Control of cooling losses at high pulverized coal injection rates

One of the problems which is encountered by many blast furnace operators is the appropriate control of the cooling losses of the blast furnace. This problem has been aggravated by the introduction of pulverized coal injection. Even with equal burden and coke composition, both Sidmar furnaces behave differently with respect to the cooling losses. This phenomenon is possibly attributable to the different profile and cooling circuitry of the furnaces. Among other parameters the angles of bosh and stack may favor the formation of scabs or not. Some operators experience a decrease of their cooling losses, other operators have problems to limit their cooling losses to an acceptable level. As a result, different operating practices exist with respect to the burden distribution. The increase of the ore to coke ratio with pulverized coal injection suggests that the coke and sinter quality has to be monitored very carefully in order to avoid permeability problems.