title: The application of thermal solar energy to high temperature processes: case study of the synthesis of alumina from boehmite.
abstract: The aim of this paper is to evaluate the feasibility of obtaining alumina from boehmite using a free, clean, and unlimited power source as the solar energy. Boehmite was obtained by hydrothermal treatment of a hazardous waste coming from aluminum slag milling. The waste is considered as a hazardous substance because of it releasing toxic gases (hydrogen, ammonia, methane, and hydrogen sulfide) in the presence of water. The as-obtained boehmite was transformed into alumina, in air atmosphere, using a solar energy concentrator (Fresnel lens). The solar installation provides a power density of 260 W · cm(-2) which allows reaching temperatures upper than 1000 °C at few minutes of exposure. Tests were performed at different periods of time that ranged between 5 and 90 min. The percentage of transformation of boehmite into alumina was followed by the water content of samples after solar radiation exposure. Samples were characterized by X-ray diffraction, infrared spectroscopy, and thermogravimetry. Metastable aluminas started to appear at 5 min and the crystalline and stable phase corundum at 10 min of solar radiation exposure.
authors: Centro Nacional de Investigaciones Metalúrgicas (CENIM-CSIC), Avenida Gregorio del Amo 8, 28040 Madrid, Spain.
authors: Isabel
authors: 0000-0001-7684-200X
authors: I
authors: Padilla
authors: Centro Nacional de Investigaciones Metalúrgicas (CENIM-CSIC), Avenida Gregorio del Amo 8, 28040 Madrid, Spain.
authors: Aurora
authors: A
authors: López-Delgado
authors: Departamento de Cristalografía y Mineralogía, Facultad de Ciencias Geológicas, UCM, C/Antonio Nováis, 28040 Madrid, Spain.
authors: Sol
authors: S
authors: López-Andrés
authors: Departamento de Cristalografía y Mineralogía, Facultad de Ciencias Geológicas, UCM, C/Antonio Nováis, 28040 Madrid, Spain.
authors: Marta
authors: M
authors: Álvarez
authors: Centro Nacional de Investigaciones Metalúrgicas (CENIM-CSIC), Avenida Gregorio del Amo 8, 28040 Madrid, Spain.
authors: Roberto
authors: R
authors: Galindo
authors: Centro Nacional de Investigaciones Metalúrgicas (CENIM-CSIC), Avenida Gregorio del Amo 8, 28040 Madrid, Spain.
authors: Alfonso J
authors: AJ
authors: Vazquez-Vaamonde
mesh_terms: D000536:Aluminum Hydroxide / Q000737:chemistry*; D000537:Aluminum Oxide / Q000138:chemical synthesis* / Q000737:chemistry; D006358:Hot Temperature; D012993:Solar Energy
chemical_list: D000536:Aluminum Hydroxide; C069471:aluminum oxide hydroxide; D000537:Aluminum Oxide