The Silver Bell district in Arizona provides a good example of various electrical and electromagnetic methods applied to the same porphyry copper deposits. Lowest resistivities in the Silver Bell area corresponded with the quartz monzonite porphyry and with zones of sericitic alteration. Likewise, highest IP responses were associated with sericitic alteration. The low resistivities at Silver Bell are caused by the strongly fractured nature of the porphyry system, particularly in sericitic zones, and its interconnected sulfide veinlets. Sericitic zones are highly conductive because of intense fracturing, abundant pyrite mineralization, and sericitic alteration. The higher resistivities of the potassic zone, on the other hand, reflect silicification, disseminated sulfides (as opposed to sulfides deposited in veinlets), and overall less abundant sulfide and clay minerals. Propylitic zones are less fractured and have much lower total sulfides and, thus, higher resistivities. Resistivity weakly correlates with the leached cap and underlying zones of enrichment.

The mine operates four open-pits (North Silver Bell, El Tiro, West Oxide and East Oxide).

All copper in pits will be extracted from the ore utilizing dump leaching.

Copper-bearing solutions from the dump leach and rubble areas are collected and pumped to the solvent extraction plant where the copper in solution is concentrated over 30 times before being pumped to the tank house. In the tank house, the copper is recovered from solution using the electrowinning process and plated on stainless steel starter sheets as high-purity cathodes.

Copper ore placed in rock heaps is leached with a dilute sulfuric acid solution. Solutions from leaching called Pregnant Leach Solution (PLS) are collected in sumps or ponds and pumped via pipelines to a SX-EW plant for increasing the concentration of copper from which electrowon copper cathode is produced. Solutions stripped of copper (called raffinate) are recycled back to the leaching circuits.

Cathode copper produced in the solvent extraction/electrowinning (SX/EW) operation is sold to producers of copper ........