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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. [ABSTRACT FROM AUTHOR]

• A small-scale locked-cycle piston press test to provide design information closed-circuit HPGR. • The test ware inspired by the Bond ball mill grindability test. • Piston Work Index describes the samples' resistance to HPGR comminution. • The test results were within ± 20% range of HPGR tests for a fine feed. The increased energy efficiency of HPGR-based circuits as an alternative to AG/SAG mill circuits has been well established. However, assessing the HPGR technology involves pilot-scale testing requiring large samples, which is expensive and may be prohibitive, particularly for early-stage projects. As a result, the uptake of HPGR technology has been slow, emphasizing the need for small-scale tests for sizing and selection. A reliable small-scale test for preliminary HPGR circuit design is essential in garnering the mining industry's interest in the broader adoption of HPGRs. Inspired by the Bond ball mill grindability test, a small-scale locked-cycle piston press test was developed to estimate the circulating load and circuit-specific energy consumption for closed-circuit HPGR operation. The test introduces the Piston Work Index, which describes the ore samples' resistance to HPGR comminution and can be subsequently used to estimate the HPGR circuit-specific energy consumption. The test results indicated that the circuit-specific energy and circulating load obtained from the small-scale piston press test were within the ± 20% range of the locked-cycle pilot scale HPGR tests for a fine feed representing quaternary stage HPGR application. [ABSTRACT FROM AUTHOR]