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Piston press test procedures for predicting energy-size reduction of high pressure grinding rolls

University of British Columbia

High Pressure Grinding Rolls (HPGR) have been used for over 20 years, however the technology has not received wide industry acceptance despite reports of substantial energy advantages. One barrier is that full and fair consideration cannot be given to HPGR-based comminution circuits for early-stage mining projects, because industry standard tests require large sample sizes for evaluation of the technology. The main objective of the research was to develop methodologies, requiring small sample quantities, to predict the energy–size reduction performance of HPGRs. A key outcome is the development of three piston press testing procedures that require significantly less sample than standard HPGR evaluation methods. One method, referred to as the direct calibration methodology, involves calibrating results of piston press tests against pilot-scale HPGR tests. This methodology was developed primarily for situations where HPGR test data is only available for a composite sample and the energy requirements of individual geometallurgical units within a deposit are to be determined. To address the case where HPGR test results are not available, a second method was developed which relies only on piston press testing and empirical equations that were determined from a database of pilot-scale HPGR results. The simulation-based methodology was also developed to be able to assess the impact of changes in HPGR operation or circuit configuration on comminution performance. An existing energy–breakage model was adopted and modified for application to particle-bed comminution. The three methodologies were compared by applying them to samples from a copper-gold deposit in central British Columbia. Through utilization of these methodologies, the energy–size reduction performance of the HPGR technology can be predicted with small sample requirements which can be applied to a broad range of ore types and provide a stronger statistical basis for the process design. During development of the methodologies, significant research outcomes resulted. Controlled piston press and HPGR pilot tests on the same samples confirmed that normalized product PSDs of the respective equipment can be regarded as equivalent. Furthermore, data from particle-bed comminution tests was used to determine master curves describing breakage appearance functions for the compression mode of breakage.

Text

2015-07-24

Attribution 2.5 Canada

http://hdl.handle.net/2429/54154

Mining Engineering

University of British Columbia

UBCV

http://creativecommons.org/licenses/by/2.5/ca/