An update review for refining crude selenium by sustainable vacuum distillation technology: Theory, applications, and life cycle assessment

Abstract

Selenium (Se) is an irreplaceable metalloid applied in various advanced materials and an essential trace element for humans. More than 90 % of selenium is industrially extracted in different grades by various recovery processes from copper electrorefining anode slime. With the urgent demand for selenium in the high-tech industry, high-quality refined selenium is becoming increasingly prominent. Vacuum distillation metallurgical technology is a clean physical process and is particularly suitable for extracting and refining crude selenium. In this study, we summarized the research progress on the vacuum distillation purification of crude selenium, including theory, technology, and engineering applications. The occurrence state of the key impurities in crude selenium, the thermodynamic theoretical fundamentals of saturated vapor pressure, the vapor-liquid equilibrium phase diagram, the kinetic theory of the volatilization characteristics, the thermodynamic properties of these impurities, and their impact on the vacuum distillation purification process were examined. A life cycle assessment was conducted, and the chemical and physical methods for preparing 4 N refined selenium were compared; recommendations were proposed to effectively reduce the environmental load of the vacuum distillation refining process. We aimed to promote scientific and technological progress in the fields of selenium extraction and selenium refining by vacuum distillation and provide future strategies for achieving green and sustainable processes to prepare high-purity selenium.