Coke and Chemistry最新文献

Generally, in underground mining, coking coal beds are gas-bearing and require degassing. Therefore, the gas dynamics of the bed is a key aspect in the development of coal–methane deposits. The prevailing standards are based on sorption theory, but current requirements are associated with new approaches to understanding gas liberation. New results based on the hypothesis of a coal–gas solid solution indicate that the irreversible decomposition of that solid solution due to the relaxation of the mine pressure provokes gas liberation from the bed in the appropriate conditions. Given the steady increase in the speed of face movement, it is clear that ideas from the past (1950s–1970s) regarding the properties of the coal bed and the processes that occur there do not meet current requirements. Since the breakdown of some part of the coal–gas solid solution changes the gas structure of the bed, we may determine the gas flow into the bed’s filtration volume by analysis of that breakdown. The gas balance equation in terms of the forms of methane in the bed takes account of the influence of methane in solid form on the sorptional potential of coal and permits quantitative assessment of changes in the gas structure within the bed under the influence of geomechanical mining processes.

Coke plant tar is oxidized at 220°C in air current at 1.8 L/min for 4.5 h. In this process, elemental sulfur is added in quantities of 20, 30, and 40 wt %. With increase from 20 to 40 wt %, penetration declines from 55 to 38 mm; and the softening temperature (determined by the ring and rod method) declines from 52 to 45°C. The change in the physicomechanical properties of the mixture when adding 20, 30, and 40 wt % S is studied by X-ray phase analysis. With 30 wt % S, the reaction of sulfur with the aromatic rings forms 2-naphthanol-6-sulfonic acid (OHС₁₀Н₆SO₃H).

Oxidized and unoxidized coal samples of various ranks are compared, as well as the humic and fulvic acids derived from those materials. Petrographic analysis shows that macerals of the vitrinite group predominate in the coal samples; the oxidized samples belong to oxidation group OK II. B coal (lignite) and D coal (long-flame coal) undergo more profound changes than G coal (gas coal) on oxidation (weathering). Compared to their unoxidized counterparts, the oxidized coal samples are characterized by higher ash content, yield of volatiles, and content of oxygen, nitrogen, and sulfur. The elemental composition of fulvic and humic acids from oxidized and unoxidized B and D coal varies widely but may be regarded as typical. Compared to fulvic acid, all the samples of humic acid are higher in carbon and lower in oxygen, nitrogen, and sulfur. Given the high yield of fulvic and humic acids from oxidized B and D coal, they may be regarded as promising raw materials for humic production. The yield of fulvic and humic acids from oxidized G coal is minimal.

Today, blast furnaces tend to operate with large quantities of injected materials—hydrogen sources. In the 1960s, the introduction of such additives prompted close attention to the chemical processes in the blast furnace. In the last few decades, many researchers have studied the reaction of coke with atmospheres containing H₂ and H₂O. This sharp increase in interest may be attributed to the increasing presence of hydrogen in blast furnaces and to the availability of powerful methods such as X-ray phase analysis and electron microscopy and also software for digital image analysis and thermodynamic analysis. The thermodynamic laws and kinetics of blast furnace processes were studied. The results show that coke reacts with H₂O more intensely and with greater intensity than it reacts with CO₂. That affects the coke strength. Other research has addressed the influence of the H₂ and H₂O content on the porosity of the coke and its disintegration. Recently, thermodynamic analysis of the gasification of carbon from coke in a CO₂ + H₂O atmosphere (solution loss reaction of coke) by various research groups shows that increase in the H₂O content in the initial gas further stimulates gasification. Thermodynamic analysis of the reactions associated with the gasification of coke by CO₂ and H₂O and the reduction of iron oxides (the coupling reaction) indicates that higher hydrogen content in the gas may shift the gasification of carbon to lower temperatures.

Production technologies for carbon-bearing binders with reduced carcinogenic impact (emissions) on carbonization are considered. Information is provided regarding the best-known European binders with reduced benzo[a]pyrene emissions on carbonization that are used in the production of refractories and carbon materials. A method is proposed for the production and use of a carbon binder that may be added to coal tar pitch in order to minimize benzo[a]pyrene emissions on carbonization.

The distribution of iron oxides on firing ceramic brick produced from interstitial shale clay and iron-bearing slag from power plants, with no traditional materials, is studied by means of Mössbauer spectroscopy. A relation between the strength, frost resistance, and iron content is established. The calculated area of the spectral doublets indicates that the reduction of iron oxides by carbon oxides converts the iron compounds at the sample surface, where oxidant predominates, mainly to hematite, whereas those at the center, where reducing agents predominate, are converted to magnetite. The increased Fe²⁺ content in the samples hastens the appearance of liquid, which facilitates mullite formation and strengthens the ceramic structure.