With the continuous advancement of blast furnace smelting technology, the requirements for blast furnace taphole work are becoming more and more stringent. In order to maintain the stability of the taphole working state and meet the needs of efficient smelting in the blast furnace, it is usually necessary to use taphole mud to seal the taphole to protect the furnace wall and furnace bottom in the taphole area. This requires taphole mud to have excellent operating performance, ensure the full filling of the taphole; have good volume stability and can be sintered quickly; have the ability to dry and harden quickly, and maintain high strength at high temperatures; in addition, taphole mud also needs to have good opening performance, easy to reopen, and be able to resist slag iron erosion, scouring and oxidation.
Blast furnace taphole mud is mainly divided into two categories: water taphole mud and waterless taphole mud. Water taphole mud is mainly made of raw materials such as coke powder, clay, fuel, water and asphalt. Although it has a low cost, its strength is poor, and its resistance to slag, molten iron erosion and scouring is weak. In contrast, anhydrous taphole clay uses corundum, silicon carbide, coke powder, clay and various binders as the main raw materials. Because it does not contain water, it has higher strength and better resistance to slag, molten iron erosion and scouring, so it has gradually become the mainstream.
There are still some problems with anhydrous taphole clay in practical applications, such as unstable product quality, difficult maintenance of the taphole depth, and insufficient corrosion resistance. These problems will lead to short tapping time, insufficient tapping volume, frequent iron seepage and leakage, which will increase production costs and reduce the production efficiency and profitability of enterprises.
This paper introduces a high-performance anhydrous taphole mud, which includes the following materials by weight: 38-48 parts of high-alumina bauxite, 18-23 parts of fused mullite, 10-14 parts of silicon carbide, 4-6 parts of boron nitride, 0.5-1 parts of hafnium oxide, 3-4 parts of graphite, 6-8 parts of silica sol, 2-3 parts of polyborosiloxane, 0.3-0.5 parts of titanium carbide whiskers, 0.1-0.3 parts of nano-cerium dioxide, and 1-2 parts of magnesium oxide.
Preparation method of anhydrous cannon mud:
Mix high-alumina bauxite, fused mullite, silicon carbide, boron nitride, hafnium oxide, graphite and magnesium oxide in proportion and dry-mill in a planetary ball mill for 4-6 hours;
Stir and mix silica sol and polyborosiloxane at 75-85℃ for 2 hours, add nano cerium dioxide after cooling to room temperature, and ultrasonically disperse for 30 minutes;
Mix the powder material with liquid binder and titanium carbide whisker and stir in a vacuum mixer for 30-60 minutes;
Isostatically press the mixture at a pressure of 20-25MPa and heat-treat it under argon protection: first keep it at 200℃ for 2 hours, then increase it to 350℃ for 4 hours, and finally cool it to room temperature to obtain the final product.
Silica sol and polyborosiloxane as binders provide good adhesion and toughness, ensure the stability and consistency of the material during processing, and at the same time improve the opening performance of the cannon mud, which is convenient for mechanical processing and use.