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Copper slag roasting modified experimental study

Author: YangTao
Tutor: WangHua
School: Kunming University of Science and Technology
Course: Physical Chemistry of Metallurgy
Keywords: copper slag oxidizing roasting magnetite fayalite kinetic
CLC: X758
Type: Master's thesis
Year: 2011
Downloads: 13
Quote: 0
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Abstract

With our economy stable and rapid development, the economic construction and infrastructure need a large amount of steel. But the iron ores in our country is relatively poverty. The iron ores demanded in our country are a considerable part of dependence on import. Only by 2009, the actual wastage of iron ores reaches 1 billion tons.628 million tons of them by import occupied the world trade of the ore more than 50%. Due to the mining giants in the world jointing prices, the iron ores prices in the international market continued to rise. The illegal profit space of domestic steel enterprises had become narrow to bear up with the increase of iron ore. To reduce the demand of the ore and expanding the source of iron ore resources is imminent. At present domestic production of copper is only less than Chile in the world, and become a major world’s copper producing country. China refining copper output is 4.57×106 tons, and discharging copper slag is 1.01×107 tons. This copper slag contains about 4.02×106 tons steel, which can be used as a substitute for iron ore. Those iron not only can replenish the enormous gap in the steel industry, but also reduce the environmental pollution.Slag-cleaning from electric furnace is roasted in aerobic atmosphere to enrich Fe3O4, and created favourable conditions for copper slag magnetic separation to enriched iron concentrates. In copper roasting process, kinetics research and the gas-solid reaction process were analyzed. The reaction of copper slag follow the shrinking unreacted core model. In the temperature rage from750℃to 900℃, the isothermal dynamics experiment was carried on. It was proved that the reaction belonged to in-diffusion control in isothermal stage. After analysis, It can be found the apparent activation energy of isothermal stage is E=42.24KJ/mol, and the rate equations may be represented as k=2.977e-5081/T.In copper roasted process, adding calcium or reducing the granularity of copper can effectively improve the rate of gas-solid reaction process. Fine granularity of copper can change structure of the crystal, increase internal defects of crystal and promote the reaction between fayalite and calcium. At the same time fine granularity of copper can increase the number of the activity centres of copper slag and improve the gas-solid reaction process. Adding calcium can be effective to the activity of fayalite and promote the overall reaction.In the condition of grinding grain 100 um, insulation two hours, the hematite ore phase diffraction peaks has become strong, but magnetite (Fe3O4) phase diffraction peaks has become strong, the peaks which gradually weakens at the temperature over 850℃. The high temperature causes of the magnetite into the hematite ore against the enrichment of magnetite. In the conditions of grinding grain 100 um, insulation temperature 850℃, With insulating prolonged the hematite ore phase diffraction peaks has been enheanced, but magnetite (Fe3O4) phase diffraction peaks do not change significantly When time more than 2 h. A long time insulation is benifical for fayalite turning into magnetite, but the resulting magnetite can be oxidized in to hematite ore with time extension. The low oxygen Potential is beneficial to copper slag in the single-stability region of magnetic mines. The low oxygen potential through nitrogen can not achieve single-stability region of magnetic mines, and a low oxygen potential reduce the reaction rate of copper slag. The better conditions of the magnetic mineral enriched in this experiment are: atmosphere in the air, the granularity of 100 um, and keeping the insulation temperature at 850℃, insulation time for two hours. In this condition, the conversion efficiency magnetite in copper turned in to 89%.

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