Refractory Gold Pretreatment Patents: Mapping Who Files and Where the Claims Sit

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.