From laboratory to industry: Preparation and mechanism analysis of organic additive-modified high-activity calcium hydroxide desulfurizer in low-temperature dry desulfurization

To address the requirements of low-temperature dry flue gas desulfurization (FGD) in hot blast furnaces of steel mills, a high-activity calcium hydroxide (Ca(OH) 2 ) desulfurizer was synthesized using a simple quicklime digestion method. The incorporation of the metal oxide Al 2 O 3 and an organic additive digestion solution (comprising 1.5 wt% urea, 1.5 wt% polyethylene glycol 400 (PEG), and 3 wt% triethanolamine (TEA)) enhanced the physical morphology and chemical properties of the desulfurizers. The specific surface area increased from 3.23 m 2 /g (quicklime) to 43.24 m 2 /g, the pore volume and average pore size are enhanced to 0.195 cm 3 /g and 0.013 nm. The synthesized desulfurizer demonstrated a remarkable 100 % removal efficiency, a high sulfur capacity of 21.49 mg/g, and an extended breakthrough time of 48.5 min under simulated flue gas conditions (100℃, 3 % O 2 , and 15 % CO 2 ). Following adaptability and carbon dioxide resistance tests in the laboratory, 10 tons of the preferred desulfurizer, designated CA@UPT #1, were produced in the quicklime digestion factory and subsequently tested in the steel mill. After two pilot tests, the improved desulfurizer, CA@UPT #2, successfully achieved the ultra-low emission standard in China (35 mg/Nm 3 ). Characterization techniques, including BET, SEM, TEM, HRTEM, XRD, XPS, and particle size distribution analysis, were employed to investigate the reaction mechanism. Additionally, kinetic and diffusion studies were conducted on both lab- and industry-produced calcium powders. The economic advantages of this desulfurizer were underscored through cost calculations. The superior performance in FGD indicates the significant potential of calcium powder desulfurization, and an analysis of influencing factors was summarized to facilitate the advancement of Ca(OH) 2 powder desulfurization technology.