Slag Chemistry and Hot Metal Quality Patents: Leaders & Trends 2026
- Concentrated at the top. The five most active filers account for 190 of 605 records in scope (31.4%), with a long tail of single- and few-filing entrants behind them.
- Filing has cooled from its 2020 peak. Activity ran from 37 records in 2020 down to 5 by 2024, a -69% swing across 2021-2024, though 2025-2026 counts are still filling in as publication catches up with filing.
- Metal extraction and steelmaking classes dominate. C22B, C21C and C21B each cover roughly a third of all 605 records, while refractories, alloys and furnace-instrumentation classes sit in single digits.
Filing growth compares 2021 (16 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 605 records in scope (CR5), not by the ranked leaders only.
What this landscape covers
This landscape tracks patent activity at the intersection of blast furnace slag chemistry and hot metal quality — the practices that govern slag basicity, silicon control, sulfur partition between metal and slag, alkali circulation, slag viscosity, desulfurization pretreatment and tapping practice. It spans 605 published records filed or published between 2015 and mid-2026.
The scope sits across several IPC subclasses rather than one: metal extraction and refining (C22B), steelmaking (C21C) and blast furnace iron production (C21B) each touch roughly a third of the corpus, with refractories, alloys and furnace instrumentation forming smaller, more specialised clusters.
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Filing trend and technology composition
Two views of the same 605 records: how filing volume has moved year over year, and which IPC subclasses the claims actually sit in.
A 2020 peak, then a documented decline
Filings rose to a peak of 37 records in 2020, then fell to 5 by 2024 — a -69% change over that three-year span. Because publication typically lags filing by around 18 months, the 2025 and 2026 counts (down to 2 in 2026) are still incomplete and should not be read as a continuation of the decline.
Three core subclasses carry the bulk of the field
C22B (metal extraction & refining), C21C (steelmaking) and C21B (blast furnace iron production) each appear in roughly a third of all 605 records. Refractories (C04B, 10.7%), alloys (C22C, 6.6%) and furnace/analysis classes (F27D, G01N, F27B, each under 5%) show far thinner claim coverage — records can carry more than one class, so these shares overlap rather than sum to 100%.
Shares are the percentage of the 605 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Slag Chemistry and Hot Metal Quality with Eureka
This page is one run against one query. Ask Eureka your own question about slag chemistry and hot metal quality and every answer comes back with the patent numbers behind it.
Try EurekaRepresentative and most-cited filings
US20240337447A1 — Blast furnace slag level estimation method, operation guidance method, method of producing hot metal, blast furnace slag level estimation apparatus, and operation guidance apparatus
A blast furnace slag level estimation method and apparatus estimate the liquid level of slag to a high degree of accuracy, using a physical model that calculates melt level for each region separated by a low permeability zone from inputs including hot metal tapping rate, slag tapping rate and hot metal production. An operation guidance method and hot metal production method then use that estimate to guide blast furnace operation.Filed by JFE Steel Corporation, published 2024-10-10.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US8337613B2 | Slagging coal combustor for cementitious slag production, metal oxide reduction, shale gas and oil recovery, … | 87 |
| 2 | US20110173139A1 | Slagging coal combustor for cementitious slag production, metal oxide reduction, shale gas and oil recovery, … | 54 |
| 3 | US6264738B1 | Method of producing cement clinker and associated device | 48 |
| 4 | US4282420A | Welding electrode | 44 |
| 5 | EP2213753A1 | Method of production of a slag-forming compound for secondary steel refining in a ladle or ladle furnace | 43 |
| 6 | CN1962897A | 改善高炉炉渣粘度的烧结矿及其制备方法 | 40 |
| 7 | US5286277A | Method for producing steel | 38 |
| 8 | US5078785A | Method of operating in-bath smelting reduction furnace | 36 |
| 9 | US4946811A | Method for mixing molten iron silicate with ferroalloy slag in order to produce fire-resistant and chemically… | 30 |
| 10 | US6332910B1 | Process for working up steel slags and iron carriers for obtaining pig iron and environmentally safe slags | 26 |
Citation counts favour older filings simply because they have had more time to accumulate citations inside this corpus — treat them as a signal of influence, not of current 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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Three read-throughs from the concentration, trend and classification data above.
The field is led, not fragmented
The top five assignees hold 190 of 605 records (31.4%) and the top ten hold 286 (47.3%). That leaves more than half of the corpus spread across a long tail of entrants filing once or a handful of times — a shape typical of a mature process technology where a handful of integrated steelmakers set the pace.
Volume has receded from its peak
Filings peaked at 37 records in 2020 and had fallen to 5 by 2024, a -69% change across 2021-2024. Treat 2025 and 2026 figures as provisional: publication lag of roughly 18 months means recent years are always undercounted at the point of measurement.
Extraction and steelmaking classes carry the field
C22B, C21C and C21B each appear in roughly a third of the 605 records, confirming that most activity sits squarely in core metallurgical process claims rather than adjacent materials or instrumentation work. Refractories and alloys trail well behind at 10.7% and 6.6%.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to slag chemistry and hot metal quality, with the prior art for and against each one.
Who is filing, and where the gate sits
The ranked leaders come from integrated steelmakers and specialist metallurgical firms; momentum in the latest year has slowed across the group, consistent with the corpus-wide trend.
A single leader well ahead of fifth place
The top-ranked assignee holds 59 records against 22 at fifth place and 18 at tenth — a gap wide enough that new entrants are more likely to compete on a specific sub-process than on the same broad claim territory.
Recent-year filing has gone quiet at the top
Several of the most active historical filers, including a -100% YoY move from one leading Japanese steelmaker, show zero filings in the latest year on record. That is consistent with the corpus-wide fall from the 2020 peak rather than a signal specific to any one firm.
Co-filing is rare and concentrated
Only seven co-assignee pairs appear in the dataset, and the strongest pair co-files six times — most work here is filed by a single organisation rather than jointly developed.
| Assignee | Recent year | YoY |
|---|---|---|
| JFE Steel Corporation | 0 | — |
| Nippon Steel Corporation | 0 | -100% |
| Science and Technology Resources Ltd. | 0 | — |
| Tata Steel Ltd. | 0 | — |
| Kobe Steel, Ltd. | 0 | — |
| Mintek | 0 | — |
| Holcim Ltd. | 0 | — |
| Armco Inc. | 0 | — |
Where to take this analysis
The dataset points to a few concrete next steps for teams deciding where to file or where to watch.
Map claims against the under-claimed branches
Real-time viscosity sensing, alkali circulation control and ladle-stage sulfur partition modelling all sit inside scope but carry thin coverage relative to the core steelmaking classes — worth a closer freedom-to-operate pass before committing claim language.
Explore white space in EurekaTrack the leader's post-2024 filings closely
With top-ranked assignees showing zero filings in the latest recorded year, any new filing from that group is likely to signal either a shift in strategy or a technology no longer worth protecting by patent.
Set up assignee monitoring in EurekaRevisit family counts, not document counts
Continuation and multi-jurisdiction filing can inflate raw document counts; the family-based ranking used here gives a fairer read on who actually controls claim territory.
Run a family-level search in EurekaCommon questions on this landscape
The ranked leader in this dataset holds 59 of 605 records, well ahead of the fifth-placed assignee at 22 and tenth place at 18. The top five combined account for 190 records (31.4% of all 605 in scope), and the top ten for 286 (47.3%). Beyond that, coverage spreads across a long tail of assignees with only a handful of filings each, so competitive pressure outside the leading group is comparatively light.
Filing peaked at 37 records in 2020 and had fallen to 5 by 2024, a -69% change across that three-year span. That said, publication typically lags filing by around 18 months, so the lower counts seen in 2025 and 2026 are provisional and should not yet be read as confirmation the decline is continuing. 2024 is the most recent year that can be treated as a complete picture.
The three largest IPC subclasses are C22B (metal extraction and refining, 35.9% of the 605 records), C21C (steelmaking, 34.7%) and C21B (blast furnace iron production, 34.4%) — each covering roughly a third of the corpus, since a single record can carry more than one class. Refractories and cement-related claims (C04B) sit further behind at 10.7%, with alloys, furnace instrumentation and material testing classes each under 5%.
This JFE Steel filing, published 2024-10-10, covers a method and apparatus for estimating blast furnace slag liquid level using a physical model driven by inputs such as hot metal tapping rate, slag tapping rate and hot metal production, applied region-by-region across zones separated by a low permeability layer. It also covers using that estimate to generate operation guidance for the furnace and for hot metal production. It is a measurement-and-control claim rather than a claim on slag composition itself, so it constrains instrumentation and control-loop design more than materials chemistry.
Relative to the dense coverage in core steelmaking and extraction classes, several adjacent sub-areas inside the search scope carry thin claim density: real-time slag viscosity sensing, alkali circulation control loops, desulfurization pretreatment reagent chemistry, tapping practice automation and ladle-stage sulfur partition modelling. These sit within the same search terms used to build this landscape but are not concentrated among the leading assignees, suggesting room for narrower, well-drafted claims rather than broad process patents.
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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.