Abstract
In order to comprehensively utilize coal gangue, we present fluidized calcination as a new thermal technology for activating coal gangue and systematical study was conducted in comparison with static calcination. The calcined products obtained by different calcination methods under various temperatures were characterized by the means of X-ray diffraction (XRD), thermal gravimetry-differential scanning calorimeter (TG-DSC), Fourier transform-infrared spectroscopy (FT-IR) and scanning electron microscope-energy dispersive spectrometer (SEM-EDS). Chemical and physical characteristics such as aluminium leaching rate, chemical oxygen demand and whiteness of calcined products were also investigated. The results show that aluminium leaching rate could reach to the maximal value 74.42% at 500 °C by fluidized calcination, while the maximal value of 66.33% could be reached at 600 °C by static calcination. Products by fluidized calcination obtained higher whiteness and lower chemical oxygen demand (COD) under the same calcination temperature. The well-crystallized kaolinite transform to amorphous meta-kaolinite under 600 °C and mullite presence under 1000 °C according to phase transformation, chemical bond variation and microstructure evolution analysis. Fluidized calcination was more efficiently for combustion of carbon/organic matter and dehydroxylation of kaolinite, which might applied in coal gangue industry in future.
Highlights
Coal gangue is an associated resource of complex industrial solid waste discharged when coal mining and washing in the production course [1,2]
We considered considered absorbing these advantages in order to form fluidized calcination technology suitable for absorbing these advantages in order to form fluidized calcination technology suitable for the coal the coal gangue utilization
The fluidized calcination were performed in a customized vertical tubular furnace system furnace system as shownexperiments in Figure 4, the internal diameter of the tubular furnace was 25 mm
Summary
Coal gangue is an associated resource of complex industrial solid waste discharged when coal mining and washing in the production course [1,2]. Many types of research have been conducted to develop its utilization as the abundant mineral resource for the production of paper, rubber, building materials, and chemical products, etc. In this crystal structure, the Si and Al elements didn‘t have the chemical activity. Thermal activation by the calcination for coal gangue at 600–900 ◦ C as the most common activation method [10,11]
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