Mineral processing plants utilize a great variety of physical separation techniques including density separation processes for particle sizes less than 3mm, e.g. high-intensity wet magnetic separation, electrical separation and photometric and radiometric sorting. To our knowledge, none of these has yet been commercially applied to beneficiation of aggregates owing to cost.
Froth flotation is employed for the beneficiation of glass sands and has been used to up-grade raw materials for cement manufacture. Its cost prohibits its use for processing aggregates and the upper particle size limit is of the order of 0.5 mm. Chemical processes such as acid leaching to remove iron minerals have also been applied to the production of glass sands and 'silver sands'. These may be incorporated in special 'white' mortars.