Algerian Silica Behavior Study at High Temperature for Carbothermic Process
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ORIGINAL PAPER
Algerian Silica Behavior Study at High Temperature for Carbothermic Process Aissa Kefaifi 1,2 & Tahar Sahraoui 2 & Ema Bobocioiu 3 & Abdelkrim Kheloufi 1 Received: 13 October 2019 / Accepted: 9 January 2020 # Springer Nature B.V. 2020
Abstract Silica is used as raw material for metallurgical grade silicon production intended for photovoltaic field. Our work consists to study the silica behavior (sandstones, quartz) from two Algerian deposits tested at high temperature in a muffle furnace. These tests show the capacity of the silica to produce very fine particles, which have an adverse effect during carbothermic process. The quartz veins from Tirek deposit (Hoggar region) and sandstone from El-Taref deposit were used as raw material (97–98% SiO2). Optical microscopy shows the presence of deformations and recrystallizations in quartz. These defects directly influence the behavior of the silica at high-temperature. The qualitative characterization at high temperature (brust tests) allows us to determine the silica thermal and mechanical properties. Based on these tests, we deduce the friability index (FI), strength thermal index (STI) and the heat index (HI) of every type of examined silica. The quartz sample from Tirek deposit presents the most required values, which are respectively HI = 52–56%, FI = 8.75–11.25%, TSI = 23.31–23.93. The obtained results show us the feasibility of using this silica in the submerged arc furnace, to obtain metallurgical grade silicon. Keywords Silica . Burst test . Thermo-mechanical properties . Microstructure . Silicon
1 Introduction The photovoltaic (PV) industry is a player in the renewable energy segment, and the electricity generation from PV solar cells is deemed to be one of the key technologies of the twenty-first century [1]. In this context, pure silica (quartz, sandstone and sand) plays a main role in the upstream segment of the photovoltaic chain value. In terms of consumption, PV market growth has become competitive with the semiconductor market. Nowadays, it depends, mainly, on the supply of the raw materials, where the need to predispose it for solar cells production with reducing their cost [2]. For this purpose, a particular interest has been given to the silica as raw material for the electrometallurgy,
* Aissa Kefaifi [email protected] 1
Centre de Recherche en Technologie des semi-Conducteurs pour l’Energétique CRTSE, Alger, Algeria
2
Laboratoire des aéronefs, Université SAAD Dahleb USD1, Blida, Algeria
3
Ecole Normale Supérieure de Lyon, Lyon, France
due to its abundance and the very large variety of siliconbased mineral structures and also for its wide variety of uses. The complete cycle of the manufacturing metallurgical grade silicon (MG-Si) consists in its characterization, silica treatment and carbothermic process in the submerged arc furnace [3–8]. However, in Algeria, the use of high purity silica as raw material in traditional industries, (building and glasses), raise a problem of valorization of these deposits, which should be used
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