Steelmaking Off Gas Energy Recovery Patents: Who Leads, Gaps 2026
- 92.8% concentration. The top 5 assignees hold 64 of the 69 records in scope, and the top 10 account for all of them — this field has no long tail of small filers.
- One company files more than the rest combined. The leading assignee alone holds 51 records against a fifth-place holder of just 1, an unusually steep drop-off.
- Filing peaked in 2020, then fell sharply. Recorded filings ran from 4 in 2021 to 0 in 2024, a -100% swing over that span — though 2025-26 figures are still filling in due to publication lag.
Filing growth compares 2021 (4 records) with 2024 (0) — 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 69 records in scope (CR5), not by the ranked leaders only.
What this landscape covers
This landscape tracks patent filings at the intersection of converter and EAF off-gas recovery and downstream handling steps: gas holder operation, dust cleaning, chemical energy recovery, carbon monoxide capture and waste heat boilers. The scope spans steelmaking-specific claims alongside adjacent process chemistry, such as sulfur and sulfuric acid recovery from tail gas streams that overlaps with Claus-process technology.
69 published records sit in scope between 2015 and the 2026-07-31 cut-off. The assignee ranking returned by the dataset covers 10 companies, and it is the complete ranking rather than a top-50 or top-100 cut — read the concentration figures against that fact.
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Filing trend and technology mix
Two views of the same 69 records: when filings happened, and which technical subclasses they touch.
Filing trend: a sharp 2020 peak, then a fast decline
Filings were absent in 2017, rose to a peak of 55 in 2020, then fell away — 4 in 2021 down to 0 in 2024, a -100% change over that three-year window. Treat 2025 and 2026 figures as incomplete: publication typically lags filing by around 18 months, so recent-year counts will still rise as more records publish.
Technology composition: heavy overlap between gas chemistry and combustion classes
C01B (non-metallic elements and inorganic compounds) touches 71.0% of the 69 records and B01D (separation processes) touches 63.8%, meaning most filings combine gas chemistry with a filtration or separation step. F23C (combustion apparatus) appears in 47.8% of records, while core steelmaking class C21C appears in only 11.6% — most patents in this set are filed around the gas-treatment side of the process, not the furnace itself.
Shares are the percentage of the 69 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Steelmaking Off Gas Energy Recovery with Eureka
This page is one run against one query. Ask Eureka your own question about steelmaking off gas energy recovery and every answer comes back with the patent numbers behind it.
Try EurekaMost-cited records and a representative filing
US20220234891A1 — Method for production of elemental sulfur by part or fully catalytic oxidation of Claus tail gas
A process and plant for producing elemental sulfur from a feedstock gas containing 15-100 vol% H2S and a stream of sulfuric acid. The route runs a substoichiometric Claus reaction furnace feed, cools and contacts a Claus-active catalyst, withdraws tail gas and elemental sulfur, then routes the tail gas through sulfur oxidation and SO2-to-SO3 catalytic conversion before converting to concentrated sulfuric acid and recycling back to the reaction furnace.Filed by TOPSOE A/S, published 2022-07-28.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | WO2020245070A1 | Method and system for producing steel or molten-iron-containing materials with reduced emissions | 49 |
| 2 | US20220235426A1 | Method and system for producing steel or molten-iron-containing materials with reduced emissions | 32 |
| 3 | JP1984044581A | Method of utilizing high-temperature waste heat | 19 |
| 4 | US20220227625A1 | Method for production of elemental sulfur and sulfuric acid | 8 |
| 5 | WO2020225062A1 | Method for production of elemental sulfur by part or fully catalytic oxidation of claus tail gas | 8 |
| 6 | US20220177306A1 | Revamping of a claus plant with a sulfuric acid plan | 7 |
| 7 | JP1983009801A | Preparation of mixed gas | 7 |
| 8 | WO2020225063A1 | Revamping of a claus plant with a sulfuric acid plan | 6 |
| 9 | WO2020225061A1 | Method for production of elemental sulfur and sulfuric acid | 5 |
| 10 | US20220234891A1 | Method for production of elemental sulfur by part or fully catalytic oxidation of claus tail gas | 4 |
Citation counts reward older filings that have had more time to accumulate citers, so treat this as a signal of influence within this corpus rather than of current technical 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 filing strategy
Three findings that shape where new claims can realistically sit in this field.
A near-total lock by a small group
With the top 5 assignees covering 64 of 69 records and the top 10 covering all of them, there is essentially no unclaimed territory among broad process claims — new entrants need to target narrow, specific mechanisms rather than the general recovery concept.
Activity cooled sharply after the 2020 peak
The peak year of 55 filings in 2020 was followed by a steep drop: 4 filings in 2021 fell to 0 by 2024. This does not necessarily mean the technology is exhausted — dense prior art from the peak years may simply have pushed filers toward adjacent chemistry.
Gas chemistry claims outnumber furnace-process claims
C01B (non-metallic elements and inorganic compounds) appears in 71.0% of records while core steelmaking class C21C appears in only 11.6%. Most competitive activity in this dataset is happening in the gas-treatment chemistry, not in furnace design itself.
Influence concentrates on a handful of early filings
The most-cited record in this set, on reduced-emission steel and molten-iron production, draws 49 citations — well ahead of the next tier. Newer filers should check whether their claims sit downstream of this lineage before assuming clear space.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to steelmaking off gas energy recovery, with the prior art for and against each one.
A steep drop from one leader to everyone else
The ranked assignee list is short and heavily front-loaded: one company holds the majority of records in scope, and the gap to the rest of the field is wide.
One filer dominates the ranked field
The leading assignee holds 51 of the 69 records in scope — well over two-thirds of the entire dataset on its own. Any new filing strategy in this space has to assume this portfolio is the first prior-art check.
No long tail of small filers
Unlike many landscapes, this dataset's ranking does not fade into dozens of one-patent entrants — it is a complete list of 10 companies, with the top 10 accounting for 100.0% of all 69 records. There is limited room for a new name to appear organically.
Recent-year filing has gone quiet across the board
Every assignee tracked for recent-year momentum shows 0 filings in the latest year, consistent with the broader -100% filing change from 2021 to 2024. Whether this reflects genuine slowdown or publication lag will only be clear once 2025-26 data fills in.
| Assignee | Recent year | YoY |
|---|---|---|
| Haldor Topsoe | 0 | — |
| Tenova S.p.A. | 0 | — |
| Sumitomo Heavy Industries, Ltd. | 0 | — |
| Nippon Steel Corporation | 0 | — |
| Xingtai Fuai Atomizer Co., Ltd. | 0 | — |
| Xi'an Shaangu Power Co., Ltd. | 0 | — |
| Fujian Sanbao Steel Co., Ltd. | 0 | — |
| Hebei University of Science and Technology | 0 | — |
Where to take this analysis
The dataset points to a concentrated field with narrow open branches. These are reasonable next steps for a team deciding where to file or partner.
Map claim scope against the leader's 51-record portfolio
Before drafting new claims, check whether they fall within the dominant assignee's existing coverage rather than the general field average.
Explore assignee portfolios in EurekaWatch the gas-chemistry classes, not just steelmaking classes
With C01B and B01D touching most records, prior art search should extend well beyond C21C-classified steelmaking documents.
Run a cross-class search in EurekaTrack 2025-26 publications as they land
Because publication lags filing by roughly 18 months, the apparent 2021-2024 decline needs revisiting once the most recent two years finish publishing.
Set a filing alert in EurekaFrequently asked questions
One assignee dominates this dataset with 51 of the 69 records in scope, far ahead of the fifth-ranked holder at just 1 record. The ranked list covers 10 companies total, and the top 5 alone account for 92.8% of all records. This level of concentration means a single portfolio is the practical starting point for any freedom-to-operate check in this space.
Filing peaked at 55 records in 2020 and then declined sharply, falling from 4 in 2021 to 0 by 2024 — a -100% change over that span. However, publication typically lags actual filing by about 18 months, so the 2025 and 2026 figures in this dataset are still incomplete and should not yet be read as continued decline. The safest read is that activity cooled substantially after the 2020 peak, with the most recent trend still unresolved.
C01B, covering non-metallic elements and inorganic compounds, appears in 71.0% of the 69 records, and B01D, covering separation processes such as filtration, appears in 63.8%. F23C combustion apparatus classes touch 47.8% of records. Core steelmaking class C21C appears in only 11.6% of records, indicating most competitive filing activity sits in gas chemistry and separation steps rather than furnace design itself.
Classes like C21B (blast-furnace iron production), F27D (furnace accessories) and F23G (incinerators) each appear in well under 12% of the 69 records, well below the dominant C01B and B01D classes. This suggests narrower opportunities around furnace-integrated waste heat boiler design and catalytic CO capture staging that have not attracted the same filing density as general gas chemistry claims. A first claim here would need to tie the recovery mechanism specifically to furnace or accessory hardware rather than to the general chemical process.
Highly concentrated: the top 5 assignees hold 64 of the 69 records in scope, or 92.8%, and the top 10 assignees account for all 69 records, or 100.0%. The complete assignee ranking for this dataset only returns 10 companies, meaning there is essentially no long tail of small independent filers. This makes the field unusually easy to map for competitive purposes, but also unusually hard to enter without engaging directly with the leading portfolio.
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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.