Increasing the valuable component content in a pregnant solution due to the activation of leaching solution with cavitation treatment in case of the borehole in-situ leaching (ISL). Methods.To obtain the cavitation effect, a laboratory cavitation plant has been produced. Studies on the sulphuric acid solution activation by means of cavitation were conducted using solutions with 10 g/l of acid content. Studies of changing the sulphuric acid solution activity during treatment with a cavitator were conducted for 3 minutes (24 passes through the cavitator), 5 minutes (40 passes), 10 minutes (80 passes) and 20 minutes (160 passes). The content in the solution of the valuable component was analysed using a KFK-3-"ZOMS" photoelectric photometer.Findings. The laboratory studies have been performed to set the influence of the cavitation process on the leaching solution activity at various degrees of activation and time of reaction. The studies have established that in order to activate the leaching solution, it is proposed to carry out cavitation treatment of sulphuric acid before to additionally fortify the mother solution, which helps to increase its activity. The solution activation leads to an increase in the valuable component content from 18 to 26% in the pregnant solution and its activity is maintained for a long time (up to 30 days).Originality. New dependences have been obtained reflecting the nature of changing the valuable component content in the pregnant solution on the reaction time and the degree of solution activation. Practical implications.The proposed activation method leads to an increase in the valuable component content in the pregnant solution compared to the basic technology, therewith, the activity is maintained for a long time. The proposed technology is characterized by low capital costs, is easily integrated into the existing system and is absolutely environmentally friendly.

Purpose. Increasing the efficiency of gold heap leaching by changing the solution rheological properties due to its mechanical activation. Semi-industrial tests were carried out to verify the results of laboratory work. Methodology. First, semi-industrial tests were carried out without activation of the solution (basic technology), and then the solution activation was applied. The ore amount in the stockpile was 600 kg; the gold content in the ore is 1.12 g/t. At the same time, the concentration of cyanide was 400 ppm. The activation degree was from 3 to 8 minutes, the leaching time was 2, 4, 6 hours, the solution temperature varied from 13 to 30 degrees. Findings. According to the results of semi-industrial tests, the dependence of gold content, pH value, and residual concentration of the reagent on the leaching time was obtained using both proposed technology and the basic one. Comparison of the semi-industrial test results related to the basic technology and proposed one (with the solution activation) showed that the maximum gold content in the productive solution with the basic technology is 1.83 mg/l, and with the activation of the solution it is 2.10 mg/l. Hence, there is an increase in the gold content by 14.7% with the solution activation Originality. Dependence of gold content in productive solution, pH value, and residual concentration of the reagent in solution on the degree of its activation has been obtained. Practical value. The optimum degree of the treatment solution activation during gold heap leaching is determined, which is from 5 minutes to 7 minutes depending on the leaching time, which increases the gold content in the solution by 14.7%.

In order to develop effective measures to ensure the operational condition of the development workings behind the face in the conditions of soft footwall rocks, the construction of local reinforced zones under the protection means has been proposed. The presence of such zones allows transferring the current load deep into the massif and creating a stable foundation under the protective structure. The results of researches concerning establishment of rational parameters of local reinforced zones with application of the method of finite elements, the method of experiment planning and the method of statistical processing of these results have been presented. The empirical dependence of the subsidence of the local reinforced footwall under the protection means on their load, deformation characteristics of the local reinforced zone and host rocks, width of protection means, strength of soft underlying rocks and geometric dimensions of the zone has been determined. The relative indicator of efficiency of local strengthening of a footwall which is used for determining of rational parameters of a locally reinforced zone has been offered.

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At mining and processing complexes, many parameters today are evaluated from the point of view of the total process from geology to the final product. Changes in certain mining parameters inevitable lead to the changes in the following downstream processes. In this article, the focus is on the ore fragmentation, which is one of the most important parameters in many mines as it affects the downstream ore preparation and processing efficiencies, productivities and costs. In most of the cases, the cheapest way to improve the fragmentation of the ore is by changing the drilling-and-blasting design parameters. It of course increases the mining costs, but at the same time decreases the costs of the following processes, which are normally significantly higher. Therefore, authors of this article propose a new way of optimization of the drilling-and-blasting process by introducing new blast design modifications. Based on the analysis, research of the scientific information and the mining practise, the authors discuss the way of creation of the preliminary stress in the block of the open pit and hence improving fragmentation. Physical experimental blasts in “Belaya Gorka” open pit were performed and shown positive results reflecting a potential for continuation of the research in this direction in the future.