In February, the hot charging rate of continuous casting billets of Baosteel Co., Ltd.’s rare earth steel plate plant hit a record high, and the production cost per ton of steel continued to decline.
As an intensive and efficient production model integrating steelmaking, continuous casting and hot rolling, hot charging of continuous casting billets is based on improving equipment accuracy and stabilizing billet quality. By optimizing group production, the time of billets in the warehouse and in the furnace is further shortened, so as to achieve the purpose of energy saving, consumption reduction, cost reduction and efficiency improvement. Since the beginning of this year, the rare earth steel plate plant has actively implemented the concept of accounting management, and has taken the improvement of the hot charging rate of continuous casting billets as an important task to carry out the attack. In February, the hot charging rate exceeded the target plan, effectively reducing the fuel consumption and burning loss of the hot rolling heating furnace, and improving production efficiency. Walking into the billet warehouse of the continuous casting operation department, you can see waves of heat rising from the neatly stacked billets from a distance. The clamp crane opens its “big hand” to grab a billet, and then puts it steadily on the roller table of the heating furnace. The furnace door slowly opens, and the roller rotates to send the billet into the fiery furnace… “When the billet of 800 degrees Celsius is loaded into the heating furnace when it goes off the line, the temperature is still above 500 degrees Celsius.” Zhang Lele, the regional technical director of the continuous casting operation department, talked about the changes before and after the technical breakthrough. In the past, most ingots needed to be stored in the warehouse for several hours and then loaded into the heating furnace after cooling and passing the surface quality inspection. Now, 86% of the ingots entering the furnace have a temperature of more than 500 degrees Celsius, and some steel ingots can be directly loaded without storage.
Ensuring the quality of ingots is a prerequisite for improving the hot charging rate. Starting with the quality of molten steel, the rare earth steel plate plant has formulated inspection standards and inspection cycles for key equipment such as casting machine crystallizers and fan-shaped segments to ensure equipment accuracy; do a good job of protecting pouring to avoid secondary oxidation of molten steel; strictly implement standardized operations, stabilize process control, and the defect rate of ingots has dropped significantly, and the initial inspection pass rate has reached the best level in history. “The time of slabs in the furnace has dropped significantly compared to before the research. The shorter the heating time, the less gas consumption will naturally be.” Du Xiong, the quality professional and technical supervisor of the hot rolling operation department, said that the hot rolling process optimizes the slab heating system, reduces the slab furnace temperature, optimizes the rough rolling mode, and increases the final rolling temperature, further shortening the slab furnace time, with the aim of achieving extreme cost reduction. In addition, the refined control of key indicators such as slab release rate, production scheduling rate, and steel charging rate is also very important. The steelmaking, continuous casting, and hot rolling processes are highly matched and coordinated, deeply optimized, and the production rhythm is improved, laying a solid foundation for further improving the hot charging rate.
