فهرست مطالب اسماعیل خفاجه

Acid mine drainage (AMD) is the most significant environmental pollution problem associated with the mining activities. AMD is caused by the oxidation of sulfide minerals in the mine tailings that occurs when these materials are exposed to atmospheric oxygen and water. Sangan processing plant annually produces 2.6 million tons of concentrate with iron content more than 66%. During this beneficiation approximately 1.3 Mt/a of tailing material containing 4% sulfur is produced and discarded to the tailings dam. The presence of sulfide minerals associated with water and oxygen in the tailing dam can generates AMD. The aim of this research is to evaluate the acid generation potential of the tailing material.  
In order to predict the acid generation potential of the tailing material, samples were taken from the final tailing (i.e., the mixture of various tailing streams of the plant) and also separately from various tailing streams of the plant. Afterwards, the acid generation potential of the samples was determined by modified acid base accounting static tests.
The results indicated that the ratio of neutralization potential to acid potential for the final tailing is 2.04.
This research showed that the tailing of Sangan iron ore processing plant is in the zone of uncertainty. Hence, additional kinetic testing must be performed for obtaining certainty about acid generation potential.

Beneficiation of a low-grade iron ore was investigated by combination of the low-intensity magnetic separation and reverse flotation methods. The main constituents of the representative sample were 36.86% Fe, 8.1% FeO, 14.2% CaO, 13.6% SiO2, and 0.12% S based on the X-ray fluorescence, titration, and Leco analysis methods. The mineralogical studies by the X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, electron probe micro-analyzer, and Fe/FeO titration methods showed that the ore minerals present in the representative sample were magnetite, hematite, and goethite, and the main gangue minerals were calcite and quartz. The effects of the operating parameters including the feed size, solid content, and drum rotation speed were investigated on the performance of the wet low-intensity magnetic separation (WLIMS). The optimum operating conditions of WLIMS were determined to be feed size = 135 μm, solid content = 40%, and drum rotation speed = 50 rpm. Under these conditions, a concentrate of 62.69% Fe grade and 55.99% recovery was produced. The tailing of WLIMS with an iron grade of 28.75% was upgraded by reverse flotation with fatty acids as the collector. The effects of five parameters on two levels were investigated using the 25-1 fractional factorial design in 16 experiments. The optimum flotation conditions were determined to be pH = 12; dosage of collector, 1 kg/t; dosage of Ca2+ as activator, 4 kg/t; and dosage of starch as depressant, 1 kg/t. Under these conditions, a concentrate of 53.4% Fe grade and 79.91% recovery was produced.

The evaluation of a magnetic separation circuit can be used to determine its working efficiency, and formulate new strategies for its future performance improvement. The aim of this research is to do performance evaluation for units number 2 and 6 of the magnetic separation circuits in Sangan iron ore complex. In both units, the run of mine ore is crushed and divided into coarse (10-30 mm) and fine (0-10 mm) sized fractions, and then each fraction proceeds to a dry low intensity magnetic separation circuit. Totally, 270 samples were taken from four magnetic separation circuits and the samples were analyzed for total iron, iron oxide (FeO) and sulfur content. The results indicated that the average Fe grade of the final product of all magnetic separation circuits was more than 57%. The average iron recoveries in the fine and coarse magnetic separation circuits for unit number 6 were 92.29 and 78.93%, and for unit number 2 were 69.25 and 55.36%, respectively. The iron recovery of coarse magnetic separation circuits is lower than that of fine circuits which is due to a lower magnetic field intensity of separators in these circuits. This is for maintaining the suitable iron grade of concentrates desspite the lower degree of freedom in the feed. The iron recovery in both magnetic circuits of units number 2 is lower than that of units number 6 which is due to inappropriate feed and operating conditions of the magnetic separators in this unit.