Reduction behaviour of electric arc furnace dust (EAFD)-bituminous coal composite pellet in tube furnace.

This article investigates the reduction behavior of electric arc furnace dust (EAFD)–coal composite pellets as a method to recover iron and manage hazardous heavy metals in steelmaking waste. Experiments conducted in a tube furnace at temperatures between 1000°C and 1300°C showed that the optimal carbon-to-oxygen (C/O) atomic ratio for reduction is 1, yielding maximum degrees of reduction (DOR) and metallization (DOM) of 89% and 76%, respectively. The reduced pellets exhibited a three-layer morphology consisting of a surface slag layer, a slag-impregnated iron layer, and a partially reduced powdery core, with higher carbon levels (C/O > 1) increasing the core size and hindering reduction due to gas pressure build-up and slag viscosity. Thermodynamic modeling with FactSage and microstructural analyses indicated that excessive carbon leads to liquid iron formation that consolidates the iron layer, restricting gas escape and reducing reduction efficiency, while rapid heating rates cause pellet disintegration, suggesting slower heating is preferable for effective reduction.