Silver froth flotation using xanthogen formate-type collectors for the valorization of a hydrometallurgical waste

This work presents a study on the concentration of silver-bearing minerals by froth flotation using xanthogen formate collectors. The objective was to valorize a jarosite waste from the zinc ore processing industry. The primary material was characterized, and several mineral phases were identified, such as sodium jarosite, anglesite, and gypsum. Silver sulfide particles were identified in the waste, while the Ag content was 0.15%. Four xanthogen formate-type collectors were synthesized and identified by UV–vis molecular absorption spectroscopy. All of them had maximum absorption wavelengths near 273 nm. Microflotation tests showed that this type of collector had higher Ag recovery with increasing of the carbon chain length. Optimization by response surface methodology showed a time of 5.2 min, pH 10.5, and a concentration of 10⁻³ mol L⁻¹ as the optimal conditions for flotation. After optimization, the Ag recovery increased from 81.36% to 96.23%. A thermodynamic study showed a chemisorption mechanism.