Abstract:
Industrial grade Kaolin deposits in Sri Lanka are located in
Boralesgamuwa and Meetiyagoda. Two distinct grades of Kaolin are produced at
Meetiyagoda refinery, based on the whiteness index (WI). The presence of iron
oxides significantly affects the WI of the Kaolin. Upgrading of the whiteness will
result in a huge increase in the product prices as high as 35%. However, no effective
methods are currently in place for the whiteness improvement at Meetiyagoda
Kaolin refinery. Hence, this study was carried out to assess the whiteness
enhancement capability of Meetiyagoda Kaolin by chemical leaching process using
oxalic and citric acids. The treatment time (0–120 min) in steps and concentration of
acids (0.01, 0.1, 0.2, 0.3, 0.4 and 0.5 M) were considered as the main variables of this
study. Leachate and treated samples were analysed by using spectrophotometric
and XRF methods respectively. The results depict that the oxalic acid is more
effective in leaching iron oxides from Kaolin compared to citric acid for the Kaolin at
Meetiyagoda. It was observed that 25% and 14% of Fe in Kaolin filter cakes can be
removed by 0.4 M oxalic and 0.5 M citric acid respectively, within a treatment time
of 120 mins at the room temperature.
Citation:
Azarudeen, M.H.M., Piranavan, S., Krishnakumar, S., Senanayake, I.P., Rohitha, L.P.S., & Weerawarnakula, S. (2016). Removal of iron oxides in Meetiyagoda kaolin by chemical leaching to improve whiteness. In P.V.A. Hemalal (Ed.), Proceedings of the ERE 2016 Annual Conference on Earth Resources Management (pp. 47-53). Department of Earth Resources Engineering, University of Moratuwa.