Decarbonization of Aluminum Reverberatory Furnaces: The Case of Plasma Melting

For decarbonization of aluminum cast houses, measures for fuel switching and to reduce energy consumption for heating, with its associated emissions, are being evaluated. In that context, the case of electric plasma torches is experimentally investigated as a solution to retrofit fossil fuel fired furnaces. This paper presents results of a test campaign on a furnace equipped with a direct-current plasma torch able to operate with nitrogen, air, or argon as plasma working gases. The performance of the furnace under varying plasma torch operating conditions (working gas, gas flow rate, power) is investigated and compared with the reference case of a 47 kW oxy-fuel burner running with natural gas. The results show that when operating with a plasma torch system the thermal profile and energy efficiency of the furnace are equivalent or better than those obtained with an oxy-fuel system without significant differences in dross formation and metal quality, hence proving the feasibility of the concept for both retrofit of existing furnaces and for new designs.