Basic Oxygen Furnace Patents: Who Leads, Where Gaps Are 2026
- 63.4% concentration. The top five assignees hold 97 of the 153 records in scope — filing here is dominated by a small group, not fragmented across the industry.
- Filings peaked in 2019. 24 records published that year against 6 in 2017; the 2026 count of 0 reflects the publication lag, not a stop in activity.
- Lining and vessel-life claims cite deep. Two of the most-cited records in the set are BOF lining profiler methods from the 1980s and 1990s, still drawing citations decades later.
Top-5 share is the combined record count of the five largest assignees divided by all 153 records in scope (CR5), not by the ranked leaders only.
What this landscape covers
This dataset tracks patent families addressing basic oxygen furnace (BOF) blowing practice: how operators control the oxygen blow to hit an endpoint, prevent slopping, manage lance height, run bottom stirring, and cope with converter lining wear. It spans records published between 2015 and mid-2026, filtered to documents that combine BOF or top-blown converter terminology with at least one of the operational control terms above.
The scope is deliberately narrow: it excludes general steelmaking metallurgy and captures only the operational-control layer of BOF practice, where process control, refractory life and endpoint chemistry intersect. Because publication lags filing by roughly 18 months, the most recent year in the trend below understates real filing activity.
Filing trend and technology composition
153 records in scope, drawn from a search combining BOF/converter terminology with operational-control terms such as slopping prevention, endpoint prediction and bottom stirring.
Filings rose to a 2019 peak, then cooled
Annual counts moved from 6 in 2017 to a peak of 24 in 2019. The apparent drop to 0 by 2026 reflects the publication lag inherent in patent data, not an actual halt in filing.
Steelmaking dominates; furnace hardware and casting trail
C21C (steelmaking) appears in 85.0% of the 153 records, far ahead of C21B (blast furnace iron production, 19.0%) and F27D (furnace details and accessories, 18.3%). Measuring and dimensional control under G01B appears in only 2.0% of records, a narrow but persistent thread tied to lance and profile measurement.
Shares are the percentage of the 153 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Basic Oxygen Furnace Blowing Practice with Eureka
This page is one run against one query. Ask Eureka your own question about basic oxygen furnace blowing practice and every answer comes back with the patent numbers behind it.
Try EurekaRecords that define the claim map
Bottom stirring tuyere and method for a basic oxygen furnace (US20190218631A1)
The filing describes a BOF bottom-stir tuyere with an inner nozzle inside an annular nozzle. Inert gas flows through both during the hot metal pour and blow phases; during tap, one nozzle carries a fuel stream and the other an oxidant, forming a flame at the tuyere tip; the flame is sustained through the slag splash phase before the inert-gas flow resumes.Assigned to Air Products and Chemicals, published 2019-07-18.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | EP3042965A1 | Process for dephosphorization of molten metal during a refining process | 43 |
| 2 | US4893933A | Automatic BOF vessel remaining lining profiler and method | 43 |
| 3 | US5125745A | Automatic BOF vessel remaining lining profiler and method | 39 |
| 4 | US6171364B1 | Method for stable operation of a smelter reactor | 22 |
| 5 | US3377158A | Converter control systems and methods | 19 |
| 6 | WO1997035038A1 | Stable operation of a smelter reactor | 16 |
| 7 | US3594155A | Method for dynamically controlling decarburization of steel | 16 |
| 8 | EP0310244A2 | Automatic basic-oxygen-furnace vessel remaining lining profiler and method | 14 |
| 9 | US6440355B1 | Apparatus for measuring bath level in a basic oxygen furnace to determine lance height adjustment | 12 |
| 10 | US20030102609A1 | Method for measuring bath level in a basic oxygen furnace to determine lance height adjustment | 11 |
Citation counts favour older records in a searched corpus; read them as a signal of influence within this field, not of current commercial weight.
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Three patterns stand out once the records are grouped by assignee, class and geography.
Filing sits with a small leadership group
The top five assignees account for 97 of the 153 records in scope, and the top ten hold 85.6%. A field this concentrated leaves little room to file a broad claim near the leaders' existing positions without running into prior art.
Steelmaking control dwarfs measurement-specific claims
C21C steelmaking classifications touch the large majority of records, while G01B measuring/dimensional claims — the kind that would cover lance-height or profile sensing hardware specifically — sit at just 2.0% of the 153 records. That gap suggests measurement and instrumentation claims are thinner than the process claims built on top of them.
Old lining-life patents still anchor the field
Two 1980s–1990s BOF lining profiler patents each carry citation counts in the same range as a 2016 dephosphorization filing. Refractory-life monitoring methods from decades ago remain reference points that newer filings still have to work around.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to basic oxygen furnace blowing practice, with the prior art for and against each one.
Who is filing, and where the momentum sits
The ranked list covers 24 companies across the full 153-record set. Recent-year momentum for the leading names shows zero new publications in the latest year for each — consistent with the publication lag rather than an actual pullback.
One assignee sets the pace by a wide margin
The leading assignee's 31 records sit well above fifth place at 10 and tenth place at 4, showing a steep drop-off rather than a gradual taper.
A compact group holds the middle tier
From second through fifth place, counts cluster in the low double digits before falling to single digits by tenth place, meaning most differentiation among challengers happens in a narrow band.
Cross-entity filing is limited but not absent
The strongest co-assignee pairing in the dataset links a single engineering group with its regional subsidiary across 8 shared records, pointing to internal group filing rather than broad industry co-development.
| Assignee | Recent year | YoY |
|---|---|---|
| Air Products and Chemicals, Inc. | 0 | — |
| Lhoist Recherche et Developpement SA | 0 | — |
| Tenova S.p.A. | 0 | — |
| Sumitomo Metal Industries, Ltd. | 0 | — |
| Nippon Steel Corporation | 0 | — |
| Tata Steel Limited | 0 | — |
| Steel Technology LLC | 0 | — |
| Tenova Industrial Technology (Beijing) Co., Ltd. | 0 | — |
Where to take this research
The landscape points to a concentrated leadership group, a thin measurement-instrumentation layer, and old lining-life patents that still anchor citation networks. Turning that into a filing or freedom-to-operate decision means going record by record.
Map claims against the leader's portfolio
Before drafting near bottom stirring or endpoint control, check which of the leading assignee's 31 records actually cover the specific mechanism in question rather than assuming the whole space is blocked.
Explore assignee portfolios in EurekaProbe the measurement-instrumentation gap
G01B's 2.0% share against C21C's 85.0% suggests sensing and profiling hardware claims are thinner than the process claims sitting on top of them — worth a dedicated search before committing to a process-only claim.
Run a white-space search in EurekaCommon questions on BOF blowing practice patents
One assignee leads the ranked list with 31 of the 153 records in scope, well ahead of the rest of the field. The top five assignees combined hold 97 records, or 63.4% of all records in scope, and the top ten hold 85.6%. This is a concentrated field: most of the filing activity sits with a small group of companies rather than being spread evenly across many entrants.
Endpoint prediction covers methods for determining when the oxygen blow has reached the target carbon and temperature without over-blowing or under-blowing the heat. It sits inside the C21C steelmaking classification, which touches 85.0% of the 153 records in this dataset, making it one of the most heavily claimed operational areas in BOF practice. Precise endpoint control affects yield, refractory wear and cycle time, which is why it draws sustained filing activity across multiple assignees rather than one company alone.
The technology mix suggests uneven density: C21C steelmaking classifications are heavily claimed at 85.0% of records, but the G01B measuring and dimensional-control classification, which would cover lance-height or profile sensing specifically, appears in only 2.0% of the 153 records. That gap indicates the instrumentation layer underneath bottom stirring and lance control is thinner than the process-control layer above it, which is where a narrowly drafted claim is more likely to find open ground.
Citation counts in a searched patent corpus tend to favour older records simply because they have had more years to accumulate citations from later filings. Two BOF vessel lining profiler patents from the late 1980s and early 1990s carry citation counts of 43 and 39 respectively, putting them on par with a 2016 dephosphorization filing also cited 43 times. That does not mean lining-wear monitoring is the most active area today — it means those early methods became reference points that later filers had to cite or design around.
Not necessarily. Filings peaked in 2019 at 24 records and the count for 2026 shows 0, but patent publication typically lags the actual filing date by roughly 18 months, so the most recent one to two years in any filing trend will always look artificially low. A meaningful growth or decline rate cannot be computed from this dataset because fewer than four complete years remain once that lag is accounted for, so the 2019 peak should be read as the most reliable recent signal rather than a final data point.
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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.