Limonite and Saprolite Heap Leach Process

Abstract

A process for the recovery of nickel and/or cobalt from a lateritic ore by heap leaching, the process including the steps of: a) forming one or more heaps from a lateritic ore body wherein that lateritic ore body includes a blend of both limonitic and saprolitic type ores; b) leaching the one or more heaps with a leach solution; and c) recovering the nickel and/or cobalt from the resultant heap leachate.

1 . A process for the recovery of nickel or cobalt from a lateritic ore by heap leaching, the process including the steps of:
 a) forming one or more heaps from a lateritic ore body wherein that lateritic ore body includes a blend of both limonitic and saprolitic type ores;   b) leaching the one or more heaps with a leach solution; and   c) recovering the nickel or cobalt from the resultant heap leachate.   
     
     
         2 . A process according to  claim 1  wherein the blend of limonitic and saprolitic type ores includes at least 15% to 85% wt of limonitic type ore and 15% to 85% wt saprolitic type ore. 
     
     
         3 . A process according to  claim 2  wherein the blend includes at least 40% to 60% wt of limonitic type ores and 40% to 60% wt of saprolitic type ores. 
     
     
         4 . A process according to  claim 1  wherein the one or more heaps include a blend of limonitic and saprolitic type ores in the weight ratio range of from about 5:1 to 1:5. 
     
     
         5 . A process according to  claim 4  wherein the blend is in a weight ratio of about 1:1. 
     
     
         6 . A process according to  claim 1  wherein the overall silicon content in the blend of limonitic and saprolitic type ores is greater than 13% wt. 
     
     
         7 . A process according to  claim 1  where the overall silicon content in the blend of limonitic and saprolitic type ores is in the range from 15% to 40% wt. 
     
     
         8 . A process according to  claim 6  wherein the overall quartz content in the blended limonitic and saprolitic type ores is greater than 28% wt. 
     
     
         9 . A process according to  claim 8  wherein the overall quartz content is within the range of from 32% to 86% wt. 
     
     
         10 . A process according to  claim 1  wherein the blend of limonitic and saprolitic type ore is predominantly transition zone ore. 
     
     
         11 . A process according to  claim 1  wherein the limonitic and saprolitic type ores are sourced separately from a limonite zone and a saprolite zone, or a combination of ores from each of a transition zone, the limonite zone, and the saprolite zone. 
     
     
         12 . A process according to  claim 1  wherein the leach solution is a mineral acid selected from the group consisting of hydrochloric acid, sulfuric acid or nitric acid. 
     
     
         13 . A process according to  claim 12  wherein the leach solution is acid supplemented fresh water, seawater or saline water. 
     
     
         14 . A process according to  claim 12  wherein the concentration of the acid is sufficient to effect dissolution of nickel from the ore. 
     
     
         15 . A process according to  claim 13  wherein the concentration of the acid is at least about 0.10 molar. 
     
     
         16 . A process according to  claim 1  wherein the ore is pelletised or agglomerated prior to forming into the one or more heaps, by mixing the ore with concentrated sulfuric acid. 
     
     
         17 . A process according to  claim 1  wherein a plurality of heaps is formed and arranged in at least a primary and a secondary heap, the process including the steps of:
 a) adding the leach solution to the secondary heap to produce an intermediate product liquor; and   b) adding the acidic intermediate product liquor to the primary heap to leach the primary heap in a counter current process, and producing a nickel and cobalt rich resultant heap leachate for further nickel or cobalt recovery.   
     
     
         18 . A process according to  claim 17  wherein the intermediate product liquor is separated into two portions; a first portion having a pH of greater than 2 that is removed and transferred downstream for nickel or cobalt recovery, and a second portion having a pH of less than 2 that is used for the leach solution for the primary heap in the counter current system. 
     
     
         19 . A process according to  claim 1  wherein nickel and cobalt are recovered in a process that includes ion exchange (IX), solvent extraction (SX), electrowinning (EW), multi-stage neutralization to produce Ni/Co hydroxides, pyrohydrolysis to produce Ni/Co oxides and sulfidation to produce Ni/Co sulphides.