What should be paid attention to in flotation of xanthate

Xanthate, chemically known as alkyl dithiocarbonate, is classified into ethyl xanthate, butyl xanthate, and amyl xanthate. It is a thiol-based flotation agent used in minerals, formed by the reaction of sulfonate groups with corresponding ions. It is a yellow powdery solid at room temperature, often darker in color due to impurities. It has a pungent odor, is toxic, ignites, and readily decomposes in water. Its unstable nature is accelerated by the addition of salt. It is soluble in water and acetone and is formed by the interaction of carbon dioxide, alcohol, and alkali.

Xanthates are divided into high-grade and low-grade xanthates. High-grade xanthates contain fewer than four carbon atoms in the hydrocarbon group and possess significantly higher collecting power than low-grade xanthates. Their collecting performance in the flotation of complex polymetallic sulfide minerals such as galena, chalcopyrite, sphalerite, pyrite, native gold, native silver, mercury, and malachite is generally superior. Generally speaking, xanthates with shorter carbon chains exhibit significantly greater selectivity than those with longer carbon chains.

For example, ethyl sodium xanthate has the highest selectivity; isopropyl sodium xanthate has low production costs, good collection capacity and selectivity, and is the most widely used; isobutyl sodium xanthate is also low-cost, but relatively strong in collection capacity; and potassium amyl xanthate has the strongest collection capacity but the lowest selectivity, often collecting pyrite and other minerals together. This process can only be inhibited by adding an appropriate inhibitor.

The typical concentration of xanthate is 10-20%. Avoid using it in strongly acidic slurries to prevent its decomposition. The typical dosage of xanthate is 23 to 90 grams per ton of ore.

As the most commonly used collector in sulfide ore flotation, xanthate requires special attention during its use and storage:

1. Use it in alkaline slurries whenever possible. Since xanthate readily dissociates in water, if not controlled, it will hydrolyze into xanthogenic acid (ROCSSH), which ultimately decomposes into alcohol and carbon disulfide, rendering it ineffective. Only when the slurry remains alkaline, that is, when the OH- mass fraction increases, can the hydrolysis reaction proceed. The higher the mass fraction of xanthate anions, the better the capture effect. Therefore, xanthate is generally used in alkaline slurries (pH > 7).

2. Xanthate solutions should be used in a balanced manner. Avoid mixing too much at once, and do not use hot water. On-site, xanthate is typically prepared as a 1% aqueous solution. Because xanthate is susceptible to hydrolysis, decomposition, and inactivation, avoid mixing too much at once. It should not be mixed with hot water, as xanthate decomposes more rapidly in hot temperatures.

3. To prevent xanthate from decomposing and inactivating, store it in a sealed container, away from moisture and water, in a dry, cool, and well-ventilated area. Keep away from heat sources and observe fire prevention measures.