الفهرس 
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Abstract
The exploitation and investment of the Egyptian natural mineral resources is one of the objectives of economic growth currently targeted, in addition to maximizing the benefit from them by raising their grade using various mining operations. Therefore, Nuclear Materials Authority is working hard to evaluate, exploit and upgrade economic heavy minerals accumulated on the southern coast of the Red Sea that have not yet been exploited. Therefore, this research aims to characterize, evaluate, concentrate and recover economic heavy minerals contained in the Quaternary stream sediments of both Daiit and Sermatai areas, southern coast of the Red Sea, Egypt.
Daiit area is bounded by latitudes of 22° 18’ and 22° 41’ N, and longitudes of 35° 55’ and 36° 18’ E, covered about 450 km2 and includes three main parts; Wadi and Delta Daiit, as well as Daiit lens. Sermatai area is located in the extremely southern part of the Eastern Desert of Egypt nears the Sudan Borders. It is bounded by latitudes 22° 00` and 22° 25` N and longitudes 36° 20` and 36° 45` E and includes two main parts; wadi and delta that cover about 50 and 35 km2 respectively.
Radiological hazard indices assessment is very important, so γ-ray spectrometric data was used to evaluate the radioactive environmental assessment in both Daiit and Sermatai areas. In Daiit area, the mean concentrations of 238U, 232Th, and 40K are 29.25, 17.92 and 347.63 Bq kg-1; respectively, which is lower than the worldwide average value. At the same time, in Sermatai area, the mean of activity concentration 238U (37.46 Bq kg-1) and 40K (798.15 Bq kg-1) is exceeded the worldwide value, and 232Th was not exceeded (22.88 Bq kg-1). The obtained radiological hazards parameters depicted that public exposure to emitted gamma radiation cannot induce various dangerous health effects.
The mineralogical characterization study via scanning electron microscope (SEM) analyses revealed that these sediments contain considerable amounts of placer ilmenite, magnetite, zircon, sphene, apatite, garnet, pyrolusite and rutile. Also present, in minor or trace amounts, are uranothorite, monazite, xenotime, fergusonite, celestine, khatyrkite and gold. This is in addition to the presence of abundant amounts of heavy green silicate minerals as pyroxene, amphibole, and epidote.
The physical concentration and separation processes were performed via a Wilfley shaking table (No. 13) in conjunction with a low-intensity and high-intensity magnetic separator in order to obtain the high-grade concentrates from the valuable heavy minerals in the studied samples. Initially, two stage wet gravity concentration processes, rougher and scavenger, were carried out via a shaking table to get rid of the associated gangue minerals and produce a clean concentrate of VHMs, which was used as feed material for the magnetic separation process. Magnetic separation was performed in order to separate ferromagnetic minerals from paramagnetic minerals as well as diamagnetic minerals to obtain clean concentration of these fractions.
After applying the optimum separation conditions, assay and material balance of the concentration steps proved that the THM content of Daiit lens increased to 89.70% with a recovery of 91.68% in a weight of 61.08% out of the original sample. While the percentage of THM content in Wadi and Delta Daiit samples increased to 48.68 and 47.67% respectively, with recovery equivalent to 71.67 and 82.06% respectively in a weight of 16.51, 18.7% respectively out of the original sample. The total heavy mineral assay increased from 8.32% to 46.04% for Wadi Sermatai, while for Delta Sermatai increased from 8.37% to 50.13% into 8.89% and 9.59%, respectively, by mass yield. The THM recovery values reach 66.84% for Wadi Sermatai and 67.23% for Delta Sermatai.
The results of X-ray fluorescence (XRF) analyses for gravity concentration products revealed that the content of SiO2%, Al2O3%, K2O%, and SO3% is significantly degraded in the concentrate relative to the feed samples while on the contrary, the contents of Ti, Fe, Mn, Ni, Zn, Pb, Zr, Cr, Y and Nb were upgraded several times in the concentrate as compared to the feed sample. This related to a doubling of the ratios of their minerals such as ilmenite, magnetite, rutile, sphene, zircon and garnet in the concentrate as a result of the high value of its specific gravity during wet gravity separation processes.
The low-intensity and then high-intensity magnetic separation processes succeeded in separating the valuable heavy minerals into four fractions, where X-ray diffraction (XRD) analyzes were used to identify and confirm the mineral content of the different magnetic fractions, which are as follows: the first fraction is the magnetite concentrate, the second fraction is the ilmenite concentrate and the third fraction is mainly consist of green heavy silicates minerals (pyroxene, amphibole, garnet and epidote) with trace amounts of monazite, xenotime and fergusonite. Finally, the fourth fraction is consists of non-magnetic mineral concentrate as zircon, apatite, sphene, rutile, gold and khatyrkite.
Finally, suggested flow sheets have been created to be used as a guide for exploiting the economic heavy minerals presented in areas under investigation and similar ones