The effective processing of cyclone dust and screenings of ferroalloys, which are formed in significant quantities during the grinding and fractionation of ingots, remains an urgent problem for domestic ferroalloy plants. This paper shows the possibility of recycling finely dispersed ferroalloys by the method of self-propagating high-temperature synthesis (SHS) using the example of the production of nitrided ferrochromium during the processing of screenings of low-carbon ferrochromium. The possibility of SН-synthesis of commercial ferrochromium nitride of two grades: FeCrN 10 (sintered) and FeCrN 4PL (melted) is shown by nitriding in the combustion mode of FeCr powders with a particle size of 150-400 μm. It has been determined that a prerequisite for the successful nitriding of such powders in the combustion mode is their preheating to a temperature of 300-600 °C. In the case of preliminary heating of the initial material to a temperature of 300-350 °C, the product contains the maximum concentration of nitrogen (10.0-10.5 % N) and has a sintered structure, the main components of which are CrN and Cr2N nitrides (with a predominance of mononitride) and iron with dissolved chromium and nitrogen. With an increase in the heating temperature of the source material to 400-450 °C, the structure of the product becomes inhomogeneous, with the presence of sintered and melted areas, while the total nitrogen content decreases, and its local concentration in various parts of the briquette can vary significantly. With an increase of the heating temperature of the initial alloy to 500-600 °C, nitriding passes into a liquid-phase mode, such a product has a cast high-density structure consisting of chromium semi-nitride, iron and chromium-iron semi-nitride. The nitrogen content in this case is evenly distributed over the volume of the ingot and is in the range of 3.5-4.5 %. As a result of industrial tests of the synthesized ferrochromium nitride, the expediency of its use for alloying stainless nitrogen-containing steel has been shown.
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Manashev et al. (2023) studied this question.