Reduced acid leaching and resin in leach extraction from acid consuming copper ores

Abstract

The invention provides processes that significantly reduce acid consumption while maintaining efficient leach recovery of copper from oxide and acid consuming ores. The invention provides a hydrometallurgical process that reduces acid required for leaching in the presence of a solid ion exchange media. The presence of the ion exchanger leads to copper extraction from solution into the ion exchange phase, the removal of the copper from solution shifts the dissolved copper equilibrium, enabling additional copper dissolution at weak acidities where normally the leaching equilibrium would be hindered. In select embodiments, the process is not reliant on an external neutralising agent to control pH but rather on the acid consuming characteristic of the ore being processed and a limit to the amount of acid added. At the pH at which the leach is controlled, iron (if present) is predominantly present as the ferrous ion, which has a lower affinity for the resin than copper.

1 . A process for extracting copper from a comminuted acid consuming copper ore, comprising:
 adding a mineral acid to the comminuted copper ore in the presence of an ion exchange medium, to reach a target leaching-and-resin-loading pH greater than pH 1 in a resin-in-leach leaching solution, wherein at the target leaching-and-resin-loading pH, copper ions leached from the ore are bound with high affinity by the ion exchange media;   maintaining leaching conditions in the resin-in-leach leaching solution for a leaching time period, adding mineral acid so as to maintain the leaching-and-resin-loading pH, so that the ion exchange media is loaded with copper ions leached from the ore, to provide a copper-loaded ion exchange media in a barren resin-in-leach solution;   separating the copper-loaded ion exchange media from the barren resin-in-leach solution;   eluting copper from the copper-loaded ion exchange media to provide a regenerated ion exchange media and a copper bearing eluate;   recycling the regenerated ion exchange media to the resin-in-leach leaching solution; and,   recovering copper from the copper eluate.   
     
     
         2 . The process of  claim 1 , wherein the target leaching pH is a pH range, and the range is between about 2 and about 4. 
     
     
         3 . The process of  claim 1 , wherein the target leaching pH is a pH value, and the pH value is between about 2 and about 4. 
     
     
         4 . The process of any preceding claim, wherein the leaching time is 2 to 12 hours. 
     
     
         5 . The process of  claim 4 , wherein the leaching time is 2 to 6 hours. 
     
     
         6 . The process of  claim 4 , wherein the leaching time is 6 to 12 hours. 
     
     
         7 . The process of any preceding claims, wherein the leaching conditions are maintained so that the percent extraction of acid soluble copper from the ore is at least 50%. 
     
     
         8 . The process of  claim 7 , wherein the percent extraction of acid soluble copper from the ore is 80-100%. 
     
     
         9 . The process of any preceding claim, wherein the solids in the resin-in-leach leaching solution are in the range of 5% to 40% by weight. 
     
     
         10 . The process of  claim 9 , wherein the solids in the resin-in-leach leaching solution are in the range of 25% to 35% by weight 
     
     
         11 . The process of any preceding claim, wherein the ore is a copper-and-iron-containing ore, and at the target the leaching-and-resin-loading pH, dissolved iron is present predominantly as ferrous ions. 
     
     
         12 . The process of any preceding claim, wherein the leaching-and-resin-loading pH is maintained at a value greater than about 2.5 to 2.8, so as to reduce the solubility of ferric ions and enhance loading of copper ions on the ion exchange media. 
     
     
         13 . The process of any preceding claim, wherein the ore comprises a copper oxide ore. 
     
     
         14 . The process of any preceding claim, wherein the ore comprises delafossite, chrysocolla, azurite, dioptase, brochatite, tennorite, atacamite, malachite or mixtures thereof. 
     
     
         15 . The process of any preceding claim, wherein the ore comprises antlerite, bonattite, chalcanthite, Brochantite, Ceruleite, Chalcosiderite, Chenevixite, Krohnkite, Lavendulan, libethenite, paramelaconite, poitevinite, posnjakite, pseudomalachite, turquoise, or wroewolfeite. 
     
     
         16 . The process of any preceding claim, wherein the ion exchange media comprises a cross linked polystyrene or acrylic polymer functionalized with iminodiacetic (IDA) groups. 
     
     
         17 . The process of any preceding claim, wherein the ion exchange media comprises a cross linked polystyrene or acrylic polymer functionalized with picolylamine groups. 
     
     
         18 . The process of any preceding claim, wherein the ion exchange media comprises a cross linked polystyrene or acrylic polymer functionalized with N-(2-hydroxypropyl)-2-picolylamine (HPPA) groups. 
     
     
         19 . The process of any preceding claim, wherein the ion exchange media comprises resin beads having an average diameter greater than about 500 μm. 
     
     
         20 . The process of any preceding claim, wherein elution of copper from the copper-loaded ion exchange media is carried out so that the copper bearing eluate is substantially free of excess free acid. 
     
     
         21 . The process of any preceding claim, wherein copper is recovered from the copper bearing eluate by electrowinning or cementation. 
     
     
         22 . The process of any preceding claim, wherein the copper bearing eluate is upgraded by solvent extraction prior to recovering copper. 
     
     
         23 . The process of any preceding claim, wherein the ion exchange medium is mixed with the comminuted copper ore at a wet settled resin volume concentration of at least 0.5%. 
     
     
         24 . The process of any preceding claim, wherein the ion exchange medium is mixed with the comminuted copper ore at a wet settled resin volume concentration of about 3% to 10%. 
     
     
         25 . The process of any preceding claim, wherein the ion exchange medium is mixed with the comminuted copper ore at a wet settled resin volume concentration of about 20% to 25%.