Recycling of galvanised steel scrap using chlorination

Abstract

The chlorination of galvanised steel in air and chlorine mixtures at 800°C was investigated by means of thermogravimetric analysis. Scanning electron microscopy, atomic absorption spectroscopy and X-ray diffraction were used to examine and characterise the reaction products. The results demonstrated that it is feasible to remove zinc from iron at 800°C, using an air/chlorine flowrate of 400/40 cm³ min⁻¹ with a ratio of 10 : 1 with respect to air and chlorine. While zinc undergoes chlorination producing a volatile zinc chloride, the oxidation of iron provides a protective oxide layer that resists the attack of chlorine and, therefore, the production of iron chlorides. This provides a novel and cheap method for the steel and related industries to recycle galvanised steel scrap.