C21B MANUFACTURE OF IRON OR STEEL
Introduced: September 1968
Classification Context
- Section:
- CHEMISTRY; METALLURGY
- Class:
- METALLURGY OF IRON
- Subclass:
- MANUFACTURE OF IRON OR STEEL
Description
C21B covers the production processes and technologies for manufacturing iron and steel, including ore reduction, pig iron production, and steel-making methods. The subclass encompasses both traditional and modern techniques such as blast furnace operation, direct reduction processes, electric arc furnace steelmaking, and oxygen converter steelmaking. It includes related aspects of heat treatment, casting, and refining of steel products during manufacture. Adjacent class C21C addresses the processing and treatment of steel after initial manufacture, while C21B focuses on the primary conversion and formation stages from raw materials to finished steel products.
Filing statistics
IPC subclass C21B recorded 31,098 patent applications worldwide between 2013 and 2023. Annual filings grew from 2,313 in 2013 to 3,647 in 2023 (+58%), peaking at 3,970 applications in 2022. The most active applicants in class C21 are JFE STEEL (7,470 applications), POSCO (POHANG IRON AND STEEL COMPANY) (4,615 applications) and JFE STEEL (4,538 applications).
Source: EPO PATSTAT, worldwide filings
Additional Content
Glossary
Pig iron intermediate product of smelting iron ore with a high-carbon fuel, e.g. coke, charcoal Slag partially vitreous by-product of smelting ore to separate the metal fraction form the unwanted faction Tuyères tubes, nozzles or pipes through which air is blown into a furnace
Limiting references
Preliminary treatment of ferrous ores or scrap Constructional features of mixers for pig-iron Electrolytic production, recovery or refining of iron group metals
Related Keywords
7 direct subcodes
Child Classifications
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- C21B 11/00 Making pig-iron other than in blast furnaces
- C21B 13/00 Making spongy iron or liquid steel, by direct processes
- C21B 15/00 Other processes for the manufacture of iron from iron compounds
- C21B 3/00 General features in the manufacture of pig-iron
- C21B 5/00 Making pig-iron in the blast furnace
- C21B 7/00 Blast furnaces
- C21B 9/00 Stoves for heating the blast in blast furnaces
Top Applicants
Top 10 applicants by patent filingsfor class C21, 2013–2023, worldwide · Source: EPO PATSTAT
- JFE STEEL JP 7,470
- POSCO (POHANG IRON AND STEEL COMPANY) KR 4,615
- JFE STEEL 4,538
- NIPPON STEEL CORPORATION JP 4,536
- ARCELORMITTAL LU 2,597
- NSSMC (NIPPON STEEL & SUMITOMO METAL) JP 2,241
- ANGANG STEEL COMPANY 2,126
- NSSMC (NIPPON STEEL & SUMITOMO METAL) 1,783
- BAOSHAN IRON & STEEL COMPANY 1,620
- HYUNDAI STEEL COMPANY KR 1,545