International Journal of Mineral Processing and Extractive Metallurgy 2016; 1(4): 33-40 http://www.sciencepublishinggroup.com/j/ijmpem doi: 10.11648/j.ijmpem.20160104.13 Enhancing the Technical Qualifications of Egyptian White Sand Using Acid Leaching; Response Surface Analysis and Optimization Mohamed Shaban 1 , Mostafa Ragab AbuKhadra 1, 2, * 1 Nanophotonics and Applications Lab, Physics Department, Faculty of Science, Beni-Suef University, Beni-Suef, Egypt 2 Geology Department, Faculty of Science, Beni-Suef University, Beni Suef City, Egypt Email address: mssfadel@yahoo.com (M. Shaban), Abukhadra89@Science.bsu.edu.eg (M. R. Abukhadra) * Corresponding author To cite this article: Mohamed Shaban, Mostafa Ragab AbuKhadra. Enhancing the Technical Qualifications of Egyptian White Sand Using Acid Leaching; Response Surface Analysis and Optimization. International Journal of Mineral Processing and Extractive Metallurgy. Vol. 1, No. 4, 2016, pp. 33-40. doi: 10.11648/j.ijmpem.20160104.13 Received: August 24, 2016; Accepted: August 29, 2016; Published: September 26, 2016 Abstract: White silica sand samples were collected from Zafarana area along the Red sea coast, Egypt. The samples were mixed and quartered to obtain representative sample for characterization. The silica content in the sample is 99.441% and the iron content is 0.112%. Such geochemical qualifications don't match the technical specification of ceramic, optics, silicon metals and solar cells. RSM in conjunction with CCRD was used to study the removal of iron from silica sand using oxalic acid in terms of three operating parameters (Contact time, Acid concentration, Temperature). The model F values indicated the high significance of the design, also the good agreement between the Actual and the predicted results (R 2 > 0.9) indicated suitability of second order quadratic polynomial model to represent the removal process. The best removal process (82%) was achieved at 8gm per ton oxalic acid concentration, 95°C temperature and 120 min leaching time. The final product exhibit high silica content (99.683% SiO 2 ) and lower iron content of (0.017%) which match the requirements of ceramic, silicon carbide, silicon metal and the production of silicon for solar cells. Keywords: White Sand, Oxalic Acid, Response Surface Methodology, Optimization 1. Introduction The world demand of high quality silica sources increase gradually with time for their applications in traditional and high-tech applications [1]. High quality silica resources of silica sand, hydrothermal quartz and pegmatitic quartz become backbone raw material in several advanced applications such as semiconductors, high temperature lamp tubing, telecommunications and optics, microelectronics, and solar silicon applications [2], [3], [4]. Natural silica resources in general contain impurities of other minerals and oxides. Such impurities have a strong influence on the chemical quality and in turn the technical qualification of the silica raw materials [5]. Among the common impurities in silica sand are iron oxide impurities which cause the highest damage by both their color and properties [6]. Iron impurities are prohibitive to some advanced applications such as optical fibers, silicon for solar cells, semiconductors, microelectronics and refractories [7]. The main ferruginous minerals which present as impurities are iron oxides, siderite, pyrite, rutile, tourmaline and mica [8, 9]. Therefore such deposits require several beneficiation and upgrading techniques to match the technical specifications of high advanced industrial applications. Physical and chemical beneficiation methods such as gravity and magnetic separation, attrition, flotation and acid or alkaline leaching are used to remove iron impurities from quartz sands [10], [11], [12]. Chemical processing to remove the iron oxide contaminants appear to be highly efficient as compared to physical beneficiation [13]. Leaching of iron bearing impurities can be performed using, H 2 SO 4 , HCl, HF, phosphoric acid and oxalic acid. Liu et al., (1996) [14] used a mixture of 10% HF acid and 90% H 2 SO 4 , HCl and HNO 3 for 3–12 h; they obtained 96.3% of