Publications

A method for determining the minimum practical energy for comminution was developed and is presented in this paper. An objective of the method was to determine experimentally the energy-breakage relationship for a wide size range in order to evaluate the energy performance of both crushing and grinding processes using one energy benchmarking value.

Single-particle compression breakage, referred to in the field of comminution as one of the more efficient forms of mechanical comminution, was the basis for a test regimen to characterize the energy-breakage properties of ores. Existing models for impact breakage were found to be valid for single-particle compression breakage when used in a modified form. A key parameter of the adopted model, the threshold energy, was also investigated for three ore types and a range of particle sizes.

The energy performance of comminution processes at a Canadian mining operation was determined by comparing the determined minimum practical energy, using the new method, with actual site specific energy requirements. In order to evaluate the energy performance of different crushing and grinding technologies, the proposed energy benchmarking method was used to compare the energy performance of alternative comminution flowsheets.

Over the last 10 years the benefits of optimizing both blast designs and operation of crushing and grinding processes, also known as drill-to-mill optimization, have been shown at a number of mining operations. Significant improvements in production and revenue potential are typically associated with the successful implementation of drill-to-mill strategies. Less information is available on the impact of energy intensity with respect to all fuels used.

To address the technical challenges of implementing drill-to-mill strategies, an energy study was carried out for a Canadian open-pit copper mine. In addition to quantifying improvements in energy intensity and impact on carbon footprint, the associated cost benefits due to increased production are also presented.

For many existing and future operations, the implementation of carbon taxes in their respective jurisdictions and increased energy unit costs have provided more economic incentive to reduce the energy intensity of mining processes. For this reason it is of interest to determine the impact of modifying blast designs on the overall energy intensity of an operation.

An energy benchmarking method was developed for mineral comminution and trialed at two SAG mill based operations in British Columbia. The method involves subjecting ore samples to single-particle compression testing to determine the minimum practical energy required to carry out the equivalent comminution duty of site crushing and grinding processes. The minimum practical energy is then compared to the actual energy consumed at the respective mining operation to determine the Benchmark Energy Factor (BEF), an energy performance indicator, of comminution processes at the plant. A key feature of the method is that it is not constrained to one comminution technology, thereby allowing the comminution energy performance of plants comprising different crushing and grinding technologies to be effectively compared. Application of the proposed test to samples prior to and after equipment upgrades provides a method to account for any variation in ore hardness and directly compare the impact of plant modification on energy performance.

Using the BEF metric, the energy performance of two operations treating copper-porphyry ore was determined. Additionally, the energy performance of different comminution technologies was compared. The energy benchmarking method was found to hold considerable potential for representing ore hardness within an Energy Management Information System and as a measurement and validation tool. Furthermore, it was identified as being a potentially valuable metric for inclusion in the TSM Energy and Greenhouse Gas Emissions Management Protocol.