Heap leaching, beyond the headlines

MINING.com spoke with some leading heap leach experts earlier this week at the first annual Heap Leach Solutions Conference in Vancouver.

For the benefit of the layman, heap leaching is an extraction process in mining in which a series of chemical reactions is used to separate metals from ore.

The technology has ancient origins, enjoyed a rebirth in the 1970s and began to gather real momentum in the 1990s.

Modern heap leaching started with uranium as the target metal, and made its way eventually to copper, "but it was with gold extraction that the technology really took off," said Henry Schnell, a mining professional with decades of heap leach experience.

Though leaching has become increasingly important to the mining industry, it has also received a great deal of negative press of late, mostly related to the use of cyanide.

Dr. David Dreisinger, a professor at the University of British Columbia and a board member of PolyMet Mining, addressed public perception at the conference, saying that there's an "unnecessary fear" over cyanide.

Others, including Dreisinger, said that the mining industry needs to do a better job of promoting itself and educating the public on its practices.

"We're facing a skeptical public and have to recognize that," said Dreisinger .

Dreisinger also spoke about progress in heap leaching technology – a technology which most people at the conference agreed was 'fully matured'.

That doesn't mean the industry is not developing. As Dreisinger points out, new applications of heap leaching are on their way.

Also speaking at the conference was John Marsden, president of Metallurgium – a consulting firm.

Marsden spoke about managing expectations during a heap leaching operations and what can happen when production ramps up.

Reluctant to generalize, Marsden did point out that investors should watch out for "unreasonably high recovery numbers" and take a close look at the company's track record.