Plasma processing of uranium-containing solid fuels

Abstract

This paper presents the results of thermodynamic and experimental investigation of plasma processing of uranium-containing Nizhneilli brown coal (NBC) of 12% ash content and Estonian dictyonema shale (EDS) of 88% ash content. The essence of plasma processing of the uranium-containing solid fuels (SF) is in the conversion of the organic mass of SF into synthesis gas, with the simultaneous release of uranium-containing compounds into the gas phase, followed by the production of uranium-free ash. Thermodynamic analysis showed that the gaseous phase of the SF plasma pyrolysis and steam gasification products consists, basically, of synthesis gas with a concentration of up to 95.2 vol% at 1800 K. At this temperature, uranium-containing compounds completely pass into the gas phase in the form of uranium oxides. Experiments on plasma pyrolysis and steam gasification of EDS were performed in entrained-flow plasma reactor. Plasma-steam gasification of EDS allowed producing the synthesis gas yield of 86%, the carbon gasification degree of 70.4%, and degree of uranium release to the gaseous phase of 83.6%. The results of the research testify to the insensitivity of the plasma processing technology to the quality of the SF used. The study showed that the integrated indices of plasma gasification of uranium-containing SF are higher than those of plasma pyrolysis.