Potassium Capture by Kaolin, Part 1: KOH

Abstract

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Dehydroxylation and Structural Distortion of Kaolinite as a High-Temperature Sorbent in the Furnace

“…[28]. In the raw kaolinite, Si atoms were assigned to a Q 3 Table 3, more than 80% of kaolinite-characterized Si was converted for flash calcination. The formation of mullite-characterized Si appeared at 1200 • C, in agreement with the result of XRD.…”

“…Coal, biomass and solid waste contain Na, K, Pb, Cd and other alkali/heavy metals. During combustion, gasification and other processes, these semi-volatile metals are prone to cause the problems such as boiler slagging, ash deposition of heat transfer area, high-temperature corrosion, and emissions of heavy metals and ultra-fine particles [1][2][3][4][5]. Kaolinite can adsorb alkali/heavy metal vapor at high temperatures, and then be captured by dust removal equipment [6][7][8].…”

“…The furnace temperatures for coal combustion and waste incineration are 1200-1500 • C and 800-1200 • C respectively, indicating that kaolinite would change to meta-kaolinite and even mullite in the furnace according to the transformation temperature mentioned above [3]. According to the theoretical calculation, Wang et al found that the structural distortion of kaolinite for dehydroxylation has a decisive influence on its performance of metal vapor adsorption [9,10].…”

Investigation of Ash Deposition Dynamic Process in an Industrial Biomass CFB Boiler Burning High-Alkali and Low-Chlorine Fuel

“…A large number of studies have indicated that the main source of element K in heating surface deposits is gas phase K in biomass combustion [4,5,[8][9][10]. In this study, with the condition of combustion temperature (800 °C) and low Cl content in fuel, K probably enters the gas phase mainly in the form of KOH in place of KCl and K2SO4.…”

“…The dominant elements in biomass ash are Ca, K, Cl and S [2,3]. During combustion, K element in biomass fuel is released to the gas phase in the form of KCl, KOH and K 2 SO 4 [4][5][6][7][8][9][10]. These potassium-containing compounds cause severe slagging due to their low melting temperature [11][12][13][14][15][16].…”