Hydrometallurgical process using resin-neutralized-solution of a heap leaching effluent

Abstract

The present invention refers to a hydro-metallurgical process using resin-in-neutralized-solution in heap leaching effluent. More specifically, the process is applicable to lateritic ore, nickel oxidate, cobalt oxidate or a mixture containing metals of interest—nickel, cobalt and other secondary metals, wherein ore is leached by adding an acid or a base with possible pH adjustment, aided by acid or base with neutralization of heap leaching effluent, by adding lime, limestone, soda or ammonia in the temperature of 70° to 95° C. range, at pH in the pH4 to pH5 range; wherein soluble impurity species can be reduced or cementing/complexation techniques, comprising a neutralized leaching effluent, as slurry, made up of solid particles (precipitated compounds) and solution, but ore-free; which is fed into the RINS (resin-in-neutralized-solution) circuit, with no need for solid-liquid separation; wherein the resin-in-neutralized-solution circuit comprises multiple sequential vats stirred in countercurrent flow and wherein the loaded resin is separated from the slurry by screening.

1 . A hydrometallurgical process for recovering value applicable to an initial material selected from the group consisting of lateritic ore, nickel oxidate, cobalt oxidate or a mixture containing metals of the group consisting of nickel, cobalt and other secondary metals using a resin-in-neutralized-solution in a heap leaching effluent, the process comprising:
 a) leaching the initial material by adding an acid or a base,   b) adjusting the pH of the initial material with an acid or base, simultaneously with optimized and selective loading of nickel and cobalt in multiple ionic-exchange stages,   c) neutralizing the heap leaching effluent by adding a neutralizing agent selected from the group consisting of magnesia, lime, limestone, soda and ammonia at a neutralizing temperature between about 70° and 95° C.; and injecting air thereto at a pH in the range of about 4-5,   d) reducing a soluble impurity species in the heap leaching effluent,   e) feeding the resultant neutralization product into the resin-in-neutralized-solution circuit with no need for solid-liquid separation,   f) separating the loaded resin from the resin neutralization solution slurry, in which the slurry's residence time is influenced by the size of the initial material's particles, the resin volume in each multiple ionic-exchange stage is about 10% to 30% of the slurry volume in each vat holding each stage, and   g) wherein the loaded resin exits a first adsorption stage and is pumped to a screen.   
   
   
       2 . The process according to  claim 1  wherein the leaching effluent is neutralized as slurry and is made up of solid particles and solution but ore-free. 
   
   
       3 . The process according to  claim 1  wherein the resin-in-neutralized-solution circuit includes the vats stirred in countercurrent flow. 
   
   
       4 . The process according to  claim 1  wherein the secondary metals are selected from the group consisting of copper, iron, chromium, aluminum, magnesium, manganese and calcium. 
   
   
       5 . The process of  claim 1  wherein an acid acting as leaching agent is selected from the group consisting of sulfuric, chloride or nitric type. 
   
   
       6 . The process according to  claim 1  operating including under atmospheric pressure conditions and temperature below about 80° C. 
   
   
       7 . The process according to  claim 1  wherein the leaching effluent's pH is adjusted by an acid or base according to selected from the group consisting of hydroxides, oxides and carbonates. 
   
   
       8 . The process according to  claim 1  wherein impurities such as trivalent iron and copper are eliminated from the solution through cementing/complexation techniques by adding an agent from the group consisting of iron, aluminum or metallic magnesium. 
   
   
       9 . The process according to  claim 1  wherein reducing agents are added in order to reduce impurities. 
   
   
       10 . The process according to  claim 1 , wherein impurities are precipitated by adding sulfides selected from the group consisting of H 2 S, NaHS, Na 2 S. 
   
   
       11 . The process according to  claim 1  wherein hexavalent chromium is eliminated from the resin-in-neutralized solution by adding a reducing agent. 
   
   
       12 . The process according to  claim 1  wherein the heap leaching effluent, following neutralization and having undergone pre-treatment to eliminate impurities, is directly fed to the resin-in-leach neutralized solution stage with no need for solid-liquid separation. 
   
   
       13 . The process according to  claim 1  wherein the resin-in-neutralized-solution stage includes stirred vats. 
   
   
       14 . The process according to  claim 1  wherein the resin neutralized solution slurry cascades down by gravity from vat to vat, containing about 25% to 45% of solids. 
   
   
       15 . The process according to  claim 1  wherein the resin-in-neutralized-solution separation occurs at an adequate temperature, coherent with the resin's thermal stability limit. 
   
   
       16 . The process according to  claim 1  wherein the resin neutralized solution slurry's total residence time is up to about twelve hours and at about thirty to sixty minutes per stage. 
   
   
       17 . The process according to  claim 1  wherein the resin volume in each stage is about 10% to 30% of the pulp volume in the vat. 
   
   
       18 . The process according to  claim 1  wherein the resin advances from stage to stage in countercurrent flow. 
   
   
       19 . The process according to  claim 1  wherein the loaded resin exits a first adsorption stage and is pumped to a screen. 
   
   
       20 . The process according to  claim 1  wherein the resin is selected from the group consisting of the functional groups of type 2 picolylamine, bis(2 picolyl)AMINE, n-METIL-2PICOLYLAMINE, n(2HYDROXIETIL)2PICOLYLAMINE, n(2HIDROXIPROPIL)2PICOLYLAMINE. 
   
   
       21 . The process according to  claim 1  wherein metal elution can occur selectively and in the multiple stages. 
   
   
       22 . The process according to  claim 1  wherein elution with acidified water (pH 2) removes iron adsorbed in resin. 
   
   
       23 . The process according to  claim 1  wherein an ammonium salt is used for copper removal. 
   
   
       24 . The process according to  claim 5  wherein the concentration of the acid is between about 0.5 and 4M for nickel and cobalt elution. 
   
   
       25 . The process according to  claim 24  wherein the concentration is about 1M. 
   
   
       26 . The process according to  claim 1  wherein the resin is regenerated and ions such as Na+, Ca2+ can be included as mobile ions. 
   
   
       27 . The process according to  claim 1  wherein nickel and cobalt in high concentrations in the eluate and with no impurity interference are separated from each other by extraction methods selected from the group selected from solvents and ionic exchange. 
   
   
       28 . The process according to  claim 1  wherein nickel is sent to an electrolysis unit for recovery in a predetermined form. 
   
   
       29 . The process according to  claim 1  wherein cobalt is recovered as an intermediary product selected from the group consisting of sulfides, hydroxides and carbonates.