Feb 06, 2018 Pre-19th century placer mining operations used mercury to dissolve the gold in crushed ore, making it easier to recover. Later innovations include the MacArthur-Forrest Process and borax flux extraction. However, one of the most interesting methods is froth flotation. Froth flotation works by exploiting the hydrophobic properties of gold molecules.Flotation constitutes a separation process that originated from mineral processing. Nowadays, wider applications have been found and compared to flotation for water and wastewater treatment. Stress in the present review paper was mainly applied to heavy metal ions recovery by flotation and the respective mechanism followed, being either ion, precipitate, or sorptive flotation.