Researchers report discovery of a completely new technology for more efficiently separating gold, silver, copper, and other valuable materials from rock and ore.

Their report on the process, which uses nanoparticles to latch onto those materials and attach them to air bubbles in a flotation machine, appears in the ACS journal Langmuir.

Robert Pelton and colleagues explain that companies use a technique termed froth flotation to process about 450 million tons of minerals each year.

The process involves crushing the minerals into small particles, and then floating the particles in water to separate the commercially valuable particles from the waste rock. The water contains "collector" substances that can attach to the valuable particles, causing them to repel water and rise to the bubbling top of the water where they can be easily skimmed off.

The researchers demonstrated an entirely new type of collector technology, consisting of water-repelling nanoparticles.

In laboratory experiments using glass beads to simulate actual mineral particles, they showed that the nanoparticles attached so firmly to the beads that flotation produced a recover rate of almost 100 per cent.