Utilisation of Mineral Slimes and Industrial Waste by Electro Flotation and Selective Flocculation.

Abstract

Electroflotation and selective flocculation or the combination of both appear to be potential techniques for the beneficiation of low grade mineral slimes and fines generated during mining, milling and other metallurgical operations. Considering the hydrodynamics of flotation process, electroflotation was proved to be an effective and viable technique to separate organic suspending particulate matter generated from leather, textile, metallurgical, oil refinery and food processing plants. Electroflotation is advantageous to process sulphide minerals and minerals that undergo surface changes when exposed to electrolytic oxygen and hydrogen. Adsorption of oxygen, liberated from the anode leads to the formation of elemental sulphur on the surface of the particles. Elemental sulphur thus formed under controlled oxidation enhances the hydrophobicity. Continuous liberation of H+ and OH- leads to drastic changes in the pH of the pulp. Hence, electroflotation technique is more disadvantageous where pH is a critical parameter. Also part of the collector will be either destroyed or dissociated under the influence of pH, electrolytic bubbles and oxidation-reduction environment changes. Selective flocculation of minerals using polymers followed by anyone of the separation techniques such as, flotation, elutriation, filtration, etc. offers considerable promise for processing non-precious oxide minerals. Natural and synthetic high molecular weight polymers have been successfully used as flocculants. Lack of desired specificity is the major set back in this process. However, specificity can be introduced by incorporating active groups in the polymers. Though there is enough literature on selective flocculation of synthetic mineral mixtures, reports on the flocculation of multi-component natural ores are scant. Further, it is generally observed that the prediction of selective flocculation on the basis of results obtained from single mineral tests fairly agrees with synthetic mineral mixtures but rarely on natural systems.