Purifying selenium via the oxide - by converting the impure selenium to the oxide and treating the oxide in an absorption column with water

摘要

Commerical 90.98% Se is purified by zone melting in a continuous melting unit at 450-650 degrees C using air-, oxygen-, or a mixt. of air and 45-55% O2, prehated to 350-450 degrees C, and cond. nitric acid as catalyst. The catalyst is introduced at a rate of 20-30 g HNO3/kg oxidised Se, by passing the air, oxygen or air/oxygen mixt. through a column filled with concd. nitric acid. The Se dioxide is passed continuously through a packed column or fluidized bed in countercurrent to deionized water of spec. resistance 2 Megohm. Se acid soln. is treated with an ion exchanger and high purity Se is pptd. in known manner.