Study of the peculiarities of the leaching process for self-crumbling limestone-kaolin cakes

Abstract

The article presents the results of an experimental study to establish the leaching indicators for limestone-kaolin cakes conducted using soda solutions with various process parameters. The experiments use the mathematical planning method that allows assessing the significance of various cake leaching parameters with the minimum number of experiments. It is shown that the temperature and concentration of the soda solution have a significant effect on the aluminum oxide recovery, with the highest recovery of 79.5 % within the selected factor variation intervals achieved at the process temperature of 50 °C, the soda solution concentration of 100 g/l, the liquid/solid ratio in the slurry of 7, and the leaching time of 25 minutes. Further studies using the coordinate-wise optimization method allowed establishing the leaching process parameters that ensure the aluminum oxide recovery of up to 85.2 %. At the same time, the paper shows a significant effect of the process temperature and time on the depth of secondary interactions leading to the deposition of aluminum oxide and requiring additional systemic studies. The established chemical and material composition of the sludge suggests that it may be effectively used as a component in raw Portland cement mixes, as well as a raw material for the regeneration and recycling of the lime component, which would reduce the consumption of natural carbonate raw materials and cut the emissions of greenhouse gases into the atmosphere. The research was carried out with the use of the laboratory equipment of the Scientific and Educational Center for Shared Use of the St. Petersburg Mining University. The work was carried out with the financial support of the Russian Science Foundation under the Agreement No. 18-19-00577 of April 26 2018 of grant for fundamental scientific research and exploratory scientific research.

High-Performance Flocculants for Purification: Solving the Problem of Waste Incineration Bottom Ash and Unpurified Water

“…The reusability of flocs was evaluated using Na 2 CO 3 by calcining at 900 °C to prepare a soluble salt. 51 By comparing XRD patterns of NaAlSiO 4 (JCPDS35-0424) characteristic peaks, formation of the target product is confirmed (Figure S3, Supporting Information). Hence, flocs can be recycled by a simple process as a green technology for resource utilization.…”

Enhanced alumina extraction from kaolin by thermochemical activation using charcoal

“…In the case of sintering at 1360°C without added charcoal, the precursor components reacted and transformed completely into the leachable calcium aluminate phase (C 12 A 7 ). The additional heat generated under these conditions facilitated the crystallization of the calcium aluminate phase (ElDeeb et al , 2019, 2020b, 2020c, 2021). The addition of charcoal up to 1.5% increased total heat during the transformation due to the combustion of charcoal in this closed system (as is indicated by the significant thermal changes on the DSC curves; Fig.…”

Mechanical Properties and Microstructure of High-Strength Alkali-Activated Concrete Including High-Volumes of Waste Brick Powder Using Response Surface Methodology

“…While the total weight loss similarly has a narrow range, between 5 and 9%, demonstrating that water is tightly bound in the hardened samples, the mass loss up to 200℃ ranges between 3 and 6% and is related to the loss of free water. Therefore, in addition to the favorable mineralogical composition of the raw materials, the apparent strength of these samples, ranging between 63 and 118 MPa, is also attributable to the proper water content present in the initial paste, which starts favorable reactions and leads to the formation of a dense structure [47,48]. The control mixture, on the other hand, exhibits completely different behaviour despite acquiring a higher compressive strength (more than 100 MPa).…”

“…Whereas the WBP-based samples displayed a less dense structure with a higher number of unreacted aluminosilicate particles. This morphological variation may result from variations in the chemical makes-up, forms, and sizes of the WBP and GGBS [46][47][48][49][50][51][52]. Therefore, the AAC mixes should have a greater rate of alkali activation reaction after forming compressed and homogenous morphology than the WBP-based samples due to the presence of GGBS (Fig.…”