Recovery of nickel and cobalt from ore

Abstract

A process is provided for the selective recovery from an impure solution of pure nickel and cobalt solutions, suitable for electrolysis of the respective metals. The impure solution may be that obtained from acid leaching of nickel/cobalt bearing laterite or oxide ore. The impure solution is contacted with a solid ion exchange resin to selectively extract nickel and cobalt, while rejecting at least one element of the group manganese, magnesium, calcium, iron(II), and chromium(III). The ion exchange resin contains bis-picolyl amine as the primary chelating group. The impure solution has sufficiently low levels of chromium(VI) and copper to allow repeated use of the ion exchange resin. The metal-bearing resin is washed and then stripped with an acid solution. This solution is then contacted with a water-immiscible organic phase for the selective extraction of cobalt, leaving nickel in the raffinate as a substantially pure nickel solution. The loaded organic phase is stripped with another acid solution to produce a substantially pure cobalt solution. The extractant contains an organic phosphinic acid as the active group for extraction. Nickel and cobalt can be recovered in essentially pure form from the respective pure nickel and cobalt solutions by a variety of conventional techniques, for example by electrowinning.

What is claimed is:  
     
         1 . A hydrometallurgical process for the recovery of nickel and cobalt comprising the steps of 
 a. providing an aqueous feed solution containing nickel, cobalt, and at least one impurity selected from the group consisting of manganese, magnesium, calcium, aluminum, iron(II), and chromium(III) ions;    b. contacting the feed solution with a solid ion exchange resin to form a nickel and cobalt-loaded resin and an ion exchange raffinate, containing at least one impurity;    c. eluting the nickel and cobalt from the resin to form an eluate containing a soluble nickel salt and a soluble cobalt salt;    d. contacting the eluate with a water-immiscible organic phase containing an extractant to load cobalt onto the extractant to form a cobalt-containing organic phase and a nickel-containing raffinate;    e. separating the cobalt-containing organic phase from the nickel-containing raffinate; and,    f. eluting the cobalt-containing organic phase with a mineral acid or other eluant to produce a cobalt-containing aqueous solution.    
     
     
         2 . The process of    claim 1    wherein the feed solution originates from mineral acid leaching of a laterite or oxide ore wherein the ore contains cobalt and nickel and wherein the mineral acid is selected from the group consisting of sulfuric acid, hydrochloric acid, nitric acid, and mixtures thereof.  
     
     
         3 . The process of    claim 1    wherein the feed solution originates from sulfuric acid pressure leaching of a laterite or oxide ore wherein the ore contains, cobalt and nickel.  
     
     
         4 . The process of    claim 1    wherein the feed solution originates from atmospheric leaching of a laterite or oxide ore wherein the ore contains cobalt and nickel.  
     
     
         5 . The process of    claim 1    wherein the feed solution originates from bioxidation of sulfide or mixed oxide/sulfide ore or concentrate which contains at least one of cobalt and nickel.  
     
     
         6 . The process of    claim 1    wherein the feed solution includes copper ions and wherein the process includes the additional step of removing copper ions from the feed solution prior to contacting with the ion exchange resin.  
     
     
         7 . The process of    claim 6    wherein the copper ions are removed from the feed solution by contacting the feed solution with an ion exchange resin selective to the removal of copper.  
     
     
         8 . The process of    claim 6    wherein the copper ions are precipitated from the feed solution by adding a sulfide-containing compound to the feed solution.  
     
     
         9 . The process of    claim 1    wherein the feed solution contains chromium (VI) ions and the process includes the additional step of removing chromium (VI) ions from the feed solution by reducing with a reductant prior to contacting the feed solution with the ion exchange resin.  
     
     
         10 . The process of    claim 9    wherein the reductant is selected from the group consisting of SO 2 , H 2 SO 3 , Na 2 SO 3 , H 2 S, iron(II), iron( 0 ) and mixtures thereof.  
     
     
         11 . The process of    claim 1    wherein the nickel and cobalt are eluted from the nickel and cobalt loaded ion exchange resin with an acid selected from the group consisting of sulfuric, hydrochloric and nitric.  
     
     
         12 . The process of    claim 1    wherein the ion exchange resin contains a chelating group selected from the group consisting of 2-picolylamine, bis-(2-picolyl)amine, N-methyl-2-picoylamine, N-(2-hydroxyethyl)-2-pocolylamine, and N-(2-hydroxypropyl)-2-picoylamine, and mixtures thereof.  
     
     
         13 . The process of    claim 1    wherein the extractant is an organic phosphinic acid.  
     
     
         14 . The process of    claim 13    wherein the extractant is bis(2,4,4-trimethylpentyl) phosphinic acid.  
     
     
         15 . The process of    claim 1    including the additional step of electrowinning the cobalt-containing aqueous solution to recover cobalt.  
     
     
         16 . The process of    claim 15    wherein a spent electrolyte is produced and is used to strip the cobalt from the cobalt-containing organic phase.  
     
     
         17 . The process of    claim 1    including the additional step of electrowinning the nickel-containing raffinate to recover nickel.  
     
     
         18 . The process of    claim 17    wherein a spent electrolyte is produced and is used to elute the absorbed nickel and cobalt form the ion exchange resin.  
     
     
         19 . The process of    claim 1    further comprising the steps of providing the resin with a series of columns and passing the feed solution serially through these columns.  
     
     
         20 . The process of    claim 1    wherein the ion exchange raffinate is contacted with at least a second ion exchange resin to form at least a second nickel and cobalt-loaded resin and at least a second raffinate.  
     
     
         21 . The process of    claim 20    including the additional steps of eluting the nickel and cobalt from the at least second ion exchange resin to form at least a second eluate containing a soluble nickel salt and a soluble cobalt salt and combining the eluate and at least the second eluate prior to contacting with the water-immiscible organic phase.  
     
     
         22 . The process of    claim 1    wherein a pH of the eluate prior to contacting with the water-immiscible organic phase is maintained at a level between about 5 and about 5.5 by the addition of a base selected from the group consisting of sodium hydroxide, ammonium hydroxide, sodium carbonate, and mixtures thereof, or a mixture of basic nickel/cobalt carbonate, nickel/cobalt hydroxide, and mixtures thereof.  
     
     
         23 . The process of    claim 1    including the additional step of contacting the cobalt-containing loaded organic phase with a strong cobalt solution to remove co-loaded nickel.  
     
     
         24 . A hydrometallurgical process for the recovery of nickel and cobalt comprising the steps of 
 a. providing an aqueous feed solution containing nickel, cobalt, and at least one impurity selected from the group consisting of manganese, magnesium calcium, aluminum, iron(II), chromium(VI) and copper ions;    b. removing any copper ions from the aqueous feed solution;    c. contacting the feed solution with a solid ion exchange resin to form a nickel and cobalt-loaded resin and an ion exchange raffinate, containing at least one impurity;    d. eluting the nickel and cobalt from the resin to form an eluate containing a soluble nickel salt and a soluble cobalt salt;    e. contacting the eluate with a water-immiscible organic phase containing an extractant to load cobalt onto the extractant to form a cobalt-containing organic phase and a nickel-containing raffinate;    f. separating the cobalt-containing organic phase from the nickel-containing raffinate; and,    g. eluting the cobalt-containing organic phase with a mineral acid or other eluant to produce a cobalt-containing aqueous solution.    
     
     
         25 . The process of    claim 24    further comprising the step of reducing the chromium(VI) to chromium(III).