Abstract
The processes of iron oxides’ reduction have a complex physicochemical mechanism, with the participation of solid, liquid, and gaseous substances. The article discusses the existing models for the reduction of iron oxides and provides data on the thermodynamic possibility of carrying out the reactions of their reduction through the solid and gas phases. Experimental data on the reduction of iron from industrial scale, obtained by the DSC (differential scanning calorimetry) method, show the kinetic dependence of the rate and completeness of recovery on external factors: pressing pressure during sample preparation and the reagents’ composition. The pressing pressure, under conditions of iron ions’ solid-phase diffusion, has the significant effect by increasing the reagents’ contact area. Under conditions of iron ions’ comprehensive diffusion, the pressing pressure does not affect the reduction processes rate. The introduction of 10 mass.% flux into the raw mixture composition leads to a partially liquid-phase diffusion of iron ions and weakens the effect of the pressing pressure in this process. An ion diffusion-catalytic mechanism is proposed to describe the observed effects during the reduction of iron oxide of technogenic origin.
Highlights
The long-term development of extractive industries in conditions of extensive nature management has led to the accumulation of a huge number of metallurgical, chemical, energy, and other technogenic formations
The mixture based on coke and scale in an argon atmosphere with the gaseous products’ removal removal from the reaction zone, i.e., in conditions that exclude the participation of gaseous products from the reaction zone, i.e., in conditions that exclude the participation of gaseous products in the in the recovery process, showed that the recovery processes are successfully implemented with a high recovery process, showed that the recovery processes are successfully implemented with a high degree degree of metallization through the solid phase
Calculations of thermodynamic characteristics and experimental data on the interaction of scale and carbon oxides show the possibility of reducing iron from Fe2 O3 oxide starting from a temperature of 700 ◦ C and from Fe3 O4 and FeO starting from a temperature of 800 ◦ C without the participation of the gaseous phase
Summary
The long-term development of extractive industries in conditions of extensive nature management has led to the accumulation of a huge number of metallurgical, chemical, energy, and other technogenic formations. At the same time, accumulated technogenic formations can be a promising source of raw materials, of which iron is the most valuable for ferrous metallurgy. The accumulated technogenic formations at the same time are the source of environmental pollution. Involvement of technogenic formations in processing will help to solve the issues of limited resource base and environmental pollution [1,2,3]. Technogenic formation of the iron oxide is presented mostly by sludge and scale [3,4,5]. The layered structure of the scale is completely consistent with the diagram of the iron-oxygen state. The temperature of 650 ◦ C, the inner layer of scale consists of wustite (FeO), the middle layer of magnetite (Fe3 O4 ), and the outer layer of hematite (Fe2 O3 ) [6]
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