Part 1 Lithium GEOLOGY Lithium is a comparatively rare element, although it is found in many rocks and some brines, but always in very low concentrations. The average amount in the earth’s upper crust has been estimated to be about 20 ppm by Vine (1980), although others have quoted values as low as 7 ppm (Bach et al., 1967; igneous rocks 6 ppm, sedimentary rocks 11.5 ppm) and as high as 60 ppm (Deberitz, 1993; 27th in rank of elemental abundance). Even with these small numbers, however, there are a fairly large number of both lithium mineral and brine deposits, but only comparatively a few of them are of actual or potential commercial value. Many are very small, others are too low in grade or located in remote areas, or too expensive to recover and process. Some of the better-known deposits are roughly located in Fig. 1.1, and esti- mates of the lithium reserves of various deposits (or countries) are listed in Table 1.1. The deposits have been formed because of lithium’s higher solubility than most other cations, so it sometimes has concentrated in flowing and cooling magma and/or its accompanying aqueous fluids, as well as in evaporating brines. Thus, its minerals are generally found in the latter stages of alkaline magma flow, intrusion and crystallization, as occurs in pegmatite formations. There are about 145 minerals containing lithium as a major component (.200 with .0.002% Li2O), and about 25 contain over 2% Li2O (Deberitz, 1993). Forty-three of the better known of these minerals are listed in Table 1.2. The high-lithium brines usually have obtained most of their lithium from geothermal waters, with perhaps some of the lithium coming from surface leaching of volcanic ash, clays or other rocks. However, lithium is very difficult to leach from the lattice structure of all rocks and minerals, so little is dissolved unless the water is very hot. Experimental studies have shown that at ambient temperatures, only 55– 170 ppb dissolves from extended contact with granitic rocks, but at 275–6008C 0.25–2.4 ppm Li can be extracted in the same agitated, long contact-period (Dibble and Dickson, 1976). Analyses of cores into deep-ocean rift or subduction zones 1 2 Part 1 Lithium Figure 1.1 Location and reserve estimate of some of the world’s lithium deposits (Anstett et al., 1990; reserves: R1 proven, R2 probable). Geology 3 Table 1.1 Estimated Lithium Reserves of Various Lithium Deposits, 1000 mt Li Reserves Brines Salar de Uyuni 5000a Salar de Atacama 3000b(4300–4600) f Salar de Hombre Muerto 800c Clayton Valley 30.4a(115–382)g,h Zabuye Salt Lake, China 1000c Qinghai Lake, China 1000c Smackover oilfield brine 1000c Great Salt Lake 526c Searles Lake 31.6a Salton Sea 1000c Dead Sea 2000c Total 14,718 Ore deposits Africa (other) .0.3a Bikita, Zimbabwe 23b Mali 26d Manono-Kitotolo, Zaire 309a Namibia 9.8e Argentina 0.2a Australia (Greenbushes) 150b Austria 10a Brazil 3.3a Canada (total) 240.5a Bernic Lake, Manitoba 73a Ontario, Quebec 139a China 500d Portugal 10c Russia 130a United States (other) 44.3a North Carolina 71c a Anstett et al. (1990). b USGS (2002). c Garrett (1998). d Lloyd (1981). e Kesler (1960). f Ide and Kunasz (1989). g Kunasz (1994). h Dillard and McClean (1991). have shown that lithium is adsorbed on, rather than leached from near-surface rocks (up to 1.8 km in depth), and only significantly leached from deeper rocks at temperatures greater than 300–3508C. Based upon the isotopic analyses of lithium in the upper rocks there is some exchange by adsorption and simultaneous leaching in 4 Part 1 Lithium Table 1.2 Formula and Group of Some of the Lithium Minerals (Vine, 1980) Name and formula Mineral group or series Amblygonite (Li,Na)AlPO4(F,OH) Amblygonite Bertossaite (Li,Na)2(Ca,Fe,Mn)Al4(PO4)4(OH,F)4 — Bikitaite LiAlSi2O6·H2O Zeolite (?) Bityite Ca(Al,Li)2[(Al,Be)2Si2(O,OH)10]·H2O Margarite Brannockite KLi3Sn2Si12O30 — Cookeite (Li,Al4)Si3AlO10(OH)8 Chlorite Cryolithionite Li3Na3Al2F12 — Eckermannite Na3(Mg,Li)4(Al,Fe)Si8O22(OH,F)2 Amphibole (asbestos) Elbaite Na(Li,Al)3Al6B3Si6O27(OH,F)4 Tourmaline Ephesite Na(LiAl2)(Al2Si2)O10(OH)2 Margarite Eucryptite LiAlSiO4 — Ferghanite LiH(UO2/OH)4(VO4)2·2H2O— 3þ 2þ Ferri-sicklerite (Li, Fe ,Mn )PO4 Sicklerite Gerstleyite (Na,Li)4As2Sb8S17·6H2O— Hectorite Na0.33(Mg,Li)3Si4O10(F,OH)2 Smectite 2þ 3þ Holmquistite Li2(Mg,Fe )3(Al,Fe )2Si8O22(OH)2 Amphibole Hsianghualite Ca3Li2Be3(SiO4)3F2 — Lepidolite K(Li,Al)3(Si,Al)4O10(F,OH)2 Mica Liberite Li2BeSiO4 — 2þ 2þ Lithiophilite Li(Mn ,Fe )PO4 Lithiophilite–triphylite Lithiophorite (Al, Li)MnO2(OH)2 — Lithiophosphate Li3PO4 — a Manandonite LiAl4(AlBSi2O10)(OH)3 Chlorite Montebrasite (Li, Na)Al(PO4)(OH,F) Amblygonite Nambulite LiNaMn8Si10O28(OH)2 — Natromontebrasite (Na, Li)Al(PO4)(OH,F) Amblygonite Palermoite (Li, Na)2(Sr,Ca)Al4(PO4)4(OH)4 Petalite LiAlSi4O10 — Polylithionite KLi2Al(Si4O10)(F,OH)2 Mica Rankamite (Na,K,Pb,Li)3(Ta,Nb,Al)11(O,OH)30 — Regularly interstratified montmorillonite-chlorite — 2þ 3þ Sicklerite Li(Mn ,Fe )PO4 — Sogdianite (K,Na)2Li2(Li,Fe,Al,Ti)2Zr2(Si2O5)6 — Spodumene LiAlSi2O6 Pyroxene Swinefordite Smectite Taeniolite KLiMg2Si4O10F2 Mica 3þ Tavorite LiFe PO4OH — Tosudite — 2þ 2þ Triphylite Li(Fe ,Mn )PO4 Triphylite–lithiophilite Virgilite — Zinnwaldite K(Li,Al,Fe)3(Al,Si)4O10(OH,F)2 Mica More recently determined lithium mineralsb Diomignite Li2(B4O6)O7?— Liddicoatite (end member of the group) CaLi2Al7B3Si6O27(OH)4 Tourmaline Chlorite, boron-bearing (end member) Li2Al5BSi2O14·4H2O Chlorite a Manandonite is listed by some as the same formula with 2H2O. b Garrett (1998). Geology 5 the temperature range of 50–3508C, but little net change (James et al., 2003; Chan et al., 2002b,c; You and Gieskes, 2001). Other rocks or higher temperature leaching conditions must allow a greater amount of lithium to be removed, since some geothermal springs have lithium values of 6–50 ppm, but in all cases the lithium concentration is still very low. When these dilute geothermal waters are concentrated by the evaporation occurring in arid climate, closed, reasonably impervious basins, comparatively strong lithium brines have resulted in a few large playa deposits. Many large medium-concentration lithium brines have also been formed in various oil or gas field waters, potash deposit end-liquors (seawater only contains about 0.17 ppm Li), and a number of miscellaneous sources such as the Salton Sea geothermal brine and end-liquors from various commercial solar pond operations. Brine Deposits As with minerals, many brines and waters contain some lithium, but as noted above it is usually found in extremely low concentrations. There are a few exceptions, but as of 2003 only three brine sources had become actual commercial operations, and each had comparatively high levels of lithium (although one only contained ,160 ppm Li), appreciable lithium reserves and good solar ponding conditions (the Salar de Atacama, Chile; Salar de Hombre Muerto, Argentina; and Clayton Valley, USA). Their brines were obtained from the porous strata under the surface of playas, and each appears to have lithium-containing hot springs as their principal source of the lithium. By-product lithium has also been recovered from Searles Lake, but its concentration in the lake brine is only 50–80 ppm Li. Because of the very dilute lithium concentration in even the best of brine deposits, they all owe their value to the availability of solar evaporation ponds to inexpensively further concentrate the lithium. Again, as an exception to this, Searles Lake used plant evaporation, but even with multiple products it became too expensive, so their lithium recovery has ceased. At the Salar de Hombre Muerto alumina-adsorption may be used to first fairly selectively separate the lithium from the other salts in the brine, but then solar evaporation would still be needed to concentrate the eluted dilute lithium solution. The projected reserves of lithium in the world’s few potential or actual commercial brine deposits has been roughly estimated as about 15 million metric tons of Li (Table 1.1), but the practical recovery of the lithium from many of these deposits would be very difficult. The more important lithium-brine deposits are separately discussed in the following sections. Clayton Valley (Silver Peak), Nevada This relatively small 83 km2 (O’Neill et al., 1969; 100 km2, Davis et al., 1986) dry lake (playa) is about 16 km long and 6.4 km wide, and has a drainage basin area of about 1300 km2 (Fig. 1.2). It is located in central Nevada about 87 km southwest of Tonopah, 274–282 km from Reno and Las Vegas, and 40 km east of the Nevada–California border. Its elevation is 1300 m, and in the porous strata under its 6 Part 1 Lithium Figure 1.2 Location map of Clayton Valley and its surrounding mountains (Davis et al., 1986). surface there is a fairly concentrated sodium chloride brine with comparatively high amounts of potassium and sulfate, but very little magnesium and other ions (Table 1.3). It also has a fairly high content of lithium in a brine pool with about a54km2 area and an average deposit depth of about 460 m. Originally the central area contained 100–800 ppm Li, and the discovery well at 229 m depth contained Table 1.3 p Various Analyses of the Clayton Valley Brine, wt.% (or ppm) Barret and O’Neill (1970) Davis (1986) p First wella Anon.