Using Piston Press Tests for Determining Optimal Energy Input for an HPGR Operation

SAG2015: The 6th International Conference on Semi-Autogenous and High Pressure Grinding Technology

Author: Z. Davaanyam, B. Klein, and S. Nadolski

Date: Sep 20th, 2015

Multiple trade-off studies have shown that grinding circuits with high pressure grinding rolls (HPGR) can be more energy efficient than the circuits with semi-autogenous (SAG) mills. However, such studies are difficult to conduct because the current practice of sizing and selecting the HPGR requires large samples for pilot-scale testing that are expensive and difficult to obtain. There is therefore a need for a small scale test procedure that can reliably predict the energy requirements of the HPGR for a given ore-body.

Three methodologies involving piston press tests were developed recently at the Norman B. Keevil (NBK) Institute of Mining:

  1. The “Direct Calibration Methodology” calibrates piston press test results to pilot-scale HPGR results on a representative composite sample from a deposit. Piston press tests can then be used to determine the energy-size reduction relationship for a range ore types within the deposit.
  2. Similarly, the “Database-Calibrated Methodology” calibrates piston press tests against a database of pilot-scale HPGR and piston press tests. The database includes results from pilot scale HPGR tests on 15 different ores for which piston press testing was also conducted.
  3. The “Simulation Methodology” involves piston press testing on five narrow size classes of particles at three energy levels from a mineral deposit. The results are used to define the energy-breakage relationship that can be used for circuit simulation.

All three test methods are valuable tools for predicting the energy-size reduction relationship for the HPGR. The ability to conduct simple piston press tests requiring less than 10kg of sample greatly assists assessment of the HPGR for early stage projects.

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