The synergistic alkali metals fixation potential of Oxygen Carrier Aided Combustion(OCAC)technology has attracted increasing attention.Using the tailings from natural ilmenite after titanium extraction and its individual compon-ents Fe2TiO5 and TiO2 as absorbents,and KCl and CH3COOK as simulated alkali sources,the high-temperature absorp-tion characteristics of alkali metal potassium by ilmenite tailings were studied in a static absorption experimental setup.The effects of various factors such as time,particle size,temperature,mass ratio,and gas-solid components on the absorp-tion performance were systematically investigated.Techniques such as X-ray diffraction,inductively coupled plasma op-tical emission spectrometry scanning electron microscopy and X-ray energy dispersive spectroscopy were used to reveal the micro-mechanisms of K enrichment on the surface and bulk phase migration within ilmenite.The results show that il-menite tailings possess good potassium absorption capabilities at high temperatures,with the absorption rate displaying a trend of rapid increase followed by a slow decline over time.Under certain conditions,reducing particle size,increasing reaction temperature,and the concentration of K in the gas phase can further enhance the alkali fixation performance of il-menite tailings.At the temperatures and alkali metal concentrations like those of actual industrial flue gases,ilmenite tail-ings can achieve a K capture rate of over 40%.The primary phase of ilmenite tailings has a unique lamellar structure com-posed of iron-rich and titanium-rich layers arranged alternately.Compared to single-component model substances,it has a more complex morphology and superior alkali fixation capabilities.The process involves an initial deposition of K on the ilmenite surface,forming an enriched layer,followed by a solid-phase diffusion inward and migration deep into the particle along the titanium-rich layers.Fe in the titanium-rich layers migrates synchronously outward,doubly impacting the absorption of K in ilmenite.Additionally,Cl can further promote the absorption of K in ilmenite by reacting with Fe on the surface to form volatile FeCl2.Minerals such as almandine calcian in ilmenite tailings also show a significant syner-gistic absorption of K.The findings further confirm the synergistic alkali metals fixation potential of OCAC technology,while also offering new insights into the resource utilization of low-grade ilmenite.
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