Preformed minerals as Synroc precursors - a technique for mitigating acid attack during Synroc processing

Stewart, MWA; Bartlett, JR; Reeve, KD

Preformed minerals as Synroc precursors - a technique for mitigating acid attack during Synroc processing

Date

1989

Authors

Stewart, MWA

Bartlett, JR

Reeve, KD

Publisher

Trans Tech Publications

Abstract

The chemical durability of "preformed mineral-route" Synroc precursors in acidic simulated high level nuclear waste (HLW) solutions was examined. The precursor powders were prepared from mixtures of CaTiO3, BaTiO3, CaZrO3, Ca3Al2O6, AI(OH)3 and TiO2. Except for Ca3Al2O6, less than 5% of the Ba and Ca was leached from these powders over a 4 hour interval in 2 mole per dm3 HNO3 solutions, whereas essentially all the Ba and Ca were leached from conventional "alkoxideroute" precursor powders under comparable conditions. Leaching in this latter case can be minimised by neutralising with NH4OH during mixing of the HLW and precursor powder. However, this strategy has a number of disadvantages, namely: (5) the NH4NO3 formed may decompose explosively during calcination; (ii) it will lead to hydrolysis and subsequent inhomogeneous precipitation of some cationic species from the HLW solution; and (iii) it represents an additional processing step. Hot-pressed Synroc samples prepared from the "preformed mineral-route" powders had properties similar to those of consolidated "oxide-route" Synroc. The microstructure, chemical durability and phase composition of monoliths incorporating HLW will be discussed.

Description

Physical copy of the journal held by ANSTO Library at DDC: 666/47. Conference name also called "2nd International Ceramic Conference and Exhibition" on preface

Keywords

Minerals, Synroc process, Leaching, Precipitation, Decomposition, Powders, Calcination, Hot pressing, Oxides, Microstructure

Citation

Stewart, M. W. A., Bartlett, J. R., & Reeve, K. D. (1989). Preformed minerals as Synroc precursors - a technique for mitigating acid attack during Synroc processing. Presentation to the International Ceramic Conference (AUSTCERAM 90: ceramics technology - sharing the knowledge), Perth, Western Australia, 26-31 August 1990. In Journal of the Australian Ceramic Society, 25(2), 75.