Enhancement of the extraction of freezing ore in sublevel caving in permafrost area

One of the factors which can impair effectiveness of sublevel caving in underground ore mining in the permafrost area is freezing of caved ore in stopes, which leads to an essential increment (1.5–2 times) in the loss of the useful component in ore drawing from extraction blocks. This article discusses applicability of chemical agents in prevention of freezing of loose ore and gangue during handling under conditions of negative temperatures in underground mining in the permafrost area. The effect of treatment of caved ore by salt solutions of various concentrations on the ore loss in freezing was estimated in physical simulation of ore drawing using a laboratory installation and a cryocell capable to model temperature conditions in underground openings in the Nezhdaninskoe deposit. The treatment agents were the solutions of 10 percent calcium chloride (CaCl2) and 15 percent sodium chloride NaCl. The solution consumption was varied in the experiments as 2.5, 5, 7.5 and 10 l/t per test series. Preparation of the solutions, treatment, as well as filling and discharge of ore was carried out in the cryocell at the temperature minus 5 °С. The test modeled ore drawing from a single stope until the ultimate ore dilution of 50% in a batch. The ore loss was determined as the difference between the filled ore mass and the discharged ore mass. The tests reveal how the performance of sublevel caving change after treatment of re-freezing ore by salt solutions and prove technical feasibility of such precautions under conditions of negative temperatures in underground ore mining in the permafrost area. Furthermore, the adverse impact exerted on the ore drawing efficiency by the increase in the treatment solution consumption higher than the optimal value due to reduced loose ore flowability is also discovered. The obtained qualitative dependences will be used to develop recommendations on improvement of the sublevel caving efficiency in underground ore mining in the permafrost area.

Zubkov V. P., Petrov D. N. Enhancement of the extraction of freezing ore in sublevel caving in permafrost area. MIAB. Mining Inf. Anal. Bull. 2020;(12):16-24. [In Russ]. DOI: 10.25018/0236-1493-2020-12-0-16-24.

V.P. Zubkov¹, Cand. Sci. (Eng.), Senior Researcher, Deputy Director for Science, e-mail: zubkov @igds.ysn.ru,
D.N. Petrov¹, Cand. Sci. (Eng.), Head of Laboratory, e-mail: petrovdn74@mail.ru,
¹ Chersky Mining Institute of the North, Siberian Branch, Russian Academy of Sciences, 677980, Yakutsk, Republic of Sakha (Yakutia), Russia.

V.P. Zubkov, e-mail: petrovdn74@mail.ru.

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