Assessment of an expediency of binder material mechanical activation in cemented rockfill
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This study is aimed to assess the expediency of applying the binder material mechanical activation in a cemented rockfill (CRF), consisting of ground smelter slag, waste of limestone and rock refuse at one of the largest mines, as well as at any other mines which use these components for CRF. The polynomial dependences have been obtained of strength variation of the CRF, which is used in the conditions of studied mine, on the time of consolidation and the ratio of backfill materials. In the CRF mixtures, the mechanical activation was carried out of the granulated blast-furnace slag, and the compliance has been assessed of CRF with the design strength of the backfill massif. In the studied conditions of the ore mine, with ratio of a binder material to filler of 0.5 and the existing cost of backfill materials, the use of mechanical activation of the binder material according to the two-stage grinding scheme turned out to be insufficiently expedient, since the production cost (materials + grinding) of the most economical backfill mixture is only 2.8% less compared with a basic composition. It is noted that the expediency of using the mechanical activation depends on the remoteness of the mineral raw material base, especially the main inert filler that significantly increases the cost of backfilling works. It is shown that in the operating conditions of other mines with a similar component proportion and a close rich mineral raw base, the mechanical activation of the binder material can be enough effective. It has been determined that with an increase in ratio of Cbin/Cin from 1.0 to 4.6, the difference in costs for the backfill mixture production in the considered compositions, where mechanical activation was performed, increases in a positive direction, but for the most economical backfill mixture, if compared to the basic one, it will be changed from 16.8 to 46.0%. An attention is focused on possible ways to increase the expediency of applying the mechanical activation of the binder material by means of forming the backfill massif with different strength along the height of the stope chamber.