Ayman A. El-Midany

Effect of Oleate/Bacteria Interactions on Dolomite Separation from Phosphate Ore

Abstract In conventional flotation, the sodium oleate is used as a collector for phosphate separation from silica. However, most of the phosphate deposits contain carbonate impurities, which deteriorate the flotation selectivity using sodium oleate. In this paper, the amenability of the carbonate separation from a sedimentary phosphate ore through bio-flotation process, as a one of various efforts to solve the carbonate problem, was tested. The interaction of two types of bacteria (Corynebacterium-diphtheriae-intermedius, CDI, and Pseudomonas aeruginosa, PA) with sodium oleate was investigated. The interaction between collector and bacteria was determined by Fourier Transform Infra-Red (FTIR) measurements, zeta potential before and after adsorption of bacteria, as well as frothing power. The results showed that bio-flotation could produce a phosphate concentrate of 0.85% MgO and 30.2% P2O5 with a recovery of 92% at pH 5.5, 1.25 kg/t sodium oleate, ≥ 1 × 108 cells of CDI bacteria. The specification of such concentrate could not be obtained by the conventional flotation experiments, in absence of bacteria, under similar conditions. This means that bacteria could play a significant role as a surface modifier due to its selective adsorption onto the mineral surface as well as its interaction with collector.

Impact of the Adsorption of Corynebacterium diphtheriae intermedius Bacteria on Enhancing the Separation Selectivity of Dolomite and Apatite

The surface modification of minerals by bacteria has recently been examined in an attempt to improve their separation selectivities. In this paper, a study of the effect of Corynebacterium diphtheriae intermedius (CDI) bacteria on the dolomite/apatite separation process is reported. Bacterial interaction with both minerals was investigated employing Fourier-transform infrared (FT-IR) spectroscopy together with measurements of the adsorption isotherm and the zeta potential. FT-IR methods were used to identify the functional groups on the surface of each mineral before and after the adsorption of bacteria, while the adsorption isotherm and the zeta potential were used to illustrate the type of adsorption process involved, i.e. physical versus chemical adsorption. The application of bioflotation processes to natural ores using CDI bacteria can lower the MgO content of the ores to less than 1%.

Do Pseudomonas Aeruginosa Bacteria Affect the Selectivity of Dolomite/Francolite Separation?

Abstract The similarity of surface properties of dolomite and phosphate minerals leads to limited or no selectivity in their separation by flotation. Many chemical additives were tested; however, a limited success was achieved. Recently, bio-surfactants and bacteria have received much focus not only because of their environmentally friendly behaviour but also for their enhanced selectivity in different processes such as flotation. In this paper, the adsorption of Pseudomonas Aeruginosa (PA) bacteria onto francolite and dolomite was investigated. The adhesion of bacteria was studied by adsorption isotherm, zeta potential, and Fourier Transform Infra-Red (FTIR) spectroscopy to reveal the effect of bacteria on the floatability of each mineral. The proposed adsorption mechanism depends mainly on physical interaction due to Van der Waals, bridging, electrostatic, as well as hydrophobic forces.

Development of artificial neural network models for supercritical fluid solvency in presence of co-solvents

This paper presents the application of artificial neural networks (ANN) to develop new models of liquid solvent dissolution of supercritical fluids with solutes in the presence of cosolvents. The neural network model of the liquid solvent dissolution of CO2 was built as a function of pressure, temperature, and concentrations of the solutes and cosolvents. Different experimental measurements of liquid solvent dissolution of supercritical fluids (CO2) with solutes in the presence of cosolvents were collected. The collected data are divided into two parts. The first part was used in building the models, and the second part was used to test and validate the developed models against the Peng-Robinson equation of state. The developed ANN models showed high accuracy, within the studied variables range, in predicting the solubility of the 2-naphthol, anthracene, and aspirin in the supercritical fluid in the presence and absence of co-solvents compared to (EoS). Therefore, the developed ANN models could be considered as a good tool in predicting the solubility of tested solutes in supercritical fluid.

Upgrading of Oil Shale by Flotation Without Collector

Oil shale impurities prevent its direct usage as a source of energy. Removing or reducing of these impurities before retorting can reduce the cost of oil shale processing. In that regard, pretreatment of oil shale by flotation represents one of the favorable solutions. Therefore, in this work, (a) microscopic examinations were carried out to study the mineralogical characteristics of oil shale sample and (b) flotation of oil shale was used to separate organic matter (kerogen) from associating gangue by adjusting the flotation pH, stirring speed and pulp density without adding a collector. The results of oil shale characterization showed that kerogen content in the studied sample was 10%, while the results of flotation experiments proved the possibility of oil shale upgrading to about 20% kerogen with recovery reaching to more than 70%.

Coal – Mycobacterium phlei Interaction and its Effect on Coal Cleaning

Abstract The adsorption of micro-organisms can be used in separation of valuable minerals from their gangue minerals. The coal is one of the important sources of energy. Most of the coal deposits are low rank coals that contain sulfur compounds and mineral matters which release harmful and toxic gases while burning of coal. In the current study, the interaction of Mycobacterium phlei (M. phlei) with coal was characterized with several techniques such as zeta potential, adsorption kinetics, adsorption isotherms and Fourier Transform InfraRed (FT-IR). In addition, the M. phlei was tested for sulfur and ash removal from coal. The results of surface characterization indicated that the optimum pH was 2–4 where the M. phlei is physically adsorbed to coal particles due to slight electrostatic interactions as well as the hydrophobic interaction. The M. phlei increases the coal separation selectivity from its associated impurities and reduces the total sulfur and ash to 0.9%and 2.1%, respectively.

Effect of Celestite-Calcite Mineralogy on Their Separation by Attrition Scrubbing

Celestite ore is one of the principle economic resources of strantium element. Naturally, it contains some impurities, with the main one being the calcite mineral. In this article, the separation of celestite from calcite was conducted using attrition scrubbing based on the difference in the hardness between the two minerals. Due to the friability of calcite, it was expected to be collected in fine fraction, however, this was not the case. The observed results showed the presence of calcite in both coarse and fine fractions. A high percentage of calcite was found in the coarse fraction and decreased as the size did as well. Yet, at certain sizes its behavior was changed in that the decrease in size increased the calcite percentage. This behavior was clarified using detailed characterization of the studied sample using size analysis, x-ray diffraction, chemical analysis, and microspcopisc investigation. In addition, a detailed microscopic analysis for the products of the attrition scrubbing was conducted to explain the observed behavior.

Valuation of chloride salts and their mixtures in coal flotation without collector

ABSTRACT Scarce of good quality water for processing especially in the surrounding area of the mining sites dictates searching for new water resources. One of the available solutions is saline water as a flotation medium particularly in the regions close to the sea. Using the saline water, the most likely, enhances the flotation of naturally hydrophobic coal particles. Therefore, in this study, MgCl2, NaCl, and CaCl2 were tested for coal flotation and for reducing its ash content. The coal sample was characterized by size analysis as well as proximate and ultimate analyses to determine the ash content, volatile matter, moisture, and fixed carbon. Flotation experiments were conducted using salts either separately or in a mixture. The statistical design was mainly used to study the main effect of each salt as well as the interactive effects of binary and tertiary mixtures. The results showed that the MgCl2, as a single salt, is the best among the used salts in decreasing the ash percentage. On the other hand, the binary and tertiary mixtures negatively affect the ash removal especially when the CaCl2 is present in the mixture. Therefore, the usage of saline water in flotation depends on its composition in terms of salts concentration, especially the presence of Ca-containing salts.

Effect of mineralogical composition and kerogen content on oil shale natural floatability

ABSTRACT Mineralogical composition is one of the important factors that affect the performance of separation processes. In the current study, two oil shale samples, from El-Nakhil and El-Bieda localities, differ in their mineralogical composition, were subjected to flotation tests. Chemical analysis, differential thermal analysis (DTA), thermo-gravimetric analysis (TGA), and microscopic examination are among the used characterization techniques. In addition, their responses for upgrading by flotation were conducted as a function of pH, solid-liquid ratio, stirring speed and different particle sizes. The characterization results indicated that the kerogen content in El-Nakhil sample was 30% while in El-Beida sample was 10%. On the other hand, the flotation results indicated that El-Bieda responses better than that of El-Nakhil in terms of the difference in kerogen % between the original sample and the concentrated ones. The difference in flotation results of two samples can be explained by the difference in kerogen morphology as well as its interaction with surrounding matrix. In El-Bieda the kerogen has a laminated structure but in El-Nakhil it appears as laminated liptinitic component, in addition to the higher carbonate content in El-Nakhil sample in comparison to higher clay content in El-Bieda sample.

Calcite–oleate–oxalate interaction in calcite flotation system

ABSTRACT Calcite is considered a semi-soluble mineral in flotation. Its solubility in acids plays a major role in its floatability. In this study, micro-flotation experiments are conducted to investigate the interaction of calcite particles with potassium oleate (KOl). Potassium oxalate is used as a depressant in the presence of HC1 or H2SO4 as pH modifiers. Flotation experiments indicated that calcite behaves differently in the presence of HCl and H2SO4. The calcite floatability is higher in the case of HCl. The different behavior is more obvious in the presence of oxalate. The depressing effect of oxalate is more pronounced in the case of using H2SO4 as a pH modifier. In addition, the sensitivity of calcite flotation to pH goes back to the amount of free Ca-ions in the solution. Ionic equilibrium of the dissolved ionic species is proved to play a crucial role in either enhancing or reducing the oleate adsorption, which in turn affects the calcite floatability.