Parameters optimization for direct flue gas CO2 capture and sequestration by aqueous mineral carbonation using activated serpentinite based mining residue (original) (raw)
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Enhancing Mg extraction from lizardite-rich serpentine for CO2 mineral sequestration
Minerals Engineering, 2013
Carbon capture and storage by mineralisation (CCSM) is a promising technology that sequesters CO 2 from flue gases into stable mineral carbonates. Although the development of indirect pH swing processes (dissolution at acid pH and carbonation at basic pH) able to recycle the chemicals used are promising, there are still limitations in reaction rate of mineral dissolution being slow in view of a large deployment of the technology. The extraction of Mg from lizardite using magnesium bisulphate has been studied as a function of temperature, reagent concentration, solid to liquid ratio, thermal and mechanical pre-activation. Although the overall highest Mg extraction (95%) was obtained after 3 hours, the reduction of the dissolution time to 1 hr can consistently reduce the volumes to be treated per unit time leading to low capital costs in a hypothetical mineralisation plant. About 80% of Mg was extracted from lizardite in 1hour at 140°C, 2.8 M NH 4 HSO 4 , particles < 250µm and a solid to liquid ratio of 100g/l. At 140°C, serpentine undergoes extensive structural modifications as indicated by XRD and FTIR analyses, producing amorphous silica and accelerating the kinetics of the reaction. Particles with diameter less than 250µm were obtained by grinding the lizardite at 925rpm for 10 minutes consuming 33kWh/t rock .
Development of a CO2 Sequestration Module by Integrating Mineral Activation and Aqueous Carbonation
2004
Mineral carbonation is a promising concept for permanent CO 2 sequestration due to the vast natural abundance of the raw minerals, the permanent storage of CO 2 in solid form as carbonates, and the overall reaction being exothermic. However, the primary drawback to mineral carbonation is the reaction kinetics. To accelerate the reaction, aqueous carbonation processes are preferred, where the minerals are firstly dissolved in solution. In aqueous carbonation, the key step is the dissolution rate of the mineral, where the mineral dissolution reaction is likely to be surface controlled. In order to accelerate the dissolution process, the serpentine can be ground to very fine particle size (<37µm), but this is a very energy intensive process. Alternatively, magnesium could be chemically extracted in aqueous solution. Phase I showed that chemical surface activation helps to dissolve the magnesium from the serpentine minerals (particle size ~100µm), and furthermore, the carbonation reaction can be conducted under mild conditions (20°C and 650psig) compared to previous studies that required >185°C, >1850psig and <37µm particle size. Phase I also showed that over 70% of the magnesium can be extracted at ambient temperature leaving amorphous SiO 2 with surface areas ~330m 2 /g. The overall objective of Phase 2 of this research program is to optimize the active carbonation process developed in Phase I in order to design an integrated CO 2 sequestration module. During the current reporting period, Task 1 "Mineral activation' was initiated and focused on a parametric study to optimize the operation conditions for the mineral activation, where serpentine and sulfuric acid were reacted, as following the results from Phase 1. Several experimental factors were outlined as having a potential influence on the mineral activation. This study has focused to date on the effects of varying the acid concentration, particle size, and the reaction time. The reaction yields and the characterization of the reaction products by ICP/AES, TGA, and BET analyses were used to describe the influence of each of the experimental variables. The reaction yield was as high as 48% with a 5M acid concentration, with lower values directly corresponding to lower acid concentrations. ICP/AES results are indicative of the selective dissolution of magnesium with reaction yields. Significant improvements in the removal of moisture, as observed from TGA studies, as well as in the dissolution can be realized with the comminution of particles to a D 50 less than 125µm. A minimum threshold value of 3M concentration of sulfuric acid was determined to exist in terms of the removal of moisture from serpentine. Contrary to expected, the reaction time, within this design of experiments, has been shown to be insignificant. Potentially coupled with this unexpected result are low BET surface areas of the treated serpentine. These results are issues of further consideration to be addressed under the carbonation studies.The remaining results are as expected, including the dissolution of magnesium, which is to be utilized within the carbonation unit. Phase 1 studies have shown that carbonation reactions could be carried out under a milder regime through the implementation of NaOH titration with the magnesium solution. The optimization of acid concentration, particle size, and reaction temperature will ultimately be determined according to the carbonation efficiencies. Therefore and according to the planned project schedule, research efforts are moving into Task 2 "Aqueous carbonation" as the redesign of the reactor unit is nearly completed. "Development of a CO 2 sequestration module by integrating mineral activation and aqueous carbonation" P a g e 2
2014
Direct dry gas-solid carbonation is a simple approach towards mineral carbon dioxide sequestration. The route theoretically implies the direct reaction of CO2 with silicates of Calcium and Magnesium in dry condition to form stable, insoluble metal carbonates. The mining regions of southern Québec have a large deposit of serpentinite residues. The current study examines the suitability of serpentinite mining residues to use as feedstock material for mineral carbonation. The focus of the present work is to assess the CO2 removal efficiency of the residue from a simulated flue gas mixture of a typical cement plant (18 Vol% CO2). This approach avoids the requirement of separate CO2 capture and preconcentration prior to mineral carbonation. The reaction parameters considered are temperature, pressure and time. The optimization of parameters is carried out for the maximum CO2 removal efficiency (%) from the feed gas. Operating condition for CO2 removal is optimized at 258 °C, 5.6 barg (pC...
Passive Mineral Carbonation of Mg-rich Mine Wastes by Atmospheric CO2
Energy Procedia, 2017
Mg-rich process tailings and waste rocks from mining operations can react spontaneously with atmospheric CO 2 to form stable carbonate minerals by exothermic reactions. Over the last decade, we have conducted a number of laboratory and field experiments and surveys on both mine waste rocks and different types of mine tailings from Ni-Cu, chrysotile, and diamond mines. The experiments and surveys cover a wide range of time (10 3 to 10 8 s) and mass (1-10 8 g) scales. Mine waste rich in brucite or chrysotile enhances the mineral carbonation reactions. Water saturation, but more importantly, watering frequency, are highly important to optimize carbonation. Adjusting the chemical composition of the interstitial water to favour Mg dissolution and to prevent passivation of the reaction surfaces is crucial to ensure the progress of the carbonation reactions. Preservation of the permeability structure is also critical to facilitate water and CO 2 migration in the rock wastes and tailings. In field experiments, CO 2 supply controled by diffusion in the mining waste is slower than the reaction rate which limits the capture of atmospheric CO 2. Industrial implementation of passive mineral carbonation of mine waste by atmospheric CO 2 can be optimized using the above parameters.
Continuing Studies on Direct Aqueous Mineral Carbonation of CO� Sequestration
2002
Direct aqueous mineral carbonation has been investigated as a process to convert gaseous CO 2 into a geologically stable, solid final form. The process utilizes a solution of sodium bicarbonate (NaHCO 3), sodium chloride (NaCl), and water, mixed with a mineral reactant, such as olivine (Mg 2 SiO 4) or serpentine [Mg 3 Si 2 O 5 (OH) 4 ]. Carbon dioxide is dissolved into this slurry, by diffusion through the surface and gas dispersion within the aqueous phase. The process includes dissolution of the mineral and precipitation of the magnesium carbonate mineral magnesite (MgCO 3) in a single unit operation. Activation of the silicate minerals has been achieved by thermal and mechanical means, resulting in up to 80% stoichiometric conversion of the silicate to the carbonate within 30 minutes. Heat treatment of the serpentine, or attrition grinding of the olivine and/or serpentine, appear to activate the minerals by the generation of a non-crystalline phase. Successful conversion to the carbonate has been demonstrated at ambient temperature and relatively low (10 atm) partial pressure of CO 2 (P CO2). However, optimum results have been achieved using the bicarbonate-bearing solution, and high P CO2. Specific conditions include: 185°C; P CO2 =150 atm; 30% solids. Studies suggest that the mineral dissolution rate is not solely surface controlled, while the carbonate precipitation rate is primarily dependent on the bicarbonate concentration of the slurry. Current and future activities include further examination of the reaction pathways and pretreatment options, the development of a continuous flow reactor, and an evaluation of the economic feasibility of the process.
Process optimization for mineral carbonation in aqueous phase
International Journal of Mineral Processing, 2014
Carbon dioxide sequestration by a pH-swing carbonation process was considered in this work. A multi-step aqueous process is described for the fractional precipitation of magnesium carbonate and other minerals in an aqueous system at room temperature and atmospheric pressure. With the aim to achieve higher purity and deliver more valuable mineral products, the process was split into four steps. The first step consists of Mg leaching from the magnesium silicate in a stirred vessel using 1 M HCl at 80 °C, followed by a three step precipitation in reactors in sequence to remove Fe(OH) 3 , then Fe(OH) 2 and other divalent ions, and finally MgCO 3 nucleation and growth. Hydrated magnesium carbonate [MgCO 3 ·3H 2 O, nesquehonite] crystals were confirmed using X-ray diffraction (XRD) as final products. The optimal pH of precipitation reactors based on the maximum solid purity and production were determined by carrying out detailed mass balance. The maximum productivity and highest purity for nesquehonite was found to be dependent on pH values for the two last steps. The results also demonstrated that the process is optimized at pH 9 and 10 for the second and third step of precipitation respectively. The highest carbonation efficiency expressed as the conversion of Mg ions to magnesium carbonate, reached 82.5wt %. The maximum magnesium content in the final product was 99.21 wt % of MgO when the second precipitation reactor pH was equal to 9. This experimental study demonstrates that carbon dioxide sequestration requires at least 3.74 times the weight of ore to provide the Mg for mineral production. This confirms the possibility to use this process route for CO 2 mitigation.
CO2 mineral sequestration: developments toward large-scale application
Greenhouse Gases: Science and Technology, 2011
ABSTRACT The years ahead will show whether CO2 mineral sequestration can be developed to a unit scale of the order of 1 Mt/a CO2 storage around the year 2020, offering additional large-scale carbon capture and sequestration (CCS) capacity besides underground CO2 sequestration. Motivated by the slow deployment of large-scale underground storage of CO2 or simply the availability of large amounts of suitable minerals, progress on mineral sequestration is being steadily made and reported by an increasing number of research teams and projects worldwide. Other well-documented advantages of the method are that it offers leakage-free CO2 fixation that does not require post-storage monitoring and an overwhelmingly large capacity is offered by mineral resources available worldwide, besides the feature that the chemical conversion releases significant amounts of heat. As recognized more recently, it also offers the possibility to operate with a CO2-containing gas directly, removing the expensive CO2 separation step from the CCS process chain. Moreover, the solid products can be used in applications ranging from land reclamation to iron- and steelmaking. With the technology overview given in the Intergovernmental Panel on Climate Change (IPCC) Special Report on CCS (2005) as a reference point, the method is reviewed and its capacity, weaknesses, and strengths are re-assessed. The state-of-the-art after twenty years of R&D work as reflected by ongoing development work inside and outside laboratories is summarized, illustrating the future prospects of CO2 mineralization within a portfolio of CCS technologies under development worldwide. Current developments include an increasing number of patents and patent applications and a trend toward scale-up and demonstration. © 2011 Society of Chemical Industry and John Wiley & Sons, Ltd
International Journal of Mining, Reclamation and Environment, 2011
The ability to sequester CO 2 under elevated temperature and pressure has been shown to be successful using MgO-rich rocks. This is achieved by mineral carbonation. Two predominant sources of substrate material are considered, namely ultramafic mine waste rock and process tailings. Each material has specific sequestration potential benefits for select mining operations to source additional revenue from the offset of anthropogenic carbon and sales of carbonate industrial products. Laboratory scale tests can determine the CO 2 fixation capacity of the proposed rocks; however, a more practical repeatable method of determining the carbonation potential is needed. Data generation from autoclave testing of applicable mining waste material facilitates the understanding of carbonation determining parameters. The development of a sequestration potential algorithm that can be applied to drill hole geochemical data is preferred. The generation of non-destructive sequestration potential values from geostatistical interpretation will facilitate their inclusion into applicable mining block models and the determination of bulk carbon sequestration capacity.