Ladle Furnace Refining Patents: Top Filers & Filing Trends 2026
- 34.1% concentration at the top. The five leading assignees hold 117 of 343 records in scope, a level of concentration that narrows the open claim space for slag reduction and alloy recovery chemistry.
- Filing has pulled back sharply since the 2022 peak. Activity ran from 21 records in 2021 to 9 in 2024, a -57% move over that span, after peaking at 42 records in 2022.
- Steelmaking dominates, refractories and furnace hardware trail. C21C appears in 69.4% of records while C04B ceramics/refractories and F27D furnace details each sit at 8.5%, suggesting hardware and lining claims are comparatively thin.
Filing growth compares 2021 (21 records) with 2024 (9) — a three-year span. 2024 is the most recent year we treat as complete: publication lags filing by roughly 18 months, so 2025 onwards are still filling in and any growth rate that ends there would understate the field. Top-5 share is the combined record count of the five largest assignees divided by all 343 records in scope (CR5), not by the ranked leaders only.
What the ladle furnace refining patent landscape covers
Ladle furnace refining sits between primary steelmaking and casting: it is where temperature is homogenised, slag chemistry is adjusted, alloys are recovered, and stirring intensity and arc efficiency are tuned before a heat goes to the caster. The 343 records in scope were pulled from filings and publications tagged against ladle furnace, ladle metallurgy and ladle arc heating language, cross-matched against process outcomes like temperature homogeneity, slag reduction, alloy recovery and arc efficiency.
Coverage runs from 2015 through the 2026-07-31 cut-off. Because publication typically lags filing by around 18 months, the most recent one to two years in any trend chart will understate actual filing activity and should not be read as a slowdown on their own.
Filing trends and technology composition
Two views of the same 343-record dataset: how filing volume has moved year over year, and how those records distribute across IPC subclasses. Since a single record can carry several IPC codes, the class shares below add to more than 100% of the record total.
Filing activity, 2017–2026
Filings rose from 3 records in 2017 to a peak of 42 in 2022, then declined to 9 by 2024 — a -57% move from the 21 recorded in 2021. 2025 and 2026 figures are still incomplete due to publication lag and should not be read as a continued fall.
Technology composition by IPC subclass
C21C (steelmaking) covers 69.4% of the 343 records, far ahead of C22C alloys (24.5%) and B22D metal casting (14.3%). C04B refractories and F27D furnace accessories each sit at 8.5%, the thinnest coverage among the classes tracked here.
Shares are the percentage of the 343 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Ladle Furnace Refining with Eureka
This page is one run against one query. Ask Eureka your own question about ladle furnace refining and every answer comes back with the patent numbers behind it.
Try EurekaRepresentative and most-cited records
Method for recovering metallic elements from slag containing metal oxides in an electric-arc furnace
The method recovers metallic elements, especially metallic chromium, from oxide-bearing slag left in an electric-arc furnace after tapping. Rather than reducing the slag in a separate step, a further scrap charge carrying reducing agents is added and melted so the slag is reduced during that same melt cycle, before both slag and metal are tapped off together.Filed by SMS Siemag Aktiengesellschaft, published 2006-09-07.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US5397379A | Process and additive for the ladle refining of steel | 108 |
| 2 | US20050076975A1 | Low carbon alloy steel tube having ultra high strength and excellent toughness at low temperature and method … | 85 |
| 3 | US20060169368A1 | Low carbon alloy steel tube having ultra high strength and excellent toughness at low temperature and method … | 67 |
| 4 | US20090101242A1 | Low carbon alloy steel tube having ultra high strength and excellent toughness at low temperature and method … | 39 |
| 5 | US20080185145A1 | Methods for extracting oil from tar sand | 30 |
| 6 | US4990183A | Process for producing steel having a low content of nitrogen in a ladle furnace | 28 |
| 7 | US7617869B2 | Methods for extracting oil from tar sand | 26 |
| 8 | US20020005083A1 | Process for the production of metal melts | 22 |
| 9 | US6241798B1 | Iron smelting process and plant according to the multiple zone smelting process | 21 |
| 10 | WO1989007499A1 | Superheating and microalloying of molten metal by contact with a plasma arc | 21 |
Citation counts inside this corpus favour older filings and should be read as a signal of influence, not current relevance — the oldest record in the table, US5397379A, is also the most cited.
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Three patterns stand out once family counts, class shares and the filing trend are read together: where claim space is already dense, where it has thinned, and where the growth story has to be handled carefully.
The top of the field is dense but not closed
The five leading assignees account for 117 of the 343 records in scope, and the top ten hold 53.6% (184 records). That leaves close to half the field spread across a long tail of single- and low-filing entrants, which is where new process combinations still have room.
Peak-year filing has cooled from 2022
Volume ran from 21 records in 2021 to a peak of 42 in 2022, then down to 9 by 2024. Because publication lags filing by roughly 18 months, 2025-2026 figures are still filling in and should not be treated as confirmation of a continued decline.
Refractory and furnace-hardware claims are thin
C21C steelmaking process claims dominate at 69.4% of the 343 records, while C04B ceramics/refractories and F27D furnace details each sit at only 8.5%. Lining materials and furnace accessory design look comparatively under-claimed relative to the process chemistry above them.
Filing offices skew toward the US, EPO and Japan
The United States (68), Europe (63) and Japan (40) lead receiving offices, ahead of India (27), Canada (26) and WIPO/PCT (22). That ordering points to where enforcement and freedom-to-operate checks matter most for a filer entering this space.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to ladle furnace refining, with the prior art for and against each one.
Who is filing, and where the field is still open
The leading assignee holds 42 records, with fifth place at 17 and tenth place at 12 — a steep drop-off that confirms most of the ranked 100 companies file only occasionally in this space. Several of the most active assignees, including multiple Japanese and Chinese steelmakers, show zero filings in the latest tracked year, consistent with the broader 2021-2024 pullback rather than any single company's retreat.
A single leader well ahead of the field
The top assignee's 42 records sit well above fifth place at 17, giving it outsized influence over process-chemistry claims in slag reduction and alloy recovery.
Clustered filing among linked entities
Ten co-assignee pairs appear in the dataset, with the strongest pairing sharing 17 records and two other pairs at 14 each, pointing to research-institute and group-company filing structures rather than isolated single-owner patents.
Even leading filers have gone quiet recently
Multiple assignees that rank among the most active historically show no recorded filings in the latest year, a pattern that lines up with the field-wide -57% move from 2021 to 2024 rather than isolated company exits.
| Assignee | Recent year | YoY |
|---|---|---|
| JFE Steel Corporation | 0 | -100% |
| Tenaris Connections AG | 0 | — |
| Sanyo Special Steel Co., Ltd. | 0 | — |
| Institute of Research of Iron & Steel, Jiangsu Province | 0 | — |
| Jiangsu Shagang Group Co., Ltd. | 0 | — |
| Nippon Steel Corporation | 0 | — |
| Zhangjiagang Rongsheng Special Steel Co., Ltd. | 0 | — |
| Material Handling Tech S.p.A. | 0 | — |
Where to take this next
The dataset points to specific next checks rather than a general read of the field.
Check freedom-to-operate against the top 5
With 34.1% of records held by five assignees, a targeted claim-scope review of their families is a faster first step than a broad landscape re-read.
Run a claim comparisonTest the under-claimed branches
Refractory and furnace-accessory classes sit at 8.5% coverage against 69.4% for core steelmaking — worth a closer look before assuming the space is occupied.
Explore white spaceTrack the post-2022 filing shift
Filing fell from a 2022 peak of 42 to 9 in 2024; watching which assignees still file through that drop identifies who is committed versus who filed opportunistically.
Monitor assignee activityCommon questions about ladle furnace refining patents
The leading assignee in this dataset holds 42 of the 343 records in scope, well ahead of the fifth-ranked filer at 17 and the tenth at 12. The top five assignees combined account for 34.1% of all records, and the top ten reach 53.6%. That leaves a long tail of the remaining ranked companies filing only a handful of records each, so ownership is concentrated at the top but far from closed.
Filing peaked at 42 records in 2022 after rising from just 3 in 2017, then declined to 9 records by 2024 — a -57% move from the 21 filed in 2021. Because patent publication typically lags actual filing by around 18 months, the 2025 and 2026 figures in any chart are still incomplete and should not be read as proof the technology is losing momentum. 2024 is the most recent year that can be treated as a reasonably complete data point.
Steelmaking process claims under IPC class C21C appear in 69.4% of the 343 records, making it by far the largest category. Alloy composition (C22C) follows at 24.5% and metal casting (B22D) at 14.3%, while refractory materials (C04B) and furnace hardware (F27D) each sit at only 8.5%. Because a single patent can carry multiple IPC codes, these shares add up to well over 100% of the record total, which is expected.
The clearest gaps sit in classes with comparatively low coverage relative to the dominant steelmaking process claims: refractory lining materials and furnace accessory design each cover only 8.5% of the 343 records, versus 69.4% for core steelmaking process chemistry. Sub-areas like stirring gas injection geometry, arc efficiency at partial furnace load, and refractory wear compensation are worth checking specifically, since dense filing in core slag-and-alloy chemistry does not mean the surrounding hardware and control claims are equally occupied.
US5397379A, covering a process and additive for ladle refining of steel, is the most-cited record in this dataset with 108 citations. Several other highly cited records relate to low-carbon alloy steel tube manufacturing rather than the ladle process itself, which is a reminder that citation counts inside a searched corpus tend to favour older filings and should be read as a signal of influence rather than of current technical importance.
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Disclaimer. This page is generated from Patsnap Eureka data drawn from a limited snapshot of global patent and scientific-literature records, and is provided for general information and reference only.
Patent data carries inherent limitations: recent filings (typically the most recent 18–24 months) are under-counted due to standard publication lag; counts may be reported at either a patent-family or a patent-record basis and are not always directly comparable; classification, applicant-name, and citation data may contain errors, duplicates, or omissions; and the underlying search query defines and constrains the scope shown. As a result, the analysis may be incomplete or inaccurate and may not reflect the full technology landscape.
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Machine translation. Assignee and organisation names originally recorded in Chinese, Japanese or Korean have been rendered into English by an AI translation step so that the tables stay readable. These renderings are best-effort and may not match a company’s registered English name; the original name is what the underlying patent record carries, and it is what any Eureka query launched from this page uses.