Ali Q. Selim

Separation of Pyritic Sulfur from Egyptian Coal Using Falcon Concentrator

Pyritic sulfur separation of El-Maghara coal ore was studied using Falcon concentrator model SB40-VFD as an enhanced centigugal gravity separator. The coal sample was ground to below 100 µm to reach liberation between pyrite and coal. Optimization of the separation process has been studied using central composite rotatable design (CCRD) and response surface method (RSM). The studied working factors were the back-water pressure (psi) and rotation frequency (Hz) and their interactions, where the feeding rate and pulp density were kept constant through all experiments. A model describing the relation between pyritic sulfur separation efficiency percentage and the previously mentioned operating variables and their interactions, have been designed. Results showed that maximum separation efficiency reached 70.61%, with decreasing total sulfur, and pyritic sulfur contents reaching 1.72% and 0.48% from original assays reaching 2.90% and 1.60%, respectively. That maximum separation efficiency was attained at 78.38 Hz rotation frequency (rotor speed 2282 rpm, 300 g) and 3.90 psi back-water pressure. The amenability of pyritic sulfur separation from the Egyptian coal using Falcon concentrator are determined. Technical difficulties within the separation process are highlighted.

Gravity Separation of Silica Sands for Value Addition

A representative white sand sample was investigated for glass industry. Complete characterization of the sample was conducted. Chemical analysis of the sample showed that iron and alumina oxides reached 0.046% and 0.044%, respectively. Dry sieving was carried out to reject +0.6 mm and −0.10 mm fractions from the sample. The classified −0.6 + 0.1 mm product was directed to attrition scrubbing. The effect of pulp density, attrition impeller speed, attrition time and mode were studied. The attrition sand product was further subjected to gravity separation using “Wilfley” shaking table. Different working conditions of table separation i.e., sand feeding rate, stroke length, deck inclination, and dressing water flow rate were optimized. Results showed that the classified −0.6 + 0.106 mm sand product contained 0.039% Fe2O3 and 0.041% Al2O3 matched the specifications for the fourth-quality sand for sheet and plate glass industry. However, iron and alumina oxides contents were further decreased to 0.025% and 0.0164% after the attrition process. The attrition product accepted as second quality for flint containers and table ware applications. The final sand product after shaking table contained 0.0180% Fe2O3 and 0.090% Al2O3, was applicable for the first quality for optical applications.

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.

Enhancing adsorption capacity of Egyptian diatomaceous earth by thermo-chemical purification: Methylene blue uptake

In the current study, calcination and thermo-chemical methods were applied in treatment of the processed diatomite fraction (<45 μm), which containing nearly 82.6 wt.% of the raw Egyptian diatomaceous earth. The untreated and modified diatomite fractions were characterized by optical microscopy (OM), X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). Thermo-chemical purification produced the highest concentration of diatom frustules (>92% SiO2) without blocking impurities and created SiOSi active sites. These fractions were tested for Methylene blue (MB) adsorption at different pH solutions (2.0-10.0). The purified diatomite via thermo-chemical treatment (PD) gave the greatest adsorption capacity for MB compared to the untreated (UD) and calcinated (CUD) diatomite fractions. Effects of experimental parameters such as MB concentration (60-200 mg L-1), contact time (5-480 min), adsorbent mass (50-250 mg) and temperature (30-55 °C) on MB uptake were investigated. Linear and non-linear forms of Langmuir, Freundlich and Dubinin-Radushkevich (D-R) models indicated that Langmuir model with a maximum adsorption capacity (qmax=105.03mgg-1) fitted well the adsorption data. The chemical nature of MB uptake was revealed by the values of mean free energy E=8.655kJ/moland correlation coefficient of the pseudo-second-order model (R2=0.9997). The calculated thermodynamic parameters (ΔH0, ΔG0 and ΔS0) indicated that the removal of MB is spontaneous and endothermic.

On Improving the Separation Efficiency of a Wet High Gradient Magnetic Separator for the Removal of Pyrite from Egyptian Coal

ABSTRACT Wet high gradient magnetic separation (WHGMS) of an Egyptian coal sample was carried out to minimize its pyritic-sulfur content reaching 1.60% (2.9% total sulfur). Optimization of the process using the Boxmag Rapid separator included feeding rate, pulp density, applied magnetic field, and the canister loading %. This was conducted through the CCRD and RSM, using Design Expert 6.0 software. Results showed that, at the optimum separation conditions, i.e., 10 l/h feeding rate, 5% pulp density, 2200 Gauss, and 0.6% canister loading, a coal concentrate assaying 0.57% pyritic sulfur was obtained with a recovery 58% and separation efficiency 79.34%.