Investigation of flocculation properties and floc structure of coal processing plant tailings in the presence of monovalent and divalent ions

Low-rank coals are generally processed with wet methods including washing, flotation, etc. Fine-sized tailings of these processes are discharged to tailing ponds with a significant amount of associated water which contains a high amount of dissolved ions. These tailings should be dewatered employing coagulation/flocculation in terms of technological and environmental aspects. In this study, the coagulation/flocculation behavior of coal processing plant tailings obtained from Manisa, Turkey was investigated in the presence of monovalent (Na+, K+) and divalent (Mg2+, Ca2+) ions and an anionic flocculant (SPP-600). First, the coagulation properties of coal tailings were determined. Then, the flocculation experiments were carried out, and the turbidity values of the suspensions were measured. Moreover, the sizes of the flocs were determined using a laser diffraction particle size analyzer to analyze the strength of the flocs. The results of the coagulation experiments showed that while divalent ions were more effective at 10-1 mol/dm3, higher settling rate and lower turbidity values were obtained in the presence of monovalent ions at 1 mol/dm3 concentration. The optimum flocculant dosage was obtained as 150 g/Mg from the flocculation experiments. The floc size and strength measurements indicated that the larger flocs were obtained with Na+ than Ca2+ in the presence of the flocculant. The strongest flocs were obtained at 10-1 mol/dm3 Ca2+ + 150 g/Mg flocculant. It can be concluded from this study that the coagulation followed by the flocculation method can be employed to obtain fast flocculation behavior and low turbidity for the dewatering of coal tailings

Digital image processing (DIP) application on the evaluation of iron-rich heavy mineral concentrates produced from river sand using a sequential mineral processing approach

In this study, the iron-rich heavy mineral concentrate production from river sand as a by-product of an alternative resource by gravity, magnetic separation, and flotation methods were investigated in detail. For the physical separation of the sample and increasing the Fe2O3 content, a shaking table and a wet high-intensity magnetic separator were used, respectively. The gravity and magnetic separation experiments included rougher, cleaner, and scavenger circuits. In the flotation experiments, cationic flotation with ethylenediamine under acidic conditions, and anionic flotation with sodium oleate under alkaline conditions were performed. The iron and silica content of the products obtained were determined by digital image processing (DIP) methods and compared with the classical analytical procedures. Finally, a flow chart was proposed for the processing of the ore according to the optimum enrichment parameters were determined from the experiments. The results obtained in this study show that it is possible to produce an iron-rich heavy mineral concentrate with Fe2O3 grade and recovery rate of 79.13% and 57.81%, respectively, in addition to a potential feed for the production of quartz sand and feldspar concentrates

A novel technique to investigate the bubble coalescence in the presence of surfactant (MIBC) and electrolytes (NaCl and CaCl2)

An efficiency of flotation process is strongly dependent upon the collecting ability of air bubbles. On the other hand, the liquid film formed between two fully or partially mobile air/liquid interfaces being in contact has low stability, which leads to fast liquid drainage. Therefore, when they approach to each other, they tend to coalescence. Therefore, bubble coalescence is usually controlled with frothers in flotation process. Meanwhile, it is known that dissolved ions inhibit bubble coalescence. In this study, the bubble coalescence in the presence of MIBC was determined using a novel technique with a modified bubble-particle attachment timer. Additionally, the effect of NaCl and CaCl2 on bubble behavior was investigated along with surface tension and bubble coalescence time aspects. As a result of study, it is seen that the bubble coalescence time can be successfully determined with a bubble-bubble coalescence timer

Evaluation of Different Dispersants on the Dispersion/Sedimentation Behavior of Halloysite, Kaolinite, and Quartz Suspensions in the Enrichment of Halloysite Ore by Mechanical Dispersion

In this study, the dispersion properties of pure halloysite, kaolinite, and quartz minerals in halloysite ore were determined in the absence and presence of dispersants (sodium silicate, STPP, SHMP). First of all, the samples were characterized by chemical, mineralogical, BET, FTIR, and TEM analyses. Afterward, the physico-chemical properties of these minerals were investigated by zeta potential measurements and dispersion/sedimentation experiments in the absence and presence of the dispersants. The zeta potential measurements showed that the surface charges of all minerals changed from negative to positive as the PH changed from basic to acidic. The presence of dispersants at natural pHs indicated that the mineral surface charges tended to become more negative as the concentration increased in the zeta potential measurements. SHMP showed the most effect on the zeta potential. In the dispersion/sedimentation experiments, settling was slowed down with the use of dispersants. Finally, the dispersion properties of halloysite ore in the presence of dispersants were explored using mechanical dispersion and pulp viscosity experiments based on the amount of material passing to <38 μm size and the chemical changes in the materials. As a result of the mechanical dispersion tests carried out in the presence of dispersants (sodium silicate, STPP, SHMP), 71.3% of the material with 30.8% Al2O3 and 50.5% SiO2 content passed to <38 μm size without using dispersant, and 73.2% of <38 μm sized material with 35.5% Al2O3 and 46.1% SiO2 content was gained in the use of 7.5 kg/ton SHMP, which was determined as the optimum within the scope of the study. In conclusion, dispersant use enhanced the mechanical dispersion effect for plastic clay mineral separation from hard minerals in an aqueous medium

Effect of Blunging/Dispersion Parameters on Separation of Halloysite Nanotubes from Gangue Minerals

Clay minerals need to be dispersed with blungers before their utilization in the related industries due to their plastic properties, and size reduction is carried out in a wet medium. Clay minerals also contain impurities such as nonplastic materials in their structure. Mechanical dispersion parameters are important in the separation of clay group minerals (halloysite and kaolinite) from their typical non-clayey gangue minerals (quartz and goethite). In this study, the removal of impurities from halloysite ore obtained from Kızıldam, Turkey, was examined in terms of mechanical dispersion parameters, namely, feed size, blunging time and speed, pulp concentration, pulp temperature, and the aging process. The effect of these parameters on halloysite dispersion was determined by particle size, chemical, and mineralogical analysis, and optical and scanning electron microscope images. The results obtained from the studies of the mechanical dispersing and particle size distribution of the products indicated that the optimum dispersion parameters were determined as −10 mm feed size, 8 h, and 1000 rpm blunging time, and speed, 35% pulp concentration at 25 °C pulp temperature. Under these optimum conditions, a 72.3% amount of −38 μm clay product containing 35.6% of halloysite, 46.5% of kaolinite, 12.0% quartz, 1.9% goethite, 0.9% gibbsite, and 3.2% other minerals were obtained from the halloysite ore, having 30.5% of halloysite, 43.4% of kaolinite, 19.1% quartz, 2.9% goethite, 1.4% gibbsite, and 2.7% other minerals. In this study, it was understood that feed size, pulp concentration, blunging time, and speed were important parameters, while pulp temperature and the aging process had no significant effect on the mechanical dispersion of Kızıldam halloysite. In addition, impurities such as quartz and iron-bearing minerals were separated from the ore by blunging and sieving