Onur Guven

Interplay of Particle Shape and Surface Roughness to Reach Maximum Flotation Efficiencies Depending on Collector Concentration

ABSTRACT Particle–particle and bubble–particle-interactions in flotation systems are governed by physico-chemical and hydrodynamic conditions of pulp. Shape factor and roughness of particles significantly affect these interactions, and hence both grade and recovery in flotation. Although many studies have been conducted to understand morphological features of particles, the underlying mechanism of their effect on flotation recovery have not been clearly shown. Towards this aim, acombination of grinding and abrasion processes was applied to mimic grinding in terms of shape and roughness in order to get their corresponding flotation recoveries at different collector levels. For this purpose, glass beads representing smooth spherical particles of –150+106 µm in size along with ground and abraded glass particles of different shapes and roughness were used to evaluate the flotation efficiency of these particles in the absence and presence of amine collector. The dependence of the shape and roughness on the flotation recoveries at different hydrophobicities as monitored by different amine collector concentrations is demonstrated. Finally, the results are discussed to see if morphology ofparticles can be tuned through grinding to achieve maximum flotation efficiencies.

Effect of Coal Moisture on the Treatment of a Lignitic Coal through a Semi-Pilot-Scale Pneumatic Stratification Jig

Dry processing methods are well known to be sensitive to the moisture content of the processed material. It is well known that cohesive forces among the particles originating from the surface moisture hinder the individual movement or appropriate stratification of particles during separation. Furthermore, high surface moisture also hampers the flow of feed material. In this study, the effect of total/surface moisture on separation of lignitic coals was investigated by using Allair stratification jig with the aim of finding possible critical surface moisture content for optimum separation. Coal samples in the size of −13 + 4 and −4 mm were processed at different particle total/surface moisture levels to recover as clean coal concentrate as possible along with obtaining tailings with minimum levels of combustibles. It is envisaged that a critical surface moisture on both classification (effective screening) and separation is available around 5.5% surface moisture (corresponding to 15% total moisture) for −13 + 4 mm whereas effective separation is not possible for the −4 mm size range even at minor changes in surface moisture of particles.

An investigation of the recovery and kinetics during the flotation of residual petroleum coke in lime calcination exhaust tailings

Flotation is one of the feasible separation methods suggested for recovery of petroleum coke from the tailings of lime calcination furnaces. In this study, analyses of ash content and calorific val...

Composite Films Based on Styrene-co-butyl-acrylate with Colemanite and Calcium Bentonite Mineral Fillers

Composites are engineered materials made from two or more constituent materials, which remain separate and distinct on the macroscopic level within the finished structure and also with significantly different physical or chemical properties. In recent years, there has been a great interest in polymer/inorganic composites, which stems from their improved properties. Mineral fillers in composites are widely used in industrial applications such as adhesives and paints. They provide better mechanical properties and thermal resistance to the systems and also reduce manufacturing costs. In this study, a comparative evaluation of colemanite and calcium bentonite minerals used as a filler in an aqueous polymer emulsion (styrene-co-butyl acrylate copolymer) is performed. The effect of amount and type of mineral additives on the mechanical properties of composites is investigated. Meanwhile, a comparison between colemanite and calcium bentonite is made on the basis of their different dispersion characteristics in a polymeric matrix. The degree of interfacial interaction between the filler and polymeric matrix is also modeled using the B parameter.