Microwave Treatment of Ores

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Microwave test work is the newest addition to Sepro Labs. Microwave treatment offers several unique benefits due to the differences in heating response between valuable minerals and the hosted gangue minerals.

Most valuable sulphide minerals are very responsive to microwave irradiation while many gangue materials have an extremely low response, and in some cases are completely transparent to microwave. As a result, thermal stress and fractures along grain boundaries are created and the valuable minerals can be freed from the gangue matrix. This unique selective heating can reduce the ore competency and improve the mineral liberation, which allows for potential reduction of comminution energy and an increase in downstream metallurgical recovery compared to untreated ores. The resulting differential heating pattern can be also captured by an infrared camera and be employed by our proprietary sorting algorithm to reject waste rocks and further preconcentrate the mill feed.

To list a few of benefits from our case studies: a coarser P80 grind size, improved mineral liberation, higher ore feed grade, and improved downstream processes such as flotation and leaching. Several improvements for the operations can be provided by microwave pre-treatment and combined sorting: increased plant throughput, easier dewatering and tailings management, higher downstream metal recovery, and potential energy savings of 10 – 46% per tonne of metal production.

To find out more about how we can apply microwave technology to your project, reach out to our team at Sepro Labs. We are happy to discuss the various aspects of our test program and how we can tailor our approach to each of your projects. We also have an existing database on the microwave response of dozens of ores. With limited mineralogical information, we can provide an educated guess about the microwave response of the ore and what the potential benefit could be.

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Phased Test Work Program

Phase 1: Evaluation of Microwave Amenability

In the Phase 1 study, we determine the microwave amenability of your ore by generating a standardized microwave heating curve using a bench-scale laboratory microwave. We also complete a comprehensive chemical and mineralogical analysis of the sample. Data generated from these tests is then compared to our proprietary microwave treatment database to determine the amenability of the sample to microwave treatment. If the results are positive, we move on to Phase 2 of our testing program.

Phase 2: Comparative Testing of Downstream Processes

The Phase 2 study investigates downstream processes with and without microwave treatment. To start, we vary different test conditions such as particle size and the power level to determine the optimal condition for microwave treatment, and then the effects of microwave pretreatment on downstream processes are evaluated by running comparative tests on treated and untreated samples. The bench-scale microwave is used for most of the tests for benchmarking, and preliminary pilot scale treatment can be included as well. Downstream processes can include ore sorting, coarse and fine comminution, gravity concentration, flotation, cyanide leaching, or other processes as determined by client needs. If the results from this phase demonstrate a significant improvement in process performance, we move on to Phase 3 of our testing program.

Phase 3: Pilot Plant Testing

The Phase 3 study uses a 150 kW, 915 MHz industrial-scale microwave system to confirm the bench-scale results at high power with ore samples at size up to 63.5 mm. The Phase 3 test work is run in a semi-continuous mode for the treatment of samples at various testing conditions for optimization of microwave energy usage and maximizing of downstream benefits. The pilot testing results are used to complete a techno-economic assessment and estimate the industrial-scale benefits of microwave technology for your specific ore.