Bhagyadhar Bhoi

Direct reduction of iron in low temperature hydrogen plasma

Abstract This paper describes the effects of various parameters on the reduction of hematite in the presence of microwave assisted non-thermal hydrogen plasma. The parameters include microwave power, hydrogen flowrate, pressure, microwave power density and temperature. It has been shown that hydrogen flowrate, pressure and microwave power are interrelated to effect the microwave power density that controls the plasma temperature. The experimental conditions encounter three temperatures: surrounding the sample, associated with the plasma and at the plasma/substrate interface. It has been deduced that the third one is the most effective in determining the rate of the reaction, and in the present case, activation energy of 20 kJ mol−1 is reported.

Preliminary investigation into direct reduction of iron in low temperature hydrogen plasma

Abstract There has been an increasing interest in reduction of iron ore by hydrogen. This study deals with the reduction of haematite in a microwave assisted non-thermal hydrogen plasma. The plasma is composed of excited hydrogen molecules, hydrogen atoms, and ionic hydrogen among other gaseous species. The reduction in hydrogen plasma occurred even at temperatures as low as 573 K. In contrast, the same could not be achieved by merely introducing hydrogen gas to the reducing environment without creating the plasma. It is only ∼1073 K that the extent of reduction by gaseous means is comparable to that of reduction by hydrogen plasma. Based on the experiments, as well as the data available from literature, it was deduced that the reduction of haematite at a low temperature in hydrogen plasma could have been due to the contribution of vibrationally excited hydrogen molecules to the reduction process.

Effect of Cerium Addition on the Microstructure and Mechanical Properties of Al-Zn-Mg-Cu Alloy

Al–8.6Zn–2.6Mg-2.4Cu–xCe(x = 0–0.4 wt. %) alloys were prepared by metal mould casting method, the effects of Ce on the microstructure and mechanical properties of the alloys were investigated. The results showed that the dendrite as well as grain size were refined by the addition of Ce, and the best refinement was obtained in 0.25 wt % Ce containing alloy. The main phases in the as-cast alloys were α-Al, Mg-Zn32, Mg32 (Al, Zn)49, and Al4Ce phase was found in the alloys containing more than 0.1%Ce. The addition of Ce improved the mechanical properties of the alloys. The strengthening mechanism was attributed to grain refinement and compound reinforced

Production of Green Steel from Red Mud: A Novel Concept

Red mud of Indian origin contains around 55% plus of Fe2O3 and is considered as a hazardous waste for the alumina industry. For production of one tone of alumina employing the Bayer’s Process, around two tones of red mud is generated from three tones of Bauxite. Conventional process of steel making is not devoid of environmental pollution. In the present investigation, efforts have been made to produce steel from red mud by adopting reduction roasting, magnetic separation and hydrogen plasma smelting route. Magnetic fraction, containing enriched iron oxide and minimal content of alumina, is produced following the first two stages which is then subjected to hydrogen plasma smelting process for production of steel. This novel concept follows a green path way for production of steel free from pollution and is termed as green steel. Further, the only by-product that is produced in the process, is water, which is eco-friendly and recyclable.

Production of Pig Iron from Nalco Redmud by Application of Plasma Smelting Technology

Red Mud, a by-product generated from the caustic leaching of bauxite to produce alumina in the Bayer Process, causes serious environmental problems and is considered as a hazardous industrial waste. A novel process has been developed for production of Pig Iron from NALCO Red Mud by employing Plasma Smelting Technology. Red Mud containing 15–40% Fe2O3 was subjected to Thermal Plasma Smelting by use of Extended Arc Plasma Reactor at a temperature of 1600°C for a period of 30 minutes and high quality Pig Iron was produced. Effect of various process parameters like basicity, amount of reductant, plasmagen gas, input electric power and reduction time for recovery of Pig Iron has been studied and optimized. Basicity of 0.3, reduction time of 25 minutes at 12.5 kW power was found to be optimum for maximum recovery of pig iron (70%) from Red Mud in 1kg scale.