Integration of the solar thermal energy for the blast preheating in the copper smelting process

Abstract

This work treats the subject of integrating a Central Tower System (SCT) as a source of thermal energy in the preheating of the blast of an Outokumpu Flash Furnace. The economic profitability of the process, as well as the environmental impact, are evaluated in addition to the analysis of the smelting process and the consequences of preheating the blast using solar thermal energy. The simulations developed in this work show clearly how removing the oil as an input of the process greatly reduce the volume of gases inside de furnace, allowing a higher feed rate and hence increasing the production and the profitability. As a contra, the removal of the fossil fuel implicates further enriching the blast in oxygen and/or preheating the blast. As the industrial oxygen is a source of economic losses for the process, and regarding the environmental impact of producing industrial oxygen, the preheating of the blast up to 600 K allows a reduction of the 17.43 mass-% of industrial oxygen. This would mean saving up to $2,443,878 per year in oil and industrial oxygen if we suppose that the copper production is kept constant at 75 ton per hour independently of the temperature of the preheating. On the other side, it has been noticed that preheating the blast expands greatly the volume of the gases inside the furnace, consequently reducing the production of copper and sulfuric acid, the two sources of economic incomes. If the down in the production is considered in the economic analysis, the results show that the inversion in a SCT system wouldn’t be economically profitable. Regarding the performance of the SCT system, it’s perfectly suitable for the preheating of the blast up to 1200 K. Without storage system, it would be possible to reach the energetic needs for the preheating 7 hours per day in average, providing around 4 MW in the case of preheating up to 600 K.