The ranking covers 41 companies, with the top-ranked assignee holding 14 of the 138 records in scope and the top five combined accounting for 42.8% of all records. That leaves a long tail of single- or double-filing entrants, so a competitive check should look at both the concentrated top group and the specific players active in the sub-area of interest, since the tail includes specialist engineering and research organisations rather than only large miners. Because families are the fairer comparison unit than raw document counts, checking family size behind any given assignee’s record count is a useful next step.

C22B, metal extraction and refining, appears in 81.2% of the 138 records in scope, making it by far the dominant IPC subclass. Furnace details (F27D, 15.2%) and solid waste disposal (B09B, 13.0%) are the next most common but sit well below C22B, with separation processes, electrolytic production and catalysis each appearing in single-digit percentages. This pattern indicates that most filing activity centres on the extraction chemistry itself rather than on furnace hardware or downstream waste handling, which is where comparatively more claim space remains open.

Filings rose from 9 in 2017 to a peak of 14 in 2022, but the record count is too short to state a reliable growth rate once publication lag is accounted for. The most recent year in the dataset shows zero filings, which reflects the roughly 18-month gap between filing and publication rather than an actual halt in activity. A reader should treat the last one to two years of any filing trend as understated and revisit the trend once more recent publications land.