No 1 (2024)

A model has been developed for deposition of rare earth elements with yttrium, trace elements, and non-ferrous metals in platform and activated structures of the Upper Amur region. Genetic types of lanthanide enrichment are considered; lanthanides are shown to concentrate non-uniformly in coal seams and in coal combustion products. Light rare earth elements predominate in coals. The capacity of peat and coal for metal extraction from aqueous solutions was proven. Criteria for a preliminary assessment of coal as a raw material for lanthanides were considered and prospects for their identification were analyzed.

Extracts – hypercoals, were obtained from Tuvinian coals of the Ulug-Khem basin by dissolving them in N-methylpyrrolidone. The yield of extracts is 27.3–79.4%, and their ash content is 0.5–0.8%. The composition of the products of pyrolysis, carried out at 420°C, of the initial coals and the extracts obtained from them was studied. It has been shown that rank “Zh” hard coal (coal from the Elegest deposit) can be extracted most effectively. The qualitative and quantitative compositions of pyrolysis products are not fundamentally different in the initial coals and the corresponding extracts. According to TGA data, the decomposition of extracts (hypercoals) occurs at lower temperatures relative to the original coals with a high yield of volatile components.

The method of differential scanning calorimetry was used to study mixtures of graphite and anthracite with lithium carbonate in an argon atmosphere and in air. It was found that in the temperature range of 100–500°C, a stronger mass loss occurs in argon than in air. This phenomenon is caused by the removal of oxygen compounds with carbon. Competing processes take place in the air – the formation of oxygen compounds with carbon, coal and desorption of oxygen-containing substances. A comparison of thermal effects on the curves of DSC and gravimetry for graphite–lithium carbonate systems in argon, in air is carried out. It was found that up to 700°C in the reaction products, the molar ratio of carbon oxides (IV; II) can be estimated at 10 : 1. Endothermic effects of lithium carbonate melting in an argon atmosphere for mixtures of graphite and anthracite with lithium carbonate were observed at 732°C and 727°C, respectively. In air, the peaks of endothermic effects do not correspond to the heat absorption curves in argon. The most probable explanations of the observed effects are given – the presence of phases of carbonate and lithium oxide; the manifestation of the stretched nature of the pre-transition region of lithium carbonate. By the method of powder X-ray diffractometry, it was found that the burnout of the carbon phase at 500°C in graphite, anthracite does not lead to a significant change in the interplane distances in lithium carbonate.

The ignition processes of mixed fuels formed on the basis of grade 3B coal from the Maikuben deposit and finely dispersed sawmill and woodworking waste have been studied. An analysis of the processes of ignition and combustion of fuel mixtures with different organization of combustion processes was performed. It has been established that the concentration of the wood component has a significant impact on the processes of the onset of oxidation and combustion of mixed fuels. When the proportion of wood component in the mixture increases to 50%, the ignition delay time decreases by an average of 18% in all cases of the studies performed.

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