| dc.description.abstract | With the advancement of technology, more stringent regulation in environmental protection and the trend of implementing circular economy policies, how to recycle valuable metals from fly ash has become a big challenge. The aim of this study is to evaluate the effectiveness of electric smelting reduction furnace (ESRF) to recover valuable metals from the fly ash collected from stainless steel industry. Analysis of the compositions of stainless steel fly ash indicates that four elements including iron, chromium, nickel, and zinc, are of the most recovery value; and they account for 30-68% of the total compositions. The granulated pellet of ash is put into the electric smelting reduction furnace with a temperature of 1550℃ and reducing agent such as coke is applied to reduce the metallic oxide in the fly ash to recover iron, chromium, nickel, and zinc. Moreover, the impact of varying basicity on the recovery rate of of the targent metals is also evaluated and the results reveal that the best recovery rates of iron, chromium, and nickel can be obtained if the basicity is controlled at 1-1.09. The recovery rates of iron, chromium, and nickel reach≧90%. The results of toxicity characteristic leaching procedure (TCLP) reveal that leaching concentrations of nickel and chromium are 0.16 and 0.1 mg/L, respectively. The results also indicate that as the basicity is controlled between 1.1 and 1.3, the leaching concentrations of nickel and chromium are the lowest, demonstrating that operation under this condition results in the best stability of slag. Analysis of the ash collected by baghouse during manufacturing process reveals the zinc oxide content in the secondary ash is around 34%. The total solid input for the test run is 2175 tons with the total output of 1158 ton. The decrease in mass is caused by the oxidation and reduction of metallic oxide in ESRF, which turn into CO2 and is discharged into the atmosphere. The electricity consumed for treating one ton of stainless steel fly ash is 3050 kWh, indicating that the process is energy-intensive. How to reduce electricity consumption and reduce operating cost remains a big challenge. Overall the result reveals the electric smelting reduction furnace can effectively recycle valuable metals from stainless steel ash and this process can turn stainless steel fly ash into harmless, recyclable, and reusable products. | en_US |