Iron or steelmaking process

In an iron or steelmaking process wherein a refractory lined generally horizontally disposed rotary furnace having an open discharge end and an inlet end for iron or steelmaking materials is rotated about its axis at such a speed that the liquid and solid furnace contents are maintained around the interior by centrifugal force, the said contents comprising liquid metal forming an outer layer in contact with the refractory lining and an inner slag layer spread on the liquid metal;

• the improvement comprising the steps of reducing the speed of rotation of the furnace during the process to reduce the centrifugal force acting on the furnace contents to promote instability of the slag and liquid metal layers adjacent the discharge end of the furnace and permit at least the liquid metal layer adjacent the discharge end of the furnace to increase in thickness whilst at least partially retaining the slag layer within the furnace, discharging a greater proportion of the liquid metal layer than of the slag layer from the discharge end of the furnace during the period of instability in which the liquid metal has increased in thickness at said discharge end of the furnace and thereafter increasing the speed of rotation of the furnace to retain both the liquid metal and slag layers within the furnace.