Environmental Benefits of the CESL Process for the Treatment of High-Arsenic Copper-Gold Concentrates

摘要

The ongoing development and implementation of hydrometallurgy for the processing of copper concentrates is driven by several factors, including: the increasing trend in global copper consumption, the increasing development of challenged resources (complex mineralogy, lower grade ores, deleterious elements), increasingly stringent environmental and occupational health and safety regulations, and the high cost and limited availability of treatment and refining options for complex concentrates. The traditional method for processing high-arsenic concentrates is blending with large amounts of clean concentrate. This is followed by the traditional processing route of smelting and refining, which results in the generation of an unstable arsenic trioxide product. Through a partnership formed in 2009 between Teck, Canada's largest diversified resource company, and Aurubis, a leading custom concentrate refiner and the world's largest copper recycler, extensive integrated pilot scale tests have been completed using the CESL Process to treat high-arsenic copper and copper-gold concentrates. The key unit operations of the CESL Process are: concentrate regrind, oxidative pressure leach with a chloride catalyst, followed by conventional solvent extraction and electrowinning. For concentrates also containing precious metals, the residue from the CESL Process is processed through a pressure cyanidation circuit followed by a traditional precious metals recovery circuit. The result is a sustainable and cost effective process for the production of high-quality copper cathode and precious metals. This paper describes the environmental benefits of the CESL Process for the treatment of high-arsenic copper and copper-gold concentrates in comparison to traditional processing routes. The CESL Process provides tangible environmental benefits to water, air, climate and soil such as: decreased fresh water consumption; decreased particulate (as arsenic trioxide) and sulfur dioxide emissions; decreased greenhouse gas emissions; and decreased unstable arsenic species for ground disposal.