Solid Fuel Chemistry

The use of anthracites from Eastern Donbass as a technological raw material for the production of filtrants and sorbents, which are widely used in many branches of industry and national economy (industrial water and wastewater treatment, oil spill response, gold and silver extraction from the pulp of mining plants, etc.), is considered.

Technologies for the conversion of coal mining and processing wastes into commercial products depending on the characteristics of raw materials are considered. It is shown that the production of construction materials from coal wastes can be most popular. The production of rare earth element (REE), aluminum, and iron concentrates; coagulants for water purification; fuel additives (energy generation coals); and additives for the metallurgical industry from coal wastes was studied. The concept of a technological complex, which makes it possible to obtain a wide range of marketable products from coal wastes in a single cycle, is proposed for the first time. The basic configuration of integrated technology was developed, and the basic equipment for technological processes was selected. The possible results of the implementation of this technology in industry are shown.

The possibility of producing synthesis gas with an H₂ : CO ratio of 2.0 or higher by the gasification of mechanically activated mixtures of biomass and tar was shown. A copper–zinc catalyst was synthesized, and its morphological characteristics were studied using electron microscopy and BET adsorption methods. It was established that the use of the synthesized catalyst makes it possible to obtain methanol from synthesis gas. Selectivity for methanol formation decreased with the synthesis temperature; in this case, the conversion of synthesis gas and carbon dioxide increased.

The use of various combustible wastes with the aim of processing them into solid, gaseous, and liquid energy carriers was studied. It was found that, on condition of appropriate preparation and proper use technology, combustible wastes can be even less hazardous to the environment than traditional energy sources, including coal.

The results of a study of the extraction of molybdenum compounds introduced into hydroconversion heavy petroleum feedstock as part of a catalyst precursor are presented. A solid phase insoluble in an organic solvent, a Mo-containing concentrate, is isolated from the vacuum hydroconversion residue by filtration. According to X-ray powder diffraction, molybdenum in the concentrate is almost completely contained in the form of MoS₂, which is transferred by hydrometallurgical method to the solution of the initial molybdenum precursor. It has been shown that the most effective solvent for isolating molybdenum concentrate from the hydroconversion residue is toluene. When a mixed aqueous solution of nitric and sulfuric acids acts on an isolated concentrate, depending on the ratio of components and solution flow rate (multiplicity) as well as temperature and processing time, a high degree (~99%) of molybdenum compound extraction into the solution is achieved.

The article reviews data on the mercury concentrations in coals of the South of Kuznetsk basin (Kuzbas) in Kemerovo region in Russia and in the surrounding soils. The Hg concentrations in the soil (30 samples) and coal (207 samples) were determined by the atomic absorption using RA-915+ mercury analyzer with pyrolytic attachment. The comparison with previous research showed that over the last 25 years the mean Hg concentration in the soils decreased by a factor of 2.8. Based on the dominating contribution of the coal dust and coal combustion products into the total Hg influx in the environment, it is possible to predict increase of the Hg background level in the city and the surrounding area along with the coal production growth in the area without using modern effective dust suppression.

In the present study, a stoichiometric thermodynamic equilibrium model has been introduced for downdraft biomass air gasifiers. Experimental data from five pilot scale downdraft gasifiers, that use different types of biomass fuels, are compared with the findings of the model. It is presented that the developed model is efficiently simulating H₂, CO, CH₄, and CO₂, volume fractions and the heating value of synthesis gas. The minimum error of comparisons has been found about 1% and the maximum error was obtained to be less than 25%. The level of sensitivity evaluation has been performed to the model to check out the effect of gasifier temperature, biomass moisture content, air to fuel ratio and equivalence ratio on the syngas form and lower heating value of syngas from the downdraft gasifier. The model results are compared with several existing experimental data of the literature. It is concluded that the findings of the study are a good candidate to model the downdraft gasifiers.