Том 59, № 5 (2016)

In the laboratory coking of production batches at OAO EVRAZ ZSMK, including those containing coal from the Elegest deposit, special attention is paid to batches with different quality of the clinkering, coking, and lean components, so as to determine the maximum possible content of Elegest coal in the batch if the coke produced is to be satisfactory quality for use in blast furnaces at OAO EVRAZ ZSMK with pulverized-coal injection.

The properties of coking batch may be stabilized by means of DK coking additive based on the products of petroleum pyrolysis, characterized by low ash content (A^d = 0.4%), high sulfur content (S_t^d= 4.1%), and high yield of volatiles (V^daf = 17.2%) relative to coal concentrates. Individual coking of DK coking additive yields a product (particle size >40 mm) with postreactive strength CSR = 77–79%, reactivity CRI = 18–22%, and density 1200–1400 kg/m³. Differential scanning calorimetry of experimental coke samples reveals six stages in their heat treatment in air: preliminary heating, intense oxidation, gasification of carbon, surface combustion of the gaseous products, their flare combustion, and oxidation of the residue. The use of DK coking additive in the coking batch shifts the oxidation process to higher temperatures and ensures the largest interval of heat liberation at elevated heating rate, with up to 50% DK additive. With increase in the content of DK additive from 30 to 50%, the activation energy is increased by 4.56 kJ/mol for each additional 10%. In that case, the supply of atmospheric oxygen to the combustion zone must be improved

Ultrasound treatment of coal tar increases the yield of pitch by a factor of 1.5 in subsequent oxidation by atmospheric oxygen. The yield of pitch may be regulated in terms of its softening temperature by changing the oxidation time. To obtain standard pitch, the following conditions are employed: ultrasound treatment for 3 h; initial oxidation temperature 260–270°C; final oxidation temperature 360–370°C; rate of air supply 63 L/h; oxidation time ~30–70 min, depending on the requirements on the final product. The concentration of aromatic derivatives of benzo[a]pyrene type in the pitch produced and in the liquid fraction (which may be used as a fuel) is considerably less than in the current industrial method. After ultrasound treatment, a 1: 1 mixture of coal tar and rectification residues from styrene yields pitch with satisfactory characteristics on oxidation by atmospheric air. That expands the range of raw materials for pitch production.

Flotation wastes at OAO TsOF Belovskaya are studied with a view to their disposal in systems for the combustion of high-ash coal. Analysis indicates that, if the flotation wastes are mixed with regular coal, they may be used as fuel in low-temperature fluidized-bed furnaces. The introduction of such furnaces in the drying department at OAO TsOF Belovskaya is recommended, for use in the drying of coal concentrates.