Non-isothermal reduction kinetics of EAF dust-based pellets

Non-isothermal kinetics studies of the reduction phenomenon of electric are furnace (EAF) dust generated in stainless steelmaking have been carried ou t The dust was mixed with carbon as a reducing agent and dolomite as a bind er to form pellets. A Thermo-Gravimetric Analyzer (TGA) was used to determi ne the weight loss of pellets heated at an average rate of 40 K/min, up to a temperature of 1500 degreesC. The degree of metal reduction was calculate d by considering the pellet weight loss, and evaporation of moisture, dust, zinc and lead at high temperature. The reduction process was divided into three different steps. The first covers the 300 degreesC to 760 degreesC te mperature range (from 7 to 18 min.), the second step ranges between 760 deg reesC and 980 degreesC (18 to 24 min.), and the third covers temperatures a bove 980 degreesC. Each step is characterized by different chemical reactio ns. Non-isothermal reduction kinetics equations were set up to describe eac h step, The kinetics parameters such as apparent activation energies and fr equency factors were established. It was found that the first step was chem ically controlled, while the second step was diffusion-controlled. Reductio n behaviour in the third step was strongly dependent on the initial carbon content in the pellet. Chromium oxide (CrO) could only be reduced in this l ast step. High temperatures and higher initial carbon content favoured the reduction of CrO.