Method for the production of cobalt and associated oxides from various feed materials

Abstract

A method is disclosed for the recovery of cobalt, nickel and manganese from ores, concentrates, tailings, scrap alloys and spent batteries in an oxidic form, which is suitable for direct use in the manufacture of lithium-ion batteries, in particular. The process is unique in being able to recover cobalt, in particular, from concentrated solutions wherein the nickel to cobalt ratio is close to unity, rather than the more common 10:1 or 1:100. The process comprises selective oxidative precipitation of each metal under differing conditions of pH and ORP (oxidation-reduction potential). Sodium hypochlorite is the preferred precipitant, since it does not generate any acid, and is therefore self-buffering at the selected pH. A unique aspect of the process is to use Mn(VII) to effect the precipitation of Mn(ll).

1 . A method for the recovery of cobalt from a Co- and Ni-containing aqueous solution, the method including:
 providing a Co- and Ni-containing aqueous solution having a pH of from about 4.5 to about 6.5 and an oxidation-reduction potential of from about 750 to about 900 mV as measured against a Pt—Ag/AgCl electrode;   treating the Co- and Ni-containing aqueous solution with an amount of a hypochlorite to oxidise and precipitate a portion of the cobalt as CoOOH and form a Co-lean Ni-aqueous solution; and   separating the CoOOH from the Co-lean Ni-containing aqueous solution.   
     
     
         2 . The method of  claim 1 , wherein the amount of hypochlorite is a sub-stoichiometric amount. 
     
     
         3 . The method of  claim 2 , wherein the sub-stoichiometric amount of hypochlorite is sufficient to precipitate up to 90% of the cobalt as CoOOH. 
     
     
         4 . The method of  claim 2 , wherein the method further includes:
 treating the Co-lean Ni-containing aqueous solution with an amount of hypochlorite to substantially oxidise and precipitate the remaining cobalt in the Co-lean Ni-containing aqueous solution as CoOOH and form a Co-barren Ni-containing aqueous solution; and   separating the CoOOH from the Co-barren Ni-containing aqueous solution.   
     
     
         5 . The method of  claim 1 , wherein the pH of the Co- and Ni-containing aqueous solution is from about 5.0 to about 5.5. 
     
     
         6 . The method of  claim 1 , wherein the oxidation-reduction potential of the Co- and Ni-containing aqueous solution is from about 800-850 mV. 
     
     
         7 . The method of  claim 1 , wherein the step of treating the Co- and Ni-containing aqueous solution is conducted for a time of less than 2 hours. 
     
     
         8 . The method of  claim 1 , wherein the step of treating the Co- and Ni-containing aqueous solution is conducted for a time of at least 30 minutes. 
     
     
         9 . The method of  claim 1 , wherein the Co- and Ni-containing solution has a Co:Ni ratio of from about 100:1 to about 1:10. 
     
     
         10 . The method of  claim 9 , wherein Co:Ni ratio is less than or equal to about 5. 
     
     
         11 . The method of  claim 1 , wherein the method further includes a Ni-precipitating step including adding a precipitant to the Co-barren Ni-containing aqueous solution to precipitate nickel; and separating the nickel from the solution. 
     
     
         12 . The method of  claim 11 , wherein the precipitant is a carbonate. 
     
     
         13 . The method of  claim 11 , wherein prior to adding the precipitant, the pH of the Co-barren Ni-containing aqueous solution is adjusted to a value of from about 7.5 to 8.5. 
     
     
         14 . The method of  claim 11 , wherein the Ni-precipitating step is conducted at a temperature of from 45-80° C. 
     
     
         15 . The method of  claim 1 , wherein the Co- and Ni-containing solution is substantially free of Cu, Fe, and Mn. 
     
     
         16 . The method of  claim 1 , wherein the method includes:
 treating a precursor solution containing at least Mn, Co, and Ni with a precipitant to selectively form a Mn-precipitate; and   separating the Mn-precipitate to form the Co- and Ni-containing aqueous solution.   
     
     
         17 . The method of  claim 16 , wherein prior to treating the precursor solution with the precipitant, the pH of the precursor solution is adjusted to a value of from about 3.5 to about 5.0. 
     
     
         18 . The method of  claim 16 , wherein the precipitant is a permanganate, and the permanganate oxidises the Mn to form a precipitate of MnO 2 . 
     
     
         19 . The method of  claim 18 , wherein sufficient permanganate is added to adjust the oxidation-reduction potential of the precursor solution to a value of from about 700 to about 800 mV as measured against a Pt—Ag/AgCl electrode. 
     
     
         20 . The method of  claim 16 , wherein prior to treating the precursor solution with the precipitant, the precursor solution is treated to remove iron and copper.