Blast Furnace Hearth Patents: Top Companies & Filing Trends 2026
- 34.0% concentration. The top 5 assignees hold 53 of 156 records in scope — a field where a handful of steelmakers and refractory suppliers already occupy a third of the claim space.
- China dominates the office split. 87 of the tracked receiving-office filings are Chinese, well ahead of Japan (12), India (8), EPO (7) and the US (7).
- Filings cooled after the 2022 peak. Activity peaked at 18 filings in 2022; the last complete comparison year shows 2021's 8 filings falling to 5 by 2024, a -38% move worth watching rather than ignoring.
Filing growth compares 2021 (8 records) with 2024 (5) — 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 156 records in scope (CR5), not by the ranked leaders only.
What this landscape covers
Blast furnace hearth life is governed by how carbon brick and ceramic pad wear against molten iron over a multi-year campaign, and by how well operators can see that erosion coming. This landscape tracks patent activity across three linked problems: refractory material composition (carbon brick, ceramic cup, titanium addition for protective layer formation), thermal and structural monitoring (cooling stave design, thermocouple placement, wear-thickness estimation), and operational wear-management practice such as salamander tapping and elephant-foot erosion control. The search spans 156 published records from 2015 through the July 2026 data cut-off.
The dataset draws on 71 ranked assignees, spanning steelmakers with in-house refractory divisions, dedicated refractory material suppliers, and university research groups. Patent families rather than raw document counts are used for the ranking, which neutralises the effect of continuation filings and multi-jurisdiction refiling by any single applicant.
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Filing trend and technology composition
Two views of the same 156 records: how filing volume has moved year over year, and which IPC subclasses the claims actually sit in. Because a single record can carry several IPC classes, the composition shares add up to more than 100% of the record total.
Filing trend, 2017–2026
Filings rose from 7 in 2017 to a peak of 18 in 2022, then eased back — 2021's 8 filings dropped to 5 by 2024, a -38% move over that span. 2025 and 2026 figures are still filling in, since publication typically lags filing by around 18 months, so the most recent two years understate real activity rather than showing a genuine slowdown.
Technology composition by IPC subclass
C21B (iron production / blast furnace) covers 64.7% of the 156 records, confirming that most filings are anchored in core blast furnace process claims rather than adjacent fields. F27D (furnace details and accessories, 26.9%) and C04B (ceramics, cement and refractories, 21.8%) form the next tier — largely stave, lining and material-composition claims. Measurement and monitoring classes (G01B, G01N, G01K) and digital-processing class G06F each sit at 5.1% or below, marking where instrumentation and data-driven wear prediction remain comparatively thin.
Shares are the percentage of the 156 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Blast Furnace Hearth and Refractory Life with Eureka
This page is one run against one query. Ask Eureka your own question about blast furnace hearth and refractory life and every answer comes back with the patent numbers behind it.
Try EurekaThe most-cited records in this field
US4272062A — Blast Furnace Hearth
A blast furnace hearth, or at least its internal surface layer, is built of carbon bricks whose pores have been reduced in size by an Si-N-O composition formed in them.Filed by Nippon Steel Corporation, granted 1981-06-09. Its age and citation count (16) mark it as a foundational reference for carbon-brick pore-sealing approaches rather than a currently enforceable barrier in most jurisdictions.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | CN101275829A | 一种测量高炉炉衬侵蚀厚度方法 | 47 |
| 2 | US20170030647A1 | Refractory lining repair material | 17 |
| 3 | US4272062A | Blast furnace hearth | 16 |
| 4 | KR1020030050868A | Estimation method for blast furnace hearth refractorythickness | 14 |
| 5 | CN204224628U | 一种高炉炉缸在线安装的热电偶 | 13 |
| 6 | CN102924097A | 高炉炉缸、炉底用碳钛基结合自护砖 | 12 |
| 7 | CN110527769A | 一种高炉炉缸碳砖残厚判断方法 | 11 |
| 8 | CN103305642A | 一种高炉扬冷避热型梯度布砖方法 | 11 |
| 9 | US3858861A | Underhearth cooling system | 11 |
| 10 | CN114896546A | 一种高炉炉缸碳砖残厚的高精度计算方法 | 9 |
Citation counts reflect influence within this searched corpus and skew toward older filings — treat them as a signal of prior-art density, not of current commercial relevance.
Patent titles are shown in the language they were filed in, not translated, so that each record stays verifiable against the original filing — a translated title will not match in Eureka or in any national register. Each row carries its publication number; clicking a row searches Eureka by that number.
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Browse MCP servers →What the data means for filing strategy
Three patterns stand out once the ranking, the trend and the IPC split are read together: where claim density already sits, where it is thinning, and where citation weight is concentrated in a small number of older documents.
A third of the field sits with five assignees
The top 5 assignees combined hold 53 of the 156 records in scope — 34.0% of the field. That is meaningful concentration without being a monopoly: the tenth-ranked assignee still holds only 4 records, so the field has a long tail of single- or few-filing entrants behind the leaders.
Filing activity is heavily China-weighted
China accounts for 87 of the tracked receiving-office filings, more than Japan, India, the EPO and the US combined. That reflects both the concentration of blast furnace capacity in China and active domestic refractory R&D rather than a global filing pattern.
Citation leadership sits with older, foundational filings
The most-cited record in the corpus, a wear-thickness measurement method, carries 47 citations — well ahead of the next tier. High citation counts here reflect age and foundational status within the searched corpus more than current enforceability or commercial weight.
Volume has pulled back from its 2022 peak
Filings peaked at 18 in 2022. Using the last comparison window that is not distorted by publication lag, 2021's 8 filings fell to 5 by 2024 — a -38% move. That is a real pullback in a niche field, not evidence the technology has stalled.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to blast furnace hearth and refractory life, with the prior art for and against each one.
Who is filing, and where the gate stands
The ranked assignee list spans steelmakers, dedicated refractory suppliers and university labs. Momentum data for the leading names shows most recent-year activity flat or down, which is consistent with a field that built up claim density earlier in the period rather than one still accelerating.
One assignee sits well clear of the rest
The leading assignee holds 29 records against a fifth-place figure of 5 and a tenth-place figure of 4 — a steep drop-off that marks this as a leader-plus-long-tail field rather than a tightly bunched one.
Co-filing is limited and mostly regional
Only 4 co-assignee pairs appear in the dataset. The strongest pair, two regional steel-group entities, shares 4 records; the next-strongest pairs, including a refractory-materials pairing, share 2 each. Cross-border joint filing is not a visible pattern here.
Recent-year activity has gone quiet among the leaders
Momentum tracking for the top-named assignees shows mostly zero filings in the latest year, with one leading steelmaker down -100% YoY. Given the 18-month publication lag, this likely understates true 2025–2026 activity rather than confirming an actual stop.
| Assignee | Recent year | YoY |
|---|---|---|
| Wuhan University of Science and Technology | 1 | 0% |
| Vesuvius Crucible Company | 0 | — |
| Vesuvius USA Corp | 0 | — |
| Nippon Steel Corporation | 0 | — |
| Angang Steel Co., Ltd. | 0 | -100% |
| Beijing Ruier Non-Metallic Materials Co., Ltd. | 0 | — |
| Magneco/Metrel Inc. | 0 | -100% |
| Wuhan Iron and Steel Co., Ltd. (WISCO) | 0 | — |
Where to take this next
The landscape points to a concentrated core and a thin monitoring layer. The next steps depend on whether the goal is freedom-to-operate, white-space filing, or tracking a specific competitor.
Run a freedom-to-operate check on core claims
With 64.7% of records sitting in C21B and a top-5 concentration of 34.0%, any new carbon-brick or hearth-structure filing should be checked against the leading assignees' portfolios before drafting.
Check claims in Eureka →Map the monitoring and prediction gap
G01B, G01K and G06F classes each sit at or below 5.1% of records, which is thin relative to the core process classes. That gap is worth a dedicated prior-art search before committing R&D budget to a sensing or predictive-model approach.
Explore white space in Eureka →Track leader momentum before it shifts
Several leading assignees show flat or declining recent-year filings, but the 18-month publication lag means 2025–2026 data is incomplete. Set an alert rather than concluding the leaders have stopped filing.
Set a monitoring alert in Eureka →Common questions on hearth and refractory patents
The ranked assignee list of 71 companies is led by a single steelmaker or refractory group holding 29 of the 156 records in scope, a clear margin over the fifth-ranked assignee's 5 records and the tenth-ranked assignee's 4. This is a leader-plus-long-tail structure rather than an evenly split field: the top 5 assignees together account for 34.0% of all records, but beyond the top ten the ranking thins quickly into single- and few-filing entrants. Anyone assessing competitive risk should focus first on the leader's specific claim scope rather than assume broad industry-wide blocking coverage.
Core blast furnace process claims under IPC class C21B cover 64.7% of the 156 records in scope, making it by far the densest area. Furnace structural details under F27D (26.9%) and refractory ceramics/cement composition under C04B (21.8%) form the next layer, largely covering cooling stave design and brick or lining material formulations. Measurement, monitoring and data-processing classes — covering thermocouple systems, wear-thickness sensing and digital prediction — each sit at 5.1% or below, indicating comparatively lighter claim density in the instrumentation side of the field.
Filing volume rose from 7 records in 2017 to a peak of 18 in 2022, then pulled back — the last complete comparison shows 2021's 8 filings falling to 5 by 2024, a -38% move. That pullback is real for the years it covers, but patent publication typically lags filing by around 18 months, so the 2025 and 2026 figures in any dataset are still incomplete and should not be read as confirmation of a continuing decline. A fair read is that the field cooled off its 2022 peak rather than that it has stopped moving.
China accounts for 87 of the tracked receiving-office filings in this dataset, far ahead of Japan (12), India (8), the European Patent Office (7) and the United States (7), with Australia at 5. This distribution tracks the concentration of blast furnace steelmaking capacity and domestic refractory supply chains in China rather than reflecting a globally even filing pattern. Anyone building a filing strategy in this space should treat Chinese-language prior art as the primary search surface, not a secondary one.
US4272062A, assigned to Nippon Steel Corporation and granted in 1981, claims a blast furnace hearth whose carbon-brick internal surface layer has pore size reduced through an Si-N-O composition formed within those pores. It is the most historically influential document of its kind in this field by citation count among older records, but its age means the original patent term has long expired in essentially every jurisdiction. Its practical relevance today is as prior art defining the pore-sealing approach that later carbon-brick composition claims must be distinguished from, not as an active enforcement risk.
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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.
Nothing on this page constitutes an exhaustive prior-art, novelty, freedom-to-operate, or validity search, nor does it constitute legal, financial, investment, or professional advice, and it should not be relied upon as such. Any patent, commercial, or strategic decision should be verified independently and reviewed with qualified patent, legal, and domain professionals. Patsnap makes no warranties, express or implied, as to the accuracy, completeness, or fitness for any particular purpose of the information presented.
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.