Lithium extraction method

Abstract

According to the present invention there is provided a method for the extraction of lithium from one or more lithium-containing ores such as spodumene, the inventive method comprising the steps of: milling said ore/s to a predetermined average particle size; optionally calcining the milled ore; further optionally performing a secondary milling step; providing an aqueous suspension of the one or more lithium-containing ores at a predetermined solids concentration; subjecting the one or more lithium-containing ores to an aqueous extraction medium defined by a predetermined partial pressure of CO2, a predetermined extraction temperature, over a predetermined time; and obtaining technical grade lithium carbonate/lithium bicarbonate therefrom. Optional concentration and/or precipitation/purification steps may follow.

1 - 3 . (canceled) 
     
     
         4 : A method for the extraction of lithium from one or more lithium-containing ores, said method comprising the steps of:
 a) milling said one or more lithium-containing ores to a predetermined average particle size to provide a milled crude ore;   b) providing an aqueous medium comprising a suspension of the milled crude ore, at a predetermined solids concentration;   c) subjecting said milled crude ore to an acidic extraction medium defined by a predetermined partial pressure of CO 2 , a predetermined extraction temperature, over a predetermined time; and   d) obtaining technical grade lithium carbonate and/or lithium bicarbonate from the extraction medium.   
     
     
         5 : A method according to  claim 4 , wherein the one or more lithium-containing ores comprise β-spodumene, or wherein the one or more lithium-containing ores consist essentially of β-spodumene. 
     
     
         6 : A method according to  claim 4 , wherein the predetermined calcining temperature is greater than about 900° C., thereby to convert α-spodumene to β-spodumene. 
     
     
         7 : A method according to  claim 4 , wherein said predetermined partial pressure of CO 2  is between about 0.1 and about 300 bar and wherein said predetermined extraction temperature is between about 20° C. and about 350° C. 
     
     
         8 . (canceled) 
     
     
         9 : A method according to  claim 4 , wherein said predetermined solids concentration is between about 0.1 and about 60% w/w. 
     
     
         10 : A method according to  claim 4 , wherein said predetermined average particle size is between about 0.1 μm and about 1000 μm. 
     
     
         11 : A method according to  claim 4 , wherein said predetermined time is between about 1 and about 1000 minutes. 
     
     
         12 : A method according to  claim 4 , giving a yield on an extracted lithium to crude lithium basis of between about 1% and about 99%. 
     
     
         13 : A method according to  claim 4 , wherein one or more impurities extracted from said one or more lithium-containing ores comprise Na, K, Mg, Ca, Mn, Fe, Al, and Si, and wherein each of said one or more impurities is present at a concentration between about 0.5% and about 40% of the lithium concentration on a molar basis. 
     
     
         14 . (canceled) 
     
     
         15 : A method according to  claim 4 , further comprising a concentration step e), wherein the technical grade lithium carbonate and/or lithium bicarbonate obtained in solution from step d) is concentrated. 
     
     
         16 : A method according to  claim 15 , wherein said concentration step comprises the addition of a concentrator, evaporation, reverse osmosis, electrodialysis, liquid-liquid extraction, selective adsorption, solid state extraction and/or membrane separation. 
     
     
         17 : A method according to  claim 15 , wherein following said concentration step e), the lithium carbonate and/or lithium bicarbonate precipitates out of solution; and wherein the method further comprises a filtration step f), thereby to separate the precipitated lithium carbonate and/or lithium bicarbonate. 
     
     
         18 - 19 . (canceled) 
     
     
         20 : A method according to  claim 4 , wherein the aqueous medium comprises water, one of more mineral acids, one or more organic acids, one or more alkaline salts, one or more ionic liquids, and combinations thereof. 
     
     
         21 : A method according to  claim 20 , wherein the one of more mineral acids are optionally supplemented with a predetermined partial pressure of CO 2  between about 0.1 and about 300 bar. 
     
     
         22 . (canceled) 
     
     
         23 : A method according to  claim 4 , wherein the lithium carbonate and/or lithium bicarbonate has a purity of at least about 85% on a molar basis. 
     
     
         24 - 26 . (canceled)