Graphite immobilisation in iron phosphate glass composite materials produced by microwave and conventional sintering routes

摘要

An investigation of microwave and conventional processing of iron phosphate based graphite glass compositematerials as potential wasteforms for the immobilisation of irradiated graphite is reported. For thebase iron phosphate glass, full reaction of the raw materials and formation of a glass melt occurs withconsequent removal of porosity at 8 min microwave processing. When graphite is present, iron phosphatecrystalline phases are formed with higher levels of residual porosity than in the sample preparedusing conventional sintering under argon. It is found that graphite reacts with the microwave field whenin powder form but this reaction is minimised when the graphite is incorporated into a pellet, and thatthe graphite also impedes sintering of the glass. Mössbauer spectroscopy indicates that reduction of ironalso occurs with concomitant graphite oxidation. Conventionally sintered samples had lower porositiesthan the equivalent microwaved ones.