Refractory Gold Pretreatment Patents: Who Leads, Gaps 2026
- 69.4% concentration. The top 5 assignees hold 84 of the 121 records in scope — filing here is dominated by a small group, not spread thin.
- Flat since 2021. Filings held at 3 in both 2021 and 2024, a 0% span, after peaking at 8 in 2022 — momentum has plateaued rather than accelerated.
- Near-total C22B overlap. 98.3% of records carry a C22B extraction/refining class, so differentiation increasingly happens in the secondary classes, not the primary one.
Filing growth compares 2021 (3 records) with 2024 (3) — 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 121 records in scope (CR5), not by the ranked leaders only.
What this landscape covers
Refractory gold ore resists direct cyanidation because sulfide minerals, carbonaceous material or arsenic-bearing phases lock up the gold or consume the leach reagents. Pretreatment routes — pressure oxidation, sulfide bioleaching, ultrafine grinding and associated arsenic stabilization or acid neutralization steps — exist to break that lock before cyanidation runs. This dataset draws together 121 published records at the intersection of ore-type description and pretreatment mechanism, spanning 2015 through the 2026 cut-off.
The scope favours process claims over equipment claims: autoclave oxidation, oxygen injection control and bioleaching conditions dominate, with comminution and separation appearing mainly as supporting steps rather than standalone inventions.
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Filing trend and technology composition
Two views of the same 121 records: how filing activity has moved year over year, and which IPC subclasses the claims actually sit in.
A flat plateau after a 2022 peak
Filings rose from a single record in 2017 to a peak of 8 in 2022, then settled back — 2021 and 2024 both sit at 3 records, a 0% span. Because publication lags filing by roughly 18 months, the 2025-2026 tail is still filling in and should not be read as a decline.
C22B dominates; differentiation happens below it
C22B (metal extraction and refining) appears on 98.3% of the 121 records, effectively a floor rather than a differentiator. The next tier — B01F mixing/stirring at 23.1%, B03D flotation at 19.8%, and B01J catalysis-adjacent processes at 14.0% — is where claims actually diverge from one another.
Shares are the percentage of the 121 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Go deeper on Refractory Gold Pretreatment with Eureka
This page is one run against one query. Ask Eureka your own question about refractory gold pretreatment and every answer comes back with the patent numbers behind it.
Try EurekaThe most-cited records anchor the field
WO2022261693A1 — Ferric/ferrous coupling in mineral processing
Filed by Oxidation Technologies Pty Ltd, this record describes an oxidant-recycling process for refractory gold ore: an oxidant, described as or including ferric iron, reacts with mineral-bearing material, a portion of the oxidant is recovered downstream, and that recovered portion is reintroduced to a further batch of feed. In the disclosed system, ore or concentrate is mixed, ground, and dosed with oxidant before comminuted product overflows to a separation tank for solid/liquid split.Published 2022-12-22
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US5071477A | Process for recovery of gold from refractory ores | 104 |
| 2 | US6482373B1 | Process for treating ore having recoverable metal values including arsenic containing components | 65 |
| 3 | EP0508542A2 | Process for treating ore having recoverable metal values including arsenic containing components | 37 |
| 4 | US20090074607A1 | Process for recovering gold and silver from refractory ores | 31 |
| 5 | US20060133974A1 | Reduction of lime consumption when treating refractory gold ores or concentrates | 29 |
| 6 | US6248301B1 | Process for treating ore having recoverable metal values including arsenic containing components | 26 |
| 7 | GB2225256A | Method and apparatus for effecting a bioreaction | 26 |
| 8 | US7604783B2 | Reduction of lime consumption when treating refractory gold ores or concentrates | 24 |
| 9 | US6159435A | Leaching of mineral ores | 20 |
| 10 | US6270555B1 | Process for treating precious metal ores | 16 |
Citation counts favour older records that have had more time to accumulate them; treat this as a signal of foundational influence, not of current filing activity.
Each row carries its publication number; clicking a row searches Eureka by that number.
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Browse MCP servers →What the concentration and citation data indicate
Three figures matter more than the raw record count: how tightly filing is held, where the oldest foundational patents still cast a citation shadow, and how flat the recent trend actually is.
Filing is concentrated, not fragmented
The top 5 assignees account for 84 of the 121 records in scope, and the top 10 extend that to 88.4%. A newcomer is not entering a fragmented field — it is entering one where a handful of players already hold most of the claim space.
The oldest patents still anchor the citation graph
US5071477A, on gold recovery from refractory ores, carries 104 citations — more than any other record in scope, followed by arsenic-focused process patents in the 30-65 range. New filings are still being read against these foundational disclosures.
A plateau, not a decline
Filings held flat at 3 records in both 2021 and 2024, after peaking at 8 in 2022. Because 2025-2026 publications are still arriving, this plateau should be read as steady-state activity rather than a cooling field.
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to refractory gold pretreatment, with the prior art for and against each one.
Who holds the claim space
29 companies make up the ranked leaders for this dataset — the entire ranking the data endpoint returns, not a filtered top-N. Activity concentrates sharply at the top before a long tail of single- or few-filing entrants.
One assignee well ahead of the field
The leading assignee holds 37 records, well clear of fifth place at 8 — a gap that signals sustained, multi-year investment in pretreatment IP rather than a single filing burst.
A steep drop by mid-table
Fifth place sits at 8 records and tenth place at just 3, showing how quickly filing density falls away outside the leading handful of assignees.
Collaboration is limited and leader-centred
Only 9 co-assignee pairs appear across the dataset, and the strongest repeated pairings all involve the same leading corporate assignee working with named inventors — collaboration here looks more like internal inventor teams than cross-company alliances.
| Assignee | Recent year | YoY |
|---|---|---|
| Barrick Gold Corporation | 0 | — |
| SINGH ASHOK ADRIAN | 0 | — |
| PLACER DOME TECHN SERVICES | 0 | — |
| ATOMAER | 0 | — |
| NEVADA GOLD MINES LLC | 0 | -100% |
| SOLVAY MINERALS | 0 | — |
| KELSO JODY | 0 | — |
| Metallurgical Technologies Inc. | 0 | — |
Where to take this analysis
The landscape figures point to a mature, concentrated core with narrower openings at the edges. Two natural follow-ups: check freedom-to-operate against the leading assignee's claim set, and pressure-test a specific white-space branch against prior art before drafting.
Run a freedom-to-operate check
With 69.4% of records held by five assignees, any new pretreatment process should be checked against the leading assignee's claims before development spend commits to a specific route.
Start an FTO scan in EurekaDraft around the under-claimed branches
Secondary IPC classes like B03C and C01G show lower filing density than core oxidation claims — a good starting point for scoping a first claim with more open space.
Explore white space in EurekaCommon questions on refractory gold pretreatment patents
Refractory gold ore is ore where gold recovery by standard cyanidation is poor without pretreatment, typically because gold is locked in sulfide minerals, encapsulated in carbonaceous material that adsorbs the dissolved gold (preg-robbing), or associated with arsenic-bearing phases that interfere with leaching. Patent filings in this dataset describe the ore by these mechanisms rather than by a single mineralogical definition, which is why the search combines ore-type terms with pretreatment mechanisms like pressure oxidation, bioleaching and ultrafine grinding. Practically, a filing is in scope if it treats the ore's resistance to cyanidation as the problem being solved, not just as background context.
The technology composition in this dataset shows C22B (metal extraction and refining) on 98.3% of the 121 records, confirming that most filings sit within general extraction/refining claims regardless of the specific mechanism named in the search string. The search terms themselves combine pressure oxidation autoclave and sulfide bioleaching as parallel routes, and both appear across the corpus rather than one dominating outright. For a route-by-route breakdown beyond IPC class, the assignee and citation data are more informative than class counts alone, since bioleaching and autoclave claims both classify under the same broad metallurgy codes.
The assignee ranking covers 29 companies, with the leading assignee holding 37 of the 121 records — well ahead of the fifth-placed filer at 8 records. This is a concentrated field: the top 5 assignees combined account for 69.4% of all records in scope, and the top 10 extend that to 88.4%. Anyone assessing competitive position in this space should treat the leading assignee's portfolio as the primary reference point rather than surveying the full ranked list evenly.
Filings grew from a single record in 2017 to a peak of 8 in 2022, then flattened — 2021 and 2024 both recorded 3 filings, a 0% change over that span. Because patent publication typically lags the actual filing date by about 18 months, the years closest to the 2026 cut-off are undercounted and should not be read as a real slowdown yet. The honest read is a plateau after a 2022 peak, not a declining field.
The secondary IPC classes carry meaningfully lower filing density than the near-universal C22B extraction class: B03C magnetic/electrostatic separation appears on 5.8% of records, C22C alloy-related claims on 5.0%, and B02C grinding/pulverising on 6.6%. These lower-density branches, alongside compound-specific arsenic stabilization under C01G at 8.3%, are where a new entrant is less likely to run into dense prior art than in core pressure-oxidation or flotation claims. That said, low density is a starting signal for scoping, not a substitute for a targeted prior-art search on the specific claim language planned.
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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.