Mechanical Properties of a Composite Backfill Material

CIM Montreal 2003
Alfred Annor, Kristie Tarr, Dan Fynn,
Abstract A research project is being conducted at CANMET- Mining and Mineral Sciences Laboratories, Natural Resources Canada, to investigate the properties of potential ground support materials for use in deep mines. As part of this investigation, composite backfill materials were prepared by combining waste rock aggregates and mill tailings in various ratios, to determine their optimal mix proportions for strength development. A few cemented rockfill and straight tailings paste backfill samples were also prepared and were used as controls for the study. Two sample sizes were used for the investigation in order to evaluate the scale effects on the material behaviour. A set of samples were cured at 44 deg. C to simulate the anticipated temperature conditions in deep mines. A second set of samples were cured at 23 deg. C to provide engineering reference data..

The test results show that compared to either the cemented rockfill or the straight tailings pastefill material, the composite backfill samples were the strongest and stiffest of all the test materials investigated in this study. The composite backfill samples also produced the lowest void ratio and porosity values compared to the cemented rockfill and the straight tailings backfill material.

This paper will present the results of the laboratory investigations to date. It will also outline the on-going work at CANMET - Mining and Mineral Sciences Laboratories to further assess the ground support potential and viability of using composite fills in deep mines.
Keywords: Mechanical properties, Deep Mining, Tailings pastefill, Waste rock aggregates, Cemented rockfill, Ground support material, Composite backfill material, Mill tailings, Special applications fill, Engineering
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