Lepidolite 1.4 Defluorination 860, 0.5 h 1 150 4:1; lime: defluor. 98.9 99.9 Yan et al. (2012c) concentrate lepidolite: 1 Zinnwaldite 1.4 Gypsum roast 950, 1 h 0.167 90 10:1 96 99 Jandová et al. concentrate (2009) Zinnwaldite 2.07% Gypsum roast 1050 0.5 85 10:1 84 –
(tailing sample) Li2O Zinnwaldite 0.19 Roasting with 975 1 90 5:1 93 – Kondás and Jandová
concentrate gypsum & Ca(OH)2 (2006)
Zinnwaldite 1.21 Roasting with CaCO3 825, 1 h 1 90–95 5:1 ~90 99.5 Jandová et al. (2010) concentrate
Zinnwaldite 1.29 Roasting with CaCO3 825 4 95 10:1 84 – Vu et al. (2013) concentrate Montmorillonite 0.3–0.6 Roasting with 750 – RT – 80 99 Lien (1985), Crocker
clay–hectorite CaCO3 900 and Lien (1987)
CaCO3–CaSO4
is obtained. Thus most of the alkaline processes involve either the Li2CO3 of ~99% purity was precipitated by the addition of Na2CO3 at heating of lithium minerals with alkali salts or in more advanced hydro- 95–100 °C. Amer (2008) reported the extraction of 90% Li from the thermal processes by decomposition in solutions containing Na2CO3, Egyptian montmorillonite type clay containing lithium in 90 min of NaOH, Na2SO4 and/or other alkali salts at elevated temperature and reaction in sulfuric acid at 250 °C. pressure. Ion-exchange processes are applied for the processing of the In order to process spodumene it is desired to convert α-spodumene leach liquors obtained from spodumene, petalite and partly from to β-phase by roasting at 1070–1100 °C (Chen et al., 2011b; Clarke, zinnwaldite. Tables 4–6 summarize recent work on lithium extraction 2013; Tahil, 2010). Tahil (2010) reported the roasting of spodumene from its minerals and clays by using different approaches. in a kiln at ~1100 °C. The calcine was mixed with sulfuric acid and roasted at 250 °C and then leached in water to yield a solution of lithium
sulfate. Reaction of β‐spodumene with H2SO4 is shown as reaction (2) 3.1.1. Acid process (Mcketta, 1988): Sulfation roasting of lepidolite followed by water leaching was recently reported by Yan et al. (2012a). The lithium extraction effi- ⋅ ⋅ þ → þ ⋅ ciency of 91.6% could be achieved at a mass ratio of lepidolite/Na2SO4/ Li2O Al2O3 4SiO2ðsÞ H2SO4ðconcÞ Li2SO4ðsÞ Al2O3 4SiO2ðsÞ þ : ð Þ K2SO4/CaO of 1:0.5:0.1:0.1 and roasting at 850 °C (Table 4). Roasting at H2OðgÞ 2 880 °C with a mass ratio of lepidolite/Na2SO4/CaCl2 of 1:0.5:0.3 resulted in improved recovery (~95% Li) of lithium (Yan et al., 2012b). Above 99.5% pure lithium carbonate was obtainedbyevaporationandprecipita- Lithium carbonate can be recovered by the addition of sodium carbon- ate to the solution after pH adjustment, purification and evaporation tion with Na2CO3. Luong et al. (2013) examined the sulfation roasting of a Korean lepidolite ore with sodium sulfate at 1000 °C, while achieving (Reaction (3)). extraction of ~ 90.4% Li. Recently, the roasting of lepidolite with iron sul- fate at 850 °C and water leaching were investigated by Luong et al. þ → þ : ð Þ Li2SO4ðaqÞ Na2CO3ðaqÞ Li2CO3ðsÞ Na2SO4ðaqÞ 3 (2014). Leaching of the calcines obtained from the open and closed sys- tems yielded leach liquors containing ~7.9 g/L Li and ~8.7 g/L Li, corre- sponding to the extraction of ~85% and ~93% Li, respectively. The world's first continuous plant to convert spodumene concentrate
Lithium extraction (N90%) by roasting a low grade zinnwaldite to lithium carbonate by calcination, roasting of calcine with H2SO4 and concentrate (0.96% Li) with sodium sulfate followed by water leaching, water leaching, was commissioned in 2012 by Galaxy Resources in was described by Siame and Pascoe (2011).AstudybySitando and China (Clarke, 2013). Crouse (2012) showed the extraction of 97.3% Li (~5 g/L) by roasting One of the drawbacks of the sulfuric acid method to treat lepidolite, a Zimbabwean petalite ore concentrate (4.1% Li2O) with concentrated petalite and zinnwaldite is the requirement of a high concentration of sulfuric acid at 300 °C followed by water leaching at 50 °C. The leach acid and complex purification processes, whereas spodumene needs liquor was evaporated till lithium was concentrated to N11 g/L and to be converted to the more leachable β‐phase at higher temperature.
Table 6 Lithium extraction from its minerals/clays by chlorination process.
Raw material Experimental conditions % Li extraction Product References
Roasting temp. (°C) Time (h) Leaching
L/S ratio Temp. (°C) Time (h)
Lepidolite 935 13 – 80 1 ~100 LiCl Löf and Lewis (1942) Spodumene (3.58% Li) 1000 4 10:1 80 1 58 LiCl Peterson and Gloss (1959)
Lepidolite concentrate (2.0% Li) 880 0.5 2.5:1 60 0.5 92.8 Li2CO3 Yan et al. (2012d)
Spodumene (7.2% Li2O) 1100 2.5 –– – 100 LiCl Barbosa et al. (2014)
Lepidolite ore (3.70% Li2O) With CaCO3 + CaCl2, 950 5 10:1 90 1 80.0 LiCl Vyas et al. (1975) P. Meshram et al. / Hydrometallurgy 150 (2014) 192–208 197
3.1.2. Alkaline process 750 °C, ~98% of the lithium contained in spodumene is converted to its Inthealkalineprocess(Table 5), spodumene or lepidolite ore concen- chloride which can be water leached (Zelikman et al., 1996). Vyas trates are ground and calcined with limestone at 825–1050 °C. The et al. (1975) reported a similar process using CaCO3 and CaCl2 to roast resulting calcine is crushed, milled and treated with water to yield lithi- Indian lepidolite at 950 °C by which 80% Li was recovered as LiCl. The um hydroxide which can be converted to chloride by reaction with hy- chlorination process with calcium chloride and/or sodium chloride drochloric acid. The recovery in this method is approximately 85–90% with lepidolite (M = Li, K, Rb, Cs) may be represented as: (Averill and Olson, 1978). The reaction during calcination of spodumene with limestone can be represented as : þ þ þ → þ ð Þ 2NaCl 6SiO2 M2O Al2O3 2NaAlSi3O8 2MCl 8 ⋅ ⋅ þ → þ ⋅ ⋅ Li2O Al2O3 4SiO2ðsÞ CaCO3 Li2OðsÞ CaO Al2O3 4SiO2ðsÞ þ : ð Þ þ þ → þ ð Þ CO2ðgÞ 4 CaCl2 SiO2 M2O CaSiO3 2MCl 9 Lepidolite was pre-roasted at 860 °C under water steam atmosphere for defluorination followed by pressure leaching of the defluorinated þ þ þ → þ : ð Þ CaCl2 2SiO2 Al2O3 M2O CaAlSi2O8 2MCl 10 mass in a lime–milk autoclave at 150 °C. In this process 98.9% lithium was extracted (Yan et al., 2012c). During the roasting with steam forma- tion of phases such as lithium aluminium silicate (beta-eucryptite) and Chlorination roasting with a mixture of CaCl2 and NaCl gives a better lithium extraction yield because of its lower melting point than either leucite (KAlSi2O6)wasnoticed(Karstetter, 1971)asperreaction(5) of the agents, which increases the fluidity of chloride melt. This allows ⋅ ⋅ ⋅ þ → ⋅ ⋅ þ 2LiF KF Al2O3 3SiO2 4H2O Li2O Al2O3 2SiO2 2KAlSi2O6 diffusion of the chlorinating agent to the surface of the lepidolite facili- þ þ : ð Þ 4H2 2F2 5 tating the lithium extraction selectively and yielding a pure product. Crocker and Lien (1987) also reported a process for selective chlorina- Extraction of lithium from a zinnwaldite containing waste was inves- tion of hectorite (0.3–0.65% Li) in clays with limestone at 750 °C using tigated by Jandová et al. (2009). The concentrate (1.40% Li) obtained 20 wt.% HCl. from dry magnetic separation of the waste (0.21% Li) was treated by the gypsum roast method (with CaSO4 and Ca(OH)2). About 96% Li was leached out from the sinter made at 950 °C. Earlier the concentrate 3.1.4. Other processes prepared from this waste by gravity and dry magnetic separation, was Chlorination roasting of ores requires corrosion-resistant equip- roasted by the gypsum method at 975 °C and water leached to recover ment. To overcome this drawback the autoclave method is used. Chen ~93% Li (Kondás and Jandová, 2006). In another study Jandová et al. et al. (2011b) reported a process to treat β-spodumene obtained in (2010) reported that the roasting of the above concentrate with the calcination of α-spodumene, by sodium carbonate solution in an au- CaCO3·Li2CO3 with 99.5% purity was separated from the leach liquors toclave at a liquid/solid ratio of 4 and Na/Li of 1.25 at 225 °C. During by either converting the alkaline liquor to the carbonated solution by pressure leaching lithium carbonate and analcime slurry are formed CO2 bubbling or by solvent extraction with LIX54 and TOPO as an according to reaction (11). extractant followed by stripping with diluted H2SO4;thefirst method provided a higher yield. Siame and Pascoe (2011) obtained recovery of β− ⋅ ⋅ þ þ → Li2O Al2O3 4SiO2 Na2CO3 nH2O Li2CO3 þ ⋅ ⋅ ⋅ : ð Þ ~84% Li from the roasted zinnwaldite concentrate at 1050 °C with lime- Na2O Al2O3 4SiO2 nH2O 11 stone, gypsum and sodium sulfate. A similar process was reported by Vu The slurry was leached in carbon dioxide to form lithium bicarbonate et al. (2013) from zinnwaldite by sintering with CaCO3 powder at 825 °C, followed by water leaching and precipitation. which on heating produced lithium carbonate of 99.6% purity as per Crocker and Lien (1987) reported the recovery of N85% Li by roasting reactions (12) and (13). montmorillonite type clays (0.3–0.6% Li) with KCl–CaSO4 or CaCO3– CaSO4 followed by water leaching. Lithium silicate in the clay was con- þ þ → ð Þ Li2CO3 CO2 H2O 2LiHCO3 12 verted to Li2SO4 by roasting a pelletized mixture of clay, limestone and gypsum at 900 °C in a direct gas-fired rotary roaster (Lien, 1985). → þ þ : ð Þ Formation of lithium sulfate may be represented by reactions (6) and (7) 2LiHCO3 Li2CO3 CO2 H2O 13