부산대학교 도서관

The electric arc furnace in Dragon Steel Corporation (DSC) is the only one in Taiwan that is charged with molten iron. This furnace has the advantages of high thermal energy input and being able to dilute harmful elements. Recently, this process is used to recycle desulfurization slag in CSC Group. However, the process efficiency becomes poor when charging desulfurization slag to the furnace; this includes lower iron recovery rate and higher energy consumption. In order to improve the efficiency of smelting and product quality, and to promote the economic benefits of the recycle, three smelting technologies have been developed. The first one is the high-efficiency melting technique for recycling desulfurization slag, which is to substitute slagging process for melting process to improve the melting efficiency of de-sulfurized slag. The second one is the EAF catch-carbon gas blow technique, it is the 'soft blow' in the early period and the 'catching carbon' in the final period of the smelting process. The last one is the EAF foamy slag smelting technique, it is to increase the slag viscosity through the control of solid particles in the slag, and to create foamy slag for saving electric power. Major benefits found from the implementation of these technologies in practice are: (1)EAF yield was increased by 3.27%, which significantly reduced the cost; (2) the smelting slag was reduced by 26.9%, and capacity for recycling desulfurization slag was increased from 5% to 10%; and as result of that, the desulfurization slag in CSC Group can be fully recycled; (3)Energy efficiency was improved by saving 34Gwh of electric power each year; (4)The quality of molten steel is improved by reducing phosphorus rejection rate from 7.2% to 0.6% and nitrogen content in the steel from 78ppm to 65ppm, and (5)The ensuing processes was able to be improved by reducing the amount of alloys in the refining process and increasing the cleanliness of steel. The overall annual benefit of these smelting technologies is nearly 1 billion TWD. The developed technologies can be applied in domestic electric arc furnace plants for the treatment of steelmaking slag and achieving slag recycling, saving energy and reducing by-products from steelmaking plants.