Abstract: The metallurgical grade silicon (MG-Si) is obtained from the reduction of silica (SiO2) in an induction furnace or an electric arc furnace. Impurities inherent in reduction process also depend on the quality of the raw material used. Among the applications of the silicon, it is used as a substrate for the photovoltaic conversion of solar energy and this conversion is wider as the purity of the substrate is important. Research is being done where the purpose is looking for new methods of manufacturing and purification of silicon, as well as new materials that can be used as substrates for the photovoltaic conversion of light energy. In this research, the technique of production of silicon in an induction furnace, using a high vacuum for fusion. Diatomaceous Silica (SiO2) used is 99 mass% initial purities, the carbon used is 6N of purity and the particle size of 63μm as starting materials. The final achieved purity of the material was above 50% by mass. These results demonstrate that this method is a technically reliable, and allows obtaining a better return on the amount 50% of silicon.
Abstract: In present study, a large deposit of oolitic iron ore of
Late Carboniferous-Permotriassic-Lower Jurassic age was discovered
in Wadi Halfa and Argein areas, North Sudan. It seems that the iron
ore mineralization exists in the west and east bank of the River Nile
of the study area that are found on the Egyptian-Sudanese border.
The Carboniferous-Lower Jurassic age strata were covered by 67
sections and each section has been examined and carefully described.
The iron-ore in Wadi Halfa occurs as oolitic ironstone and contained
two horizons: (A) horizon and (B) horizon. Only horizon (A) was
observed in southern Argein area. The texture of the ore is variable
depending on the volume of the component. In thin sections, the
average of the ooids was ranged between 90%-80%. The matrix
varies between 10%-20% by volume and detritus quartz in other
component my reach up to 30% by volume in sandy massive ore.
Ooids size ranges from 0.2mm-1.00 mm on average in very coarse
ooids may attend up to 1 mm in size. The matrix around the ooids is
dominated by iron hydroxide, carbonate, fine, and amorphous silica.
The probable ore reserve estimate of 1.234 billion at a head grade of
41.29% Fe for the Wadi Halfa Oolitic Ironstone Formation. The iron
ore shows higher content of phosphorus ranges from 6.15% to 0.16%,
with mean 1.45%. The new technology Hatch–Ironstone Chloride
Segregation (HICS) can be used to produce commercial-quality of
iron and reduce phosphorus and silica to acceptable levels for steel
industry. The presence of infrastructures in addition to the presence
of massive quantities of iron ore would make exploitation
economically.
Abstract: This article presents summary on preparation and
characterization of zinc, copper, cadmium and cobalt chromite
nanocrystals, embedded in an amorphous silica matrix. The
ZnCr2O4/SiO2, CuCr2O4/SiO2, CdCr2O4/SiO2 and CoCr2O4/SiO2
nanocomposites were prepared by a conventional sol-gel method
under acid catalysis. Final heat treatment of the samples was carried
out at temperatures in the range of 900−1200 ◦C to adjust the
phase composition and the crystallite size, respectively. The resulting
samples were characterized by Powder X-ray diffraction (PXRD),
High Resolution Transmission Electron Microscopy (HRTEM),
Raman/FTIR spectroscopy and magnetic measurements. Formation
of the spinel phase was confirmed in all samples. The average size of
the nanocrystals was determined from the PXRD data and by direct
particle size observation on HRTEM; both results were correlated.
The mean particle size (reviewed by HRTEM) was in the range from
∼4 to 46 nm. The results showed that the sol-gel method can be
effectively used for preparation of the spinel chromite nanoparticles
embedded in the silica matrix and the particle size is driven by the
type of the cation A2+ in the spinel structure and the temperature
of the final heat treatment. Magnetic properties of the nanocrystals
were found to be just moderately modified in comparison to the bulk
phases.