Transbaikal State University, Chita, Russia

V. V. Medvedev, Head of Department, Candidate of Engineering Sciences, medvedevvv1963@mail.ru
V. V. Pakulov, Associate Professor, Candidate of Engineering Sciences

Goaf filling in mineral mining uses different materials to maintain stable equilibrium inside rock masses. Thick ore bodies are extracted by blocks, and the mined-out voids are filled with backfill materials, which creates an artificial rock mass to ensure safe extraction of neighbor blocks without rock caving. To this effect, cemented paste backfills made of a mixture of cement, sand-and-gravel and water are widely used. The costs of backfilling total about 26 % of the overall costs of stoping. The research of the strength and rheological properties of backfill mixtures, implemented with a view to reducing the costs of backfilling and to cut-down the backfill setting time, allowed higher efficiency of mining operations owing to the optimization of backfill composition, with a binder (cement) partly replaced by fly ash from power generation plants, thanks to the selected regime of the backfill preparation and transportation to a placement site, as well as due to the reduced loss of the backfill in transportation and to the lower cost of the binder. The proposed stronger composition of the backfill mixture will allow working under the
backfill mass earlier and at the increased ore output in the systems of mining with backfill, or can reduce the expenses connected with binders at the preserved rated strength and within the set cure time of the backfill.

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