Technical Director, Mineral Processing
Wardell Armstrong International
A Chartered Mineral Processing Engineer with over 35 years of experience specialising in gold CIP/CIL/heap/dump leaching and tin/tungsten/base metal gravity and flotation processes. Experience includes site operational management, plant commissioning, greenfield start-ups and expert consultancy, including due diligence reviews, scoping, pre-feasibility and feasibility studies and NI 43-101 reporting. Acted as site metallurgical superintendent at various overseas projects including in Ivory Coast, Mauritania, Guinea, Ghana, Philippines, Bulgaria, Kazakhstan, Venezuela, Brazil, South Africa and UK.
Refractory Gold Ores – An Overview of the Advantages and Disadvantages of Different Processing Methods
Refractory gold ores are those where the gold is very fine and encapsulated within sulphide mineralisation, typically pyrite and/or arsenopyrite. The presence of “preg-robbing” carbonaceous material can also result in refractoriness of the ore. The four traditional processes for sulphide ore pre-treatment include Ultra-Fine Grinding (UFG), BIOX®, Roasting and Pressure Oxidation (POX). Each process has advantages and disadvantages and process selection is project-specific based on ore mineralogy, gold and sulphur grades, metallurgical testwork results, environmental requirements and, ultimately, what is the optimum for the project economics based on the projected capital and operating costs. With over 30% of the remaining world’s gold resources deemed to be refractory, these and other processes being developed will become more mainstream. These processes are expensive and, historically, relatively high gold feed grades have been required to justify their use. With generally declining head grades, there is an emphasis on improving process efficiency and costs, both capital and operating, and developing new cheaper technologies.