Processing of lithium containing material including hcl sparge

Abstract

A process ( 10 ) for the treatment of a lithium containing material ( 12 ), the process comprising the steps of: (i) Preparing a process solution from the lithium containing material ( 12 ); (ii) Passing the process solution from step (i) to a series of impurity removal steps, one of which is an HCl sparging step 58 , thereby providing a substantially purified lithium chloride solution; and (iii) Passing the purified lithium chloride solution of step (ii) to an electrolysis step ( 70 ) thereby producing a lithium hydroxide solution. An additional step in which the lithium hydroxide solution produced in step (iii) is carbonated by passing compressed carbon dioxide ( 88 ) through the solution, thereby producing a lithium carbonate precipitate, is also disclosed.

1 . A process for the treatment of a lithium containing material, the process comprising the steps of:
 (i) Preparing a process solution from the lithium containing material;   (ii) Passing the process solution from step (i) to a series of impurity removal steps, one of which is an HCl sparging step, thereby providing a substantially purified lithium chloride solution; and   (iii) Passing the purified lithium chloride solution of step (ii) to an electrolysis step thereby producing a lithium hydroxide solution,   wherein the process solution is not subjected to a concentration step prior to the series of impurity removal steps of step (ii).   
     
     
         2 . The process according to  claim 1 , wherein the lithium hydroxide solution produced in step (iii) is carbonated by passing compressed carbon dioxide through the solution, thereby producing a lithium carbonate precipitate. 
     
     
         3 . The process according to  claim 1 , wherein the process solution of step (i) is prepared in the form of a pregnant leach solution. 
     
     
         4 . The process according to  claim 3 , wherein the pregnant leach solution is formed by passing a lithium containing material to a leach step in which the material is leached with hydrochloric acid. 
     
     
         5 . The process according to  claim 1 , wherein the lithium containing material is an alpha-spodumene ore or ore concentrate and the process further comprises a first step in which that alpha-spodumene ore or ore concentrate is calcined to produce beta-spodumene. 
     
     
         6 . The process according to  claim 1 , wherein the HCl sparging step of step (ii) comprises the sparging of HCl gas into the process solution whereby the HCl concentration thereof increases to a point at which a substantial proportion of any sodium and potassium present precipitates. 
     
     
         7 . The process according to  claim 6 , wherein the HCl concentration of the process solution is increased to:
 (i) at least about 30% w/w; or   (ii) at least about 36% w/w.   
     
     
         8 . The process according to  claim 6 , wherein the HCl sparging step is followed by a filtration step to remove the precipitated sodium and potassium. 
     
     
         9 . The process according to  claim 1 , wherein the HCl sparging and filtration steps are followed by an HCl recovery step. 
     
     
         10 . The process according to  claim 1 , wherein the lithium hydroxide solution produced in step (iii) is thickened by evaporation of water to provide lithium hydroxide monohydrate crystals. 
     
     
         11 . The process according to  claim 1 , wherein a first portion of the lithium hydroxide solution produced in step (iii) is thickened by evaporation/crystallisation to provide lithium hydroxide monohydrate crystals and a second portion thereof is carbonated by passing compressed carbon dioxide through the solution, thereby producing a lithium carbonate precipitate. 
     
     
         12 . The process according to  claim 1 , wherein the impurity removal steps of step (ii) further include one or more of hyrdropyrolysis of Al and Fe chlorides, pH increase to precipitate hydroxides of Al, Fe, Mg and Mn, and lithium carbonate precipitation for removal of Ca. 
     
     
         13 . The process according to  claim 12 , wherein the impurity removal steps further comprise an ion exchange step that removes substantially all calcium, magnesium and other multivalent cations remaining in the pregnant leach solution. 
     
     
         14 . The process according to  claim 12 , wherein the impurity removal steps further comprise an ion exchange step that removes substantially all calcium, magnesium and other multivalent cations remaining in the pregnant leach solution to a level of less than about 10 ppm. 
     
     
         15 . The process according to  claim 5 , wherein the beta-spodumene is milled prior to the first step to a size of:
 (i) less than about 300 μm; or   (ii) a P 80  of about 75 μm.   
     
     
         16 . The process according to  claim 3 , wherein a leach step that produces the pregnant leach solution is conducted at elevated temperature. 
     
     
         17 . The process according to  claim 3 , wherein the pregnant leach solution is formed by passing a lithium containing material to a leach step in which the material is leached with hydrochloric acid at 20% HCl w/w. 
     
     
         18 . The process according to  claim 3 , wherein a leach step that produces the pregnant leach solution is conducted at an elevated temperature that is about the boiling point of hydrochloric acid solution used in the leach step, and the leach step is conducted at atmospheric pressure. 
     
     
         19 . The process according to  claim 3 , wherein a leach step that produces the pregnant leach solution is conducted in a chlorination kiln at about 108° C. over a residence time of: