Safety first in mining

Renaissance of heap leaching for valuable metals


A very broad range of processes are used for the recovery of valuable metals. Heap ­leaching as a hydrometallurgical process is one of the cheapest methods and particularly useful in the case of ores with a low metal content. These characteristics are especially ­attractive to so-called junior mine operators who have relatively little available capital. However, the subject of leaching is a controversial one, because its use for the recovery of gold and silver requires the use of highly-toxic sodium cyanide as the leaching agent and therefore involves a number of hazards. On the other hand, the biological heap leach processes that have become established for nickel and copper recovery have proved to be environmentally-sound methods. This report provides details of market trends, technologies and safety standards and discusses the economic background of selected projects.

1 Introduction

Heap leaching is the term used for hydrometallurgical extraction processes in which crushed and ground ore is heaped up and then sprayed with an aqueous chemical solution in order to dissolve the valuable metals out of the rock [1]. Since the 1970s, heap leaching has become accepted as a practical and cost-effective process for recovering valuable metals like gold, silver and copper from ores with a low metal content. More recently, the process was also used for recovering nickel, zinc and other metals. Relatively low capital cost and operating expenses compared to conventional...

Related articles:

Issue 06/2015

Giant leap in copper leaching technology

The top ore layer of an open pit copper mine is easily processed using heap leach in tandem with solvent extraction and electrowinning to produce copper cathodes. The copper mineral most predominate...

Issue 10/2017

Energy efficiency • Energy intensity in copper and gold mining

1 Introduction In recent years, many mining companies have been able to reduce their specific energy requirements in the ore processing of base metals, gold, silver and platinum group metals, thereby...

Issue 11/2018 Trend reversal

Metal ore mining in Europe

1??? Introduction It‘s been over 150 years since Europe dominated the mining industry. Measured by the production of metal ores, Europe still accounted for 62?% of world revenues in 1860. However,...

Issue 10/2011


Canada’s mining industry experiencing an upswing

1 Introduction In comparison with the Euro countries, Canada’s economy suffered little damage during the recent global economic crisis. The average real economic growth was 2.1?% between 2000 and...

Issue 07-08/2015

Enduring Technology

Flotation of Metallic Ores – an Overview, Part 2

5?Flotation of metal ores Metal-bearing ores can be classified as follows for the purposes of flotation [29]: “Class b” metal sulphides and “borderline” metals, in particular lead, zinc, copper,...