Three inhibitors commonly used in mineral processing reagents
1、 Sodium sulfide
Sodium sulfide is an activator of nonferrous metal oxide ore, and it is also an inhibitor of sulfide ore when the dosage is large enough.
Sodium sulfide is prepared by burning coal, lignocellulose and other reducing gases to reduce sodium sulfate (Na2SO4). Sodium sulfide is used as depressant of sulfide ore in flotation operation. In practice, sodium sulfide inhibits pyrite and kerosene is used as collector to flotation molybdenite. Because molybdenite has good natural floatability, it is not inhibited by sodium sulfide, which inhibits pyrite. After many times of concentration, qualified molybdenum concentrate is obtained.
When sodium sulfide is added to the pulp, the pulp is alkaline, so the surface of sulfide minerals forms hydrophilic hydroxide film and is hydrophilic, thus sulfide minerals are inhibited.
2、 Sodium cyanide (potassium)
Sodium cyanide is used to inhibit sulfide minerals such as pyrite, sphalerite and chalcopyrite when preferential flotation process is used in polymetallic deposits. The mixed use of sodium cyanide and zinc sulfate has a good inhibitory effect on sphalerite. When the content of sodium cyanide is low, pyrite can be inhibited; when the content of sodium cyanide is low, sphalerite can be inhibited; when the content of sodium cyanide is high, all kinds of copper sulfide can be inhibited.
In practice, because of the toxicity of sodium cyanide, sulfur dioxide or sodium sulfite are often used instead. The inhibition of sulfur dioxide and sodium sulfite is weaker than that of sodium cyanide. However, due to their low toxicity and easy oxidation by air, wastewater is usually used for easy treatment. Another advantage is that minerals inhibited by sulfur dioxide and sodium sulfite are more likely to be activated by copper sulfate, while minerals inhibited by sodium cyanide are more difficult to be activated.
3、 Zinc sulfate
The preparation of zinc sulfate is carried out by the action of zinc waste from metal processing plant and dilute sulfuric acid. Zinc sulfate is an inhibitor of sphalerite, and its effect is not obvious when used alone. When it is used with alkali, sodium cyanide and sodium sulfite, the inhibition effect is very strong. The higher the pH of pulp, the better the inhibition effect.