C21C PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS (refining metals in general C22B9/00)
Description
C21C covers the refining of pig iron and the production of wrought iron and steel through various metallurgical processes, including treatment of ferrous alloys in their molten state. This subclass encompasses converters, furnaces, and processing methods designed to remove impurities and adjust chemical composition to achieve desired steel grades and properties. Technologies include basic oxygen processes, electric arc furnace operations, ladle metallurgy, and related thermal and chemical treatments. The scope extends to ferroalloy processing and molten metal handling techniques essential to modern steelmaking, but excludes mining, ore preparation, and the initial production of pig iron in blast furnaces (covered under C21B).
8 direct subcodes
Child Classifications
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- C21C 1/00 Refining of pig-iron; Cast iron
- C21C 2100/00 Exhaust gas
- C21C 2200/00 Recycling of waste material
- C21C 2250/00 Specific additives; Means for adding material different from burners or lances
- C21C 2300/00 Process aspects
- C21C 3/00 Manufacture of wrought-iron or wrought-steel
- C21C 5/00 Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel
- C21C 7/00 Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00 (treating molten metals during moulding B22D1/00, B22D27/00; remelting ferrous metals C22B)
Top Applicants
Top 10 applicants by patent filingsfor class C21, 2013–2023, worldwide · Source: EPO PATSTAT
- JFE STEEL JP 8,270
- NIPPON STEEL CORPORATION JP 5,222
- POSCO (POHANG IRON AND STEEL COMPANY) KR 4,824
- JFE STEEL 3,311
- ARCELORMITTAL LU 3,239
- NSSMC (NIPPON STEEL & SUMITOMO METAL) JP 2,659
- HYUNDAI STEEL COMPANY KR 1,492
- ANGANG STEEL COMPANY 1,318
- BAOSHAN IRON & STEEL COMPANY 1,233
- KOBE STEEL JP 1,228