The comminution of mineral products is reported to consume 4% of electrical energy globally and is responsible for 50-70% of mine site energy consumption. In the Canadian context where a significant proportion of electricity is generated from fossil fuel sources (9.5% from coal, 8.5% from natural gas, and 1.3% from petroleum), reducing the energy required for processing translates directly to a reduction in greenhouse gas emissions. This is particularly true for mining and mineral processing operations which are often located in remote regions and rely on small-scale diesel power generation. The need to reduce the energy required for comminution and the consequent CO2 emissions is increasingly acute as high-grade deposits are depleted and industry moves towards the processing of low-grade ores which often require fine grinding and tend to require high throughputs to be economically viable. Microwave technology lends itself to clean electrical (vs fossil) energy sources and supports the conversion of fossil-sourced power on mine sites to renewables.
Metallurgical applications of microwave technology have been investigated for over 30 years; however, scale-up has remained a challenge. We propose to combine microwave-assisted sorting and comminution for maximum benefits with minimum energy input. Copper, nickel and gold ores will be exposed to high-power microwave radiation for short times at large particle size (up to 150 mm). The treatment will selectively heat value minerals, resulting in micro-fracture along grain boundaries that will reduce ore competency and increase mineral liberation after grinding. It will also generate a thermal signature that can be used to sort ore particles so that only those that contain value minerals are subjected to fine grinding. We anticipate that comminution energy can be reduced by 24 to 72% using our technology.
The project will result in the establishment of a new disruptive technology whereby the proposed solution will utilize microwave technology to achieve a step-change reduction in the energy required for comminution by:
- Pre-fracturing ores thereby reducing the competency of ores and energy required for grinding
- Preferentially liberating valuable minerals thereby increasing the liberation size
- Rejecting waste rock through microwave-assisted thermal sorting thereby reducing the mass of material to be processed while maintaining throughput of valuable minerals
UToronto, Sepro, Glencore-XPS, COREM, QueensU
Presentation June 4, 2018 by Erin Bobicki
Promotional Video as Part of the Crush It! Challenge