Removal of Platinum Group Metals Contained in Molten Glass Using Copper

Abstract

Removal of platinum group metals (PGMs) such as Pd, Ru, and RuO2 from molten glass by using various amounts of liquid Cu was done as a basic study on a new vitrification process for a high-level radioactive waste. We prepared two types of borosilicate glasses containing PGMs and Cu, respectively. These glasses were mixed together and heated at 1,473 K for 4 h in Ar atmosphere. More than 95% of Pd were removed as a spherical metal button composed of Pd-Cu alloy when Cu was added in an amount 0.5 times the weight of Pd. Nearly 95% of Ru was also removed as a spherical button with 2.5–5 times as much Cu addition as Ru in weight. Ruthenium oxide was reduced to metallic Ru by a reaction with Cu in the molten glass. The removal fraction was increased by increasing the amount of Cu and reached 63% when Cu addition was 7.5 times as much as RuO2 in weight. By addition of Si as a reducing agent, nearly 90% of Pd and Ru were removed with Cu and Si metal composites even under O2:Ar = 20:80 (v/v) condition.