Tungsten Ore Flotation Organic Inhibitor – Citric Acid

Among tungsten ore flotation inhibitor, sodium silicate is the most widely used one. But when encounters some complex accompanying tungsten mine deposition, sodium silicate may become useless. Although organic inhibitor can not deal with every case like sodium silicate, it has diverse structure and has good selectivity for mineral. It is promoted in recent years.

Citric acid is an important organic acid, it is transparent crystal, containing one molecular of crystal water, smells sour. Citric acid is a kind of strong organic acid, containing three H+, can be decomposed into many products under heating, reacts with acid, alkali and glycerinum.

Citric acid can be used to inhibit calcite and mica in tungsten scheelite. They both are calcium carbonate mineral in scheelite. In flotation, it is hard to separate them apart with tungsten scheelite. Tungsten ore with calcite and mica has no economic value. Citric acid can inhibit them in flotation process, simple and effective.

Chemical formula of citric acid is H3C6H5O7, its inhibiting principle is the same as oxalic acid, which is the group can chelate with lattice ions on the surface of the gangue to form Ca2+ chelating. Citric acid has four groups of polar hydrophilic. Research shows that for calcite and fluorite, when pH <10, surface of calcite carries positive electricity, tartaric acid and Ca²⁺ in lattice can chelates. It will absorb on the surface of mineral by electrostatic force and inhibit. When pH >10, surface of calcite carries negative electricity. If concentration of citric acid is low, then it will chelate with Ca2+ in the solution and reduce precipitation function of Ca2+ toward oleic acid and improve flotation environment. If using amount of citric acid increases, then there will be chelating reaction and create strong inhibiting function.

Inhibiting function of organic inhibitor not only depends on chelating capability but also water affinity of polar group. In structure of citric acid, there are three –COOH and one OH hydrophilic group, so it has the best performance among all micromolecule organic inhibitor. It is also used in food industry, non-toxic and easily accessible. So it is favored mostly in all inhibitors.

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