Separating minerals by making the valuable ones stick to bubbles — the dominant process route for sulphide ores.
A mineral processing method that uses chemical reagents and air bubbles to separate valuable minerals from waste rock based on differences in surface properties. Flotation is widely used for copper, zinc, lead, and some gold ores.
Flotation produces a concentrate rather than a finished metal, which means smelter terms, transport costs and payability all sit between the mine and the revenue. That is a different business from a gold mine pouring its own doré.
Concentrate grade and the impurities alongside it decide what a smelter will pay. Arsenic, antimony and mercury attract penalties heavy enough to sink an otherwise sound project.