PNEUMATIC LIME/DOLOLIME INJECTION SYSTEM IN OPERATION AT NORTH STAR BLUESCOPE STEEL (USA).
North Star Bluescope Steel is a 50/50 joint venture between BlueScope Steel and Cargill Inc. and has an annual capacity of 2 million tons of hot-rolled bands. The mini-mill includes a twin shell / twin shaft AC EAF, two LFs, slab caster for medium thick slab, tunnel furnace and rolling mill with eight stands, two roughing stands and six finishing stands.
The MORE lime pneumatic/injection technology installed in the meltshop replaced the conveyor belts Dololime & HiCa transportation/management by pneumatic system, MORE supply includes: Four MOLI dispensers (2800liters-740gal capacity) for the pneumatic transportation of 'Dololime' and 'HiCal' from the external main storage silos to the internal day-bins; three MOLI dispensers (2800liters-740gal capacity) for pneumatic injection of 'Dololime' and 'HiCal'from from the day-bins to the EAFs; four LIMEJET multi-functional burner/lime injectors (4 x 160Kg/min-350Lb/min; 4 x 3.5MW) installed on board of the EAF shells, two LIMEJET for each EAF shell, one dedicated for the HiCal and one for the Dololime; integration of the automation system/HMI in the chemical energy package.
The system in operation has shown the following benefits:
- Complete management of Dololime and HiCal for EAF melting process requirements via pneumatic transportation/injection system. - Improvement in the fluxes efficiency due to direct injection in the slag. - Improvement in the foaming slag conditioning due to the fluxes injection distributed during the melting and superheating phases. - Elimination of fluxes charged through the roof hole or bucket charge. - Elimination of expensive maintenance for the conveyors belts transportation system from silos to EAF. - Elimination of fluxes losses from the conveyors transportation system. - Elimination of dust generation from the conveyors transportation systems.