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In the present work, we report the successful extraction of high purity silica from the Algerian siliceous sand. We improved the chemical extraction process of silica using acid pretreatment before purification and studied the effect of sodium hydroxide (NaOH) solution molarity on the purity of as-obtained silica. X-ray diffraction, Energy-dispersive X-ray spectroscopy, and Scanning Electron Microscopy analyses were carried out on the samples before, during, and after chemical purification. The results show the improvement of the purity of the resulting powder with the change of the alkaline concentration. The results showed a decrease in the impurity concentration of the sand after acid leaching. The extracted silica has a purity of more than 99% and has an amorphous and mesoporous nature, confirmed by the mentioned analysis techniques, together with Fourier Transform Infrared Spectroscopy, thermogravimetric analysis, and the Physical Adsorption Analysis, which makes our chemical extraction method very promising, and the resulted silica is a good source to elaborate solar grade silicon used in photovoltaic applications.

Carbothermal reduction of light metals and semiconductor such as Al, Ti and Si under argon gas not only can reduce the reaction temperatures but can also minimize the formation of carbides and oxy-carbides intermediate compounds. The calculation of the gas phase diagram of Al-O-C, Ti-O-C and Si-O-C system suggests the possibility of the enhancement of the Al, Ti and Si product yield by the increase of the ratio of the partial pressure Al2O/CO, TiO/CO and SiO/CO. Thermodynamic considerations associated with this process are discussed along with the experimental results obtained over a wide range of parameters under argon gas using an induction heating furnace (IH) in a high temperature reactor. Powder mixtures were prepared of stoichiometric mixtures using powders either of alumina or silica or Titania with carbon. Experimental results obtained in induction furnace setup such as the pure element’s yields as a function of the CO partial pressure, PCO, temperatures range in the reaction zone of 1400–1800 °C and different deposition temperatures are presented. In this research work, we calculated the thermodynamic phase diagram with the partial pressure ratio of Al2O/CO, TiO/CO and SiO/CO. This diagrams suggests the possibility of enhancement of Al, Ti and Si yield by the increase of P(Al2O, TiO and SiO)/P(CO). At the optimal condition, the Al and Si yield was improved comparably to Ti which still under research.