Separation and Identification of Minerals Composing the Silica Sands (Southwestern Tunisia)
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Separation and Identification of Minerals Composing the Silica Sands (Southwestern Tunisia) Kais Elghniji 1
&
Chaima Ouled Amor 1 & Constantin Virlan 2 & Aurel Pui 2 & Elimame Elaloui 1
Received: 28 November 2018 / Accepted: 16 July 2020 # Society for Mining, Metallurgy & Exploration Inc. 2020
Abstract Separation and identification of minerals composing the Tunisian silica sands have been conducted by acid etching and hot filtration/sedimentation (HFS) without affecting the quartz component. It was found that the hot acid etching process is an effective method to separate quartz and clay minerals in the silica sand. The SEM micrographs of the silica sand show rough surface and some cracks with irregular shapes. The surface becomes clean and smooth after acid etching process. After chemical dissolution, the clay minerals were recovered by hot filtration following by sedimentation at low temperature. FT-IR, EDS maps, and secondary electron (SE) analyses of separated clay minerals reveal the presence of Fe2O3, montmorillonite, and kaolinite minerals. The LIBS analysis of clay minerals shows the presence of Al, Fe, Ca, Al, and Mg. The sequential etching process can be introduced in the purification methods as an effective way to separate quartz from clay minerals. Keywords Sand . Quartz . Clay minerals . Separation . Etching
1 Introduction Silica sand is one of the cost-effective raw materials that have been used for extracting quartz and non-crystalline silica with high reactivity. Silica sand consists of small grains or particles of mineral and rock fragments [1]. Although these grains may be of any mineral composition, the dominant component of silica sand is the mineral quartz, which is composed of silica (silicon dioxide). Although quartz is commonly found in nature, either in a relatively pure state as in naturally occurring sand or in the form of complex ores such as pegmatites, granites, and many others, it is almost always associated with substantial impurities consisting chemically of Al2O3, K2O, Na2O, Li2 O, Fe2O3, and FeO. These impurities are usually present as distinct (i.e., non-quartz) minerals such as feldspar (K, Na, aluminosilicates), micas, kaolinite, and ironcontaining aluminosilicates [2–5]. These impurities are loosely associated minerals (not chemically bonded to the quartz)
* Kais Elghniji [email protected] 1
Materials, Environment and Energy Laboratory (UR14ES26), Sciences Faculty of Gafsa 2112, University of Gafsa, Gafsa, Tunisia
2
Faculty of Chemistry, “AlexandruIoanCuza” University of Iasi, Carol I Bd., no. 11, 700506 Iasi, Romania
or as mineral fragments which are chemically and physically bonded to the quartz crystal. In order to remove impurities, various processing methods were proposed, including magnetic separation, froth flotation, selective flocculation, acidic leaching, and bioleaching [6]. However, the above techniques could improve the removal of physically associated impurities but are not effective in removing chemically bonded impurities, occluded impurities, or pa
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