The global production of iron and steel continues to rise steadily, leading to the accumulation of byproducts such as oxide scales, dust, and sludge. The presence of heavy metals in these wastes poses significant environmental challenges for their disposal. Traditionally, hydrometallurgical techniques have proven economically unfeasible for recycling these materials, whereas pyrometallurgical methods have gained traction and found broader applications.This research focuses on recycling electric arc furnace (EAF) dust, sponge iron dust, and oxidized scale pellets as secondary sources of iron. To achieve this goal, two methodologies were employed: a) the production of double-layer pellets and b) the concentration and recovery of iron from EAF dust through hydrometallurgical processes. In the fabrication of the double layer pellets, a core was initially formed using sponge iron dust in a disk pelletizer, incorporating 0.1% to 2% bentonite and 5% to 15% EAF dust as additives, resulting in pellets with a diameter of 12 to 15 millimeters. A secondary layer, measuring 1 to 2 mm in thickness, was formed from oxidized fines, with bentonite added in concentrations ranging from0.1% to 2%. The mechanical properties of the resulting pellets were eva‎luated and found to meet existing industry standards for single-layer pellets. Specifically, the tumble index of these pellets was approximately 3, the average compressive strength was about 92.4 g/cm2, and the average dry strength was 1,120 g/cm2. To concentration and recovery of iron from EAF dust, leaching was initially performed using 2 Molar sulfuric acid for three hours at 98 ºC. After cooling the solution, chemical precipitation of the constituent elements was carried out. The results indicated that the pelletizing method effectively prevents the oxidation of sponge iron dust particles before their introduction into the melt, thus eliminating the need for sintering and requiring only drying. This enables the direct use of the pellets in electric arc furnaces. In the chemical concentration method, the results demonstrated that a single stage of dissolution effectively facilitate the separation of iron from other elements, such as calcium and magnesium. Consequently, the concentration of iron present in EAF dust allows for its utilization as a high-purity source in the initial pelletizing process.

مسعود پنجه پور , مهدي احمديان

محمود مراتيان اصفهاني , رحمت اله عمادي