Greening Pathways for Synthetic Talc Production Based on the Supercritical Hydrothermal Flow Process

Abstract

Recent efforts in chemistry have led to development of a fast and continuous process for the production of synthetic talc in a supercritical hydrothermal reactor. This attractive process compatible with industrial requirements leads to advantageous physicochemical characteristics including submicrometer size, hydrophilicity, and high chemical and mineralogical purity. In addition, the high speed of the process and moderate reaction conditions have potential advantages from a viewpoint of the impacts on the environment. To verify environmental advantages and seize further opportunities to improve environmental performance, the current study evaluates the new process using the life cycle assessment (LCA) methodology. A cradle-to-gate assessment considers the production of synthetic talc from different magnesium and reagent acid precursors at different concentrations. The findings suggest high impacts of precursors (65–94%, depending on their concentration) and low impacts of process energy and water. Substituting magnesium acetate with magnesium sulfate could reduce greenhouse gases from 4.8 to 2.6 kgCO2 and cumulative energy use from 86 to 34 MJ per 1 kg of synthetic talc. Discussion draws on previous LCA studies on the supercritical hydrothermal process and applications of synthetic talc considering its environmental performance and characteristics in comparison to the conventional (natural) talc.