Selenium Production
Selenium Production
Sulphuric acid production sludge as well as copper-electrolyte slimes are the main source of selenium recovery. After flotation concentration the separation of molten selenium is the next step. Selenium is extracted from residues after via leaching by Na2S or Na2SO3 with H2SO4. Oxidizing roasting with water capturing of the sublimated product and bottoming by NaHSO3 in HCl or slime sintering with Na2CO3 is also applied. After that leaching, HCl acidifying SeO2 residue is filtered out and bottomed by FeSO4 for Se(VI) reducing and SO2.
Sulphide cycle processing based on reversible reaction between selenium and Na2SO3 is one of alternative chemical methods of selenium preparation. Other methods include selenium oxidizing (burning in O2), sublimation refining of the yielded SeO2, vapours filtering, ion exchange etc., with following SeO2 reduction. High purity selenium is obtained refining H2Se, SeOCl2 and so on.
Refined the selenium is remelted, filtered through fiberglass fiber fabric or activated coal, exposed to vacuum distillation and or put to rectification in inert atmosphere.