Experimental Study On Different Producing Process Of Magnesia Pellet In Baotou Steel

During the BF producing at BISCO, the content of alkali metal is very high, in order to keep the balance between the desulfurization and excreting alkali, the suitable basicity is1.00-1.10, and the suitable content for MgO is10%-12%, which could not only improve the desulfurization capacity of slag, but also increase the quantity of dealkalization. This is an effective measure to solve the confliction between desulfurization and alkali discharging in the slag. Furthermore, BISCO·s pellet reduction swelling index has been high. With the increase of Barun concentrate, which including fluoride, potassium, sodium, the deterioration in the BF will happen frequently.In order to improve the content of MgO in the slag and solving the possibility of high RSI during the pellet producing.the magnesium pellets were studied systematically by the author, who based on the grate kiln process, the roasting machine process and the raw material conditions, reduced the RSI to15%, create favorable conditions for the stable operation of the BF at BISCO.There were five kinds of iron concentrates used in pellets producing been selected by the author. In accordance with the iron concentrates proportion in two kinds of process, experiments were made to study the magnesia pellet for grate kiln process and belt type roasting machine process by the author. Through the study of material performance, green ball properties, preheating pellet properties, roasting temperature, pellet properties, obtained the following research results:(1) Considering the grate-rotary kiln process characteristics and raw material configuration. The author recommend produce magnesia pellet with2.5%serpentine. MgO content in1.79%(theoretical value), calcination temperature is1260℃, calcined time10min. Iron content of pellets produced in the experiment was62.41%, MgO content is1.77%(actual value analysis), compressive strength is2700N/P, the RSI is15.2%, the RI is41.2%, initial softening temperature is1153℃, softening interval is126℃, the melting temperature is1252℃,158℃dropping interval. (2) The raw material configuration of the belt type roasting machine were taken into account, we recommend to produce the magnesia pellet with1.5%serpentine. MgO content is1.51%(theoretical value), roasting temperature is1280℃, roasting time10min. Iron content of pellets produced in the experiment was63.05%, MgO content is1.49%(actual value analysis), compressive strength is2581N/P, the RSI is14.3%, the RI is40.4%, initial softening temperature is1182℃, softening interval is142℃, the melting temperature is1272℃,140℃dropping interval.