Preparation of nanometer-sized black iron oxide pigment by recycling of blast furnace flue dust

Blast furnace (BF) flue dust is one of pollutants emitted by iron and steel plants. The recycling of BF flue dust can not only reduce pollution but also bring social and environmental benefits. In this study, leaching technique was employed to the treatment of BF flue dust at first. A mixed solution of ferrous and ferric sulfate was obtained and used as raw material to prepare nanometer-sized black iron oxide pigment (Fe3O4, magnetite) with NaOH as precipitant. The optimal technological conditions including total iron ion concentration, Fe3+/Fe2+ mole ratio, precipitant concentration and reaction temperature were studied and discussed carefully. The spectral reflectance and oil absorption were used as major parameters to evaluate performance of pigment. Furthermore, Fe3O4 particles were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Under optimized conditions obtained pigment has low average spectral reflectance (<4%), good oil absorption (∼23%), high black intensity, and narrow size distribution 60-70 nm.