China Nonferrous Metallurgy

In view of the problems of poor adaptability of raw materials and incomplete separation of impurities in the current preparation methods of high-purity selenium, such as oxidation volatilization method, regional melting method, vacuum distillation method, etc., this paper uses crude selenium dioxide ( purity 98%) as raw material. The 4N high-purity selenium was prepared by ion adsorption impurity removal-formic acid reduction process, and the optimization parameters of the process were investigated by single factor test. The following main conclusions were obtained. In the resin impurity removal stage, the removal rates of tellurium and arsenic were mainly investigated (other impurities had little effect on the preparation of high-purity selenium). When the solution flow rate was controlled at 2 BV, the removal rates of tellurium and arsenic were more than 99% and 96%, respectively. The optimum process parameters for the reduction of selenite by formic acid were as follows: reaction temperature 80℃, excess multiple of formic acid 1.1 times, stirring speed 200r/min and reaction time 4h. Under these conditions, the reduction rate of selenium was more than 99%. The 4N high purity selenium prepared by this method meets the requirements of standard YS/T 1354—2020 ‘selenium powder’. The results of this study can provide data and technical reference for related enterprises to prepare high-purity selenium.