Purification Of BaCl₂ As A Phosphate Glass Material

Metaphosphate is an essential component to prepare phosphate glass. The glass made from metaphosphate, in which the total content of transition metal ions as impurity is less than 3 ppm, can be used to produce glass of high-power laser due to its excellent optical transmission. It can also be used as lens of missile. So the related preparation technique of the metaphosphate with high purity is important for military industry.In general, Ba(PO3)2,which is one of the basic materials for making phosphate glass, can be obtained by heating the mixture of BaCl₂ and NH4H2PO4. In this work, a phosphate glass material, BaCl₂ with high purity has been prepared by ion exchange methods. Two methods were chosen to adsorb the transition metal ions as impurity. The first method was an ordinary ion exchange method. Three types of ion exchange resins, including two chelating resins D840 and D405-II and a weakly basic anion exchange resin 703 were chosen to adsorb the transition metal ions as impurity. The sorption capabilities, regeneration capability and the factor such as reaction time and temperature that can exert effects on the exchange properties were investigated. The results showed that the transition metal ions as impurity in BaCl₂ can not be reduced to≤3 ppm by these resins.Another method was ion exchange chromatography. A chelating resin D751 was chosen to separate the transition metal ions from alkaline earth ions. The mass of chelating resin D751 and concentration of hydrochloric acid can exert effects on the separation degree of the transition metal ions from Ba2+. Under the optimum conditions, the total impurity content in the BaCl₂ was reduced with the D751 from 36.8 ppm to≤3 ppm. The yield was 22%. This work provides parameters for large-scale preparation of BaCl₂ with high purity.