Revealing new patterns in resource­saving processing of chromium­containing ore raw materials by solid­phase reduction

Abstract

The physical and chemical properties of products from the carbon-thermal reduction of oxide chromo-containing ore raw materials have been investigated. This is necessary to determine the parameters that reduce the loss of Cr in the processing of ore materials and the use of metallized chromium doping additives in steelmaking. It has been determined that the increase in processing temperature from 1,250 K to 1,450 K led to an increase in the manifestation of Cr 23 C 6 and (Cr, Fe) 7 C 3 . In this case, the diffraction maxima of Cr 2 O 3 corresponded to the trend of weakening and, having been treated at 1,450 K, had a residual character. Cr 3 C 2 on the diffractograms was only evident after processing at 1,250 K. The phase of the metallic Cr was traced in the samples after processing at 1,350 K and 1,450 K with the increased intensity of manifestation when the heating temperature rose. It has been determined that the microstructure of reduction products is heterogeneous with the presence of particles of different sizes and chemical compositions. The increase in the reduction temperature from 1,250 K to 1,350 K and 1,450 K and the development of reduction processes were accompanied by particle sintering with the formation of a spongy microstructure. We have detected regions that characterized inclusions and the phases where Cr content amounted to 65.10 % by weight, Fe ‒ to 16.13 % by weight. Some local areas with particles with a relatively high content of ore impurities and carbon have also been found. It follows from the results of our study that the most acceptable temperature for reduction is 1,450 K. In this case, the reduction is ensured with a predominance in the phase composition of the metal Cr and carbides (Cr, Fe) 7 C 3 and Cr 23 C 6 relative to the oxide component of Cr 2 O 3 . In this case, the lower residual carbon content was due to the higher efficiency of the reducer compared to other temperature regimes. The spongy microstructure allows for a faster dissolution compared to standard ferroalloys, thereby reducing the duration of smelting