Filtered tailings technology removes most of the water from mine tailings using pressure or vacuum filtration, producing a cake that can be transported and stacked without a water-retaining dam. Dry stacking refers to the resulting practice of piling this dewatered cake in engineered stacks rather than storing slurry behind a tailings dam. The patent record in this space concentrates on the mechanics of achieving low cake moisture, keeping the filter cloth from blinding, and moving the cake off the filter and into the stack efficiently.

The ranking returned for this search covers 12 companies, with a single leader holding 17 records and a steep drop to 1 record by fifth place. That pattern indicates one organisation with sustained, multi-year claim depth alongside a long tail of companies that have filed only once or twice in this space. Because the ranking is exhaustive for this search rather than a curated top-50 or top-100, absence from it does not mean a company is inactive elsewhere in tailings management.

Filing activity peaked at 14 records in 2020 and then fell -89% from 9 records in 2021 to 1 in 2024, the most recent year this dataset treats as complete. That is a genuine decline over that window, but patent publication lags filing by roughly 18 months, so the very low counts shown for 2025 and 2026 are provisional and will rise as more applications publish. A fair read is that the initial wave of filings has passed its peak, not that filing has stopped.