Polar Division, Norilsk Nickel, Norilsk, Russia:

A. V. Bylkov, Deputy Director for Mining, andreevaiv@tf.nk.nornik.ru
O. A. Gets, First Category Specialist of Geodynamic Safety Department

Institute of Integrated Mineral Development — IPKON, Moscow, Russia:
V. V. Arshavskiy, Leading Researcher, Candidate of Engineering Sciences

VNIMI Institute, Saint-Petersburg, Russia:
V. I. Khutsishvili, Senior Researcher

With the purpose of tailings utilization within the framework of the environmental program accepted at Norilsk Nickel, Komsomolsky Mine has built and commissioned a full-scale plant for manufacturing backfill mixtures using tailings of Talnakh Processing Plant. At the early stage of operation, it appeared that backfill mixture exhibited low kinetics of strength development. A cause was probable sulfate corrosion of concrete, that induced high stresses in hardened cement paste resulting in its destructuring, deformation and strength loss. Considering the hypothesized corrosion of backfill mixture made of Talnakh Processing Plant tailings and the urgently required stabilization of the mixture curing kinetics, it was decided to undertake comprehensive study of the mixture composed of slag, tailings and cement by compression testing with defi nition of rheological properties and by physicochemical testing. The studies showed the absence of sulfate corrosion of slugs-tailings-cement concrete. In preparation of lowgrade mixture M30, the best strength performance was achieved with a backfill mixture composed of S (slag) = 600 kg/m³, T (tailings) = 800 kg/m³, C (cement) = 170 kg/m³. At the same time, the mixture possessed sufficient flowability — the haulage distance in the available concrete-delivery pipelines on horizontal sites is under 100 m. Aiming to improve rheological properties and flowability of this backfill without considerable reduction in the portions of slag and tailings, various mixture preparation circuits were tested and the best variant was joint ball milling of slag, tailings and cement. The optimum mix formulation was: S = 300–350 kg/m³, T = 1050–1100 kg/m³, C = 160–180 kg/m³. The actual operation of the developed full-scale plant has proved the validity of the above conclusions.
The authors appreciate contribution of Guzanov P. S., Lytneva A. E., Tolparov K. B. and Smolov K. V. to this study.

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