Xanthate (PAX, SIBX, SIPX, SEX) 140-90-9

Xanthates are salts of xanthic acid with the general formula [R−O−CS₂]⁻M⁺, where R is an alkyl group and M is typically sodium or potassium . They are produced by treating an alcohol with carbon disulfide and an alkali metal hydroxide, a process called xanthation . The resulting xanthate salts are yellow crystalline solids available in powder, granule, flake, stick, and solution forms .

The four common xanthates differ in their alkyl chain length and counter ion. PAX (Potassium Amyl Xanthate) has the longest alkyl chain, giving it the strongest collecting power and is used for difficult-to-float ores. SIBX (Sodium Isobutyl Xanthate) has intermediate chain length and is the most widely used general-purpose collector . SIPX (Sodium Isopropyl Xanthate) and SEX (Sodium Ethyl Xanthate) have shorter chains, providing greater selectivity for finer separations .

Xanthates act as collectors in froth flotation by selectively adsorbing onto sulfide mineral surfaces through their polar dithiocarbonate head group, while the non-polar alkyl tail makes the mineral particle hydrophobic. This allows air bubbles to attach to the mineral particles and float them to the surface for recovery. The chain length determines collecting power and selectivity.

Xanthates are effective for recovering a wide range of sulfide minerals including chalcopyrite and chalcocite (copper), galena (lead), sphalerite (zinc), pentlandite (nickel), pyrite (iron), and precious metal-bearing sulfides. They are the primary collectors used in the flotation of copper, lead, and zinc sulfide ores worldwide.

Xanthates should be stored in a cool, dry, well-ventilated area in tightly sealed containers away from moisture, heat, and acids. They decompose in the presence of acids to release carbon disulfide and the parent alcohol . They are also sensitive to heat and moisture. Under proper storage conditions, shelf life is typically 6-12 months. Use appropriate PPE including gloves and respiratory protection when handling xanthate powders.