The direct reduction of metals from a complex oxide with low iron content by solid carbon and indirect reduction by CO gas were studied in a vertical laboratory resistance furnace at 1300 °C for an hour reduction time. The experimental results were described from the point of view of the electrochemical nature of the metal reduction process, that involves the interaction of ions and electrons in the oxide lattice. The technique was developed by using the two different software programs for the quantitative estimation of the areas, average size and number of the metal forming in a complex oxide with extensive fields of vision. The obtained results of the quantitative characteristics of the metal forming during solid-phase carbo-thermal reduction were presented. The processes of reduction by solid carbon and CO gas based on the areas occupied by metal particles were quantitatively compared. The experimental results and the prospects for further experimental work were assessed and outlined.
There is a lack of complete understanding of the mechanism and kinetics of reduction of metals from oxides. This paper presents results and methods of a series of experiments on direct reduction of metals by solid carbon in the form of graphite from a complex oxide with a low iron content in a laboratory muffle furnace at temperatures of 1300, 1400, 1500, 1600 °C and holding time of 1, 3, 5, 7 hours. The statistical analysis of amount and average size of reduced iron particles inside the oxide was studied. Dependence of amount and average size of the reduced iron particles on temperature and time of reduction is presented. The phenomena of iron crystals’ growth, occurring as a result of changes in the crystal lattice of oxide, was studied under experimental conditions. The influence of temperature and holding time on iron particles’ nucleation and their growth in the crystal lattice of a complex oxide were compared. Investigation of mechanism of metals’ reduction from complex oxides and influence of experimental conditions on the nucleation and growth enables to identify new patterns in the process of reduction of metals from their oxides, in general.
The phase composition change as a result of the solid-phase carbothermal reduction of metal from a bulk complex oxide with a low iron content-dunite was explained. The experiments were conducted in a laboratory resistance furnace (Tamman's furnace) to study solid-phase carbothermal reduction of iron from dunite at temperature 1300 °C and for 1 hour holding time. A comparison of the results of the micro-X-ray and X-ray phase analysis of the initial dunite samples with samples after the solid-phase carbothermal reduction was performed. The phases in the initial samples of dunite were:
Metallurgical Industry slowly moves towards wider utilization of complex ore minerals. Reduction behavior of complex crystalline structures can hardly be interpreted applying kinetic modeling adopted for pure oxides. The quantitative mathematical analysis of the metal particles forming during solid state reduction of a complex mineral has been suggested. The analysis with 95% reliability showed that during solid phase reduction of dunite at 1300 °C for 60 min about 360 particles with an average size about 0.62 mm formed from the total area S = 20880 mm. Such an approach could be useful for development of sophisticated kinetic models applied for reduction of a low-grade complex ore.
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