Research On Pre-processing Of Bentonites Pellets Into The Final Pellet And Firing Properties

With the continuous development of iron and steel industry, a reasonable iron-bearing raw material is urgent needed in blast furnace, and high basicity sinter adding acid pellet is becoming an ideal blast furnace burden structure. Nowadays, many iron and steel enterprises produce oxide pellets to optimize blast furnace burden structure in our country. However, due to the pelletizingproperty of domestic pellet raw material--concentrate is low, many pellet enterprises solutethis problem through adding high percentage proportion of bentonite. It not only creates high cost of pellet production, but also has an unfavorable effect to later process--iron-making.In this paper, grinding treatment has been given to bentonite and the size of bentonite has been reduced, which has changed the physical and chemical properties of bentonite and improved performance index of bentonite. Reduced the amount of bentonite improve the iron content of pellets.After 90 minutes repeatedly grinding, the size of bentonite has been improved from A₀ contains 87.80% content of-0.074 mm and 11.79% content of-0.040 mm in original ore to A₅ contains 97.92% content of-0.074 mm and 48.75% content of-0.040mm.Calcium bentonite of Baoan added Na₂CO₃ and sodium modified by using dry mixing technology, the effect of sodium chloride modified was obvious, and the physical and chemical properties index of bentonite had been improved greatly. The percentage proportion of Na₂CO₃ was 2%, the time of sodium chloride modified was 10 minutes. The absorptivity of methylene blue was 98.9mmol/100g, the expansion capacity of bentonite was 13.2 ml/g and the colloid index of bentonite was 103ml/15g.The final result of this experiment indicated that calcium bentonite, which was coped with repeatedly grinding process, can reduce the size and improve the physical and chemical properties of bentonite, thus it can reduce the percentage proportion of bentonite. Sodium chloride modified bentonite can improve the physical and chemical properties of bentonite and enhance the main parameter index, which will greatly improve the properties of pelletizing and roasting. At the same time, it can inhibit reducing of pellet iron content and decrease harmful impurity coming into blast furnace, which causes by adding excessive bentonite. This has explored a new way of saving coke, increasing iron content and increasing economic benefits for blast furnace.