Patent ID: 8728194

Claim:
A method for controlling foamed slag in a stainless melt in an electric arc furnace, comprising: continuously detecting slag level in the electric arc furnace thermographically using a thermal element installed in a wall of the electric arc furnace, wherein the temperature (T) of the thermal element is a function of time (t) and the slag level (h) as represented by: T=f ( t )= f ′( h ); and (1) dT=df ′( h ), (2) a temperature signal as a time function being represented by equation (1) and a temperature gradient as a time function being represented by equation (2); and adding foaming material based at least in part on a temperature and a temperature gradient of the electric arc furnace, wherein when a mathematical sign of the temperature gradient is positive, the addition of the foaming material proceeds at a constant rate, and when the mathematical sign of the temperature gradient is negative or the temperature gradient is zero, the addition of the foaming material is completely stopped or proceeds at a decreased rate.