Abstract
In this work, from the MgO-enriched residue originated from ludwigite ore, value-added magnesium hydroxide sulfate hydrate (MHSH) whiskers were prepared via sulfuric acid leaching and leachate purification, followed by hydrothermal synthesis. During sulfuric acid leaching, 98.2% magnesium and 99.6% silica were removed under the optimal leaching conditions: sulfuric acid concentration of 40%, leaching temperature of 80 °C, leaching time of 90 min, and liquid to solid ratio of 4 mL/g. After purification of the acidic leachate via oxidation and precipitation to remove impurities including iron and aluminum, the Mg2+-rich solution was used to prepare magnesium hydroxide sulfate hydrate whiskers (5Mg(OH)2·MgSO4·2H2O, abbreviated as 512MHSH) via hydrothermal synthesis. Finally, 512MHSH whiskers were obtained with 30–100 μm in length, 0.5–1.0 μm in diameter and aspect ratio of approximately 100. The physicochemical characteristics of whiskers were further characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS), Fourier Transform Infrared Spectroscopy (FT-IR) and Thermogravimetry-Differential Scanning Calorimetry (TG-DSC).
Highlights
Magnesium hydroxide sulfate hydrate (MHSH) is a group of magnesium salts with a general formula of xMg(OH)2 ·yMgSO4 ·zH2 O [1,2]
As boron and in the presence of soda ash, 72.1% boron and 95.7% iron were extracted in the forms of sodium metaborate iron could be recovered efficiently, magnesium could be enriched in the nonmagnetic material and metallic iron, As boron and iron could of bemagnesium-containing recovered efficiently, magnesium topowdery a great extent
The infrared spectrum of magnesium hydroxide sulfate hydrate (MHSH) whiskers was characterized by using Fourier transform infrared spectroscopy (FT-IR, 830, Shimadzu, Kyoto, Japan)
Summary
Magnesium hydroxide sulfate hydrate (MHSH) is a group of magnesium salts with a general formula of xMg(OH)2 ·yMgSO4 ·zH2 O (referred to as xyz MHSH, including type 513, 512, 123, 318, 131, etc.) [1,2]. After reductive roasting in the presence of soda ash, 72.1% boron and 95.7% iron were coal-based direct reduction has shown its potential and promising future [25,26]. Transformation of magnesium-containing minerals during soda-ash roasting, the non-magnetic material. The no-magnetic material with high MgO content could be used as a potential magnesium hassource excellent solubility in acidic liquor. The no-magnetic material with high MgO content could for the synthesis of MHSH whiskers. In this study, derived from ludwigite ore was used asand the starting material material to prepare MHSH whiskers via acid leaching, leachate purification hydrothermal to synthesis. After removing impurities of acid leachate, hydrothermal synthesis was performed to prepare MHSH whiskers
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