Converter
A converter, also known as a converter furnace, is a steelmaking vessel. Generally, it refers to a tilting cylindrical vessel used for oxygen-blown steelmaking, and it is also employed in copper smelting. The furnace body is cylindrical and mounted on a horizontal shaft, which allows it to rotate. Based on the blowing method, converters are classified as bottom-blown, side-blown, or top-blown; based on the refractory lining, they are categorized as basic or acid. Converter steelmaking does not require an external heat source and relies primarily on liquid pig iron as the feedstock. On December 24, 1964, Shougang built the first 30-ton oxygen top-blown converter in New China. Modern converter steelmaking incorporates intelligent technologies, such as "one-key steelmaking" and automatic tapping systems. Environmental protection measures include ultra-clean primary flue gas treatment systems and metal film dust collectors, which help achieve ultra-low emissions.
Basic Characteristics
The converter consists of a cylindrical furnace body supported by horizontal trunnions. The outer shell is welded with 20-50mm thick steel plates, and the refractory lining can reach a thickness of 400-800mm. Standard furnace capacities range from 30 to 400 tons, with domestic mainstream equipment concentrated in the 120-300 ton range. The tilting angle is controlled within 0-90 degrees by a hydraulic system.
Converters can also be classified by lining material (basic or acid), by blowing position (bottom, top, or side), and by the gas used (air or oxygen).
Smelting Process and Technology
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 steelmaking combines the advantages of top-blowing and bottom-blowing.
The combined blowing process, which integrates top and bottom oxygen injection, has been adopted by Shijiazhuang Iron and Steel Company to enhance 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 for the carbon-chromium oxidation reaction is expressed as log(PCO)=1160/T+2.003, which differs significantly from that of 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.
