The reduction of electric arc furnace dust in carbon monoxide

In a typical electric arc furnace (EAF) operation, approximately 1 to 2% of the charge is converted into dust, which is collected in the baghouse. These EAF dusts have been classified as hazardous wastes due to their lead, cadmium, and hexavalent chromium contents; however, these dusts also contain large quantities of zinc and iron whose recovery is economically attractive. Thermodynamic studies indicate that the selective reduction of the zinc oxide from the dust particles, while at the same time maintaining the iron content in an oxide form, is feasible under controlled conditions of temperature and reduction potential.; In the present work, a high zinc-containing EAF dust was processed in-flight using a 24 kVA AC plasma furnace under a carbon monoxide {dollar}rm(COsb{lcub}(g){rcub}){dollar} atmosphere. The degree of zinc removal from the product slag phase, {dollar}Rsb{lcub}Zn{rcub},{dollar} was determined as a function of the three operating parameters: reactor temperature {dollar}rm(spcirc C),{dollar} EAF dust feedrate (g/min), and reactant ratio (grams of dust per litre of {dollar}rm COsb{lcub}(g){rcub}).{dollar} The experimentally determined zinc recovery as a function of these variables was fitted to the following model:{dollar}{dollar}eqalign{lcub}Rsb{lcub}Zn{rcub} &= 39.1614 + 0.0793 {lcub}bf T{rcub} - 2.3090 {lcub}bf F{rcub} + 7.1298 {lcub}bf R{rcub} + 0.0032 {lcub}bf F{rcub}sp2cr &- 0.6592 {lcub}bf R{rcub}sp2 + 0.0009 {lcub}bf T{rcub}{lcub}cdot{rcub}{lcub}bf F{rcub} - 0.0056 {lcub}bf T{rcub}{lcub}cdot{rcub}{lcub}bf R{rcub} - 0.05569 {lcub}bf F{rcub}{lcub}cdot{rcub}{lcub}bf R{rcub}{rcub}cr{dollar}{dollar}; The experimental results indicated that the most important parameter affecting the value of {dollar}Rsb{lcub}Zn{rcub}{dollar} was the reactor temperature, although the other parameters were also found to be significant. (Abstract shortened by UMI.)...