Zonia Copper Oxide Project, Arizona
The Zonia project would employ open pit mining with a conventional copper acid heap leach system. The mineralized material would be crushed in a three-stage crushing circuit to a nominal P80 size of 25mm. The crushed material would be agglomerated with acid containing solutions using either raffinate or fresh sulfuric acid, and then be delivered to the heap via overland conveyor and grasshopper conveyors and stacked in 10-metre (m) lifts with a radial stacker operating in retreat mode. The heap is designed to contain up to 10 lifts for a maximum height of 100 m, each with an interlift liner.
The SX circuit consists of two extraction stages and one stripping stage using a conventional mixer/settler arrangement. The electrowinning (EW) circuit consists of two parallel banks of 50 polycement cells with 1m2 cathodes. The plated copper cathodes are stripped using a mechanized stripping system after being washed. Copper cathodes are then sampled and bundled for shipment.
Good copper extractions were achieved from the majority of the metallurgical samples at Zonia, and range from 59% to 81% in a 91-day locked cycle column leach test (excluding the high sulfide and low grade samples). The copper extraction from the master composite sample, with a nominal P80 size of 25 millimetres (mm), was 77.8%. The overall copper extraction based on the total copper assay (%TCu) for the deposit is estimated to be between 71% and 75%. For pit optimization, copper recovery has been assigned based on mineral type: copper oxide minerals at 73%, secondary copper sulfides at 70% and primary copper sulfides at 0%.