Basic Definition of Converter
A converter is a cylindrical steelmaking furnace with a body that can rotate around a horizontal axis. The furnace body is made of steel plates in a cylindrical shape and lined with refractory materials. According to the lining, it is divided into basic and acid types; according to the gas blowing method, it is divided into bottom-blown, side-blown, and top-blown types; and according to the gas used, it is divided into air converters and oxygen converters. Converter steelmaking is a steelmaking method that does not require an external heat source and mainly uses liquid hot metal as the raw material. Converters have the advantages of simple equipment, low cost, and high production efficiency, and they can also be used for smelting metals such as copper and nickel.
Basic Characteristics of Converter
The converter consists of a cylindrical furnace body supported by horizontal trunnions. The outer shell is welded from 20-50mm thick steel plates, and the refractory lining can reach a thickness of 400-800mm. Standard furnace capacities range from 30 tons to 400 tons, with domestic mainstream equipment concentrated in the 120-300 ton range. The tilting angle of the furnace body is controlled within the range of 0-90 degrees through a hydraulic system.
Converters are classified according to the refractory lining material as basic (with magnesite or dolomite lining) or acid (with siliceous material lining); according to the part of the furnace where the gas is blown in, they are classified as bottom-blown, top-blown, or side-blown; and according to the gas used, they are classified as air converters or oxygen converters.
The modern high-efficiency basic oxygen converter is the product of over 50 years of continuous development, achieving significant progress in furnace life, increased charge capacity, and reduced maintenance. Converter design faces the challenges of high temperature, mechanical impact, and thermal stress. The suspension system is highly important in achieving long converter life.
Smelting Process and Technology of Converter
Converter steelmaking is a steelmaking method that does not require an external heat source and mainly uses liquid hot metal as the raw material. Converters are classified according to the refractory lining material as basic or acid; according to the part of the furnace where the gas is blown in, they are classified as bottom-blown, top-blown, or side-blown; and according to the gas used, they are classified as air converters or oxygen converters. Basic oxygen top-blown converter steelmaking (LD/BOF process) is the main method of modern steelmaking. In bottom-blown oxygen converter steelmaking, oxygen is blown through bottom nozzles. Combined blowing converter steelmaking combines the advantages of top-blowing and bottom-blowing. The combined blowing process combines top and bottom oxygen blowing technology, which has been adopted by Shijiazhuang Iron and Steel Company to improve bath stirring efficiency. Modern converter smelting widely employs sublance systems, bottom stirring, slag stoppers, automatic control systems, and other technologies. The sublance system measures temperature, carbon content, and bath level, enabling timely measurement during blowing. Slag stoppers reduce slag carryover in the ladle and decrease deoxidizer consumption. The bottom inert gas stirring technology utilizes the advantages of bottom blowing to improve bath stirring. During stainless steel smelting, the bath temperature must be maintained at 1650-1700°C. The equilibrium constant formula for the carbon-chromium oxidation reaction is log Pco=1160/T+2.003, which shows significant differences from traditional electric furnace processes. Slag splashing for lining maintenance can extend furnace life to 8,000-12,000 heats. The application of slag stopping balls increases steel yield by 1.2-1.8 percentage points. Technologies such as "one-key steelmaking," automatic tapping, and intelligent blowing have been successfully applied. One-key steelmaking technology achieves fully automated steelmaking through static models that precisely calculate scrap charge, oxygen lance position, and sublance measurement timing. The automatic tapping system utilizes image recognition, laser ranging, three-dimensional calculation, and other technologies to complete fully automated tapping processes including converter tilting, ladle car movement, and alloy addition. Key technologies for intelligent steelmaking include multi-channel monitoring and intelligent intervention, which can improve the hit rate of carbon content, temperature, and timing at the end of blowing.
Applications of Converter
Currently, converters serve as the core equipment in the "blast furnace-converter" long-process steelmaking route, accounting for approximately 90% of China's total crude steel production. In recent years, intelligent applications in converters have been widely promoted. For example, TISCO has successfully implemented "one-key steelmaking" and automatic converter tapping systems; Tangsteel has applied intelligent blowing technology to achieve efficient smelting; Luoyuan Mingguang has completed its second-phase 110-ton converter steelmaking project; and Hongda Group has built an active lime production line to supply auxiliary materials for converters.
