Strategies for the Upgrade of a TBZC Product (Tetra Basic Zinc Chloride) by Selective Removal of the Impurity Chlorine

When recycling materials containing zinc in hydrochloric acid processes, the precipitation of zinc can lead to the formation of various compounds which can be assigned to the group of zinc hydroxide chlorides. This paper compares different approaches for the selective removal of chlorine from tetra basic zinc chloride to obtain a cleaned zinc product. The removal of chlorine via soda leaching at atmospheric conditions as well as under overpressure in an autoclave was investigated. Furthermore, concepts were considered in which the chlorine can be evaporated as a compound and thus separated via selective temperature and atmospheric control. Thereby, a focus is on the simulation of pyrohydrolysis and clinkering for the separation of chlorine via gaseous compounds whereby zinc remains and can be brought to further processing. The simulations with multivariant parameters are carried out using the thermochemical calculation software package FactSage.

Automated summary

This paper compares different methods for removing chlorine from tetra basic zinc chloride during the recycling process and explores the separation of chlorine through pyrohydrolysis and clinkering simulations.