Study On Direct Reduction Process And Mechanism Of Dust Of EAF Containing Zinc And Lead By Microwave

Dust of electric arc furnace(hereinafter referred as EAF) is an important secondaryresources rich in Fe, Zn, Pb, which is characterized by fine granularity, complex composition,high impurity content and low comprehensive utilization rate. In order to effectively utilize thesevaluable resources, in the light of the basic study of thermodynamics, while employing themicrowave heating technique to conduct the research of the direct reduction process of the dustof EAF, the paper studied the relevant factors that have an impact on reduction and discussed themechanism of action.The warming performance study showed that, the dusts of EAF, coke, anthracite andbituminous coal have a strong ability of absorption the microwave, under the condition of qualityof10g, microwave power for900w, the heating rate of the dust of EAF, coke and anthracitewere higher than100℃/min, which embodied the efficiency of microwave heating. For the dustof EAF with carbon, it can be significantly conducive to the heating rate to increase the outputpower of the microwave and to mix with fine particles of coke.The results of direct reduction by microwave heating showed that, without protectionatmosphere, and under the conditions of carbon/oxygen being0.9, reduction temperature being1100℃, reduction time being15min, and reducing agent being anthracite of particle size-0.096mm, the reduction product metallization rate could reach90.33%, and the removal rate of zinc,lead was96.26%and88.89%respectively. In addition, the direct reduction adopting microwaveheating technique uses powder material as raw material, compared with the regular methodwhich is pelletizing first and reduction second, it attains the advantages of shorter process, lowerenergy consumption, and higher reduction efficiency.TG-DSC, XRD and SEM analyses showed the direct reduction process of the dust of EAFas follows: as the temperature went up, adsorption water and structure water were successivelyremoved, the organic matter in anthracite were decomposed and volatilized, then happened thecarbon gasification and direct and indirect reduction of franklinite, hematite, magnetite iron oreand wustite; when the reduction temperature exceeded900℃, tricalcium silicate and dicalciumsilicate were generated, metal oxide in the dust was reduced gradually, and the metal ironparticles produced before were constantly concentrating and accumulating; when the reductiontemperature reached1100℃, the reduction products were mainly the granular iron of larger size.