New Leaching Processes for the Recovery of Copper from Primary Copper Resources

Dear Colleagues,

The hydrometallurgical treatment of primary copper ores and concentrates continues to be an active field of innovation. Flotation, smelting, converting and electrorefining continues to be the preferred route for the recovery of copper from primary sulfide resources, accounting for about 80% of world copper production. However, there are many cases where alternatives to the conventional flotation and smelting process are sought by mine operators. These reasons may include: low grade ores which are difficult to concentrate; high impurities, such as arsenic, which may incur stiff penalties or even render the concentrate unacceptable to the smelter; a local need for low-grade sulfuric acid, such as a heap leaching operation; existing capital at the mine site in the form of underutilized solvent extraction and electrowinning capacity; valuable byproducts in the concentrate which may not be well paid at the smelter; or a government mandate to process copper within the country of origin; among others.

It is well known among hydrometallurgists that chalcopyrite, the main mineral source of copper, is among the most difficult sulfide minerals to leach, owing to its tendency to passivate under oxidation. The recent history of innovation in chalcopyrite hydrometallurgy is one of devising clever and practical ways to overcome the difficulty in leaching this important mineral.

Over the last 30 years, the recovery of copper via heap leaching of amenable ores has advanced rapidly to account for approximately 20% of world copper production. Ore-containing copper oxides or secondary copper sulfides are easily treated by heap leaching or heap bioleaching technologies, respectively. The use of heap leaching for primary copper mineralization is now advancing rapidly with the goal of avoiding the costly grinding necessary to prepare these ores for flotation. The key obstacle to heap leaching of primary ores is the low recoveries achieved by conventional heap leaching. However, several technologies currently under development attempt to address this issue through the use of alternative lixiviants or specific additives which catalyze the oxidation of chalcopyrite.

The atmospheric leaching of copper concentrates is also an attractive option. Several promising technologies have been developed over the last two decades, and a few are on the path to commercialization. These technologies are especially attractive for lowgrade or bulk concentrates, and most recover sulfide sulfur primarily as elemental sulfur, thus minimizing reagent and neutralization costs.

The pressure leaching of copper concentrates continues to be attractive for rapid, complete oxidation of sulfide minerals with high copper extraction and arsenic stabilization of iron–arsenate minerals and precipitates. In many cases, the excess sulfuric acid from the autoclaving process can be used to make up the acid demand for associated copper ore heap and dump leaching operations.

Bioleaching of whole ores and concentrates is another promising technology which continues to receive attention in both stirred tanks and heaps.

The purpose of this Special Issue is to collect works related to research and development of novel processes for the recovery of copper from primary copper sulfide resources. It is my pleasure to invite you to submit manuscripts for this Special Issue. Full papers, communications and reviews are all welcome.

Prof. David Dixon
Guest Editor

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• chalcopyrite
• enargite
• alternative lixiviants
• chloride
• iodide
• glycine
• catalysts
• silver
• thiocarbonyl
• galvanic
• heaps
• tanks