Scientific experimental bases for dry beneficiation of mineral ores

The article presents the results of research on the development of processes and equipment for ore preparation and pneumatic dry beneficiation of mineral ores. The methods of crushing and grinding before enrichment of minerals have been considered, dry enrichment of geomaterials is investigated. Highly efficient prototypes of beneficiation equipment are developed and tested: crushers of multiple dynamic impact RD-MDV-900, DKD-300, centrifugal grinders CMVU-800 and VCI-12, pneumatic separator POS-2000. Fundamental designs are created, and a number of new ore preparation and pneumatic beneficiation instruments are being designed. The efficiency of approbation of an autonomous dry beneficiation complex with new safe environmental standards for the processing of gold-bearing ores, which makes it possible to fully release and extract free gold with a particle size from 10,000 to 100 µm, is shown. The introduction of the dry beneficiation method is very promising for the mining industry. It will allow to reduce capital costs for the construction of stationary beneficiation plants, completely or partially withdraw from the use of process water, the construction of a water supply system, a traditional tailing dam, etc

Расчетно-экспериментальные исследования механических характеристик композитных матереалов

Research and use of composite materials for scientific experiments, engineering activities, as well as industrial purposes has expanded significantly, since the development of technologies for the production of composite materials has made it possible to create and research new types of their physical and chemical properties, reinforcement schemes and fiber lengths, etc. This paper presents the results of computational and experimental studies of the elastic and damping properties of a composite material. The studies were carried out on samples of laminated fiberglass, the dimensions of which are 160 × 16 × 4 mm, cut in three directions, in the direction of the warp, weft and at an angle of 45 degrees, five samples were cut in each direction. To study the mechanical properties of the obtained cantilever samples, the electrodynamic shaker was used. The study of damping properties was carried out by the Oberst method based on the experiment of the frequency response characteristics of cantilever samples. The determination of Young's moduli of laminated fiberglass samples was carried out by the dynamic method, and also the theory of vibrations of continuous systems was used. The experimental data obtained are compared with the results of numerical solutions performed by the finite element method (FEM). Geometric and finite element models were constructed and the natural frequencies and vibration modes of the samples were determined. Frequency and phase response characteristics are given. To reduce the error according to the results of the experiment, statistical processing was carried out. The values of the mathematical expectation and the standard deviation of the mechanical loss coefficient are calculated. The estimation of the measurement error was made on the assumption of the normal distribution of the error.В работе представлены результаты расчетно-экспериментальных исследований упругих и демпфирующих свойств композитного материала. Исследования проводились над образцами стеклопластика СТФ, вырезанных в трех направлениях. Исследование демпфирующих свойств выполнено методом Оберста на основе экспериментальных амплитудно-частотных характеристик консольных образцов. Определение модулей Юнга образцов стеклопластика выполнено динамическим методом. Проведено сравнение полученных экспериментальных данных с результатами численных решений, выполненных методом конечных элементов. Построены геометрические и конечно-элементные модели и определены собственные частоты и формы колебаний образцов. Приводятся амплитудно-частотные и фазо-частотные характеристики

Thermodynamic Analysis of the Low-Grade Heat Sources for the Improvement in Efficiency of Oxy–Fuel Combustion Power Cycles

Today, most of the electrical energy in the world is generated by fossil fuel incineration. This causes significant emissions of harmful substances into the atmosphere. The noted problem can be solved by switching to power plants with zero emissions, operating in semi-closed cycles, and producing electricity through oxygen combustion of fuel. A significant drawback of most of the known oxygen–fuel cycles is the lack of useful utilization of various sources of low-grade heat, which is especially typical for power plants operating on gasified coal fuel; as a result of the gasification process, a significant amount of excess heat is released into the atmosphere. This paper presents the results of the development and study of oxygen–fuel cycle thermal schemes of increased efficiency with coal gasification. It was determined that the modernization of the scheme using the carbon dioxide Rankine cycle for the utilization of low-grade heat makes it possible to achieve an increase in the net electrical efficiency equal to 1.2%

Comparative Analysis of Low-Grade Heat Utilization Methods for Thermal Power Plants with Back-Pressure Steam Turbines

Thermal power plants (TPPs) with back-pressure steam turbines (BPSTs) were widely used for electricity and steam production in the Union of Soviet Socialist Republics (USSR) due to their high efficiency. The collapse of the USSR in 1991 led to a decrease in industrial production, as a result of which, steam production in Russia was reduced and BPSTs were left without load. To resume the operation of TPPs with BPSTs, it is necessary to modernize the existing power units. This paper presents the results of the thermodynamic analysis of different methods of modernization of TPPs with BPSTs: the superstructure of the steam low-pressure turbine (LPT) and the superstructure of the power unit operating on low-boiling-point fluid. The influence of ambient temperature on the developed cycles’ efficiency was evaluated. It was found that the usage of low-boiling-point fluid is thermodynamically efficient for an ambient temperature lower than 7 °C. Moreover, recommendations for the choice of reconstruction method were formulated based on technical assessments

Possibility of implementation of dry technology of gold-bearing ores roughing: case study of “Gurbey” deposit

The aim of the research is to identify the ability/feasibility of dry roughing of ore taking as the example “Gurbey” deposit in Irkutsk Region and to develop a rational scheme for processing ores containing free gold. Studies of the dry processing technology of gold-bearing ore at “Gurbey” deposit with the initial weight of 1,123.8 kg were carried out by semi-industrial plants: the DKD-300 combined shock impact crusher, the CMVU-800 centrifugal mill and the POS-2000 air separator developed by CNMI SD RAS. The sample was subjected to two cycles of crushing and four cycles of grinding followed by pneumatic separation. The circulating load is class +12 mm after the DKD-300 crusher, and for the mill, all screening products are +3 mm, as well as the products of classification -3 + 1 mm of the POS-2000 concentrate. As a result of treatment of the concentration products, 23.93 grams of free gold was recovered (concentration on tables: control, recleaning, concentration of the Mosely minerals by analyzer, magnetic separation, heavy medium separation on bromoform). At the same time, it was established that gold from the ore with initial size of 150 mm can be completely stripped and recovered with the POS-2000 air separator with a particle size of up to 100 microns. At the same time gold extraction into the primary concentrate is up to 60%. Based on the results of the research, a basic scheme for dry roughing of “Gurbey” ore containing “free” native gold was developed using the ore treatment devices: RD-MDV-900, DKD-300 crushers, CMVU-800 centrifugal mill and POS-2000 air separator. The technological scheme is fundamental for gold-bearing ores containing "free" gold of fineness over 100 microns

Minimally invasive surgical treatment for Kimmerle anomaly

Introduction: Kimmerle anomaly is the bony ridge between the lateral mass of atlas and its posterior arch or transverse process. This bony tunnel may include the V3 segment of the vertebral artery, vertebral vein, posterior branch of the C1 spinal nerve, and the sympathetic nerves, which results in the clinical symptoms of this disease. Reports on the surgical treatment of Kimmerle anomaly are rare. There are no reports on minimally invasive surgical treatment of this pathology. Materials and Methods: Six patients with Kimmerle anomaly were treated from 2015 until 2016. Three patients underwent routine surgery through the posterior midline (posterior midline approach [PMA] group). The other three patients underwent decompression with a paravertebral transmuscular approach (PTMA group). The operation time, intraoperative blood loss, clinical symptoms before and after surgery as well as intra- and post-operative complications were compared between the PTMA and PMA groups. Results: The results of the surgical treatments were assessed at discharge and 1 year later. Blood loss, operation time, and intensity of pain at the postoperative wound area were lower in the PTMA group. There were no postoperative complications. The delayed surgical treatment outcomes did not depend on the method of artery decompression. Conclusions: Surgical treatment of vertebral artery compression in patients with Kimmerle anomaly is preferable in cases where conservative treatment is inefficient. A minimally invasive PTMA is an alternative to the routine midline posterior approach, providing direct visualization of the compressed V3 segment of the vertebral artery and minimizing postoperative pain

Possibility of implementation of dry technology of gold-bearing ores roughing: case study of “Gurbey” deposit

The aim of the research is to identify the ability/feasibility of dry roughing of ore taking as the example “Gurbey” deposit in Irkutsk Region and to develop a rational scheme for processing ores containing free gold. Studies of the dry processing technology of gold-bearing ore at “Gurbey” deposit with the initial weight of 1,123.8 kg were carried out by semi-industrial plants: the DKD-300 combined shock impact crusher, the CMVU-800 centrifugal mill and the POS-2000 air separator developed by CNMI SD RAS. The sample was subjected to two cycles of crushing and four cycles of grinding followed by pneumatic separation. The circulating load is class +12 mm after the DKD-300 crusher, and for the mill, all screening products are +3 mm, as well as the products of classification -3 + 1 mm of the POS-2000 concentrate. As a result of treatment of the concentration products, 23.93 grams of free gold was recovered (concentration on tables: control, recleaning, concentration of the Mosely minerals by analyzer, magnetic separation, heavy medium separation on bromoform). At the same time, it was established that gold from the ore with initial size of 150 mm can be completely stripped and recovered with the POS-2000 air separator with a particle size of up to 100 microns. At the same time gold extraction into the primary concentrate is up to 60%. Based on the results of the research, a basic scheme for dry roughing of “Gurbey” ore containing “free” native gold was developed using the ore treatment devices: RD-MDV-900, DKD-300 crushers, CMVU-800 centrifugal mill and POS-2000 air separator. The technological scheme is fundamental for gold-bearing ores containing "free" gold of fineness over 100 microns

Comparative Analysis of Low-Grade Heat Utilization Methods for Thermal Power Plants with Back-Pressure Steam Turbines

Thermal power plants (TPPs) with back-pressure steam turbines (BPSTs) were widely used for electricity and steam production in the Union of Soviet Socialist Republics (USSR) due to their high efficiency. The collapse of the USSR in 1991 led to a decrease in industrial production, as a result of which, steam production in Russia was reduced and BPSTs were left without load. To resume the operation of TPPs with BPSTs, it is necessary to modernize the existing power units. This paper presents the results of the thermodynamic analysis of different methods of modernization of TPPs with BPSTs: the superstructure of the steam low-pressure turbine (LPT) and the superstructure of the power unit operating on low-boiling-point fluid. The influence of ambient temperature on the developed cycles’ efficiency was evaluated. It was found that the usage of low-boiling-point fluid is thermodynamically efficient for an ambient temperature lower than 7 °C. Moreover, recommendations for the choice of reconstruction method were formulated based on technical assessments