A heap leaching irrigation system. (Image courtesy of Netafim.)

Heap leaching is one of the most important preliminary processes in mineral extraction, but manually monitoring heap leaching is laborious, often requiring teams of workers to walk for miles to check air valves, control valves, plugging and to perform troubleshooting.

Fortunately, a new automated system for monitoring heap leaching enables operators to pinpoint problem locations and address issues immediately.

What is Heap Leaching?

In heap leaching, refined ore is poured in heaps onto a plastic covering. Sprinklers then spray a chemical-leaching solution over the heap surface area and desired minerals are dissolved and collected. These minerals include gold, copper, nickel and uranium.

Some ores are collected over one or two months while others can take up to two years. Although irrigation is sometimes used, drip irrigation of the chemical solution is preferred to prevent evaporation, protect minerals that are exposed to the air and maintain an even distribution of the leaching solution.

In addition to drip line irrigation, the leaching process can be made much more efficient using an agglomerating rotary drum prior to spreading the mound of ore onto plastic. The agglomeration process breaks down particles evenly to facilitate solution permeation. There is also the added benefit of spraying the leaching solution into the agglomerating drum to mix throughout the ore fines prior to spreading the ore onto leaching pads.

After leaching, the ore solution is transferred to a processing plant where desired minerals are then extracted. Recovery can range between 30 and 90 percent, with the remaining unrecovered minerals recycled to the heap.

Automating Heap Leaching

The new automated system from Netafim is designed to allow users to closely monitor the solution flow to the leaching pad and remotely adjust settings for optimal operation. It includes software, hardware and support equipment. Specialty skids incorporate radio or cellular controls, control and air vales, meters, gauges and other sensing equipment.

The skids collect pertinent data, such as line pressures, air valve gauge settings, leaching solution flow and record logs to keep maintenance up to date. The system also immediately alerts operators to major problems in the leaching process, such as line plugging or decreased solution flow to the leaching pads, to ensure that uniform drip irrigation is maintained.

The end result is reduced labor costs, reduced human error and a significantly improved leaching process.

For more information, visit Netafim’s website .