Abstract
Copper slag, an important by-product of the copper smelting process, is mainly composed of 2FeO SiO2, Fe3O4, and SiO2. Due to the sufficient metal oxides, copper slag is regard as a potential oxygen carrier (OC), which can be applied in chemical looping technology. This research proposed to use the granulated copper slag particles as precursor to produce oxygen carrier. Through this method, waste heat of the high-temperature slag can be fully recovered, eliminating the complicated copper slag pretreatment process. In this paper, the reactivity of granulated copper slag after redox calcination was studied by X-ray diffractometer (XRD) and Scanning Electron Microscope (SEM), the highest reactivity occurred at 1,000°C. In addition, the oxygen release and absorption performance of OC were tested in thermal-gravimetric (TG). According to theoretical calculations, the mass loss caused by oxygen release accounts for 70.57% of the total loss and the mass reached by 4.2% at 1,000°C in oxygen absorption experiment. The copper slag modified through calcining in redox condition was proved to be a promising oxygen carrier in chemical looping process. Furthermore, the performance research on OC also provided theoretical references for the operating paraments of OC circulating between air reactor and fuel reactor in practical chemical looping processes.
Highlights
Chemical looping technology is an emerging combustion technology which expected to achieve 100% CO2 capture efficiency with a low energy consumption (Abuelgasim et al, 2021)
The mineral phase of initial copper slag was analyzed by X-ray Diffractometry (XRD)with a scanning rate of 4°/min from range of 2θ 10o–90o and the elements composition was tested by X-ray Fluorescence (XRF)
Fayalite was decomposed into main phases (Fe3O4, Fe2O3, and SiO2) in the air (Gyurov et al, 2011), the intensity of Fe2O3 in the calcined sample gradually increased and Fe3O4 phase decreased as the calcined temperature increased from 900°C to 1,100°C. It indicates that the transformation rule of iron phase in copper slag during calcination process is “2FeO·SiO2→Fe3O4→αFe2O3” shown in R1-R2 (Gorai et al, 2003)
Summary
Chemical looping technology is an emerging combustion technology which expected to achieve 100% CO2 capture efficiency with a low energy consumption (Abuelgasim et al, 2021). There have been significant advances in metal oxide OC such as Fe, Ni, Cu, and Mn for chemical looping applications (Kang et al, 2010; Gu et al, 2015; Jiang et al, 2017). Among these materials, Fe-based OC has attracted increasing attention because of its high oxygen release capacity (Cheng et al, 2018), cost benefits (He et al, 2013; Mayer et al, 2018) as well as environmental compatibility (Luo et al, 2014; Chen et al, 2021). Due to their sulfur tolerance, Fe-based oxygen carriers can react with acid gases or even solid sulfur fuels without
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