Nanotechnology can offer a more efficient method to separate gold, silver, copper and other valuable materials from rock and ore, Canadian researchers say.

About 450 million tons of minerals are processed each year in a technique known as froth flotation, in which mineral ores are crushed into small particles and floated in water containing “collector” substances that can attach to the valuable particles and cause them to rise to the bubbling top of the water where they can be easily skimmed off.

Robert Pelton of McMaster University in Ontario and his colleagues say a new technology takes advantage of water-repelling nanoparticles as the “collectors,” an article in the American Chemical Society journal Langmuir reported.

In laboratory trials using glass beads to simulate mineral particles, the researchers found the nanoparticles attached so firmly to the beads that the flotation process produced a recovery rate of almost 100 percent.