Deep refinement of tellurium: equipment and process improvement through process simulation

Abstract

Simulation data have been presented on a process of deep refinement of tellurium based on Authors-developed refinement technique implemented through analysis of the process unit thermodynamical condition using Flow Simulation software, from SolidWorks software product. The technique put forward herein has been implemented in a plant comprising a vertical air-tight reaction chamber arranged inside a multi-zone thermal unit and executing a sequence of refinement stages which use different techniques and are integrated in a single process. The experimental data which have been the basis for calculations have allowed one to determine the boundary conditions of the mathematical model taking into account previous operation experience of the software product used. Temperature profile calculation has been carried out taking into account all the types of heat transfer in the system, the weight / dimensions parameters of system units and the physicochemical properties of refined tellurium, materials of equipment fittings and reactor media. The temperature modes of the process stages have been accepted as the boundary conditions for the thermal calculations, with temperatures being measured at equipment fitting locations at which temperature gages connected with a PID controller have been installed. The simulation of specific refinement process conditions allowed process modes and equipment fitting component design to be corrected. We have developed and produced test models of process and imitation equipment. Analysis of the thermal fields for the final model has shown good agreement with the mathematical model. Equipment upgrading and process parameter improvement on the basis of the simulation results have allowed T-u Grade tellurium (99.95 wt.%) refinement to a 99.99992 wt.% purity by 30 main impurities in the course of physical experiments, the product yield being at least 60%.