Hazen Tour and Presentation on Gold Recovery from Refractory Ores

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Abstract and Biography

Tour: Hazen Research, Inc. is an employee-owned industrial research and development firm located in Golden, Colorado. The company was founded in 1961 by a small group of metallurgists with strong backgrounds in research and process development for the mining and chemical industries. Over the years, Hazen has grown to its present size of 220 employees with 17 buildings containing an extensive inventory of laboratory and pilot plant equipment. Hazen serves clients from all over the world on projects ranging from bench-scale experiments and analyses to multimillion-dollar continuous pilot plants.

Hazen has developed hundreds of hydrometallurgical, pyrometallurgical, and mineral beneficiation processes for most commercial metals and industrial minerals, and for many inorganic chemicals. Energy clients have utilized Hazen’s expertise to develop processes involving coal upgrading, combustion of alternative fuels, and conversion of a wide variety of feedstocks into energy sources. Waste characterization and treatability studies, waste reduction options, and valuable byproduct recovery from waste streams are routinely performed for industrial clients.

During the tour, you will see a number of bench-scale and pilot plant facilities utilizing a wide number of unit operations for processing ores and other feedstocks into valuable products. The data generated from the laboratory and pilot projects are used to evaluate the technical and economic feasibility of processes and provide engineering data for the design of commercial plants.

Presentation: “Processing Refractory Gold Ores”
Gold has held an allure to mankind through the centuries and is still sought for its value and commercial applications. However, easily extractable gold deposits are rare and current development efforts center on lower-grade, refractory ores. In some ores, the gold is contained in sulfide minerals, such as pyrite, marcasite, or arsenopyrite, that must be oxidized to expose the gold to subsequent leaching and recovery. Other gold ores contain carbonaceous matter that adsorbs gold from solution. This is known as preg-robbing and significantly reduces gold recovery.

Three process options are generally considered for refractory gold ores that oxidize sulfide ores and deactivate preg-robbing carbonaceous matter: thermal oxidation (roasting) in air, aqueous pressure oxidation at elevated temperature and pressure, and biological oxidation using microbes. Each of these will be discussed, demonstrating the need for a deep understanding of science and engineering when developing processes, while staying focused on commercial profitability. Since 1961 Hazen Research has completed more than 1,500 gold-related projects. Many of the commercial gold plants in the United States and throughout the world treating refractory ores utilize process information developed at Hazen.

David Martin: Mr. Martin is a project manager with over 40 years’ diversified engineering, management, and manufacturing experience in the food, energy, chemical, and pharmaceutical industries. With a strong background in chemistry, engineering, and chemical engineering, he has worked in research and development, design, sales, construction, and management. His experience includes research, sales, operations, engineering, and technical staff management. He has held positions of responsibility for capital and operating budgets ranging in scope from small-facility retrofit projects to the design and construction of pharmaceutical facilities valued at more than $10 million. Mr. Martin received his BS in chemistry from Colorado State University in 1972, completed graduate studies in chemical engineering at the Colorado School of Mines, and an MBA from the University of Phoenix in 1994.

Dennis Gertenbach: Dr. Gertenbach is a chemical engineer with over 30 years’ experience. He has been involved with a wide variety of process development projects involving inorganic and bio-based feedstocks. The projects range from laboratory studies through managing pilot plants that demonstrate a particular process. He also has commercial process design, startup, and troubleshooting experience. Projects have included processes to extract and purify metallurgical products, reduce or eliminate waste streams, develop industrial feedstocks from biological sources, and manufacture natural products for the food and health industries. Dr. Gertenbach earned his BS in 1974, MS in 1977, and PhD in 1980 in chemical engineering from the Colorado School of Mines.