C21C
Processing of pig-iron
Official title: Processing of pig-iron, e.g. refining, manufacture of wrought-iron or steel; treatment in molten state of ferrous alloys
C21C (Processing of pig-iron) appears on 4,012 US grants and 2,216 published applications in this corpus.
Search patents in C21C- Granted patents
- 4,012
- Published applications
- 2,216
- Assignees
- 1,533
- Inventors
- 7,505
- Latest grant
- 22 Sep 2026
Filings by year
| Year | Granted patents | Published applications |
|---|---|---|
| 1976 | 149 | 0 |
| 1977 | 136 | 0 |
| 1978 | 126 | 0 |
| 1979 | 97 | 0 |
| 1980 | 126 | 0 |
| 1981 | 112 | 0 |
| 1982 | 90 | 0 |
| 1983 | 134 | 0 |
| 1984 | 124 | 0 |
| 1985 | 113 | 0 |
| 1986 | 98 | 0 |
| 1987 | 115 | 0 |
| 1988 | 116 | 0 |
| 1989 | 97 | 0 |
| 1990 | 99 | 0 |
| 1991 | 70 | 0 |
| 1992 | 68 | 0 |
| 1993 | 72 | 0 |
| 1994 | 86 | 0 |
| 1995 | 66 | 0 |
| 1996 | 76 | 0 |
| 1997 | 49 | 0 |
| 1998 | 60 | 0 |
| 1999 | 73 | 0 |
| 2000 | 75 | 0 |
| 2001 | 73 | 22 |
| 2002 | 90 | 42 |
| 2003 | 66 | 70 |
| 2004 | 53 | 85 |
| 2005 | 35 | 51 |
| 2006 | 21 | 74 |
| 2007 | 27 | 82 |
| 2008 | 35 | 76 |
| 2009 | 53 | 90 |
| 2010 | 59 | 102 |
| 2011 | 71 | 115 |
| 2012 | 83 | 105 |
| 2013 | 71 | 82 |
| 2014 | 70 | 93 |
| 2015 | 64 | 91 |
| 2016 | 69 | 100 |
| 2017 | 79 | 78 |
| 2018 | 52 | 73 |
| 2019 | 66 | 78 |
| 2020 | 66 | 72 |
| 2021 | 47 | 79 |
| 2022 | 51 | 108 |
| 2023 | 59 | 107 |
| 2024 | 76 | 133 |
| 2025 | 88 | 119 |
| 2026 | 61 | 89 |
By publication year. Applications have been published since 2001. 2026 runs to 8 Oct.
Main groups
Granted patents with any code in the group
- C21C 5/00Manufacture of carbon-steel2,727
- C21C 7/00Treating molten ferrous alloys1,368
- C21C 1/00Refining of pig-iron601
- C21C 2300/00Process aspectsIndexing code102
- C21C 2100/00Exhaust gasIndexing code62
- C21C 2250/00Specific additivesIndexing code25
- C21C 2200/00Recycling of waste materialIndexing code21
- C21C 3/00Manufacture of wrought-iron or wrought-steel2
Recent patents
- Direct current electric arc furnace22 Sep 2026US 12,742,218 B2Masercata Oy
- Non-oriented electrical steel sheet, method for producing same, and hot-rolled steel sheet22 Sep 2026US 12,742,223 B2Nippon Steel Corporation
- High-carbon biogenic reagents and uses thereof1 Sep 2026US 12,723,211 B2Carbon Technology Holdings, LLC
- Blast furnace—converter steel production method based on carbon cycling28 Jul 2026US 12,692,561 B2Cisdi Engineering Co., Ltd
- Electric induction heating and melting furnace refractory life cycle wear imaging and processing28 Jul 2026US 12,692,564 B2Inductotherm Corp.
- Tuyere for a metallurgical furnace1 Oct 2026US 2026/0297694 A1Paul Wurth S. A.
- Novel process for the smelting of a blend of hot and cold metalliferous feedstock material yielding reduced carbon emissions1 Oct 2026US 2026/0297695 A1Metix (Proprietary) Limited
- Method for melting iron source1 Oct 2026US 2026/0297697 A1Nippon Steel Corporation
- Novel process for the smelting of a metalliferous feedstock material yielding reduced carbon emissions1 Oct 2026US 2026/0297698 A1Metix (Proprietary) Limited
- Method for producing molten steel1 Oct 2026US 2026/0297699 A1Jfe Steel Corporation
Most cited
By later US patents
- Probe for taking gas samples and heat measurements in a shaft furnace485US 5,108,192 APaul Wurth S. A. · 1992
- Apparatus and method for submerged injection of a feed composition into a molten metal bath151US 5,443,572 AMolten Metal Technology, Inc. · 1995
- Apparatus for purifying molten metal140US 4,351,514 A1982
- Melting metal particles and dispersing gas with vaned impeller135US 5,143,357 AThe Carborundum Company · 1992
- Dispersing gas into molten metal131US 4,954,167 A1990