Processing of lithium containing material

Abstract

A process ( 10 ) for the treatment of a lithium containing material, 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 ( 36 ) 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.

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 (ii) to a series of impurity removal steps 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.   
     
     
         2 . The process of  claim 1 , wherein the process solution of step (i) is prepared in the form of a pregnant leach solution. 
     
     
         3 . The process of  claim 2 , 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. 
     
     
         4 . The process of any one of the preceding claims, wherein the impurity removal step (ii) further comprises a concentration step such that the process solution is concentrated to near saturation of lithium chloride. 
     
     
         5 . The process of any one of the preceding claims, wherein the lithium hydroxide solution produced in step (iii) is thickened by evaporation of water to provide lithium hydroxide monohydrate crystals. 
     
     
         6 . The process of any one of the preceding claims, 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. 
     
     
         7 . The process of any one of the preceding claims, 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. 
     
     
         8 . The process of any one of  claims 1  to  6 , wherein the lithium containing material is a lithium containing brine. 
     
     
         9 . The process of  claim 6 , 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. 
     
     
         10 . The process of any one of the preceding claims, wherein the impurity removal steps of step (ii) include one or more of hyrdropyrolysis of Al and Fe chlorides, pH increase to precipitate hydroxides of Al, Fe, Mg and Mn, lithium carbonate precipitation for removal of Ca, and fractional crystallisation for the removal of Na and K. 
     
     
         11 . The process of  claim 10 , wherein the fractional crystallisation for the removal of Na and K is conducted immediately after the concentration step. 
     
     
         12 . The process of  claim 10  or  11 , wherein the impurity removal steps further comprises an ion exchange step. 
     
     
         13 . The process of  claim 12 , wherein the ion exchange step removes substantially all calcium, magnesium and other multivalent cations remaining in the process solution. 
     
     
         14 . The process of  claim 13 , wherein such multivalent cations are removed to a level of less than about 10 ppm. 
     
     
         15 . The process of  claim 13  or  14 , wherein such multivalent cations are removed to a level of about 1 ppm. 
     
     
         16 . The process of any one of  claims 9  to  15 , wherein water evaporated from the solution in evaporation/crystallisation is recompressed, combined with make-up steam and utilised in evaporation/crystallisation. 
     
     
         17 . The process of any one of  claims 9  to  16 , wherein the evaporation/crystallisation step utilises a vacuum evaporative crystalliser. 
     
     
         18 . The process of any one of  claims 7  to  17 , wherein the beta-spodumene is cooled and milled prior to the leach step. 
     
     
         19 . The process of  claim 18 , wherein the beta-spodumene is milled to less than about 300 μm. 
     
     
         20 . The process of  claim 18  or  19 , wherein the beta-spodumene is milled to a P 80  of about 75 μm. 
     
     
         21 . The process of any one of  claims 3  to  20 , wherein the leach of step (ii) is conducted at elevated temperature. 
     
     
         22 . The process of any one of  claims 3  to  21 , wherein the hydrochloric acid solution used in the leach step is about 20% HCl w/w. 
     
     
         23 . The process of  claim 22 , wherein the elevated temperature of the leach of step is about the boiling point of the hydrochloric acid solution used in the leach step. 
     
     
         24 . The process of any one of  claims 3  to  23 , wherein the leach step is conducted at atmospheric pressure. 
     
     
         25 . The process of any one of  claims 3  to  24 , wherein the leach step is conducted in a chlorination kiln at about 108° C. over a residence time of about 6 to 10 hours. 
     
     
         26 . The process of  claim 25 , wherein the leach step is conducted over a residence time of about 8 hours.