Summary of Waste Calcination at INTEC

Abstract

A summary of waste calcination in full-scale and pilot plant calciners has been compiled for future reference. The summary includes feed chemical composition and process operating parameters for: 1) Waste Calcining Facility (WCF) cold operation and hot campaign H-1 through H-9 from 1961 to 1981; 2) New Waste Calcining Facility (NWCF) cold operation and hot campaigns H-1 through H-4 from 1981 to 2000; and 3) smallscale feed blend tests conducted using non-radioactive simulants in various sizes of pilot plant calciners with fluidized-beds from 4 in. diameter up to 2 foot square. These summaries provide a historical record of calcination development at INTEC, give the range of feed compositions and feed additives that have been tested, and will be useful for evaluating calcinability of future wastes.In the calcination process, the liquid wastes are sprayed using air-atomizing nozzles into a fluidized bed of heated spherical calcine particles, evaporating water and nitric acid in the wastes and leaving behind solid-phase metal oxides. Heat was originally provided by re-circulating liquid eutectic sodium/potassium alloy through heat exchange tubes located in the bed. In 1970 the heat input was changed to in-bed combustion (IBC) of kerosene fuel, sprayed directly into the bed through oxygen atomized fuel nozzles, and the calcination temperature was increased to 500 o C. NWCF testing at 600°C with IBC was performed during AprilJune 1999 and April-May 2000.The successful calcination of a given waste is dependent primarily on the major chemical constituents (greater than about 0.05 molar) and the concentration (or diluteness) of dissolved solids in the waste feed. Chemical additives used for calcination have been calcium nitrate to control halide volatility, boric acid to promote amorphous alumina formation, and aluminum nitrate to dilute the sodium content in the calcine. Wastes which were difficult to calcine alone due to diluteness, inability to control particle size, or formation of agglomerates could often be calcined as blends with more amenable wastes. vi vii ACKNOWLEGEMENTS I would like to acknowledge Billie J. Newby for his years of hard work and dedication, over his 30+ years at the Idaho Chemical Processing Plant. His meticulous notes on calcination have been extremely helpful over the years. A great many others, too numerous to mention, worked on calcination development and operation over the years; and they should all be proud to have pioneered the most successful high-level radioactive waste solidification process in the Department of Energy (DOE) complex. I would also like to acknowledge R. M. Gifford for typing and preparing this report for publication.viii ix CONTENTS