Mechano-Chemical Processing of Diaspore Sample for Extraction and Synthesis of Gamma-Alumina and Potash Values
- PDF / 2,337,234 Bytes
- 10 Pages / 593.972 x 792 pts Page_size
- 74 Downloads / 151 Views
https://doi.org/10.1007/s11837-020-04222-4 Ó 2020 The Minerals, Metals & Materials Society
ALUMINUM: RECYCLING AND CARBON / ENVIRONMENTAL FOOTPRINT
Mechano-Chemical Processing of Diaspore Sample for Extraction and Synthesis of Gamma-Alumina and Potash Values ASHWINI KUMAR,1 SHREY AGRAWAL,1 and NIKHIL DHAWAN
1,2
1.—Extractive Metallurgy Laboratory, Department of Metallurgical and Materials Engineering, Indian Institute of Technology, IIT-Roorkee, Roorkee, Uttarakhand 247667, India. 2.—e-mail: [email protected]
In this study, a diaspore sample is evaluated as a dual source of alumina and potash. The thermal treatment of diaspore with sodium hydroxide yielded alumina and potash values. Microwave heating resulted in enhanced diffusion with improved precipitate purity and recovery with a significant reduction in reaction time. The thermal treatment precipitate comprises alumina purity of 48% with a recovery of 49%. The mechanical milling route yields optimal conditions of 8 h milling followed by acid leaching in 2 M HCl at 50°C for 1 h with 70% and 45% potash and alumina extraction, respectively. The dissociation of the muscovite structure is crucial for high extraction values, and milling time was found to be the significant factor. The milling route at optimal conditions yielded an alumina precipitate with 89% purity with a surface area of 104.6 m2/g and a sylvinite-rich solution, which can be used in fertilizer application.
INTRODUCTION Bauxite is the primary ore employed for alumina production.1 The increasing demand for aluminum metal and other allied applications such as refractory material, abrasive, and catalyst leads to high alumina consumption.2–4 The available bauxite reserves are inadequate to meet the growing demands, and industries rely on alternative nonbauxite sources for production. The annual aluminum production in India reached 3.4 million tons in 2018, with an annual growth of 17% and alumina production of 6.12 million tons.5 The primary aluminum minerals in bauxite ore are gibbsite (cAl(OH)3), boehmite (c-AlO(OH)), diaspore (aAlO(OH)), and clay minerals such as kaolinite, halloysite, and aluminous goethite.6 The bauxite ore with high diaspore content is not considered ideal for alumina production using Bayer’s process because of the low Al-to-Si ratio, considerable red mud generation, high temperature, and pressure requirements for processing.7 The alternative processing route employed for alumina recovery from diasporic bauxites, nepheline syenite, and kaolin can be broadly classified into a hydrometallurgical
route involving acid leaching and a combined pyroand hydrometallurgical route. Aluminum-bearing phases exist in different forms such as g, c, d, h, b, j, v, and a-alumina crystalline structures, where calumina is an important structure having applications such as catalysts, composite structures, and thermal insulation in oil hydrogenation, chemical synthesis, petroleum refining, and aerospace industries.8–10 High-purity c-alumina is commercially prepared from aluminum precurso
Data Loading...
