Novolipetsk Steel Company (NLMK), Lipetsk, Russia:

V. N. Titov, Cand. Eng., Associate Prof., Chief Specialist in Ore-Thermal Processes Optimization, Technology Development Dept.

Lipetsk State Technical University, Lipetsk, Russia:
A. V. Karpov, Cand. Eng., Associate Prof., Dept. of Metallurgical Technologies, e-mail: antonkrpv@rambler.ru
R. I. Khopersky, Assistant, Dept. of Chemistry

The relevance of the issue of using carbon-neutral types of raw materials in metallurgical production is considered. One of the promising directions is the use of biomass pyrolysis product - biochar, which has a high carbon content and, as a result, a calorific value relative to biomass. A comparative analysis of the main characteristics of biochar and pulverized coal injected fuel (PCI) produced from "T" and "G" coal grades was carried out. Biochar contains less carbon and ash with a higher content of volatile substances compared to PCI. To study the combustion process of biochar in the blast furnace tuyere zone, a study of the kinetics of its combustion in a laboratory installation for the solid fuel combustion was carried out. In order to adapt the obtained biochar combustion kinetics to the conditions of the blast furnace tuyere zone, a similar study was carried out for the considered types of pulverized coal. The results of the experimental study of the combustion kinetics of the studied types of fuel are presented, according to which the fuel combustion process in front of the tuyeres consists of two phases: the first one is accompanied by a high oxygen consumption for the combustion of volatile substances; the second one is characterized by slow afterburning of the carbon residue. The longest burning time of 0.6 g fuel at a temperature of 1200 °C is 762 s for T-grade PCI. Pulverized coal grade “G” and biochar have the similar combustion kinetics, but the latter burns faster: grade “G” pulverized coal burns in 369 s, and biochar in 162 s. The conclusion is made about a higher degree of biochar afterburning in the conditions of the blast furnace tuyere zone in comparison with pulverized coal fuel.

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