Abstract: According to the actual needs of using dolomite instead of doloma slagging in converter steelmaking, the dissolution experiment of the dolomite and doloma in converter steelmaking slag was carried out. By scanning electron microscopy and energy spectrum analysis, the dissolution mechanism of dolomite and doloma were compared and analyzed, and the industrial test of slagging with dolomite instead of doloma is carried out. Results show that the dissolution mechanism of dolomite is different to doloma in LD slag. Dolomite firstly occurs pyrolysis reaction in steelmaking temperature, then it becomes MgO, CaO tiny particles and take dissolves reaction with liquid slag. Moreover,  because of the stirring effect of CO₂ bubbles, dolomite dissolve faster than doloma. Dolomite is found to decompose into CaO, MgO and CO₂ in one step at the converter steelmaking temperature. By using dolomite slagging, dephosphorization rate increases from 83.2 % to 84.1 % and sulfur mass fraction increment reduce from 78×10^-6 to 71×10^-6. Final slag properties also conducive to the maintenance of furnace lining, and the cost of steelmaking flux decrease 2.98 yuan/t.

Key words: LD steelmaking, dolomite, doloma, dissolution