Blast Furnace Burden Distribution Patents: Leaders & Filing Trends 2026
- 42.5% concentration. The top five assignees alone account for 1,793 of the 4,222 records in scope — filing is concentrated at the top of an otherwise long tail.
- Filing has cooled from its 2021 peak. Filings fell 52% from 211 in 2021 to 101 in 2024, the last year the trend can be read as complete.
- C21B dominates but doesn't monopolise. Iron production classifications cover 44.1% of records, leaving refractories, furnace hardware and layered materials as adjacent, less-crowded ground.
Filing growth compares 2021 (211 records) with 2024 (101) — 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 4,222 records in scope (CR5), not by the ranked leaders only.
What this landscape covers
Burden distribution governs how ore, coke and flux layers are charged and arranged inside a blast furnace — a control problem that sits at the intersection of mechanical charging equipment (bell-less top chutes), thermodynamics (gas utilization, permeability) and operating strategy (ore-to-coke ratio, center coke charging). This landscape draws on 4,222 published records filed between 2015 and mid-2026 that combine burden-distribution search terms with operating parameters such as chute angle setting, layer thickness and gas utilization.
The dataset spans equipment claims on bell-less top chutes and charging mechanisms, process claims on ore-coke layering and center coke charging, and adjacent materials claims on refractories and layered panel products that appear because they share classification codes with furnace lining and structural components.
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Filing trend and technology composition
Two views of the same 4,222-record dataset: filing activity by year, and how records distribute across IPC subclasses.
Filings rose to a 2021 peak, then declined
Annual filings climbed from 124 in 2017 to a peak of 211 in 2021, then fell to 101 by 2024 — a 52% decline over that three-year span. Because publication lags filing by roughly 18 months, the 2025 and 2026 figures (down to 24 for the partial latest year) are still filling in and should not be read as a continuation of the decline.
Iron production classifications lead, but materials classes are substantial
C21B (iron production, blast furnace) covers 44.1% of the 4,222 records, followed by C04B (ceramics, cement and refractories) at 16.2% and C22B (metal extraction and refining) at 13.3%. Furnace hardware classes F27B and F27D together account for a meaningful share, while B32B (layered products), G01N (material testing) and E04B (building structures) show that burden-distribution filings routinely cross into materials and structural engineering. Since a single record can carry multiple IPC codes, these shares sum to more than 100% of the record total.
Shares are the percentage of the 4,222 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Blast Furnace Burden Distribution with Eureka
This page is one run against one query. Ask Eureka your own question about blast furnace burden distribution and every answer comes back with the patent numbers behind it.
Try EurekaA representative filing and the most-cited prior art
US4976780A — Blast furnace operation management method and apparatus
Filed by NIPPON STEEL CORPORATION, this 1990 filing describes a data-and-knowledge-base method for managing blast furnace operation: gathering furnace data at short intervals, inferring furnace state over longer intervals, and forecasting burden distribution under various control combinations to select an optimum charging action.One of the earliest filings in this dataset to tie burden-distribution forecasting to an operator decision-support system rather than a single mechanical adjustment.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US6620487B1 | Structural sheathing panels | 302 |
| 2 | US20060168906A1 | Non-combustible reinforced cementitious lighweight panels and metal frame system for a fire wall and other fi… | 184 |
| 3 | US8038790B1 | High performance non-combustible gypsum-cement compositions with enhanced water durability and thermal stabil… | 170 |
| 4 | US5912070A | Laminated film and packaging material | 139 |
| 5 | US6126718A | Method of producing a reduced metal, and traveling hearth furnace for producing same | 125 |
| 6 | US6200681B1 | Application of microcapsules as latent heat accumulators | 123 |
| 7 | US4926586A | Box for cultivating plant | 123 |
| 8 | US20090088611A1 | Methods and devices for continuous and mobile measurement of various bio-parameters in the external auditory … | 122 |
| 9 | US5502021A | Highly reactive reagents and compositions for purifying exhaust gases and wastewater, production and use ther… | 117 |
| 10 | US20060144005A1 | Non-combustible reinforced cementitious lightweight panels and metal frame system for flooring | 101 |
Citation counts reflect influence within the searched corpus and skew toward older filings; they are not a measure of current commercial importance.
Each row carries its publication number; clicking a row searches Eureka by that number.
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Browse MCP servers →What the numbers mean for strategy
Reading concentration, technology mix and filing momentum together points to where claim space is defensible and where it is still open.
Filing is concentrated but not closed
The top five assignees hold 1,793 records, 42.5% of all 4,222 in scope, and the top ten extend that to 57.7%. That leaves a long tail of single- and few-filing entrants working around the core charging and layering claims rather than inside them.
Core iron-production claims dominate, materials classes trail
C21B alone covers 44.1% of records, but C04B refractories and C22B metal extraction each clear 13-16%, showing that materials and lining claims are a substantial secondary front rather than a niche.
Post-peak decline, not yet a trend reversal
Filings dropped from 211 in 2021 to 101 in 2024. Given the roughly 18-month publication lag, the 2025-2026 figures are incomplete and should not be read as confirming a continued slowdown.
Japan leads filing venues, EPO and US follow closely
Japan accounts for 1,362 records, ahead of Europe (528) and the United States (513), with India, Australia and China each holding meaningful shares — indicating this is a globally filed technology rather than one concentrated in a single jurisdiction.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to blast furnace burden distribution, with the prior art for and against each one.
Who is filing, and where the gate sits
The ranked leaders combine integrated steelmakers with materials suppliers, but recent-year filing counts show most players slowing rather than accelerating.
A single leader well ahead of the field
The top-ranked assignee holds 524 records against 199 for fifth place and 63 for tenth, a steep drop-off that marks this as a leader-plus-long-tail landscape rather than an evenly split one.
Leaders are flat or pulling back, not accelerating
The top-ranked assignee filed 4 records in the latest year with 0% year-on-year change, while several other ranked assignees show double-digit percentage declines in the same period — consistent with the broader post-2021 pullback in filing volume.
Co-filing is limited and concentrated
Only ten co-assignee pairs appear in the dataset, and the strongest pairings link a steelmaker to its own research institute or an equipment partner, suggesting most burden-distribution IP is developed in-house rather than through joint filing.
| Assignee | Recent year | YoY |
|---|---|---|
| Nippon Steel Corporation | 4 | 0% |
| JFE Steel Corporation | 1 | -92% |
| Sika Technology AG | 1 | -67% |
| Pohang Iron & Steel Co., Ltd. (POSCO) | 1 | — |
| Paul Wurth S.A. | 1 | -86% |
| Kawasaki Steel Corporation | 0 | — |
| United States Gypsum Co. | 0 | — |
| Nippon Kokan KK | 0 | — |
Where to take this analysis
The dataset points to specific next steps depending on whether the goal is freedom-to-operate, portfolio positioning or scouting for licensing partners.
Map claim boundaries around the leading assignee
With 524 records at the top of the ranking, understand which claim elements the leader has locked down in chute geometry and charging sequence before drafting near that territory.
Explore assignee claims in EurekaCheck the under-claimed branches for a filing angle
Layer-thickness instrumentation and gas-utilization prediction show lighter concentration than core C21B charging claims and may offer more room to establish a defensible position.
Run a white-space search in EurekaWatch for the 2025-2026 publication catch-up
Because publication lags filing by about 18 months, the apparent slowdown after 2021 will firm up or reverse as 2025-2026 filings continue to publish — worth re-checking in six to twelve months.
Set a monitoring alert in EurekaCommon questions about this landscape
The assignee ranking is led by a single company with 524 records, well ahead of fifth place at 199 and tenth place at 63. The top five assignees together hold 1,793 records, 42.5% of the 4,222 records in scope, and the top ten extend that to 57.7%. This is a leader-plus-long-tail structure: one dominant filer, a handful of strong followers, and then many companies with only a few filings each.
Filings rose from 124 in 2017 to a peak of 211 in 2021, then fell to 101 by 2024, a 52% decline over that three-year window. Figures for 2025 and 2026 are lower still, but publication typically lags filing by about 18 months, so those recent years are undercounted and should not be read as proof the field is dying. The safest complete read is the 2021-to-2024 decline; anything drawn from 2025-2026 needs revisiting once more filings publish.
Beyond core iron-production claims (C21B, 44.1% of records), the dataset shows meaningful overlap with refractories and cement (C04B, 16.2%), metal extraction and refining (C22B, 13.3%), and furnace hardware (F27B and F27D). Smaller but notable shares appear in layered products (B32B), material testing (G01N) and building structures (E04B), reflecting how furnace lining, sensor instrumentation and structural design all intersect with charging and layering technology. A single filing often carries several of these classes at once.
Japan is the largest receiving office with 1,362 records, followed by the European Patent Office at 528 and the United States at 513. India (327), Australia (251) and China (236) also carry meaningful volumes. This spread indicates the technology is filed globally rather than concentrated in a single jurisdiction, which matters for freedom-to-operate checks that only look at one region.
The core charging and layering claims under C21B are dense, but adjacent branches such as layer-thickness instrumentation, chute-angle sensing feedback and gas-utilization prediction show lighter concentration relative to the core. Co-filing is also limited, with only ten co-assignee pairs recorded, suggesting most companies develop this IP in-house rather than jointly — which can leave partnership-driven filing angles less explored. Anyone scouting a filing position should compare a target claim against the specific sub-area's density rather than the field average.
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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.