Composite agglomeration process (CAP) for preparing blast furnace burden

An innovative process of preparing ironmaking burden - the composite agglomeration process (CAP) has been developed. In CAP, part or all of the fine grained iron bearing materials are separately made into 8-16 mm diameter green pellets in a balling disc or drum, and the rest of fine grained and all of the coarse grained materials are granulated after first mixing with return fines, fuels and fluxes. The two granular materials are then subject to a secondary mixing, and the secondary mixture is charged onto the sintering strand. After ignition, sintering and cooling, the mixture is made into a composite agglomerate in which acid pellets are embedded in basic sinter. Investigation shows that the new process has a series of advantages over traditional sintering or pelletising such as ability to use diverse iron bearing materials, significant improvement in the material bed permeability and productivity of sintering machine, low energy consumption, and ability to prepare a low basicity charge with good metallurgical performance. Additionally, the use of the composite agglomerates in blast furnaces is capable of obviating the influence of the differences in quality of sinter and pellets on the operation. The new process has successfully been put into production in China.