https://ogma.newcastle.edu.au/vital/access/ /manager/Index en-au 5 https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:35220 in operando grinding technique which does not require feedstocks which have been subjected to prior ultrafine grinding nor heat-activation. Concurrent grinding is shown to result in a significant increase in magnesite yields for non-heat activated feedstock, prepared such that fines (<20 µm particles) were excluded from the feed. We assert that concurrent grinding may be a suitable technique for the processing of feedstocks such as those containing significant proportions of forsterite and pyroxene, minerals which are unresponsive to thermal activation for use in aqueous mineral carbonation. This study also investigates the effect of different grinding media particle size on reducing the particle size distribution (PSD) of the feed. Optimum ratio of grinding media size to feed particle size, optimum grinding media and slurry concentrations, optimum time for grinding and optimum impeller designs are determined for the system under study. The quantitative effect of grinding media concentration, slurry concentration, pressure and temperature on magnesite yield has been investigated.]]> Wed 10 May 2023 14:51:12 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:47580 2) enables its subsequent reaction to form magnesium carbonate, a process called aqueous mineral carbonation. The dissolution rate of magnesium ions (Mg²⁺) from thermally activated serpentine and the factors influencing the rate and extent of dissolution have been studied in our research group. The current contribution focuses on the effect of temperature and pH on the dissolution of heat activated lizardite (a polymorph of serpentine). The extent of dissolution of thermally activated lizardite was measured experimentally as a function of temperature (25 °C≤T≤75 °C) and pH (1.2 ≤ pH≤9.8). It was found that at higher temperatures the level of Mg extraction is greater during the initial stage of dissolution but is then hindered by the re-precipitation of amorphous silica. Thermodynamic modelling was used to assess the susceptibility of solid phase formation and confirmed the likelihood of re-precipitation of amorphous silica from the solutions. For the first time, in this work, the crackling core model (CCM) was used to model experimental data at different pH values.]]> Mon 23 Jan 2023 14:14:29 AEDT ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:49540 Mon 22 May 2023 08:45:16 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:38019 29Si solid-state nuclear magnetic resonance (²⁹Si SS NMR), inductively coupled plasma-optical emission spectrometry (ICP-OES), and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) to characterize carbonation products and to understand the mechanism of formation and the structure of silica-rich byproducts. Thermodynamic analysis predicts the formation of magnesite and amorphous silica in the process of direct aqueous carbonation of heat-activated lizardite under the experimental conditions studied. Characterization of carbonation products disclosed the presence of magnesite, amorphous silica, and magnesium silicate phases. Analysis of supernatant solutions obtained from direct aqueous carbonation by MALDI spectroscopy showed the presence of silica polymers, which precipitate during the carbonation experiments. The precipitated amorphous silica on the surface of reacting particles was found to subsequently adsorb the dissolved magnesium (Mg) from the solution to form a magnesium silicate phase.]]> Fri 23 Jul 2021 15:47:33 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:42229 Fri 19 Aug 2022 11:35:30 AEST ]]> https://ogma.newcastle.edu.au/vital/access/ /manager/Repository/uon:24039 Fri 04 Nov 2016 15:50:53 AEDT ]]>