- Title
- Mineral carbonation of CO₂ using alternative feedstocks
- Creator
- Rashid, Muhammad Imran
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2019
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- Mineral carbonation converts CO₂ into stable mineral carbonates. This research explores the utilisation of serpentinised dunite (which is comprised of 61% lizardite) as a potential feedstock for mineral carbonation. Heat activation, ex-situ regrinding and concurrent grinding techniques were employed to enhance the reaction rate and yield, and to provide information on the carbonation reaction mechanism. The order of reactivity assessed through carbonation was found to be; heat-activated dunite (630 °C, 4 h) soaked > heat-activated dunite > raw dunite with regrinding > heat-transformed dunite (800 °C, 3 h) > raw dunite > raw lizardite. Silanol nests formed in a side reaction during carbonation of heat-activated dunite as determined using FTIR and TGA-MS analysis. Concurrent grinding (grinding of the mineral within the reactor during the course of the carbonation reaction) was introduced to break Mg-depleted shells (8.3-18 μm) which appear during reference (absence of grinding media) experiments. Concurrent grinding was shown to result in a significant increase in magnesite yields for non-heat activated feedstock (dunite, olivine and lizardite). This study also investigated the effect of different grinding media bead size on reducing the particle size distribution of the feed. The optimum ratio of grinding media size to feed particle size, grinding media and slurry concentrations, time for grinding and reactor impeller design were determined. The quantitative effect of grinding media concentration, slurry concentration, pressure and temperature on magnesite yield was investigated. For two-stage aqueous mineral carbonation (extraction of magnesium as a separate step to precipitation of the solid carbonate) dissolution experiments, different grinding media concentrations were examined with 60 wt% concentration being optimal. Mg extractions using 30 wt% grinding media and the reference experiment (absence of grinding media) were similar due to silica-rich layers formation. For the ground product from the 60 wt% media dissolution experiments, Mg extraction was higher as silica-rich layers were disrupted. Multi-stage grinding, involving successive occurrences of grinding, was introduced to achieve higher Mg extractions. However, in these dissolution experiments it was observed that particle size of the ground product increased during second occurrence of grinding despite a revised and potentially improved selection of grinding media being made. This particle size increase was determined to be due to fines agglomeration and polyacrylic acid, a commercial grinding aid was used to reduce this agglomeration. This study show successful utilisation of serpentinised dunite, olivine and lizardite as potential feedstocks for mineral carbonation. Silica-rich layers which appear during reference experiments were disrupted using concurrent grinding and significantly higher magnesite yields and Mg extractions were obtained.
- Subject
- climate change; CO₂ sequestration; mineral carbonation; concurrent grinding; grinding media; statistical experimental design
- Identifier
- http://hdl.handle.net/1959.13/1403442
- Identifier
- uon:35170
- Rights
- Copyright 2019 Muhammad Imran Rashid
- Language
- eng
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| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | ATTACHMENT01 | Thesis | 13 MB | Adobe Acrobat PDF | View Details Download | ||
| View Details Download | ATTACHMENT02 | Abstract | 1 MB | Adobe Acrobat PDF | View Details Download |