Processing of zinnwaldite waste to obtain Li2CO3

In this study, Li2CO3 was extracted from a zinnwaldite concentrate with 1.21% Li and 0.84% Rb prepared from zinnwaldite wastes (0.21% Li, 020% Rb). These wastes originated from dressing of Sn-W ores, which were mined in the Czech Republic in the past. Processing of the zinnwaldite concentrate consisted of roasting the concentrate with CaCO3 followed by water leaching of the resulting calcines. This method made it possible to extract about 90% of Li as well as Rb. Lithium carbonate products were separated from leach liquor using two different procedures. The first one comprised conversion of the original alkaline leach liquor to carbonated solution by CO2 bubbling, solution purification and Li2CO3 crystallization during water evaporation. The second procedure consisted of lithium solvent extraction from the original leach liquor using LIX 54 and TOPO as an extraction agent followed by stripping with diluted H2SO4, solution purification and lithium carbonate precipitation with K2CO3. Water-washed lithium carbonate salts were produced in both procedures and contained almost 99.5% Li2CO3 with the first method providing higher yield. Mother liquors after Li2CO3 crystallization and/or inorganic phases after lithium solvent extraction are suitable intermediates for production of rubidium compounds, such as Rb2CO3, Rb2SO4 or RbOH. (C) 2010 Elsevier B.V. All rights reserved.