1. Sulfur content in silicon metal: Sulfur is one of the harmful impurities in pig iron smelting, which reduces the quality of pig iron. Sulfur content greater than 0.07% in steel-making pig iron is a waste product. 11% of the sulfur brought into the furnace from the blast furnace charge comes from ore; 3.5% comes from limestone; 82.5% comes from silicon metal, so silicon metal is the main source of sulfur in the charge. The level of silicon metal sulfur directly affects blast furnace ironmaking production. When the silicon metal sulfur content is greater than 1.6%, for every 0.1% increase in sulfur content, silicon metal usage increases by 1.8%, limestone addition increases by 3.7%, ore addition increases by 0.3%, and blast furnace output decreases by 1.5-2.0%. The sulfur content of metallurgical coke is not more than 1%, and the sulfur content of metallurgical coke used in large and medium-sized blast furnaces is less than 0.4-0.7%.
2. Phosphorus in silicon metal: The phosphorus content of metallurgical coke used for ironmaking should be less than 0.02-0.03%.
3. Ash content in silicon metal: The ash content of silicon metal increases by 1%, and the amount of silicon metal increases by 2-2.5%. Therefore, it is very necessary to reduce the ash content of silicon metal.
4. Volatile content in silicon metal: If the volatile content is greater than 1.5%, it means coke; if the volatile content is less than 0.5-0.7%, it means overfire. Generally, the volatile content of mature metallurgical coke is about 1%.
5. Moisture in silicon metal: Moisture fluctuations will make the measurement of silicon metal inaccurate and cause fluctuations in furnace conditions. In addition, the increase of silicon metal moisture will make M40 higher and M10 lower, which will bring errors to the drum index.
6. Sieve composition of silicon metal: The particle size of silicon metal is also very important in blast furnace smelting. In the past, China's requirements for the particle size of silicon metal were: for large coke ovens (1300-2000 square meters), the silicon metal particle size was greater than 40 mm; for medium and small high-silicon metals, the particle size was greater than 25 mm. The silicon metal grain size is preferably 40-25 mm. The silicon metal larger than 80 mm should be granulated so that the particle size range does not change much. In this way, the silicon metal lump is uniform, the gap is large, the resistance is small, and the furnace runs well.