| The research for this dissertation is associated with a new steelmaking technology, in which microwave heating and electric arc heating are used as heating methods. The innovative core of this technology is the microwave assisted electric arc furnace (MEAF) process, which can produce molten steel directly from pellets consisting of iron ore and powdered coal. The direct steelmaking technology is a revolutionary change from conventional steelmaking. This technology is intended to offer a competitive solution, which meets the challenge of increasing environmental and energy pressures currently confronted by the steel industry.; As a key apparatus for investigating the direct steelmaking technology, a bench-scale microwave assisted electric arc furnace was designed and implemented. This furnace mainly consists of an electric arc heating subsystem and a microwave heating subsystem, whose output power is 6000 W and frequency is 2.45 GHz.; A series of direct steelmaking tests were conducted in the bench-scale MEAF. The effects of pellet composition, binder, microwave/electric arc heating ratio, and heating times on steel yield were investigated. Based on the evaluation of steels and slags, the effects of pellet composition, refractory materials and linings on steel quality and slag basicity were investigated. In addition, the role of microwave heating in the MEAF process was studied and demonstrated in three specially-designed direct steelmaking experiments.; In order to calculate the actual specific energy consumption of MEAF process, an energy consumption model was developed. In this model, the different contributions of coal as fuel and as reductant to energy input were distinguished. Equations for calculating the actual specific energy consumption of MEAF process and the minimum coal ratio of pellet sample were presented. The energy efficiency of the new direct steelmaking technology was assessed by comparing with the two popular routes of conventional steelmaking. (Abstract shortened by UMI.)... |
