A growing demand for products made of jewelry and ornamental stones, including nephrite, requires an increase in mining volume. However, only less than 30% of the extracted raw material is suitable for processing. The rest of the low grade nephrites are substandard and unclaimed, and they negatively affect various life spheres. In this regard, their involvement in industrial turnover is an actual task. One of the directions of mining waste use is production of building materials, in particular, cements. The low grade nephrite can act here as mineral additives. In the course of the research, the optimal amount of low grade nephrite waste additive was determined, which is 30% of the cement mass. The grinding time of a raw mix is 10 min. It was found that introduction of the additive affects the hydration activity of cement compositions. Compressive strength of the mixed cement is 25% higher than that of the control sample. At the same time, new phases in the hydrated cement were not recorded. Good physical and mechanical properties of the obtained cements are achieved when hardening in normal humidity conditions. Heat and humidity treatments do not facilitate the hydration processes in binary systems. The conducted studies have shown that low grade nephrite can be used as mineral additives in cement production. This will allow development of not only a new type of product, but also reduction of the negative impact of cement production on the environment.

At present, there is a shortage of high-quality feedstock to produce widely used building materials—concretes. Depletion of natural resources and growing restrictions on their extraction, in connection with environmental protection, necessitate the search for an equivalent replacement for conventional raw materials. Magnesium–silicate rocks are a waste of the mining industry. We researched the possibility of using these rocks as coarse and fine aggregates in heavy concrete production. Following the requirements of the national standards, we studied the physical and mechanical characteristics of the obtained material. It was found that the strength of concrete, made of magnesium–silicate rock coarse aggregate, at the age of 28 days of hardening is within 28 MPa, while the strength of the control sample is 27.3 MPa. Replacing quartz sand with dunite sand also leads to an increase in concrete strength (~4%). Complete replacement of aggregates facilitates an increase in strength by 15–20% than the control sample. At the same time, the density of the obtained materials becomes higher. Concretes have a dense structure that affects their quality. Concrete water absorption is within 6%. The fluxing coefficient is 0.85–0.87. The application of magnesium–silicate rocks in concrete production enables the complete replacement of conventional aggregates with mining waste without reducing the quality of the obtained materials. Furthermore, the issues of environmental protection in mineral deposit development are being addressed.

Relevance. The need to dispose ash and slag waste from CHPP-1 and CHPP-2 in Ulan-Ude, which have a negative impact on the environment. A promising way to eliminate environmental damage is the biological reclamation of ash dumps. Its result is manifested in greening dumps and reducing ash deflation. Aim. To study ash and slag wastes from thermal power plants in Ulan-Ude and establish the possibility of reclamation of ash dumps to reduce the negative impact on the environment. Objects. Ash and slag wastes from the ash dumps of CHPP-1 (ASW-1) and CHPP-2 (ASW-2) in Ulan-Ude. Methods. Chemical, X-ray phase, granulometric, microscopic methods of analysis. Results. The authors have determined chemical, mineralogical and grain compositions of ash and slag wastes from thermal power plants. It was established that they have a high content of silicon, aluminum and a low content of calcium and magnesium. Ash and slag contain vitreous, crystalline and organic components. In the waste, to a greater extent, there is a crystalline phase containing silica, mullite, hematite, magnetite and, to a lesser extent, a glass phase, represented mainly by minerals of the orthoclase group. In terms of granulometric composition, the waste from CHPP-1 is dominated by a finer fraction compared to CHPP-2. Laboratory studies of soil mixtures based on ash and slag waste and local ameliorants (sewage sludge, lignin and chicken manure) were carried out. The optimal ratio of soil components was determined, equal to 4:1:1:1. A beneficial effect of sewage sludge was revealed, as well as a negative effect of high doses of bird droppings on growth and development of plants. Pure ash and slag from CHPP-1 and CHPP-2 without introduction of ameliorants can act as an independent substrate for perennial grasses. Актуальность исследования обусловлена необходимостью утилизации золошлаковых отходов ТЭЦ-1 и ТЭЦ-2 г. Улан-Удэ, которые негативно воздействуют на окружающую среду. Перспективным способом устранения экологического вреда является биологическая рекультивация золоотвалов, результат которой проявляется в озеленении отвалов и снижении дефляции золы. Цель: изучить золошлаковые отходы теплоэлектроцентралей г. Улан-Удэ и установить возможность рекультивации золоотвалов для снижения негативного воздействия на окружающую среду. Объекты: золошлаковые отходы из золоотвалов ТЭЦ-1 (ЗШО-1) и ТЭЦ-2 (ЗШО-2) г. Улан-Удэ. Методы: химический, рентгенофазовый, гранулометрический, микроскопический методы анализа. Результаты. Определен химический, минералогический и зерновой составы золошлаковых отходов теплоэлектроцентралей. Установлено, что они имеют высокое содержание кремния, алюминия и низкое – кальция, магния. Отмечено, что золошлаки содержат стекловидные, кристаллические и органические составляющие. В отходах в большей степени присутствует кристаллическая фаза, содержащая кремнезем, муллит, гематит, магнетит и в меньшей – стеклофаза, представленная в основном минералами группы ортоклаза. По гранулометрическому составу в отходах ТЭЦ-1 преобладает более мелкая фракция по сравнению с ТЭЦ-2. Проведены лабораторные исследования почвенных смесей на основе золошлаковых отходов и местных мелиорантов (осадки сточных вод, лигнин и куриный помет). Определено оптимальное соотношение компонентов почвогрунта, равное 4:1:1:1. Выявлено благоприятное воздействие осадков сточных вод, а также негативное влияние высоких доз птичьего помета на рост и развитие растений. Отмечено, что чистые золошлаки ТЭЦ-1 и ТЭЦ-2 без внесения мелиорантов могут выступать в качестве самостоятельного субстрата для многолетних трав.

The relevance. In recent years, there has been an increased interest in nephrite. Demand for it requires the development of new fields. However, more than 70 % of the extracted nephrite containing raw materials is of poor quality, unclaimed, having a negative impact on different spheres of life. In addition, there is a plunder of substandard nephrite and its involvement in illegal trafficking. In this regard, its use in production is an urgent task not only from the environmental but also from the technological side. The main aim of the research is to establish the possibility of using substandard nephrite containing raw materials in production of building materials. Objects: nephrite-containing rocks of Ulan-Khoda Deposit of Eastern Sayan. Methods: chemical, granulometric, mechanical methods of analysis. Results. The characteristic of Ulan-Khoda Deposit of Eastern Sayan is given. Substandard rocks formed as a result of extraction and separation of valuable fractions from nephrite containing raw materials were studied. It is established that break-stone from them has high quality. It belongs to the First group of gravel, resistant to all kinds of decay and to the environment. The sand from the crushing screenings of substandard nephrite is large sand with grains of angular shape, ensuring the quality of the obtained materials. The acidity modulus of the rock was determined to be 1,59; basicity modulus - 0,63; silicate modulus - 12,66; and quality factor - 0,66. According to its indicators, substandard nephrite is of high quality and can be used in production of building materials. However, it is established that it does not have the ability to harden on its own, but is able to act as a hydraulic additive in composite materials. Cement binding compositions with the addition of substandard nephrite containing raw materials were obtained, their physical and mechanical properties were studied. It is established that the strength of materials depends on the amount of additives and the grinding time of the raw mixture. The technological parameters of obtaining heavy concretes using nephrite were determined. Summary. Thus, substandard nephrite is a promising raw material for production of new types of building materials. Its involvement in production turnover will allow extracting additional profit in processing nephrite-containing raw materials, as well as minimizing the negative impact of mining enterprises on the environment. In addition, the disposal of substandard nephrite prevents its plunder and involvement in the illegal trafficking.

The goal of this study is to safely reduce dust emissions from ash dumps and create green landscapes at waste storage sites. The most effective way to achieve this is through revegetation, which allows ash dumps to be transformed into green landscapes. Unlike similar studies, this paper examines the revegetation of a sand-covered ash dump under the extreme conditions of a sharply continental climate. The following perennial plant species were selected: Festuca pratensis, Bromus inermis, and Medicago polymorpha. Laboratory studies revealed that Festuca pratensis was the most adapted to the laboratory conditions in an indoor environment, while Medicago polymorpha showed poor development. The maximum height reached by Festuca pratensis was 0.27 m, Bromus inermis reached 0.23 m, and Medicago polymorpha reached 0.10 m. In the field experiments, over three months of vegetation, maximum plant heights were as follows: Festuca pratensis—0.09 m, Bromus inermis—0.11 m, and Medicago polymorpha—0.30 m. Medicago polymorpha exhibited a higher rate of development compared to the grasses. Thus, revegetating ash dumps from thermal power plants presents a promising solution for creating green spaces, aligning with the principles of sustainable urban development.