Characterization of DD1 algerian kaolin and the effect of potassium salts on mullitisation of kaolinite

Abstract

This work aims to characterize local Kaolin from Djebbal Dbagh (DD1), Guelma, Algeria, in raw state and after being sintered to improve its refractoriness by mullitisation of the main phase known as kaolinite in order to exploit DD1 as a basic material to elaborate refractory bricks. The characterization of DD1was carried out by different methods of analysis such as chemical analysis, XRD, DTA/TG analysis and scanning electron microscopy (SEM). Furthermore, the measurement of some physical properties such as apparent density, porosity and microhardness of sintered material was performed. The mullitisation was tested without and with addition of potassium salts such as K 2 CO 3 , KNO 3 and K 2 SO 4 as mineralizers to find out the effect of these salts on transition phase from kaolinite to mullite and the inhibition of cristobalite existence versus sintering temperature from 1300°C to 1450°C. The influence of these mineralizers at the cited temperatures was evaluated using XRD. The results show that the additives K 2 CO 3 and KNO 3 have an effective role to accelerate the formation of mullite which is considered as the most favorite phase for high refractoriness.