Acid resistant binders for use in copper heap leaching

Heap leaching is process being used to recover metal from low grade ore deposits. The main problem faced during heap leaching was the migration of fine grained particles through the heap, forming impermeable beds which result in poor solution flow. The poor solution flow leads to less contact between the leach solution and the ore, resulting in low recovery rates. Agglomeration of ore into coarse, porous masses prevents fine particles from migrating and clogging the spaces and channels between the larger ore particles. There was one facility in the United States which used agglomeration. This operation agglomerated their ore using leach solution (raffinate), but was still experiencing undesirable metal recovery from the heaps due to agglomerate breakdown. The use of a binder, in addition to the leach solution, during agglomeration would help to produce stronger agglomerates that would not break down during processing. However, there were no known binders that would work satisfactorily in the acidic environment of a heap, at a reasonable cost. As a result, operators of many facilities see a large loss of process efficiency due to their inability to take advantage of agglomeration.;This study has developed multiple standardized testing methods which can be used to evaluate agglomerates. Several binders have been identified, through these testing methods, which will be able to improve metal recovery rates if used in agglomeration for copper heap leaching.