In Egypt, large quantities of coarse solid wastes are produced annually during the processing of phosphate ores and quarrying operations of marble and granite rocks. These wastes are stored in piles around or near mine sites, which are aesthetically unattractive and often degrading the environment. Various solutions have been sought for this major environmental problem and the best solution found is recycling. However, these wastes , because of their similarity to the conventional aggregates , represent a potentially useful source of material for a variety of applications ( in roadbed and dam construction , as railroad ballast ,as aggregate in concrete and asphalt mixes , …) The main purpose of this research is to investigate the possibility of utilizing the above mentioned three waste materials in road construction (base and sub base) and as a replacement layers for the problematic soil in foundations. Experimental tests were carried out on these wastes to assess their physical, mechanical and chemical properties, according to the Egyptian standards. The modified proctor and California bearing ratio (CBR) are the most important tests of soil compaction to assess the suitability of any waste materials. The CBR value of phosphate waste is 88% , 95% for crushed marble and about 41% for crushed granite. The obtained results proved that these kinds of wastes can be used in base and sub-base layers in road construction and as replacement soil under foundations. The potential uses of these wastes are considered beneficial from the economic and environmental points of view and saving the natural resources of aggregate.
In Egypt, large quantities of coarse solid wastes are generated during the processing of phosphate ores and quarrying operations of marble and granite rocks. These solid wastes are stored in piles around or near mine sites, which cause many environmental problems. Various solutions have been sought for this major environmental problem and the best solution found is recycling. However these wastes, because of their similarity to the natural aggregate, represent a potentially useful source of material for a variety of applications. The main purpose of this research is to investigate the possibility of utilizing over screen reject generated during phosphate ore processing and rock fragments of quarrying marble and granite rocks in concrete production as full replacement of natural gravel in concrete mix. A number of tests were carried out on these wastes to determine their physical, mechanical and chemical properties, according to the ECP 203 of natural aggregate. So, concrete mixes using the above mentioned wastes as coarse aggregate were done, and then tests for fresh and hardened concrete were carried out. The mean value of uniaxial compressive strength of standard concrete cubes after 28 days of curing was found to be in order of 193 Kg/cm 2 for phosphate waste, 262 kg/cm 2 for marble waste, and 272 kg/cm 2 for granite waste, which approach the conventional concrete used in building. The obtained results proved that these kinds of wastes can be used for concrete mix in civil construction. Admixtures may be used to improve the strength of the first one. The positive uses of these wastes are considered beneficial from the economic and environmental points of view.
Grinding processes are very costly because of significant energy requirements to achieve particle reduction. It was estimated that about 5-6% of the power generated all over the world is consumed in size reduction of raw materials necessary for mineral, cement, and ceramics industries. Mineral processing comminution is always the most energy intensive operation. The energy consumption may vary considerably for different ore types and flowsheets with values ranging from 10 kwh/t to 30 kwh/t and corresponding to 30 to 50% of the total energy cost. Factors affecting the process of comminution include the design and operating parameters of the comminuting machine as well as the physical and mechanical properties of the comminuted rock. Consequently, the main objective of this work is to study the effect of the most important physical and mechanical properties of rocks on their grindability. It is applied on marble, ilmenite ore and granite samples using a laboratory scale ball mill. The performance of each experiment is measured by the percentage of-1.25 mm in the product. 2 n factorial method is applied as an experimental design method on each studied rock. Optimum values of the studied operating parameters and their gradation according to their effect on the process are achieved for each studied rock it is concluded that the performance decreases as the compressive strength and hardness of the studied rocks increase and increases as the abrasion value increases. It is also found that optimum values of the studied operating parameters and their gradation depend on the mechanical properties of the studied rocks.
Most deposits which can be mined and processed economically to produce a concentrate with a grade of about 28-38% P2O5 are considered commercial phosphate deposits. Because of the increasing world demand, the grade of a great portion of the mined phosphate deposits is declined and many low-grade phosphate deposits became economically mineable. Methods and techniques used in the processing of ore are depending on its grade, type and quantity of gangues associated with the phosphate mineral. Phosphate deposits in Egypt occur with large quantities in the Nile valley, red sea, and the new valley areas. Therefore, the main objective of this review is to shed some light on the locations, reserves, and the beneficiation trials of the different localities of the Egyptian phosphate ores, with focusing on water conservation in the dressing plants and positive uses of solid wastes. It is recommended to use the bio-flotation, column flotation, and the new types of reagents, as recent trends to upgrade the Egyptian phosphate ores. It is also advised to pay attention towards the recovery of phosphate from its slimes. KeywordsBeneficiation of phosphate ore -Nile Valley Egyptian phosphate ore -Red Sea Egyptian phosphate ore -Abu Tartur Egyptian phosphate ore.
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