Characterization and beneficiation of Ethiopian kaolin for use in fabrication of ceramic membrane

Abstract

Kaolin (china clay) is a rock material that is very rich in kaolinite. A kaolin ore from Debre Tabor, Ethiopia containing 59.2 wt% SiO2, 24.9 wt% Al2O3, 2.4 wt% Fe2O3, and 8.22 wt% loss on ignition (LOI) was physically beneficiated, chemically leached, and thermally treated for possible industrial use, especially for ceramic membrane fabrication. The leaching experiments were carried out using oxalic acid solutions as leaching reagents for the iron extraction process. The effect of acid concentration, reaction temperature, and contact time on iron leaching was investigated. It was determined that the rate of iron extraction increased with the oxalic acid concentration, leaching temperature, and contact time. A substantial reduction of iron oxide (2.4 to 0.36 wt%) from the raw kaolin was observed at operating conditions of 2.0 M oxalic acid, the temperature of 120 °C, and contact time of 120 min. A maximum kaolin whiteness index of 81.4% was achieved through this leaching process. Finally, the physically beneficiated, chemically leached, and thermally treated kaolin raw material was used to fabricate a low-cost kaolin-based ceramic membrane. After firing at 1100 °C the ceramic membrane was found to have a mass loss of 11.04 ± 0.05%, water absorption of 8.9 ± 0.4%, linear shrinkage of 14.5 ± 0.05%. It was demonstrated to be chemically stable, having less than 3% mass loss in acid solution, and less than 1% mass loss in alkali solution. The newly developed membranes have thus properties comparable to commercial ceramic membranes.

Physiochemical Characterization of Ethiopian Mined Kaolin Clay through Beneficiation Process

“…Te raw and benefciated kaolin clay indicates well-defned difraction at 2-theta values of 18.42, 24.16, 27.62, 51.6, and 58.52 °, these major peaks are characteristically matching to the kaolinite [34]. Whereas, other peaks are equivalent to the 2-theta values of 29.57, 35.4, and 40.5 °typically corresponding to quartz [35][36][37]. Te obtained XRD showed that the benefciated kaolin material is rich in kaolinite and quartz.…”

Characterization and treatment effects on Mutaka kaolin for additive in coatings: Mineral composition, thermal and structural modifications

“…After mixing the kaolin and oxalic acid solution, the resulting mixture was transferred into Falcon® tubes. The tubes were then centrifuged using a Megafuge™ 8 centrifuge at 4500 rpm for 10 min [ 31 ]. The supernatant, which contained the liquid portion of the mixture, was discarded, while the residue product, which consisted of the treated kaolin, remained in the Falcon® tubes.…”

“…The resulting sediment was subjected to multiple rinses with deionized water to remove residual impurities. Finally, the sample was dried at 100 °C for 24 h to achieve a complete moisture removal [ 31 ]. The dried samples were well-mortared for subsequent characterizations.…”

“…These are particularly important in optimizing the raw materials for specific applications, including creating coatings and paints with desired properties and improved stability. Previous studies have predominantly examined treatment or beneficiation methods for the kaolin [ 15 , [24] , [25] , [26] , [27] , [28] , [29] ], but few have specifically investigated the impact of different treatment methods on kaolin and characterizing the resulting treated kaolin [ 14 , 30 , 31 ]. These processes can potentially induce changes in physical and chemical properties, including morphology, crystal structure, particle size distribution, and pH, which can subsequently affect the formation of kaolin [ 32 , 33 ].…”

Synthesis of ceramic tubular membrane from low‐cost clay precursors for blood purification application as substitute of commercial dialysis membrane

“…27 Ceramic-based membranes are rapidly attaining prominence in the medical field as a solution to these problems due to their thermal efficiency, chemical stability, mechanical strength, higher separation efficiency, long lifetime and antifouling properties. [28][29][30][31] To the best of our knowledge, a tubular membrane made of ceramic material has never been used for hemofiltration. Thus, the generation of a ceramic tubular membrane for application to hemofiltration may be considered novel.…”