Ash and slag waste (ASW) from coal combustion is a potential source of many valuable components, while their processing also solves an important environmental problem. This study assessed the possibility of extracting valuable components, mainly rare earth elements (REE), from the ASW of the Primorskaya thermal power plant (TPP), Primorsky Krai, Russia. Processes of REE extraction using n-tributyl phosphate from liquid ASW decomposition products have been studied. A significant dependence of the extraction degree on the method of ash leaching, the acidity of the environment, and the content of matrix components is shown. For nitric acid solutions, the degree of extraction of most rare earth elements was more than 90

Ash and slag waste from coal combustion is considered as a source of valuable metals. The results of a study of ash and slag waste from CHPPs in Primorye, coal combustion products in the Amur oblast, and some products of ash and slag waste fractionation for gold and scandium content are presented. The concentration levels of these metals were studied by instrumental neutron activation analysis for a preliminary assessment of their possible industrial significance.

Извлечение угольного концентрата из отходов

Complete elemental analysis of ash and slag wastes (ASW) of Primorskaya thermal power plant (TPP) Primorsky Krai, Russia was carried out. As a result of the research, it was found that among the rare and rare earth elements (REE). The highest content is noted for: Sc (20.9 ppm), Y (36.93 ppm), La (38.97 ppm), Ce (82.51 ppm), Nd (34.41 ppm). That fact correlates with data on the average world content of such components in industrial waste from coal combustion. Various methods for extracting REE from the ASW were tested including fusion with alkali and treatment with various mineral acids. The highest degree of REE extraction (more than 70

The results of scientific research on the development of a comprehensive technology for processing waste from coal mining and coal refining, including in building materials and mineral binders, are presented. The technology of extraction of underburning, slag sand, iron-containing concentrate and microspheres has been tested in production conditions.

The results of research on the development of technological solutions for the production of a new rubber-bitumen binder for asphalt concrete based on the use of industrial waste: used car tires, used car oil and microdispersed aluminosilicate spherical particles obtained from the processing of ash and slag waste (ASW) from thermal power plants are presented. The proposed technological solutions make it possible to obtain high-quality polymer additives for modifying the properties of road bitumen. The elements of novelty of the developed approach include the use, to obtain a granular modifier, of micro-sized hydrophobized aluminosilicate spheres, which are extracted as an additional product during the complex processing of ASW. The positive economic efficiency of technological solutions is ensured by the use of large rubber crumb (more than 8 mm) or rubber chips, their devulcanization together with hydrocarbon fractions of used engine oil and petroleum bitumen at a given temperature to form a gel-like mass, which is further subjected to mechanical grinding in a mill.

The processing of ash/slag wastes were studied, while a complete analysis of the bottom ash of the Luchegorsk thermal power plant in the Primorsky Territory was carried out, and a study was performed on the separation of rare earth elements by various methods. The ash was previously cleaned from unburned coal (underburnt) and iron oxides, the resulting product was processed with various methods. Isolation and separation of products was carried out in several stages. The acidity of the medium was determined, which corresponds to the quantitative precipitation of iron and aluminum matrix ions depending on the initial concentrations of the solutions. Silicon oxide of 97% purity with a high specific surface area was obtained, as well as a solid product with a content of rare earth elements more than 100 times higher than in the original ash samples. The content of rare earth elements in the final product is 74.5% of the content of these elements in the original material, and the product is also enriched with other trace elements such as zirconium, hafnium, and tungsten. When the ash is processed, solid waste remains, which can be further utilized to fabricate ceramic materials and membranes with high technical performance.

The trend in building materials science is to replace the different proportions of Portland cement in the binder. Therefore, the paper proposes the principles of controlling the static and dynamic strength of fiber-reinforced concrete, consisting in the complex effect of the hydro-removed ash and slag mix and basalt fiber on the processes of structure formation of the cement composite. A four-stage purification system for the hydro-removed ash and slag mixture has been developed, including disintegration, flotation and two-stage magnetic separation. It was found that the density of the fresh mix from the dose behaves naturally, and the density of solid samples at low doses slightly decreases. High early strength of the developed composites is noted, in particular, for specimens with ASM, one and a half increase in compressive strength is traced in comparison with non-additive specimens. Combinations of "fiber + ASM" with a quadrupling of strength have a significant effect on bending strength. Successful approximations of the compressive strength and bending strength on the ASM dose for different ages (1, 7, 28 days) are traced with the regular behavior of the coefficients in the power dependences. Revealed a multiple increase in the impact strength of the developed compositions. The use of the results will lead to the possibility of designing high-strength concretes, including for special structures.

The article is devoted to determining the patterns of improving the performance of concrete using hydro-remote ash-slag mix and polypropylene fiber. For this, a four-step methodology was developed for producing purified aluminosilicates from ash-slag mix. A set of experimental studies included the study of both raw materials and developed composites. The compressive strength, flexural strength, and freeze-thaw resistance were chosen as the target characteristics. The mechanism of the effect of purified aluminosilicates on the compaction of the composite structure was determined. At the same time, polypropylene fiber effectively inhibits the formation of cracks and they growth. The optimal composition is the replacement of cement with an ash-slag mix in an amount of 50% and in the presence of fiber. In this case, the compressive strength was increased by 19%, and the flexural strength by 122% compared with the reference composition. Thus, it was proved that both hydro-remote ash-slag mix and polypropylene fiber, and especially from combined use, make it possible to create effective fiber-reinforced concrete with excellent mechanical and durability characteristics.

The possibility of extracting iron oxides from ash and slag wastes of the Primorskaya GRES power plant - (Luchegorsk, Primorsky Kray) was investigated. The positive influence of the energy of ultrasonic vibrations with frequency of 22 kHz and power at1 kW, on the increase in the percentage of extraction of iron from ash and slag waste from thermal power is presented. The optimal time of exposure to ultrasound radiation on ash and slag pulp is determined. A comparison of the magnetic separation of ash and slag waste (ASW) without additional grinding with magnetic separation with preliminary grinding of sample materials down to 90 and 40 microns is carried out. The positive effect of preliminary grinding of the ASW sample on the efficiency of the subsequent magnetic separation is presented. With double magnetic separation of the ASW sample in a magnetic field of 300 T and preliminary crushing of the sample to a particle size class of less than 40 microns, a concentrate was obtained with an iron oxide content of 52.9; the extraction rate of iron oxides equaled 84.2%.

The research paper deals with the prospects of using fly ash and slag waste from the heat power industry of the Primorsky Krai, Russian Federation as an effective filler for composite cement binder. An integrated assessment of the possibility of using this industrial waste is based on the results of studying its microstructure, the assessment of its radioactive background, and the results of X-ray phase and differential thermal analyses, as well as morphological characteristics of the particles.

The objective of this research is to develop new ceramic materials using hazardous serpentine asbestos extraction dust waste (45-70 wt%), clay-sand mix (30-50%) and glass waste (0-5%). The raw materials and ceramics were characterized by XRD, XRF, SEM/EDS and LAMMA analyses. The ceramic bodies were formed by axial pressing, drying and sintering in an electric oven at temperatures of 950 degrees, 1000 degrees, 1050 degrees, 1100 degrees, 1150 degrees, 1200 degrees, 1250 degrees and 1300 degrees C. The flexion resistance values of the ceramics varied in the range of 2.85-56.97 MPa, the water absorption rate ranged from 0.28 to 17.61% and linear shrinkage, between 5.80 and 11.66%. These values of the mechanical properties were achieved due to the chemical interaction of the raw materials and syntheses of mainly glass formations with inclusions of enstatite and forsterite. Using the present findings at the industrial level will provide an opportunity to solve a serious ecological problem of serpentine dust wastes contamination, to recover the ecological situation in the areas of serpentine mining and to avoid the accumulation of serpentine wastes. (C) 2019 Elsevier Ltd. All rights reserved.

The article presents the results of studies on the development of fiber-reinforced concrete using composite binders and basalt fibers obtained in an experimental plasma reactor. To reduce the negative impact of Portland cement on the mineral fiber, composite binders based on Portland cement and fly ash were used in the study. To reduce the normal density in the composition of the binder, a polycarboxylate type superplasticizer was used in the work. The microstructure of cement stone was studied using SEM and IR-spectroscopy. The compressive strength was tested on cubes with an edge of 100 mm according to EN 12390-6, flexural strength – on prisms with a size of 100×100×500 mm according to EN 12390-3. The optimum content of fly ash (30 %) in the composite binder is evaluated, which allows to obtain high mechanical properties. It was revealed that the combined use of composite binder and fiber leads to an increase in compressive and flexural strength of fiber concrete. With the addition of fly ash, both hardening of the structure of the cement stone and a decrease in the alkaline effect of the basalt fiber binding on the surface are observed. Infrared spectroscopy of cement systems showed a change in the phase composition and a decrease in the basicity of the resulting calcium hydrosilicates upon addition of fly ash into the composition binder.

Abstract The results of laboratory studies of the composition and structure of microspheres of ash and slag wastes of Russian Far East energy enterprises (in particular, CHPP-2, Vladivostok) are presented in this scientific work. It has been established that the microspheres are concentrated in particles of technogenic wastes with a size of up to 500 μm, with the prevailing mass of valuable geomaterial (75-80 %) being in narrow granulometric classes from 71 to 100 μm and 100 to 200 μm. Part of the microspheres is represented by unusual techogenic metal alloys (for example, antimony with aluminium), has a density of more than 1g/cm3, and when wet enriched in water precipitates. From a practical point of view, the investigated microspheres cannot be considered a ready commercial product, since they contain a significant amount of carbon concentrate, which is unburned solid fuel particles. In this connection, it is required to develop effective technological solutions for the extraction and purification of microspheres from ash and slag wastes from the thermal power industry of the Far East of the Russian Federation.

In the research paper a computer model of the operation of a vibrational concentrator used to separate the slurry into individual fractions of a grain size by depositing particles of specified characteristics in the field of centrifugal forces is created and verified using the methods of computational hydrodynamics with the Ansys software complex. Using the model will make it possible to: 1) to study the operation of concentrators of various sizes and designs under different operating conditions, with a change in hydraulic characteristics (speed of treated liquid, speed of rotation of the bowl); 2) in the future study the problems of depositing suspended particles of specified characteristics (density, size) in a centrifugal field and determine the concentration of the sediment in the treatment process. The results of the work will make it possible to increase the efficiency of the enrichment of ash and slag waste due to a more thorough understanding of interaction mechanisms between the centrifugal concentrator and the enriched geomaterial.

The results of an investigation of ash and slag wastes (ASW) of enterprises of the energy sector of Primorsky Krai are presented. The averaged contents of the main elements and mineral complexes in Primorsky Krai are given. It is shown that the mineral composition of the ASW data makes it possible to separate the primary raw materials into fractions with different compositions. A scheme is proposed for dividing the initial ash extractors into separate mineral fractions by the particle size and by their physical properties. The predominant concentration of gold, platinum, rare earth elements (REE) and a number of other valuable components in the heavy non-magnetic fraction isolated from the primary ASW was detected. Almost complete absence of gold, noble metals and REE in underburning of coal, magnetic and micro-dispersed fractions of ASW has been demonstrated. A device was offered for complex processing of ash and slag wastes of enterprises of the power industry of Primorsky Krai, which makes it possible to divide the initial ASW into mineral fractions, being raw materials for various industries.