Extraction of zinc from dust from electric arc furnaces by high-temperature chlorinating sintering

Abstract

The paper presents the results of comprehensive studies of the processing of ferrous metallurgy dust by high-temperature sintering together with CaCl₂. Using modern research methods of X-ray fluorescence spectroscopy, inductively coupled plasma mass spectroscopy ICP-MS (Agilent 7700s ICP-MS System Technologies), powder X-ray diffraction (Ultima III (Rigaku Corporation, USA), the composition of dust and the forms of metals in them have been studied: zinc in dust is mainly represented in in the form of zincite (ZnO) and in the form of franklinite (ZnFe₂O₄). Zinc chloride hydrates (Zn₅Cl₂·(OH)8·H₂O) were found in a small amount. Lead was found in a metallic form. The results of the influence of temperature and consumption of CaCl₂ on the distribution of Zn, Pb between sintering products (clinker, sublimates) are presented. The optimal process parameters were established: t = 900ºC, τ = 60 minutes, the consumption of CaCl₂ is 1.3 times higher than its consumption from the SRQ. High quality zinc sublimates were obtained, % by weight: 40.87 Zn; 0.16 Pb; 44.82 Cl; 13.04 O; others. A high recovery of zinc in distillates has been achieved – 98.9%. The presence of a minimum lead content in the distillates will not significantly affect their quality. New data on the extraction and distribution of zinc and lead between the products of high-temperature sintering of clinker together with CaCl₂ have been obtained. It was found that at temperatures above 700ºC, the zinc content in the clinker decreases sharply. The minimum zinc content in the clinker of 0.62% corresponds to a temperature of 900ºC. An increase in temperature to 1000ºC only slightly reduces the zinc content in the clinker to 0.6%.