NEW HORIZONS — Microwaves and metallurgy: A Maritime innovation

A New Brunswick-based technology company has developed what it believes is an efficient and economic process for treatment of refractory gold ores and concentrates.

For the past eight years, Fredericton-based EMR Microwave Technologies has been developing its suite of microwave-based technologies. This development phase is the culmination of more than 20 years of engineering research by President James Tranquille, whose academic career prior to the founding of EMR included a wide range of applications of electromagnetic energy, including high-power microwaves.

The company’s team includes four PhDs, seven electrical engineers, a geochemist, a chemical engineer and a mechanical engineer, and its laboratory facilities include more than 100 kW of installed microwave capacity, with associated microwave hardware and instrumentation. In recent years, EMR has formed associations with the University of New Brunswick’s engineering and geology departments, the Canada Centre for Mineral and Energy Technology, and the Research and Productivity Council of New Brunswick.

The notion of using microwave energy to solve metallurgical problems has surfaced from time to time over the past decade in Canada, Australia and the U.S. Typically, however, iniatives in this area have been restricted to the small scale of laboratory experiments and were never expanded and developed for commercial-scale applications.

To protect its technological lead, EMR carried out its developments without public disclosure (pending patent applications). These developments are now well-advanced, and the company is already discussing the application of its technology with mining companies.

More than 600 ore and concentrate samples from at least 30 different sites worldwide have been treated and analyzed by EMR, and the company is confident it has identified a large application market to which its technology may be advantageous, both economically and environmentally.

The subject of its first pilot operation will be arsenopyritic gold ore concentrate. “Pre-pilot” runs have been completed, and EMR says third-party analysis has verified its success. Leach optimization tests are nearing completion and plans are in hand for a continuous, 1/10-scale pilot operation, to be completed by the end of 1995.

EMR says its pre-pilot test results on an arsenopyritic concentrate have confirmed complete oxidation of the pyrite-arsenopyrite into (primarily) magnetite, with solid capture of both the sulphur and arsenic components and no gas effluents. The calcine stream is then introduced directly into a cyanide leach using conventional gold recovery techniques.

The expected capital and operating costs of the EMR concentrate pretreatment process are 5%-10% and 5%-8%, respectively, of the pretreatment costs associated with oxygen pressure leaching, roasting and bio-oxidation. Overall plant capital and operating costs are expected to be 68%-80% and 48%-58%, respectively, compared with the above, alternative techniques.

The company will carry out engineering work on the plant in order to expand the scale of the pyrite-arsenopyrite process, while, at the same time, continuing with research and development. In addition to metal-bearing ores and concentrates, the company believes its process is applicable to tailings, particularly those with high pyrite-arsenopyrite concentrations. EMR is also involved in a project involving the application of microwave energy to liquefy heavy oil and oil sands. This project is said to represent the company’s most advanced technology.

The company hopes to achieve the development and early application of all these technologies through “strategic partnerships” with key industry performers.

— New Horizons provides information on mining-related technology in the research-and-development stage.