Discharge of Simulated High Level Liquid Waste During Rotary Calcination

In the two-step cold crucible vitrification process, high level liquid waste is evaporated, denitrated, and calcined in a calciner to form metal oxides. These oxides then fall into the cold crucible, where they are melted together with base-glass frit to produce a vitrified waste form. To ensure coordination between the calcined material and glass frit during the integrated operation of the calciner and cold crucible, and to guarantee that the waste loading of the final glass product meets requirements, this study investigated various process parameters in standalone calciner tests. These included the salt content of the waste solution, rotational speed of the furnace, sucrose dosage, as well as discharge rate and stabilization time under different operating conditions. The experimental results show that the calcined material enters a stable discharge period after a 25-30 minutes accumulation and transition stage. Factors such as lower salt content in the waste solution, reduced rotational speed, decreased sucrose addition, and higher feed rate all prolong the time required to reach stable discharge, with rotational speed having the most significant effect. During stable discharge, a change in the feed rate leads to a transition period of about one hour before discharge stabilizes again. After stopping the feed, all material inside the calciner can be discharged within 15-20 minutes. This study on the discharge behavior of calcined materials provides valuable guidance for optimizing and improving the calcination process, enabling integrated operation of the calciner and cold crucible, and advancing the two-step cold crucible vitrification technology toward engineering application.