Process for recovering metals and metal compounds from mined ore and other metal-bearing raw source materials

Abstract

A filter cake, including a first metal in an insoluble form and/or filtrate comprising Cr in a soluble form, obtained by a method involving filtering an aqueous slurry of a metal-bearing raw source material comprising the first metal in an insoluble form, soluble and/or insoluble Cr in a Cr bearing material as a second metal, and organic and inorganic compounds, after adjusting the pH of the slurry to an alkaline pH sufficient to convert soluble Cr present to an insoluble form and selectively leaching the Cr by adding a leaching agent in an amount sufficient to convert Cr to a soluble form while the first metal remains in the slurry in an insoluble form.

1 . A filter cake produced by a method for selectively recovering a metal from a metal-bearing raw source material, the method comprising:
 a) mixing with an aqueous medium a metal-bearing raw source material comprising a first metal in an insoluble form, soluble and/or insoluble Cr in a Cr bearing material as a second metal, and organic and inorganic compounds to obtain a slurry comprising the first metal in an insoluble form, soluble and/or insoluble Cr in a Cr bearing material and the organic and inorganic compounds;   b) adjusting the pH of the slurry to an alkaline pH sufficient to convert soluble Cr present to an insoluble form;   c) optionally adding a first oxidizer to the slurry to facilitate subsequent oxidation steps;   d) selectively leaching the Cr by adding a leaching agent in an amount sufficient to convert Cr to a soluble form while the first metal remains in the slurry in an insoluble form;   e) filtering the slurry to obtain a filter cake comprising the first metal in an insoluble form and a filtrate comprising Cr in a soluble form;   f) recovering the filter cake comprising the first metal in an insoluble form and/or filtrate comprising Cr in a soluble form; and   
       comprising said first metal. 
     
     
         2 . A filtrate produced by the method for selectively recovering a metal from a metal-bearing raw source material, the method comprising:
 a) mixing with an aqueous medium a metal-bearing raw source material comprising a first metal in an insoluble form, soluble and/or insoluble Cr in a Cr bearing material as a second metal, and organic and inorganic compounds to obtain a slurry comprising the first metal in an insoluble form, soluble and/or insoluble Cr in a Cr bearing material and the organic and inorganic compounds;   b) adjusting the pH of the slurry to an alkaline pH sufficient to convert soluble Cr present to an insoluble form;   c) optionally adding a first oxidizer to the slurry to facilitate subsequent oxidation steps;   d) selectively leaching the Cr by adding a leaching agent in an amount sufficient to convert Cr to a soluble form while the first metal remains in the slurry in an insoluble form;   e) filtering the slurry to obtain a filter cake comprising the first metal in an insoluble form and a filtrate comprising Cr in a soluble form;   f) recovering the filter cake comprising the first metal in an insoluble form and/or filtrate comprising Cr in a soluble form; and   comprising Cr in a soluble form.   
     
     
         3 . The method for selectively recovering nickel (Ni) and chromium (Cr) from a metal-bearing raw source material, comprising:
 a) mixing with an aqueous medium a metal-bearing raw source material comprising Ni compound(s) in an insoluble form as a first metal, insoluble and/or soluble Cr compound(s) as a second metal, and organic and inorganic compounds to obtain a slurry comprising Ni in an insoluble form, insoluble and/or soluble Cr, and the organic and inorganic compounds;   b) adjusting the pH of the slurry to facilitate subsequent oxidation steps;   c) adding a first oxidizer to the slurry to oxidize the organic and inorganic compounds,   d) adding MnO 4   −  to the slurry in an amount sufficient to oxidize the Cr into a soluble form while the Ni remains in the slurry in an insoluble form;   e) filtering the slurry to obtain a filter cake comprising Ni in an insoluble form and a filtrate comprising Cr in a soluble form;   f) recovering the filter cake comprising Ni in an insoluble form;   g) optionally recovering the filtrate comprising Cr in a soluble form;   wherein step g) further comprises:   (I) treating the filtrate comprising Cr in a soluble form with an acid to obtain an acidic solution;   (II) adding a reducing agent to the acidic solution while mixing to reduce the Cr in a soluble form to an insoluble form;   (III) adjusting the pH of the acidic solution to a basic solution to form a solution comprising Cr hydroxide precipitate (Cr(OH) 3 ); and   (IV) filtering the solution comprising Cr(OH) 3  precipitate to obtain a filter cake comprising Cr(OH) 3  and a basic solution.   
     
     
         4 . The method according to  claim 3 , further comprising
 (V) reslurrying the Cr(OH) 3  filter cake to wash out sulfates and other water soluble compounds, and   (VI) filtering the slurry comprising washed Cr(OH) 3  filter cake to obtain a second Cr(OH) 3  filter cake.   
     
     
         5 . The method according to  claim 3 , further comprising adding a sufficient amount of reducing agent to step (II) to obtain a reaction as follows:
   2CrO 4   −2 +2Na 2 S 2 O 5 =2Cr +3 +4NaSO 4 +O 2 .  (3)
   
     
     
         6 . The method according to  claim 5 , wherein a sufficient amount of base is added to obtain a reaction as follows:
   Cr +3 +3NaOH=Cr(OH) 3 +3Na +   (4)
   wherein Cr(OH) 3  is a precipitate.   
     
     
         7 . The method for selectively recovering nickel (Ni) and chromium (Cr) from a metal-bearing raw source material, comprising:
 a) mixing with an aqueous medium a metal-bearing raw source material comprising Ni compound(s) in an insoluble form as a first metal, insoluble and/or soluble Cr compound(s) as a second metal, and organic and inorganic compounds to obtain a slurry comprising Ni in an insoluble form, insoluble and/or soluble Cr, and the organic and inorganic compounds;   b) adjusting the pH of the slurry to facilitate subsequent oxidation steps;   c) adding a first oxidizer to the slurry to oxidize the organic and inorganic compounds,   d) adding MnO 4   −  to the slurry in an amount sufficient to oxidize the Cr into a soluble form while the Ni remains in the slurry in an insoluble form;   e) filtering the slurry to obtain a filter cake comprising Ni in an insoluble form and a filtrate comprising Cr in a soluble form;   f) recovering the filter cake comprising Ni in an insoluble form;   g) optionally recovering the filtrate comprising Cr in a soluble form;   wherein step g) further comprises:   passing the filtrate comprising Cr in a soluble form over an ion exchange column, wherein the ion exchange column binds Cr and provides a cleaned aqueous fraction, eluting the ion exchange column with a buffer to obtain a fraction comprising Cr in a soluble form, and optionally concentrating the fraction comprising Cr in a soluble form.   
     
     
         8 . A Cr(VI) product produced by the method according to  claim 7 . 
     
     
         9 . A filter cake produced by the process according to  claim 6 , wherein the filter cake comprises Cr(OH) 3 . 
     
     
         10 . A method for selectively recovering nickel (Ni) and chromium (Cr) from a metal-bearing raw source material, comprising:
 a) mixing with an aqueous medium a metal-bearing raw source material comprising Ni compound(s) in insoluble form, insoluble and/or soluble Cr compound(s) and organic and inorganic compounds to obtain a slurry comprising the first metal in an insoluble form, insoluble Cr, and the organic and inorganic compounds;   b) adding a hydroxide to the slurry to raise the pH of the slurry to 12.0-12.5 and in an amount sufficient to form chromium hydroxide (Cr(OH) 3 ), chromium oxide (Cr 2 O 3 ), or mixtures thereof;   c) adding a first oxidizer comprising calcium hypochlorite to the slurry in an amount sufficient to oxidize said organic and inorganic compounds;   d) adding a second oxidizer comprising MnO 4   −  to the slurry in an amount sufficient to react with the Cr(OH) 3 , Cr 2 O 3 , or mixtures thereof as follows:
   2Cr(OH) 3 +4MnO 4   − =2CrO 4   −2 +MnO 2 +3O 2  or  (1)
 
   2Cr 2 O 3 +4MnO 4   − =4CrO 4   −2 +8MnO 2 +3O 2 ,  (2)
 
   
       wherein CrO 4   −2  is soluble and remains in the slurry to provide a chromate solution and MnO 2  is an oxide precipitate;
 e) filtering the slurry to obtain a filter cake comprising Ni in an insoluble form and filtrate comprising chromate; 
 f) recovering the filter cake comprising Ni; 
 g) treating the filtrate comprising Cr(VI) with acid in an amount sufficient to obtain an acidic solution comprising Cr(VI); 
 h) adding sodium metabisulfite to the acidic solution in an amount sufficient so that the Cr(VI) reacts with the sodium metabisulfite to obtain a reaction as follows:
   2CrO 4   −2 +2Na 2 S 2 O 5 =2Cr +3 +4NaSO 4 +O 2   (3)
 
 
 i) adjusting pH of the acidic solution with a hydroxide in an amount sufficient to obtain a reaction as follows:
   Cr +3 +3NaOH=Cr(OH) 3 +3Na +   (4)
 
 
 
       wherein Cr(OH) 3  is a Cr hydroxide precipitate;
 j) filtering the solution comprising Cr(OH) 3  to obtain a Cr(OH) 3  filter cake; and 
 k) recovering the Cr filter cake. 
 
     
     
         11 . A filter cake obtained by the process according to  claim 10 , wherein the filter cake comprises Ni. 
     
     
         12 . A filter cake obtained by the process according to  claim 10 , wherein the filter cake comprises Cr(OH) 3 . 
     
     
         13 . A method for selectively recovering nickel (Ni) and chromium (Cr) from a metal-bearing raw source material, comprising:
 a) mixing with an aqueous medium a metal-bearing raw source material comprising Ni in insoluble form, soluble and/or insoluble Cr in a Cr bearing material and organic and inorganic compounds to obtain a slurry comprising the first metal in an insoluble form, soluble and/or insoluble Cr, and the organic and inorganic compounds;   b) adding a hydroxide to the slurry to raise the pH of the slurry to 12.0-12.5 and in an amount sufficient to form chromium hydroxide (Cr(OH) 3 ) chromium oxide (Cr 2 O 3 ), or mixtures thereof;   c) adding a first oxidizer comprising calcium hypochlorite to the slurry in an amount sufficient to oxidize said organic and inorganic compounds;   d) adding a second oxidizer comprising MnO 4   −  to the slurry in an amount sufficient to react with the Cr(OH) 3 , Cr 2 O 3 , or mixtures thereof as follows:
   2Cr(OH) 3 +4MnO 4   − =2CrO 4   −2 +MnO 2 +3O 2  or  (1)
 
   2Cr 2 O 3 +4MnO 4   − =4CrO 4   −2 +8MnO 2 +3O 2 ,  (2)
 
   
       wherein CrO 4   −2  is soluble and remains in the slurry to provide a Cr(VI) solution and MnO 2  is an oxide precipitate;
 e) filtering the slurry to obtain a filter cake comprising Ni in an insoluble form and a filtrate comprising Cr(VI); 
 f) recovering the filter cake comprising Ni in an insoluble form; 
 g) passing the filtrate comprising Cr(VI) over an ion exchange column, wherein the ion exchange column binds Cr(VI) and provides a cleaned aqueous fraction; 
 h) eluting the ion exchange column with a buffer to obtain a concentrated Cr(VI) fraction having Cr in an amount 5-10 fold more than present in the filtered Cr(VI) solution; and 
 i) recovering a concentrated Cr(VI) fraction. 
 
     
     
         14 . A filter cake obtained by the process according to  claim 13 , wherein the filter cake comprises Ni. 
     
     
         15 . A Cr(VI) fraction produced by the process according to  claim 13 , wherein the filter cake comprises Cr.