Vol 59, No 7 (2016)

Coking coal of the same rank from different countries and fields may be distinguished in terms of use value by rating on the basis of seven technological and petrographic characteristics that determine the coke yield and properties: the ash content A^d; the total sulfur content S_t^d; the yield of volatiles V^daf; the plastic-layer thickness y; the vitrinite reflection coefficient R_o; the content of vitrinite-group macerals Vt; and the basicity index B_b. A range of values and a rating (on a scale from 1 to 10) are established for each of these parameters. Each rating corresponds to a particular score (from 0.1 to 1.0). Ranges of A^d, S_t^d, Vt, and B_b are established for the whole metamorphic series, while ranges of V^daf, y, and R_o are established for individual ranks and groups of ranks. Altogether, 105 coking coals from Ukraine, Russia, the United States, Australia, and Canada that are used at Ukrainian coke plants are investigated. The range of rating scores and their mean values are determined for individual coal ranks and groups. As an example, three bituminous coals from Ukraine, the United States, and Australia are compared by the proposed method. This method permits objective assessment of the technological value of coal within a single rank and the selection of the best purchase option.

Some physicochemical properties of carbon adsorbents produced by chemical activation with alkali are determined: specifically, their total ash content, the content of water-soluble ash, the total iron content (recalculated for Fe³⁺), and the content of water-soluble iron compounds. Their content of water-soluble ash and the total iron content are minimal; no water-soluble iron compounds are observed in the sorbents. However, the total ash content in the sorbents is impermissibly high. With increase in potassium content in the initial content, the total ash content of the sorbents is reduced to 16.5%.

The thermokinetic parameters of the thermal decomposition of coal and its processing wastes (filter cake) used in the preparation of coal–water and organic coal–water fuels are determined experimentally by thermogravimetry in an inert atmosphere. The dependence of the thermokinetic parameters of decomposition on the coal’s metamorphic stage is established; the activation energy of decomposition varies from 39.1 kJ/mol (lignite) to 109.4 kJ/mol (anthracite). There is practically no difference between coal and its processing wastes in the thermokinetic parameters of thermal decomposition. The results provide the starting point for an experimental database that may be used in modeling the ignition and combustion of coal and its derivatives: coal–water and organic coal–water fuels.

Means of improving the efficiency of water circulation of coke plants are considered. A systemic approach is adopted. The goal is to minimize corrosion in the water-circulation system by means of phenolic wastewater and corrosion inhibitors. The corrosion rate is investigated as a function of the dose of inhibitor and the operating parameters. On the basis of the models derived, the operation of the water-circulation system at coke plants may be better predicted.