Analysis of chromium valence state changes in refractory bricks for coal gasifiers and chrome corundum permeable bricks for RF refining furnace
This article states the usage of X-ray diffraction analysis(XRD)to characterize the phase composition of chromium containing compounds,and the employment of X-ray photoelectron spectroscopy(XPS)and inductively coupled plasma-optical emission spectroscopy(ICP)to determine and analyze the chromium valence state and water-soluble hexavalent chromium content in refractory bricks for coal gasifier and chrome corundum permeable bricks for RF refining furnace.Research has shown that when chrome corundum permeable bricks for RF refining come into contact with high-erosion media containing alkali metal oxides(K2O,Na2O)or corrosive media with a high CaO content in an oxidizing atmosphere,hexavalent chromium compounds are generated in high amounts.There is also a conversion of Cr(Ⅲ)to Cr(Ⅵ)in the refractory brick layer near the hot working surface of the coal gasifier,which may be related to the changes in the atmosphere in the coal gasifier.
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