Obtaining Alumina from Kaolin Clay via Aluminum Chloride

Abstract

A method of alumina production based on hydrochloric acid processing of kaolin clays from the East Siberian deposits was studied. Hydrochloric acid leaching was carried out at 160 °C. The leaching solution was subjected to a two-stage crystallization of aluminum chloride hexahydrate (ACH). The precipitated crystals were calcinated in air at a temperature above 800 °C to produce alumina. The main part of water and chlorine during thermal decomposition of ACH was removed at 400 °C. The influence of temperature and duration of ACH calcination on the residual chlorine content in alumina was studied. The optimal temperature of ACH calcination was 900 °C with a duration of 90 min. It was shown that the increase in calcination temperature contributed to the decrease in chlorine content in the final product. However, an increase in calcination temperature above 900 °C led to the transition of the well-soluble γ-Al2O3 phase to the insoluble α-Al2O3, which negatively affected the further electrolysis of aluminum. The size of alumina particles was not affected by the calcination mode. The rate of dissolution of the prototype Al2O3 in Na3AlF6 was higher than for the alumina obtained by the classical method. Alumina content, particle morphology, and particle size distribution for the obtained alumina were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and laser diffraction methods. The obtained alumina is suitable for aluminum production according to the studied characteristics.

The Investigation of Organic Binder Effect on Morphological Structure of Ceramic Membrane Support

“…Moreover, it is a significant raw material to refractories and to catalyst, cement and fiberglass industries [9,10]. Alumina can also be produced by hydrochloric acid treatment of kaolin clays [11]. The increasing demand for aluminum worldwide increases the interest in marginal technologies to produce alumina from clays.…”

“…The new technologies have been developed so far. For example, a method of alumina production based on hydrochloric acid processing of kaolin clays was developed and physico-chemical properties of alumina obtained by the hydrochloric acid technology were investigated [11]. The extraction of alumina from the kaolin was also obtained through the leaching process, using aqueous solutions of sodium carbonate as a leaching agent [12].…”

Acid and Acid-Alkali Treatment Methods of Al-Chloride Solution Obtained by the Leaching of Coal Fly Ash to Produce Sandy Grade Alumina

“…Further calcination at 1000 • C resulted in the entire surface of the particles consisting of pores, and the specific surface area for SGA-C increased to 71.2 m 2 /g. Due to such a high specific surface area of the SGA-C obtained by the acid treatment, its dissolution rate in cryolite (Na 3 AlF 6 ) was faster than the SGA obtained by the Bayer alkaline method [46].…”

Enhanced alumina extraction from kaolin by thermochemical activation using charcoal

“…Moreover, kaolinite exhibits an intrinsically smaller hardness (i.e., cost-effective and energy-efficient grindability producing ultrafine powders dominated with size fractions < 2 µm) and a relatively lower degree of thermal decomposition (457 -711 °C) than the abundant non-clay aluminium bearing silicate minerals (e.g., orthoclase, plagioclase, nepheline, leucite, kyanite and pyrope-garnet) (Aldabsheh et al, 2015;ElDeeb & Brichkin, 2018;Erdemoğlu et al, 2018;Brichkin et al, 2019;ElDeeb et al, 2019;Küster et al, 2021;Nzeukou Nzeugang et al, 2018;Pak et al, 2019;Scorzelli et al, 2008;Sule & Sigalas, 2020;Tantawy et al, 2019).…”

“…It is worth noting that the lime-sinter is the lowest cost-effective, timesaving and energy-efficient method for alumina extraction from kaolin at 1360 ºC, when compared with the other pyro-hydrometallurgical (i.e., the Bayer and the soda-lime sinter) methods (ElDeeb et al, 2019(ElDeeb et al, , 2020a. These positive effects and advantages of the lime-sinter process are as a result of the crystallographic transformation of the dicalcium silicate (C 2 S) from β to γ phases during the cooling stage, the resulting sinter is self-disintegrated into a highly desirable ultrafine powder with a higher surface area, and therefore no pre-leaching grinding is required, that produced to a high leaching performance with a minimal low reagent consumption (Al-Ajeel et al, 2014;Pak et al, 2019;ElDeeb et al, 2019ElDeeb et al, , 2020a.…”