Study on Reaction Behavior and Phase Transformation Regularity of Montmorillonite in High-Calcium Sodium Aluminate Solution System
Year: 2024
Type: article
Abstract: The diaspore is a typical representative of bauxite resources in China, which is the primary raw material for the Bayer process in alumina production, particularly in regions such as Shanxi, Guangxi, Guizhou, and Henan. Clarifying the phase transformations and reaction mechanisms of the silicon-containing minerals during the Bayer leaching process of diaspore is essential for improving the efficiency of alumina production. This article focuses on montmorillonite, which is one of the silicon-containing minerals of diaspore-type bauxite, investigating the reaction mechanisms and phase changes of montmorillonite under the high-calcium sodium aluminate solution system by using X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Magic Angle Spinning Nuclear Magnetic Resonance (MAS–NMR) and Fourier Transform Infrared Spectroscopy (FTIR). The results show that montmorillonite dissolved and transformed into Na6(AlSiO4)6 (hydrated sodium aluminosilicate) under the high-calcium sodium aluminate solution system, and calcium oxide and sodium aluminate in the solution reacted to form (CaO)3Al2O3(H2O)6 (hydrated calcium aluminate). With the increase of reaction temperature, caustic alkali concentration (Nk), and reaction time, hydrated calcium aluminate and hydrated sodium aluminosilicate react and transform into Ca3Al2SiO4(OH)8 (hydrogarnet). Under the optimal reaction conditions of a 120 min reaction time, a temperature of 240 °C, an Nk of 240 g/L, and a CaO–to–SiO2 mass ratio (C/S) of 3.5:1, the montmorillonite reaction degree can reach a maximum of 93.71%.
Source: Minerals
DOI: 10.3390/min14111077
Authors: Zhenchen Tu, Yang Chen, Yibing Li, Weiguang Zhang, Xuejiao Cao
Institution: Guilin University of Technology
Language: English
Subfield: Mechanical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $2,728
OpenAlex ID: W4403761877