Chemical looping gasification using Nickel-containing electroplating sludge and dyeing sludge as oxygen carrier

Nickel-containing electroplating sludge (NiES) and dyeing sludge (DS) were used to prepare oxygen carriers (OCs) for chemical looping gasification (CLG) of DS. X-ray diffraction (XRD), surface area and porosity analysis were employed to investigate the crystal structure and pore structure of NiES and DS ash OCs. It was found that OCs prepared at 850 ℃ for 8 h (850NiES8, 850DS8) exhibited good characteristics in terms of pore structure. X-ray fluorescence (XRF), hydrogen temperature programmed reduction (H₂-TPR) and thermo-gravimetric (TG) were employed to explore the elemental composition, reactivity, redox behavior and their effect on DS pyrolysis of the two selected OCs. The influence of mass ratio of 850NiES8, 850DS8 to DS (850NiES8/DS, 850DS8/DS) and reaction temperature on DS CLG were investigated. It showed that the addition of two OCs significantly promoted the gas yield of DS while accelerating the gasification process. It showed a better performance of 850NiES8 than that of 850DS8 when it was below 900 ℃. On the other side, 850DS8 showed more advantage between 900 and 950 ℃. And high carbon conversion (η_C) of 80.94%,77.59% and acceptable valid gas yield (V_g) of 0.192,0.190 Nm³/kg could be obtained at 850 ℃ when 850NiES8/DS, 850DS8/DS were 1, respectively. In this process, the reduction and energy recovery of dyeing sludge were implemented, and two promising OCs (850NiES8, 850DS8) were developed. In addition, a new harmless method of NiES recycle treatment was also provided.