Orhan Ozdemir

A review of induction and attachment times of wetting thin films between air bubbles and particles and its relevance in the separation of particles by flotation

Bubble-particle attachment in water is critical to the separation of particles by flotation which is widely used in the recovery of valuable minerals, the deinking of wastepaper, the water treatment and the oil recovery from tar sands. It involves the thinning and rupture of wetting thin films, and the expansion and relaxation of the gas-liquid-solid contact lines. The time scale of the first two processes is referred to as the induction time, whereas the time scale of the attachment involving all the processes is called the attachment time. This paper reviews the experimental studies into the induction and attachment times between minerals and air bubbles, and between oil droplets and air bubbles. It also focuses on the experimental investigations and mathematical modelling of elementary processes of the wetting film thinning and rupture, and the three-phase contact line expansion relevant to flotation. It was confirmed that the time parameters, obtained by various authors, are sensitive enough to show changes in both flotation surface chemistry and physical properties of solid surfaces of pure minerals. These findings should be extended to other systems. It is proposed that measurements of the bubble-particle attachment can be used to interpret changes in flotation behaviour or, in conjunction with other factors, such as particle size and gas dispersion, to predict flotation performance.

The effect of zeolite treatment by acids on sodium adsorption ratio of coal seam gas water

Many coal seam gas (CSG) waters contain a sodium ion concentration which is too high relative to calcium and magnesium ions for environment acceptance. Natural zeolites can be used as a cheap and effective method to control sodium adsorption ratio (SAR, which is a measure of the relative preponderance of sodium to calcium and magnesium) due to its high cation exchange capacity. In this study, a natural zeolite from Queensland was examined for its potential to treat CSG water to remove sodium ions to lower SAR and reduce the pH value. The results demonstrate that acid activated zeolite at 30%wt solid ratio can reduce the sodium content from 563.0 to 182.7 ppm; the pH from 8.74 to 6.95; and SAR from 70.3 to 18.5. Based on the results of the batch experiments, the sodium adsorption capacity of the acid-treated zeolite is three times greater than that of the untreated zeolite. Both the untreated and acid-treated zeolite samples were characterized using zeta potential, surface characterization, DTA/TG and particle size distribution in order to explain their adsorption behaviours.

Understanding the role of ion interactions in soluble salt flotation with alkylammonium and alkylsulfate collectors

There is anecdotal evidence for the significant effects of salt ions on the flotation separation of minerals using process water of high salt content. Examples include flotation of soluble salt minerals such as potash, trona and borax in brine solutions using alkylammonium and alkylsulfate collectors such as dodecylamine hydrochloride and sodium dodecylsulfate. Although some of the effects are expected, some do not seem to be encompassed by classical theories of colloid science. Several experimental and modeling techniques for determining solution viscosity, surface tension, bubble-particle attachment time, contact angle, and molecular dynamics simulation have been used to provide further information on air-solution and solid-solution interfacial phenomena, especially with respect to the interfacial water structure due to the presence of dissolved ions. In addition atomic force microscopy, and sum frequency generation vibrational spectroscopy have been used to provide further information on surface states. These studies indicate that the ion specificity effect is the most significant factor influencing flotation in brine solutions.

Surface Properties and Flotation Characteristics of Boron Minerals

Flotation of soluble salt minerals such as potash, trona and borax exhibits similarities because all are conducted in their brine solutions. The most commercially important boron minerals in the world are borax (Na2B4O7.10H2O), colemanite (Ca2B6O11.5H2O), ulexite (NaCaB5O9.8H2O), and kernite (Na2B4O7.4H2O). Most of them contain low grades when mined and must be upgraded by mineral processing techniques to commercially acceptable quality for the production of basic chemicals, such as boric acid. Boron minerals exhibit a spectrum of solubilities depending upon the cations in the lattice structure. Accordingly, a classification of semi-soluble (colemanite and ulexite) and soluble (borax and kernite) boron minerals may be appropriate as each class of minerals behaves differently in flotation. While borax has to be concentrated from its saturated brine, colemanite and ulexite can be recovered by flotation as is the case for other semi-soluble salt minerals. A common problem encountered in both classes of boron minerals is the presence of sig- nificant amounts of clay type minerals which adversely affect flotation recoveries in the form of slime coating. Despite the successful application of flotation technology in the potash industry, flotation has not yet been well developed for boron recovery. This may be attributed to inherent difficulties such as high ionic strengths, high viscosity brines, interaction of cations at the solid/liquid interface, and particularly the presence of clay minerals acting as persistent slimes. In this paper, we have reviewed the flotation chemistry studies on the interaction of boron minerals with anionic (sodium dodecylsulfate) and cationic (dodecylamine hydrochloride) surfactants along with the electrokinetics properties of boron minerals.

Field Properties and Performance of Surface Paste Disposal

A significant amount of tailings with a high content of cyanide or sulphur arises from the beneficiation process of metallic mines such as gold, silver, copper, and lead. The influence of these hazardous tailings on the environment may have multiple aspects. The control and configuration of this kind of environmentally dangerous tailings in terms of isolation at disposal site, construction of impermeable layers, transportation from plant, stabilization, safety, their effects on water, and soil quality are the main parameters that could be considered carefully. In this context, tailings management are very important to selection of the optimum disposal method. Also, the some parameters such as physical and chemical characterization of tailings, properties of newly formed material (e.g. acid potential, stabilization, cost and applicability of the paste tailings etc.) should be evaluated. Safely disposal of mine tailings under surface conditions is of great importance in the aspect of environment.

Report for SWEMP2016/CAMI2016

‘16th International Symposium on Environmental Issues and Waste Management in Energy and Mineral Production (Swemp2016)’ and ‘6th International Conference on Computer Applications in the Minerals Industries (CAMI2016)’ symposiums were taken place in Istanbul, Turkey from 05–07 October 2016. Total of 93 delegates have attended to the symposiums which provided excellent international forum for sharing knowledge and expertise for students, researchers and industry. Total of 124 scientific papers (68 in SWEMP2016 and 56 in CAMI2016) were published in the symposium proceedings.