Paper No. 958 INTERACTION BETWEEN MIBC AND SODIUM METASILICATE IN FLOTATION OF COAL SLIMES M Zolghadri 1 , A Ghaffari 2 , M Amiri Parian 3 and H Haghi 4, * ABSTRACT MIBC and sodium metasilicate are used as a frother and a dispersant in coal flotation respectively. In order to study interaction between them, flotation experiments were performed on fine coal (<150 microns). It was found that if the frother (MIBC) dosage is in excess of a certain limit, it has an activation effect on the gangue minerals associated with coal. In addition, it was found that however sodium metasilicate can disperse clay slimes eliminating slime coating, but in the case of excess dosage, could intensify activation effect of MIBC, which is undesirable in coal flotation. Keywords: coal flotation, sodium silicate, frother, dispersion, activation INTRODUCTION Froth flotation is the best method in beneficiation of coal slimes (<150 μm). Depression of coal particles and activation of mineral matter could so decrease flotation efficiency that the separation results are lower than washability curve of coarser size fractions (approximately 0.5 to 1 mm). Some of undesirable peripheral effects lead to this phenomenon such as slime coating, which is an important undesirable phenomenon reducing flotation performance. Although both clay slimes and coal were commonly considered to carry an overall negative surface charge over a wide range of suspension pH, the slime coating is accrued due to electrostatic attraction between negatively charged coal particles and positively charged edges of clays (Xu et al, 2003). It has been proven that frothers such as MIBC acts not only on the air-water interface but also on the solid-water interface and activates high-ash particles, especially at size fractions lower than 53 microns (Erol et al, 2003). Use of an appropriate modifier could improve separation efficiency by dispersion of clay slimes. Sodium metasilicate could be a favorable modifier. Dissolution of sodium metasilicate is relatively complex and consists of its hydration and formation of NaOH, followed by dissolution of silica. Sodium orthosilicate hydrolyses according to the equation 1 (Bulatovic, 2007). (1) Theoretically, sodium silicate disperses particles with two mechanisms (Bulatovic, 2007): 1. Iranian Academic Center for Education, Culture and Research (ACECR) at Tarbiat Modares University,Nasr Bridge, Jalal-e Al-e Ahmad Highway, Mineral processing research group, ACECR at TMU, Tehran, Iran. Email: majidzolghadri@gmail.com 2. Iranian Mineral Processing Research Center (IMPRC), Karaj, Iran. 3. Department of Mineral processing, Faculty of Engineering, Tarbiat Modares University, Tehran, Iran. 4. School of Mining Engineering, College of Engineering, University of Tehran, Iran. North Karegar St., passed Jalal Al-e-Ahmad Hwy, School of Mining Engineering, College of Engineering, P.O. Box 1439957131, Tehran, Iran. Email: hhaghi@ut.ac.ir , hamed.haghi@gmail.com XXVI INTERNATIONAL MINERAL PROCESSING CONGRESS(IMPC) 2012 PROCEEDINGS / NEW DELHI, INDIA / 24 - 28 SEPTEMBER 2012 06258 XXVI INTERNATIONAL MINERAL PROCESSING CONGRESS(IMPC) 2012 PROCEEDINGS / NEW DELHI, INDIA / 24 - 28 SEPTEMBER 2012 06258