Influence of coal ash on potassium retention and ash fusibility during gasification of corn stalk coke

The potassium fixation ability and ash fusibility in gasification of corn stalk coke blended with coal ash were studied in CO₂ atmosphere using a tube reactor. The ash samples were analyzed by inductively coupled plasma atomic emission spectrometer (ICP-AES), X-ray diffraction (XRD) and ash-melting point measuring device. The results show that coal ash has a certain ability of fixing potassium in the biomass ash as the reference of kaolin and the potassium retention ratio (PRR) increases when adding more coal ash. On the other hand, ash fusion temperatures (AFTs) of the blended ash increase by adding the coal ash, compared with the biomass ash. XRD patterns show that the reaction between alumina/silica compounds in coal ash and potassium that volatilized into the gas phase and existed in slag phase leads to formation of potassium aluminosilicates(KAlSi₃O₈, KAlSi₂O₆ and KAlSiO₄), which are high melting point compounds. It confirms that coal ash is a potential additive for not only fixing potassium, but also increasing the ash fusion temperatures of easy-to-slagging biomass.