The ranking covers 37 companies across 206 records in scope, and it is heavily concentrated: the top five assignees together hold 123 records, or 59.7% of the total, while the leader alone accounts for 57. That leaves a long tail of companies with just one or a handful of filings each, which is a common shape in equipment-heavy mining technology fields. Anyone assessing competitive position in this space should treat the top five as the group setting the boundaries of core mill-hardware claims, and the tail as where niche or regional innovation happens.

Filings rose from 5 in 2017 to a peak of 50 in 2019, then declined to 21 by 2021 and to 3 by 2024, an 86% drop over that three-year span. That looks like a clear slowdown, but publication typically lags filing by around 18 months, so the 2025 and 2026 figures in the dataset are still incomplete and should not be read as confirmation of a continuing decline. The safest complete-year comparison right now is the 2021-to-2024 window, which is the one the -86% figure reflects.

The B02C subclass, covering crushing, grinding and pulverising, appears in 84.0% of the 206 records in scope, far ahead of any other classification. Wet separation (B03B), flotation (B03D) and sieving and sorting (B07B) each appear in roughly 8-10% of records, meaning most patent activity is about the mill itself — liners, grates, media, ball charge control — rather than how it integrates with downstream separation or flotation stages. That imbalance is useful for spotting where circuit-level integration claims remain comparatively open.