Acid Rock Drainage Patents: Leaders, Trends & White Space 2026
- Filing has cooled sharply. 2021 to 2024 (the last complete year) fell -80%, from 5 to 1 filing, after a 2020 peak of 20.
- Ownership is split, not dominated. The leader holds 21 records; the ranked leaders' top 5 combine for 32.4% and the top 10 for 50.0% of all 204 records in scope.
- Water treatment claims crowd out everything else. C02F covers 63.2% of records, while microbial and bioreactor routes (C12N, C12M, C12P) each sit under 14%.
Filing growth compares 2021 (5 records) with 2024 (1) — 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 204 records in scope (CR5), not by the ranked leaders only.
What this landscape covers
Acid rock drainage forms when sulfide minerals in waste rock or tailings oxidise on contact with water and oxygen, releasing acidity and dissolved metals into surrounding watersheds. This landscape tracks 204 published records filed against a search built around neutralisation potential, oxygen barriers, passive treatment, seepage collection, sulfide oxidation rate and microbial oxidation — the mechanisms and countermeasures that define how prevention is actually claimed. It spans 2015 through the 2026 data cut-off, giving a decade-long view of how filing activity, assignee concentration and technology mix have moved.
The scope favours engineered and biological countermeasures over pure site geochemistry, which is why water and wastewater treatment claims dominate the IPC mix. Readers using this page to plan freedom-to-operate work should treat the most recent one to two years as incomplete: publication lags filing by roughly 18 months, so 2025 and 2026 figures will rise as records catch up.
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Filing trend and technology composition
Two views of the same 204 records: how filing volume has moved year over year, and which IPC subclasses carry the claims. Because a single record can carry several IPC codes, the class shares below add up to more than 100% of the 204-record total.
A decade of rise and retreat
Filings rose from 6 in 2017 to a peak of 20 in 2020, then declined through the most recent complete year: 2021's 5 filings fell to 1 by 2024, an -80% move. Treat 2025 and 2026 as undercounted rather than as confirmation the field has stopped.
Water treatment carries the claim density
C02F (water & wastewater treatment) touches 63.2% of the 204 records, far ahead of C12N (microorganisms & genetic engineering, 13.7%), B09C (soil & contaminated land reclamation, 11.8%) and C22B (metal extraction & refining, 10.8%). Bioreactor apparatus (C12M), chemical detox (A62D), fermentation routes (C12P) and electrolytic production (C25B) each sit at single-digit-to-low-teens shares, marking them as secondary rather than core claim territory.
Shares are the percentage of the 204 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Acid Rock Drainage Prevention with Eureka
This page is one run against one query. Ask Eureka your own question about acid rock drainage prevention and every answer comes back with the patent numbers behind it.
Try EurekaThe most-cited prior art in this space
US6991405B2 – Application of inert gas mixtures to prevent and/or to control sulfide mineral oxidation and the generation of acid rock drainage
A system, computer program product and method of preventing and controlling sulfide mineral oxidation and generation of acid rock drainage in a mass of sulfidic waste is provided. The mass of sulfidic waste includes a cover. The method involves applying under the cover of an oxygen deficient/non-reactive gas mixture, substantially throughout the mass of sulfidic waste, in a quantity sufficient to create a pressure differential between the inside of the mass of sulfidic waste and the open atmosphere outside and adjacent to the mass of sulfidic waste, such that the oxygen gas concentration inside the mass of sulfidic waste is substantially equal to, or less than, the atmospheric oxygen gas concentration.Filed by Terraquest Technologies, Ltd.; granted 2006-01-31. Claims a gas-displacement mechanism rather than a solid or liquid barrier, which is the distinguishing feature to check against when evaluating cover-based designs.
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | WO2011139804A2 | Use of oxyhydrogen microorganisms for non-photosynthetic carbon capture and conversion of inorganic and/or c1… | 97 |
| 2 | US20130149755A1 | Use of oxyhydrogen microorganisms for non-photosynthetic carbon capture and conversion of inorganic and/or c1… | 65 |
| 3 | US20130189763A1 | Method and apparatus for growing microbial cultures that require gaseous electron donors, electron acceptors,… | 62 |
| 4 | WO2013090769A2 | Method and apparatus for growing microbial cultures that require gaseous electron donors, electron acceptors,… | 53 |
| 5 | US20030062306A1 | Remediation of metal contaminants with hydrocarbon-utilizing bacteria | 42 |
| 6 | WO2003011487A1 | Remediation of metal contaminants with hydrocarbon-utilizing bacteria | 40 |
| 7 | US5898093A | Treatment process for contaminated waste | 34 |
| 8 | US20150232349A1 | Modified Biochar Treatment Media, System and Method | 32 |
| 9 | US6203700B1 | Process for treating metal-containing acid water | 32 |
| 10 | WO2014059141A1 | Modified biochar treatment media, system and method | 27 |
Citation counts inside a searched corpus favour older filings that have had more time to accumulate references — read them as a signal of influence on later work, not as a ranking of current commercial relevance.
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Browse MCP servers →What the numbers mean for a filing decision
Three patterns stand out once concentration, technology mix and citation data are read together.
Ownership is spread past the leader
The single leader holds 21 records, but the top 5 combined account for only 32.4% of the 204 records in scope, and the top 10 for 50.0%. Half the field sits outside the ranked leaders entirely, in a long tail of single- and few-filing entrants.
Water treatment claims set the baseline
C02F's 63.2% share means most prevention approaches are ultimately claimed as a water or wastewater treatment step, even when the underlying mechanism is biological or geochemical. Filing here means clearing dense prior art in treatment-stage claims regardless of which upstream method is used.
Recent activity has thinned, not vanished
Filings fell from 5 in 2021 to 1 in 2024, and none of the most active named assignees show activity in the latest tracked year. That is consistent with a maturing claim landscape rather than an abandoned one; publication lag means the true 2025-2026 picture is still forming.
Influence clusters around gas-based microbial methods
The most-cited records in this set describe oxyhydrogen-microorganism carbon capture and gas-fed microbial culture apparatus, not conventional cover or liner designs. That signals where downstream biological remediation work has drawn most heavily on prior art, even though these methods sit outside the dominant C02F claim category.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to acid rock drainage prevention, with the prior art for and against each one.
Who is filing, and where the gaps sit
The assignee ranking covers 88 companies and research institutions across the 204 records in scope. Filing is led by a mix of mining-technology firms, national geoscience institutes and universities, with several South African universities and government bodies appearing alongside single-company entrants.
One clear leader, no runaway gap to fifth
The leading assignee holds 21 records against a fifth-place figure of 9 and a tenth-place figure of 5 — a steep drop-off after the top few, then a gradual taper rather than a cliff.
Half the field sits outside the top 10
With the top 10 combining for only 50.0% of the 204 records, the remaining half is distributed across dozens of assignees, many with just one or two filings. That is where freedom-to-operate searches need the most care, since these positions are less visible in headline rankings.
Collaboration is limited and concentrated
Only 10 co-assignee pairs appear across the dataset, with the strongest links all involving the same corporate assignee paired with individual named inventors. Cross-company joint filing is rare in this space.
| Assignee | Recent year | YoY |
|---|---|---|
| Kiverdi Inc. | 0 | — |
| University of the Free State | 0 | — |
| Korea Institute of Geoscience and Mineral Resources | 0 | — |
| University of South Africa | 0 | — |
| APPLIED INTELLECTUAL CAPITAL LTD | 0 | — |
| WATER RES COMMISSION | 0 | — |
| University of the Witwatersrand | 0 | — |
| The Regents of the University of California | 0 | — |
Where to take this analysis
The dataset points to specific next steps depending on whether the goal is freedom-to-operate, licensing, or R&D direction.
Stress-test a design against the top-cited prior art
The most-cited records describe gas-fed microbial culture methods, not conventional covers. Any new microbial or bioreactor-based prevention design should be checked against these claims before further development.
Explore prior art in EurekaMap the long tail before filing
With half of all records held outside the top 10 assignees, a manual review of headline players alone will miss a large share of relevant claims. A full-ranking search is needed to clear a new filing.
Run a full landscape search in EurekaWatch for a filing rebound as lag resolves
The -80% drop from 2021 to 2024 is real but recent years are undercounted due to publication lag. Re-check filing trend data in 6-12 months before concluding the field has gone quiet.
Track filing trends in EurekaCommon questions on acid rock drainage patents
This landscape tracks 204 published records filed between 2015 and the 2026 data cut-off, built around a search covering neutralisation potential, oxygen barriers, passive treatment, seepage collection, sulfide oxidation rate and microbial oxidation. The true figure for very recent years understates activity because publication typically lags filing by around 18 months. Anyone using this number for a freedom-to-operate assessment should treat 2025 and 2026 figures as provisional and expect them to rise.
Filing is led by a single assignee with 21 records, but ownership is not tightly concentrated: the top 5 assignees combined hold only 32.4% of the 204 records in scope, and the top 10 hold 50.0%. The remaining half of the field is spread across a long tail drawn from an 88-company ranking, including mining-technology firms, national geoscience institutes and university research groups. This spread means no single player controls the core prevention mechanisms outright.
Filings peaked at 20 in 2020 and have since declined, with the last fully comparable window showing a fall from 5 filings in 2021 to 1 in 2024, an -80% change. That said, publication lag means 2025 and 2026 counts are still filling in and should not be read as confirmation of a permanently shrinking field. The honest reading is that visible activity has thinned through the most recent complete year, not that the technology area is closed.
Water and wastewater treatment claims, IPC class C02F, appear in 63.2% of the 204 records in scope, making it by far the largest single category. Microorganism-related claims (C12N), soil and land reclamation (B09C) and metal extraction (C22B) each sit in the 10-14% range, with bioreactor, chemical detox, fermentation and electrolytic production classes trailing further behind. Because records can carry multiple IPC codes, these figures overlap rather than sum to 100%, but the gap between C02F and everything else is consistent and wide.
US6991405B2, assigned to Terraquest Technologies, claims a method of injecting an oxygen-deficient or non-reactive gas mixture under a cover over sulfidic waste to create a pressure differential that keeps oxygen concentration at or below atmospheric levels, preventing sulfide oxidation. It blocks gas-displacement approaches to oxidation control specifically, not solid covers, liquid barriers, or biological treatment methods, which sit in different claim territory. Anyone designing a gas-based barrier system should review its claims closely; anyone working in cover materials, passive treatment or microbial routes faces a different prior-art set entirely.
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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.