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Run your analysis now →https://www.patsnap.com/resources/blog/rd-blog/zinc-roasting-leaching-and-electrowinning-patent-landscape/ · Patsnap · data cut-off 2026-07-31 · downloaded from the live page
Patent Landscape · Zinc HydrometallurgyZinc roasting, leaching and electrowinning patents: mapping who holds the process ground
- 43.6% concentration. The top 5 assignees alone account for 206 of the 472 records in scope — filing here is unusually concentrated at the very top.
- C22B dominates at 88.8%. Nearly nine in ten records touch metal extraction and refining claims, while flotation and wet separation each sit under 3%.
- Filing is still growing, not fading. 2021 to 2024 (the last complete year) rose 33%, even as the field's 2017 peak of 15 filings a year has not been repeated.
472
Published Records
44%
Top-5 Share of All Records
+33%
Filing Growth 2021→2024
US
Leading Jurisdiction
Filing growth compares 2021 (3 records) with 2024 (4) — 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 472 records in scope (CR5), not by the ranked leaders only.
Published byPatsnap Research··7 min readSourced from Patsnap Eureka
Field Overview
What this landscape covers
This landscape covers 472 published patent families filed against a search built around zinc calcine leaching, zinc electrowinning, jarosite precipitation, iron removal, cadmium cementation, cell house operation, manganese dioxide deposit control and acid balance. The scope spans the full hydrometallurgical chain: roasting the concentrate to calcine, leaching it into solution, purifying that solution of iron and cadmium, and recovering metallic zinc at the cell house. Publication lags filing by roughly 18 months, so the most recent one to two years in any trend understate real filing activity.
Receiving-office data shows the heaviest filing pressure in the United States, Australia and Canada, with Finland and China both represented at meaningful volume — a spread consistent with a process technology practiced by producers with mines and refineries on several continents rather than one dominated by a single national industry base.
Filing activity by year, 2015–2026
Source: Patsnap Eureka. Assignee ranking and totals. Derived from a Patsnap search on Zinc Roasting Leaching and Electrowinning covering 2015–2026, data cut-off 2026-07-31. Counts reflect published records only and shift as new filings publish.Run this in Eureka MCP
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The Numbers
Filing trend and technology composition
Two views of the same 472-record dataset: how filing has moved year over year, and which parts of the international patent classification the claims actually sit in.
A field that peaked in 2017 and has not gone quiet
Filings peaked at 15 in 2017 and have not returned to that level, but the trend is not a simple decline: 2021 to 2024, the last year that can be treated as complete, rose from 3 to 4 filings — a 33% increase. Years after 2024 will fill in further as publication catches up with filing.
Claims cluster tightly around metal extraction
C22B (metal extraction and refining) appears in 88.8% of all 472 records, making it the backbone class for this entire search. C01G (compounds of other metals, 23.7%) and C25C (electrolytic metal production, 22.7%) are the two secondary clusters — consistent with leaching chemistry and cell-house electrowinning being the two technical centres of mass. Separation-adjacent classes such as B01D, C02F, B03D and B03B each sit under 4.5%, marking them as thinner, more open ground.
Shares are the percentage of the 472 records in scope. A patent can carry several IPC classes, so the shares add up to more than 100%.
Source: Patsnap Eureka. Filing trend and technology composition. Derived from a Patsnap search on Zinc Roasting Leaching and Electrowinning covering 2015–2026, data cut-off 2026-07-31. Counts reflect published records only and shift as new filings publish.
Go deeper on Zinc Roasting Leaching and Electrowinning with Eureka
This page is one run against one query. Ask Eureka your own question about zinc roasting leaching and electrowinning and every answer comes back with the patent numbers behind it.
Try EurekaKey Prior Art
The patents other filings have to cite around
Representative Filing
Countercurrent leaching for zinc recovery (US20060213332A1)
OUTOTEC OYJ
The invention relates to method for leaching zinc-containing materials in connection with the electrolytic recovery of zinc. According to this method, the feed materials i.e. zinc calcine and zinc sulphide, are leached in three stages, in which the sulphuric acid content of the stages rises in accordance with the direction in which the solids are moving. The solids and solution formed in the leaching stages are routed throughout the process countercurrently in relation to each other.Filed by Outotec Oyj; illustrates the countercurrent, multi-stage leaching architecture that recurs across the most-cited prior art in this set.
Most-cited records in this dataset
| # | Publication no. | Patent title | Citations |
|---|---|---|---|
| 1 | US4338168A | Hydrometallurgical treatment of copper-bearing hematite residue | 85 |
| 2 | US4378275A | Metal sulphide extraction | 81 |
| 3 | US4004991A | Two-stage pressure leaching process for zinc and iron bearing mineral sulphides | 69 |
| 4 | US4272341A | Process for recovery of metal values from lead-zinc ores, even those having a high carbonate content | 63 |
| 5 | US5667553A | Methods for recycling electric arc furnace dust | 55 |
| 6 | US20040237720A1 | Zinc recovery process | 49 |
| 7 | US5538532A | Methods for recycling electric arc furnace dust | 49 |
| 8 | US6277341B1 | Process for the rapid leaching of chalcopyrite in the absence of catalysts | 48 |
| 9 | US3867268A | Recovery of zinc from zinc sulphides by direct pressure leaching | 42 |
| 10 | CN103409622A | 一种单独处理高铁硫化锌精矿的方法 | 39 |
Citation counts are drawn from within this searched corpus and favour older filings by construction — treat them as a signal of influence on later filers, not as a ranking of current commercial importance.
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.
Source: Patsnap Eureka. Citation counts and representative records. Derived from a Patsnap search on Zinc Roasting Leaching and Electrowinning covering 2015–2026, data cut-off 2026-07-31. Counts reflect published records only and shift as new filings publish.Run this in Eureka MCP
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What the data means for a filing decision
Three read-outs from the concentration, classification and citation data that matter more than the raw counts on their own.
Concentration
43.6%
of 472 records held by top 5
The top of the field is unusually tight
The leading assignee alone accounts for 78 records, and the top 5 combined hold 206 of the 472 records in scope — 43.6% of the entire dataset. The top 10 extend that to 60.6%. New entrants are not filing into open ground at the core of the process; they are filing around an already-dense set of positions.
Top 10 hold 60.6% of all records
Classification
88.8%
of records touch C22B
Extraction and refining claims are the main event
C22B appears in nearly nine of every ten records, meaning almost any new filing in this space will need freedom-to-operate analysis against that class specifically. The secondary classes, C01G and C25C, each sit near a quarter of records — leaching chemistry and electrowinning cell design are the two next-most-contested areas.
C01G 23.7% · C25C 22.7%
Citations
85 cites
on the most-cited record
Foundational art is decades old, not recent
The most-cited records in this dataset — covering hydrometallurgical treatment of residues, sulphide extraction and pressure leaching — were filed well before the 2015 window this landscape tracks. That is expected: citation counts inside a searched corpus favour older filings, so treat them as evidence of foundational influence, not of what is currently active.
US4338168A cited 85 times
Eureka AI Agent
Looking for what nobody has claimed yet?
Eureka can read the same corpus for gaps instead of for coverage: under-claimed branches adjacent to zinc roasting leaching and electrowinning, with the prior art for and against each one.
Source: Patsnap Eureka. Co-assignee relationships and derived observations. Derived from a Patsnap search on Zinc Roasting Leaching and Electrowinning covering 2015–2026, data cut-off 2026-07-31. Counts reflect published records only and shift as new filings publish.Run this in Eureka MCP
Assignee Landscape
Who holds the ground, and where the gates sit
The assignee ranking returns 100 companies counted across the 472 records — not a top-50 or top-100 cut, but the full ranked set the data endpoint produces. Filing here concentrates hard at the top and then tails off quickly.
Leader
78 records
held by the top-ranked assignee
A single assignee sets the pace
The leading assignee's 78 records are more than three times the fifth-placed assignee's 21, and more than six times the tenth-placed assignee's 13 — a steep drop-off that marks this as a field with one dominant filer rather than several evenly matched ones.
5th place: 21 · 10th place: 13
Co-filing
10 pairs
co-assignee relationships found
Collaboration is limited and clustered
Only ten co-assignee pairs appear across the dataset. The strongest pairing, at 11 shared records, links two organisations with an established research relationship; the next strongest pairs sit at 5 and 2 shared records. Co-filing here is the exception, not the norm.
Strongest pair: 11 shared records
Momentum
0
latest-year filings among leading assignees
Recent activity has gone quiet among incumbents
None of the leading assignees show filings in the latest tracked year — consistent with the broader publication lag rather than a sign the leaders have exited the space. It also means recent activity, once it publishes, is likely to come from outside today's top-ranked names.
Publication lag of ~18 months applies
Recent-year filing momentum by assignee
| Assignee | Recent year | YoY |
|---|---|---|
| Outotec Oyj | 0 | — |
| Outokumpu Oy | 0 | — |
| Sherritt Inc. | 0 | — |
| Noranda Inc. | 0 | — |
| Intec Ltd. | 0 | — |
| Tecnicas Reunidas SA | 0 | — |
| F.L. Smidth & Co. A/S | 0 | — |
| McGill University | 0 | — |
Source: Patsnap Eureka. Assignee-level momentum. Derived from a Patsnap search on Zinc Roasting Leaching and Electrowinning covering 2015–2026, data cut-off 2026-07-31. Counts reflect published records only and shift as new filings publish.Run this in Eureka MCP
Next Steps
Where to take this analysis
The landscape numbers point to where the crowded ground is and where it thins out. Turning that into a filing or freedom-to-operate decision means going deeper on specific claims.
Run a freedom-to-operate check on C22B claims
With 88.8% of records touching this single class, any new leaching or electrowinning filing needs a targeted search against the specific claim language in this subclass before drafting.
Explore claim analysis in EurekaTrack the leading assignee's live filings
The dominant assignee holds 78 records but shows no filings in the latest tracked year in this dataset — worth monitoring as publication catches up.
Set up assignee monitoring in EurekaScope the under-claimed branches
Flotation, wet separation and wastewater-integrated iron removal each sit under 4.5% of records — thin enough to warrant a first-claim feasibility check.
Draft a claim scope in EurekaSource: Patsnap Eureka. Forward-looking reading of the same dataset. Derived from a Patsnap search on Zinc Roasting Leaching and Electrowinning covering 2015–2026, data cut-off 2026-07-31. Counts reflect published records only and shift as new filings publish.Run this in Eureka MCP
FAQ
Common questions about this landscape
One assignee leads clearly with 78 of the 472 records in this dataset, more than three times the fifth-placed assignee's 21 records. The top 5 assignees combined hold 206 records, or 43.6% of the entire field, and the top 10 extend that to 60.6%. This is a steeply concentrated landscape rather than one with many evenly matched competitors, so any competitive analysis should start by mapping the leader's specific claim scope before looking at the long tail.
C22B, covering metal extraction and refining, appears in 88.8% of all 472 records — by far the dominant classification. C01G (compounds of other metals) and C25C (electrolytic metal production) follow at roughly a quarter of records each, reflecting the two other technical centres of the process: leaching chemistry and cell-house electrowinning. Because a single record can carry several IPC classes, these shares add up to well over 100% and should not be read as a breakdown of the whole field into non-overlapping parts.
Filings peaked in 2017 at 15 in a single year and have not returned to that level since, but the more recent complete-year data shows growth, not decline: filings rose from 3 in 2021 to 4 in 2024, a 33% increase over that span. Because patent publication lags filing by roughly 18 months, the years closest to the present in any dataset understate actual filing activity, so it would be premature to read 2025 or 2026 figures as a slowdown.
The classification data points to several thinner branches: flotation-related claims (B03D) sit at 2.1% of records, wet separation of solids (B03B) at 1.7%, and wastewater treatment integration (C02F) at 2.3%, all far below the 88.8% concentration in the core C22B extraction class. These lower-density classes are where a new filing is more likely to find open claim space, though a full freedom-to-operate search against the specific prior art in each class is still necessary before drafting.
Collaboration is limited: the dataset contains only 10 co-assignee pairs across all 472 records. The strongest pairing shares 11 records, and the next two strongest share 5 and 2 records respectively. Most filing activity in zinc roasting, leaching and electrowinning is done by single assignees rather than through joint filings, which is worth noting when assessing potential licensing or partnership patterns in the space.
Answers are grounded in the same dataset. Derived from a Patsnap search on Zinc Roasting Leaching and Electrowinning covering 2015–2026, data cut-off 2026-07-31. Counts reflect published records only and shift as new filings publish.Run this in Eureka MCP
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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.