Mineral flotation separates ore from waste rock using bubbles. Hydrophobic mineral particles attach to air bubbles rising through a slurry, float to the surface, and are skimmed off. The process handles billions of tonnes of ore annually and is the foundation of base metals extraction worldwide.
Fine particles — below about 20 micrometers — have always been the problem. Conventional bubbles (0.5-2 mm diameter) collide with fine particles too rarely. The probability of a bubble-particle collision scales with the square of the particle-to-bubble size ratio. When the bubble is a thousand times larger than the particle, most particles never touch a bubble.
Nanobubbles — smaller than 1 micrometer — persist in liquid for days or months and have far higher collision probability with fine particles. In flotation tests, fine particle recovery increased by up to 25%, while collector and frother chemical concentrations were reduced by 50% and 60% respectively. The operation also completed 20 seconds faster.
Smaller bubbles, less chemistry, faster processing, better results. This breaks the typical resource-processing tradeoff where higher recovery requires more reagents. The bottleneck was always the mismatch between tool size and target size — conventional bubbles were simply too large to interact efficiently with fine particles. Operating at a finer scale simultaneously improved performance and reduced inputs, because the problem was geometric, not chemical.