C21B
Manufacture of iron or steel
Official title: MANUFACTURE OF IRON OR STEEL (preliminary treatment of ferrous ores or scrap C22B1/00)
C21B (Manufacture of iron or steel) appears on 3,579 US grants and 2,191 published applications in this corpus.
Search patents in C21B- Granted patents
- 3,579
- Published applications
- 2,191
- Assignees
- 1,377
- Inventors
- 6,309
- Latest grant
- 6 Oct 2026
Filings by year
| Year | Granted patents | Published applications |
|---|---|---|
| 1976 | 81 | 0 |
| 1977 | 130 | 0 |
| 1978 | 109 | 0 |
| 1979 | 101 | 0 |
| 1980 | 95 | 0 |
| 1981 | 106 | 0 |
| 1982 | 104 | 0 |
| 1983 | 110 | 0 |
| 1984 | 81 | 0 |
| 1985 | 74 | 0 |
| 1986 | 70 | 0 |
| 1987 | 74 | 0 |
| 1988 | 62 | 0 |
| 1989 | 72 | 0 |
| 1990 | 59 | 0 |
| 1991 | 64 | 0 |
| 1992 | 40 | 0 |
| 1993 | 55 | 0 |
| 1994 | 45 | 0 |
| 1995 | 77 | 0 |
| 1996 | 69 | 0 |
| 1997 | 59 | 0 |
| 1998 | 59 | 0 |
| 1999 | 97 | 0 |
| 2000 | 83 | 0 |
| 2001 | 140 | 32 |
| 2002 | 97 | 62 |
| 2003 | 78 | 49 |
| 2004 | 38 | 60 |
| 2005 | 28 | 39 |
| 2006 | 15 | 58 |
| 2007 | 24 | 62 |
| 2008 | 22 | 56 |
| 2009 | 41 | 78 |
| 2010 | 54 | 89 |
| 2011 | 61 | 100 |
| 2012 | 65 | 111 |
| 2013 | 81 | 76 |
| 2014 | 69 | 112 |
| 2015 | 86 | 100 |
| 2016 | 68 | 111 |
| 2017 | 70 | 67 |
| 2018 | 73 | 70 |
| 2019 | 69 | 69 |
| 2020 | 69 | 64 |
| 2021 | 42 | 74 |
| 2022 | 44 | 101 |
| 2023 | 45 | 109 |
| 2024 | 57 | 163 |
| 2025 | 95 | 146 |
| 2026 | 72 | 133 |
By publication year. Applications have been published since 2001. 2026 runs to 8 Oct.
Main groups
Granted patents with any code in the group
- C21B 13/00Making spongy iron or liquid steel, by direct processes1,700
- C21B 7/00Blast furnaces988
- C21B 2100/00Handling of exhaust gases produced during the manufacture of iron or steelIndexing code622
- C21B 5/00Making pig-iron in the blast furnace553
- C21B 3/00General features in the manufacture of pig-iron426
- C21B 2400/00Treatment of slags originating from iron or steel processesIndexing code271
- C21B 11/00Making pig-iron other than in blast furnaces196
- C21B 9/00Stoves for heating the blast in blast furnaces135
Recent patents
- Method for manufacturing direct reduced iron and DRI manufacturing equipment6 Oct 2026US 12,753,452 B2ArcelorMittal
- Wire rod for 5000 MPa-grade diamond wire and production method therefor15 Sep 2026US 12,735,763 B2Institute of Research of Iron and Steel, Jiangsu Province/Sha-Steel, Co. Ltd (Cn)
- Method and system for adaptive learning of models in manufacturing systems15 Sep 2026US 12,737,673 B2Tata Consultancy Services Limited
- Zigzag flow reactor for heterogenous thermochemical reduction8 Sep 2026US 12,728,457 B2Arizona Board of Regents on behalf of Arizona State University
- High-carbon biogenic reagents and uses thereof1 Sep 2026US 12,723,211 B2Carbon Technology Holdings, LLC
- Reoxidation retardant and method for hindering reoxidation of direct reduced iron8 Oct 2026US 2026/0308704 A1
- Method of producing reduced iron8 Oct 2026US 2026/0308705 A1Jfe Steel Corporation
- Estimating element content in molten material at openings of metallurgical vessels8 Oct 2026US 2026/0309629 A1Paul Wurth S. A.
- Estimating element content in molten material at openings of metallurgical vessels8 Oct 2026US 2026/0309630 A1Paul Wurth S. A.
- Zigzag flow reactor for heterogenous thermochemical reduction1 Oct 2026US 2026/0295671 A1Arizona Board of Regents on behalf of Arizona State University
Most cited
By later US patents
- Cryoplasty device and method384US 5,868,735 ASciMed Life Systems, Inc. · 1999
- Cryoplasty device and method227US 6,290,696 B1SciMed Life Systems, Inc. · 2001
- Cryoplasty device and method182US 6,648,878 B2SciMed Life Systems, Inc. · 2003
- Cryoplasty device and method170US 7,022,120 B2SciMed Life Systems, Inc. · 2006
- Process for making refractory shapes119US 4,150,078 ALava Crucible Refractories Company · 1979