Separation and recovery of zinc, lead and iron from electric arc furnace dust by low temperature smelting

Abstract

Electric arc furnace dust (EAFD), an important secondary resource, is categorized as hazardous solid waste which contains multiple heavy metals such as zinc, lead and chromium. Smelting-Reduction is considered as an effective method to recover metal elements from EAFD. To efficiently separate the zinc, lead, iron and slag from EAFD, a novel and clean process developed to enhance reduction and lower smelting temperature through sodium carbonate was proposed herein. Thermodynamic analysis and laboratory experiments were carried out to determine the feasibility and reliability of this new process. The optimal conditions were determined as temperature of 1450 °C, sodium carbonate dosage of 4%, C/O of 0.8, holding time of 30 min and basicity of 0.8, and the corresponding volatilization of Zn and Pb could be 99.78% and 89.47% respectively; besides, the reduction of iron could reach 98.98%. Simultaneously, the recovery of iron reached 98.62% and the grade of iron amounted to 93.8%. The melting reduction process of zinc, lead and iron could be divided into three stages according to both the experimental results and the thermodynamic analysis. The short process which is characteristic of high efficiency and low energy consumption, aims to provide a clean and sustainable approach to utilize EAFD.