Considerations for scale-up of ferronickel electric smelting furnaces.

With progression to shielded arc operation in ferronickel smelting, the power dissipated in the arc zone partially offsets the power dissipated in the slag zone, thus reducing sidewall heat fluxes and metal temperatures. The liquid zone of the crucibles are subjected to less arduous conditions, but the intensity of the furnace operation is shifted to the electrodes. Closer attention should therefore be paid to factors such as the local electrode gas fluxes (or superficial gas velocities), freeboard and off-gas temperatures, for any given calcine feed quality, to optimise electric furnace reduction and its resultant alloy nickel grade and overall recovery. An approach to quantifying the electrode gas flux is suggested which provides an improved link between ferronickel calcine feed characteristics, the product alloy Ni grade and the electrode power density metric, as a means to define conditions capable of giving stable shielded arc operation. Further understanding of the local electrode conditions is needed to assist with scale-up of processes to over 100 MW.
With progression to shielded arc operation in ferronickel smelting, the power dissipated in the arc zone partially offsets the power dissipated in the slag zone, thus reducing sidewall heat fluxes and metal temperatures. The liquid zone of the crucibles are subjected to less arduous conditions, but the intensity of the furnace operation is shifted to the electrodes. Closer attention should therefore be paid to factors such as the local electrode gas fluxes (or superficial gas velocities), freeboard and off-gas temperatures, for any given calcine feed quality, to optimise electric furnace reduction and its resultant alloy nickel grade and overall recovery. An approach to quantifying the electrode gas flux is suggested which provides an improved link between ferronickel calcine feed characteristics, the product alloy Ni grade and the electrode power density metric, as a means to define conditions capable of giving stable shielded arc operation. Further understanding of the local electrode conditions is needed to assist with scale-up of processes to over 100 MW.