The demand for ornamental stone material has led to an increase in the amount of rock mass being processed. However, the production of lapidary works and jewelry result in a significant amount of waste. This study aims to investigate the material composition and physical and mechanical properties of the solid wastes generated during the processing of dolomite type nephrite in the Vitim region. The accumulation of such waste leads to increased costs of transportation, storage, security, and negative environmental impact. The majority of dolomite type nephrite deposits are located in the Northwest, Northeast, and South of China, in South Korea, Australia, Italy, and Poland, with a large deposit in the Vitim region of Russia. In this study, the waste from the Kavoktinsky deposit, the most productive in Russian, was used. A visual and petrographic examination of nephrite, skarn and amphibolite which are components of the solid waste, was conducted. The macro- and microchemical composition of nephrite of different colors was studied, and X-ray phase analysis was performed. The decorative properties of the waste were determined. A radiation and hygienic certificate was obtained. The waste has a crushability grade of 1200, abrasion grade of I1, and frost resistance of F400. The study has shown that the waste does not contain grains of incompetent rocks, clay, dust, and clay particles. The solid waste form the Vitim nephrite processing is of high quality and meets the requirements of GOST 8267-93, except for an increased content of flagstone (flattened) and large size fragments. It can be used for the production of ordinary, decorative, and mosaic concrete, decorative plates, interior decoration of premises, bathrooms, and saunas, and the manufacture of souvenir products. However, further research is needed to investigate the application of the waste as a raw material for stone casting and a slow-release fertilizer. The utilization of this waste not only solves the problem of waste disposal but also improves economic performance of mineral extraction.

Forecasting the thermal regime of mine workings and the surrounding rock mass is a necessary element of the design of underground structures in cryolithic zone. This is particularly necessary when substantiating and selecting reliable methods and means of rock supporting, in order to ensure safe operation of underground structures during the entire standard service life. Changes in the temperature of discontinuous permafrost rocks in the range of negative values (below the ice point in the rock) can lead to a decrease in their strength characteristics, and consequently to a decrease in the stability of workings. The aim of the research was to compare two ways of considering absolute heat sources (point sources and sources uniformly distributed along the length of a mine working) when forecasting the thermal regime in mine workings of underground structures. The dependencies used to determine temperature differences in various methods of considering absolute heat sources were established. For the sake of generality, the dependencies were produced in dimensionless (criterial) form. The variants were calculated, and the results are presented in the form of graphs. The aim is to visually present the influence of the method of heat sources when considering the accuracy of air temperature prediction in an underground facility. Key qualitative and quantitative features of the formation of thermal regime in workings at different methods of considering absolute heat sources were established. It was shown in particular that during the transition from a negative temperature in a working to a positive one, incorrect consideration of the action of absolute heat sources can lead to an almost 30 % (1.26 times) difference (i.e., error) in the calculated depth of thawing of discontinuous rocks. It was also established that at a positive temperature, when the initial air temperature in a structure is more than 7.5 oC, there is no fundamental difference in engineering calculations results depending on the method of considering of absolute heat sources.

The objective of this research is to study the removal of coloring impurities from Algerian kaolin ore (Tamazert kaolin, TK) located in the eastern region of Algeria, utilizing froth flotation process. The results obtained from XRF, SEM, and XRD characterization demonstrate that this local material is an alumino-silicate containing kaolinite, along with impurities such as Fe2O3 (> 2.7 % by weight) and TiO2 (0.28 % by weight) which contribute to its coloring. After homogenization, crushing and milling, several froth flotation tests were conducted on TK. The results revealed that Tamazert kaolin exhibits favorable performance with froth flotation, in order to improve its properties. Based on the results obtained, it can be concluded that all fractions can be treated effectively using froth flotation with an optimal mass yield (weight recovery) of 79.84 % in concentrate for the fraction of 20–40 μm. Iron and titanium, the main coloring impurities in Tamazert kaolin, were reduced from 2.7 % to 0.08 % by weight for Fe2O3 in the fraction 20-40 μm, and from 0.28 % to 0.04 % by weight for TiO2 in the same fraction, as determined by the optimum test. The significant reduction in coloring impurities (Fe2O3 and TiO2) achieved through the flotation process confirms that iron is present in a free state in Tamazert kaolin. It can be ultimately confirmed that the froth flotation process can be a potentially effective process to improve the quality of Tamazert kaolin ore by removing Fe2O3 and TiO2 with satisfactory results which meet the requirements of local companies.

This paper presents the findings of a prolonged field studies that ained to assess the feasibility of using the sewage sludges (SS) form a regional water and wastewater services enterprise to expedite the establishment of a resilient erosion-control plant cover in sand pits located in the Arctic region of the Russian Federation. The study confirms the beneficial impact of the SS on the seed germination, subsequent growth, and development of plants.
The study shows that SS can be used in two ways: first, by applying a continuous layer measuring 5 to 10 cm thick on the soil surface or by fragmentarily applying a layer 2–3 cm thick. Second, through early-winter sowing of seeds directly on the soil surface (under the SS layer) or on top of the sewage sludge. In both cases, an annual enhancement of the qualitative and quantitative parameters of the artificially formed stand of grass was observed. This included a significant increase in its height and density, biomass, foliage cover, and thickness of the formed sod, in contrast to the reference sample.
The present study investigates the characteristics of the floristic composition of the phytocenoses formed in a sand pit. The findings demonstrate that the use of sewage sludge (SS), regardless of the quantity and application method, accelerates the restorative succession in the sand pit. The thick stand in the experimental variants, resulting from the attraction of pioneer vegetation, promotes the complexity of its structure and species composition, rapid vegetation of inner bare areas, and the emergence of natural phytocenoses elements that are specific to the zonal type of vegetation. Additionally, the use of SS stabilizes erosion processes in the study ares. Consequently, the plant community formed in the experiment using SS can be classified as ecologically sustainable, with the potential for independent existence and further development.
These results can serve as a foundation for monitoring efforts and the development of measures to optimize the vegetation of such ecotopes.

Electrical energy consumption in the opencast coal mine is very high. Electric shovels, pumps and coal handling plants consume 75% of the total electricity consumption of an opencast coal mine. In this paper, a modelling framework has been developed for electrical energy use benchmarking (internal as well as cross-sectional) of the mine. To develop a mine specific model for benchmarking electrical energy use statistical approach (linear regression method) has been applied. Specific power consumption (SPC) is used as a benchmarking index to assess the operating energy performance of a specific mine and multiple coal mines of India based on the field studies. Seasonal analysis of the electrical energy usage has also been analysed. Our results show the benchmark SPC as 0.50 kWh/t and the energy-saving potential as 10.7% for a single mine and the benchmark SPC of multiple coal mines as 0.52 kWh/t. The result concludes that SPC widely depends on its capacity and mining method and the developed model are useful for benchmarking and targeting for efficient electrical energy use in opencast mine.

In the oil and gas industry, continuous processes such as oil and gas refining play a great role and are sensitive to many external factors. Such processes require special procedures for stopping and restarting. In order to maintain a sustainable process, the entire system needs to be cleaned by removing of unreacted components. Rejected raw materials are often dumped into a flare leading to tangible environmental problems and significant economic disadvantages. Electrotechnical systems (ETS) play an important role in ensuring continuous technological processes in oil and gas industry. Electric motors are one of the key elements of ETS. The majority of the electrical machines used in industry today are Asynchronous motors (AM) – no less than 80 %. Ensuring their trouble-free operation is one of the key factors in the design, simulation, and analysis of asynchronous motor relay protection systems, including unbalanced conditions of their operation. These conditions can occur due to unbalanced AM connection circuits, supply voltage unbalance, or as any faults in a machine itself. Operating a motor under these conditions will result in shorter motor life, reduced power, wear and aging of the insulation. The study subject was an Asynchronous motor drive of a recycle compressor of a gasoline hydrotreating unit at the fuel hydrotreating integrated unit at the Astrakhan Gas Refining Plant (AGRP). The authors used Matlab simulations to study the facility and its protection systems/devices operation. The method of symmetrical components was selected as the main theoretical method. The authors developed a model of an asynchronous motor drive of a recycle compressor. This involved establishing a set of relay protections (RP) and developing the models of the following protections: sequence filter (symmetrical component filter) (SF), negative sequence (nps) O/C protection, and overload protection. It was demonstrated that the specified relay protection complex fully protects the motor from unbalanced operation conditions. The authors conducted a study of the protection complex operation under different supply voltage unbalances, with different motor loads. They formed a conclusion about the performance of the developed protection complex, and gave recommendations for its technical implementation in a business environment. The study findings can be used as a basis for the development and testing of relay protection components of the entire electrical system of the fuel hydrotreating unit at the Astrakhan Gas Refining Plant.