Papers by Ahmed Seifelnassr
Hydrometallurgy, Jun 1, 2024
This study reports the effect of sodium fluoride on the dissolution kinetics of pure metallic tit... more This study reports the effect of sodium fluoride on the dissolution kinetics of pure metallic titanium in a citric
acid solution. The effects of sodium fluoride concentration, citric acid concentration, temperature, stirring speed,
and disc surface area were examined. The dissolution rate of titanium increases strongly with increasing citric
acid and sodium fluoride concentrations. Fluoride ions react with hydrogen ions to form hydrofluoric acid, which
removes the passive layer of titanium dioxide. An increase in the concentration of NaF and acid causes the
formation of a brown layer on the surface of titanium. X-ray diffraction and SEM-EDX analyses showed that the
layer composition is mostly of titanium fluoride (TiF3) and titanium fluoride oxide (TiOF2). A mixed kinetic
model with an activation energy of 26.4 kJ/mol can be used to explain the reaction kinetics.
RESOURCES PROCESSING, 1997
This paper deals with the application of froth flotation techniques to the beneficiation of fine ... more This paper deals with the application of froth flotation techniques to the beneficiation of fine waste coal of El-Maghara colliery. Different reagent systems of oily collector-frother were investigated. The main object of this study is to investigate the feasibility of recovering the combustible matter from waste fine coal. The attention is also paid to highlight the oily collector-frother interaction. INTRODUCTION Gravity coal beneficiation techniques are fairly unproductive fine coal processes. Hence, flotation, selective flocculation and selective agglomeration are widely used in fine coal processing. A satisfactory number of studies on fine coal flotation have been reported [1-4]. However, relatively few studies have been dedicated to the action and mechanism of flotation reagents in coal flotation [5, 6]. With recent increased public awareness of environmental problems and with increasing legislation, it is becoming even more important to control mine disposal. Approximately 10 mill. tones of dirt and waste fine coals will be disposed from EL Maghara mine as a result of coal preparation and mining operations [7]. Hence, significant amounts of coal would be lost each year, as fines and ultrafines. Therefore, to increase the commercial value of such coal, methods must be found to effectively separate coal fines from associated shale and other containing minerals. The reclamation of such fine-size waste would eliminate many of the environmental problems and would result in conservation and development of additional natural resources in Egypt. Froth flotation is a unit operation that has found its greatest application in the mineral industry for separation finely divided solid particulate dispersed in aqueous sus
JES. Journal of Engineering Sciences, 2011
This study is concerned with the processing of low grade chromite ores, Ingassena Hills, Sudan, b... more This study is concerned with the processing of low grade chromite ores, Ingassena Hills, Sudan, by froth flotation techniques. For this purpose, representative samples were taken from four different mines. Mineralogical examinations indicated that, the major minerals are chromite and serpentine. Olivine, iron oxides and talc have been identified as minor minerals. Adequate degree of liberation of chromite was obtained by grinding the ore to minus 180µm. Froth flotation was used to upgrade this chromite ore. Oleic acid was used as collector. Several operating parameters influencing the floatability of the Sudanese chromite ores were investigated. These include the collector and depressant dosages, pulp pH, and conditioning time. From an ore feed grading 20.27% Cr 2 O 3 , a chromite concentrate of 28.71% Cr 2 O 3 with recovery of 94.54 % could be obtained by flotation at collector dosage of 0.300 kg /t , pH 9 , 2 min conditioning time, and 20% pulp density.
Mining, metallurgy & exploration, Aug 30, 2022
Iron is a key detrimental impurity in silica sands that determines their contribution to high-tec... more Iron is a key detrimental impurity in silica sands that determines their contribution to high-technology industries. Herein, a simple ecologically sound approach is investigated for iron removal from a silica sand sample obtained from the El-Zaafarana area-Egypt. The sample was subjected to a detailed microscopic mineralogical study supported by XRD and XRF characterization. The sample was beneficiated using distilled water attrition scrubbing and screening over a 25 μm sieve followed by leaching using a mixture of equal amounts of phosphoric and oxalic acids. Leaching experiments were designed and analyzed using the Box-Behnken design (BBD) methodology. A model was developed and evaluated using the analysis of variance technique to map the relationship between the residual iron oxide in the produced concentrate and selected variables such as leaching temperature, oxalic acid, and phosphoric acid concentrations. XRD and mineralogical analysis reveal that quartz is the most dominant constituent of the studied sand and other minerals such as kaolinite, iron oxide, rutile, and zircon exist in trace amounts. The head sample shows a silica and iron oxide content of 95.69% and 2379 ppm, respectively. Attrition and separation over a 25 μm sieve increase the silica content to 97.05% and decreases the residual iron oxide to 455 ppm. The final product after leaching under optimized conditions shows 99.82% silica and 55 ppm iron oxide.
Mining, Metallurgy & Exploration, 2018
The main forces acting on minerals in conventional size reduction units are compression, impact, ... more The main forces acting on minerals in conventional size reduction units are compression, impact, attrition, and/or abrasion. Usually a combination of these forces shares the breakage action of the minerals with one or more of these forces dominating the breaking action, depending on the machine used. The present work concentrates on the behavior of quartz when stressed with compression force in a confined piston die. Several size fractions within the size range minus 10 mm to plus 0.85 mm were compressed in the piston die. The measured parameters are compression load, bed thickness, displacement as a result of compression, rate of displacement, and the size distribution of the products. It was found that the size distributions are, to some extent, different from those produced by the ball mill or the high-pressure roll mill. This is mainly because of the differences in the type of the acting forces in each case. It was also found that the cumulative weight of the distributions is reasonably normalizable with respect to the median particle size of the product. The specific energy expended is inversely proportional to the median size of the products, and the reduction ratios, x f /x p , are directly proportional to the applied compression force, and hence, to the specific energy expended. A simple model is suggested for predicting the particle size distribution as a function of the expended energy. The calculated values of the size distributions match fairly well with the experimental values, except at the very low energy levels, where most of the energy expended is consumed in the rearrangement and packing of the particles in the confined space with little or no breakage.
Journal of Petroleum and Mining Engineering
Comminution tests are a vital element in the proper design of mineral processing plants. Several ... more Comminution tests are a vital element in the proper design of mineral processing plants. Several grindability tests have been developed over the years for different applications and each test has its strengths and weaknesses. Among test methodologies considered, is the universally accepted high-pressure grinding roller (HPGR) test procedures based on small-scale tests. The present work has been carried out to compare the grinding characteristics of different ore minerals. It was observed that all tested minerals, (quartz, chromite, marble, hematite, magnesite, dolomite) showed a general similar trend while being compressed. Moreover, because those minerals have wide differences in their mineralogical, physical, and mechanical properties they have different comminution behaviour under compression. The consumed energy as well as the reduction ratios are affected by the mineral hardness. The percentage product at a certain cut-size was found to be proportional to the expended energy for each mineral. A convenient grindability index under compression has been suggested as the specific productivity, in ton/kWh. This index is quite sensitive to the material hardness.
Fizykochemiczne Problemy …, 1998
In this work, the amenability of upgrading the reject generated from beneficiating Abu-Tartur pho... more In this work, the amenability of upgrading the reject generated from beneficiating Abu-Tartur phosphate ore by magnetic separation was investigated by two methods: leaching with acetic acid solutions and froth flotation. The reject is characterized by its ferriferous dolomite impurities. To optimize the leaching process, the effects of grain size, acetic acid concentration, acid/solid ratio and the reaction time on loss on ignition percent were investigated. The results of this series of experiments gave unsatisfactory results. Separation of phosphate minerals from the associated impurities has been successfully achieved by flotation. The studied parameters such as particle size distributions, conditioning time, mode of collector addition and depressant type were investigated to reach optimum conditions. The experimental results show that, it is possible to obtain phosphate concentrate assaying 30% P 2 O 5 and 0.75% MgO with P 2 O 5 recovery of about 75% from a feed assaying 23% P 2 O 5 and 3.77% MgO.
Abstract. This study investigates the effectiveness of gravity and magnetic concentration techniq... more Abstract. This study investigates the effectiveness of gravity and magnetic concentration techniques for the beneficiation of a Sudanese iron ore, the newly discovered Wadi Halfa iron ore deposit. It is a low-grade type of ore with high silica content, more than 45% SiO 2 , and an average iron content of about 35% Fe. Based on the fact that there are appreciable differences in specific gravity and magnetic susceptibility between the desired iron minerals and the gangue minerals, it was suggested that gravity separation and/or magnetic separation may be useful to concentrate this type of ore. These two techniques were adopted for the beneficiation of the Wadi Halfa low-grade iron ore. As a result of the fine dissemination of the iron minerals and the most abundant gangue mineral, quartz, the optimum degree of grinding is around 150 micrometers. The rougher tests of both the gravity separation and magnetic separation produced concentrates of about 44% Fe. Each of these two concentrate...
Physicochemical Problems of Mineral Processing, 1996
Abstract: This paper presents a comparative study between the grindabiltiy of quartz by compressi... more Abstract: This paper presents a comparative study between the grindabiltiy of quartz by compression and impact forces as two different modes of size reduction in mineral comminution. The compression tests are carried out in a piston die, and the impact tests are performed using a stamp mill. Two quartz size fractions, (-6.3+4.75mm) and (-2.36+1.7mm) at sample weights of 150 and 100 grams were used for comparison of the behavior of quartz under the two different modes of material disintegration forces. The obtained results showed that the cumulative weight of the product size distributions is reasonably normalizable with respect to the median particle size, X50, for both compression and impact modes. The specific energy expended is inversely proportional to the median size of the products, and the reduction ratios (RR), X50f/X50p, are directly proportional to the applied forces in both grinding modes, and hence, to the specific energy expended. However, under the studied conditions, ...
Fizykochemiczne Problemy Mineralurgii - Physicochemical Problems of Mineral Processing
This study investigates the effectiveness of gravity and magnetic concentration techniques for th... more This study investigates the effectiveness of gravity and magnetic concentration techniques for the beneficiation of a Sudanese iron ore, the newly discovered Wadi Haifa iron ore deposit. It is a low-grade type of ore with high silica content, more than 45% SiO2, and an average iron content of about 35% Fe. Based on the fact that there are appreciable differences in specific gravity and magnetic susceptibility between the desired iron minerals and the gangue minerals, it was suggested that gravity separation and/or magnetic separation may be useful to concentrate this type of ore. These two techniques were adopted for the beneficiation of the Wadi Haifa low-grade iron ore. As a result of the fine dissemination of the iron minerals and the most abundant gangue mineral, quartz, the optimum degree of grinding is around 150 micrometers. The rougher tests of both the gravity separation and magnetic separation produced concentrates of about 44% Fe. Each of these two concentrates was cleane...
Journal of Mining, 2013
Since the identification and characterization of iron and sulfur oxidizing bacteria in the 1940s,... more Since the identification and characterization of iron and sulfur oxidizing bacteria in the 1940s, a rapid progress is being made in minerals engineering based on biological activities. Microorganisms can play a beneficial role in all facets of minerals processing, from mining to waste disposal and management. Some of the applications, such as biologically assisted leaching of copper sulfide ores, uranium ores, and biooxidation of refractory sulfide gold ores, are now established on the scale of commercial processes. A variety of other bioleaching opportunities exist for nickel, cobalt, cadmium, and zinc sulfide leaching. Recently, other uses of microorganisms are potentially possible. These include the bioleaching of nonsulfide ores, bioflotation, and bioflocculation of minerals, and bioremediation of toxic chemicals discharged from mineral engineering operations. These activities acquire considerable opportunities for further research and development in these areas. This paper is a...
International Journal of Mineral Processing, 2013
ABSTRACT The iron ore deposit of the Northern State of Sudan, at Wadi Halfa, is a huge deposit, b... more ABSTRACT The iron ore deposit of the Northern State of Sudan, at Wadi Halfa, is a huge deposit, but is low in grade. It assays 36% Fe and 48% silica. The present study is an attempt to investigate the amenability of this newly discovered ore for upgrading. Based on the appreciable differences in specific gravity and magnetic susceptibility between the desired iron minerals and the gangue minerals, it was suggested that gravity separation and/or magnetic separation may be useful to concentrate this type of low-grade ore. As a result of the fine dissemination of the iron minerals and the most abundant gangue mineral, quartz, the optimum degree of grind is around 150 μm. Using two-stage separation, roughing and cleaning, it was possible to obtain a high grade concentrate assaying about 64% Fe at a recovery of 72%.
This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/authorsrights Keywords: Beneficiation of Wadi Halfa iron ore Concentration of a low-grade iron ore Magnetic separation Gravity concentration Combined gravity/magnetic beneficiation. The iron ore deposit of the Northern State of Sudan, at Wadi Halfa, is a huge deposit, but is low in grade. It assays 36% Fe and 48% silica. The present study is an attempt to investigate the amenability of this newly discovered ore for upgrading. Based on the appreciable differences in specific gravity and magnetic susceptibility between the desired iron minerals and the gangue minerals, it was suggested that gravity separation and/ or magnetic separation may be useful to concentrate this type of low-grade ore. As a result of the fine dissemination of the iron minerals and the most abundant gangue mineral, quartz, the optimum degree of grind is around 150 μm. Using two-stage separation, roughing and cleaning, it was possible to obtain a high grade concentrate assaying about 64% Fe at a recovery of 72%.
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Papers by Ahmed Seifelnassr
acid solution. The effects of sodium fluoride concentration, citric acid concentration, temperature, stirring speed,
and disc surface area were examined. The dissolution rate of titanium increases strongly with increasing citric
acid and sodium fluoride concentrations. Fluoride ions react with hydrogen ions to form hydrofluoric acid, which
removes the passive layer of titanium dioxide. An increase in the concentration of NaF and acid causes the
formation of a brown layer on the surface of titanium. X-ray diffraction and SEM-EDX analyses showed that the
layer composition is mostly of titanium fluoride (TiF3) and titanium fluoride oxide (TiOF2). A mixed kinetic
model with an activation energy of 26.4 kJ/mol can be used to explain the reaction kinetics.
acid solution. The effects of sodium fluoride concentration, citric acid concentration, temperature, stirring speed,
and disc surface area were examined. The dissolution rate of titanium increases strongly with increasing citric
acid and sodium fluoride concentrations. Fluoride ions react with hydrogen ions to form hydrofluoric acid, which
removes the passive layer of titanium dioxide. An increase in the concentration of NaF and acid causes the
formation of a brown layer on the surface of titanium. X-ray diffraction and SEM-EDX analyses showed that the
layer composition is mostly of titanium fluoride (TiF3) and titanium fluoride oxide (TiOF2). A mixed kinetic
model with an activation energy of 26.4 kJ/mol can be used to explain the reaction kinetics.