This study presented a novel method for purification of three different grades of diatomite from China by scrubbing technique using sodium hexametaphosphate (SHMP) as dispersant combined with centrifugation. Effects of pH value and dispersant amount on the grade of purified diatomite were studied and the optimum experimental conditions were obtained. The characterizations of original diatomite and derived products after purification were determined by scanning electron microscopy (SEM). X-ray diffraction (XRD), infrared spectroscopy (IR) and specific surface area analyzer (BET). The results indicated that the pore size distribution, impurity content and bulk density of purified diatomite were improved significantly. The dispersive effect of pH and SHMP on the separation of diatomite from clay minerals was discussed systematically through zeta potential test. Additionally, a possible purification mechanism was proposed in the light of the obtained experimental results. (C) 2013 Elsevier B.V. All rights reserved.