Carbonation Of Wollastonite Research Articles

Alkali Activation of Metakaolin and Wollastonite: Reducing Sodium Hydroxide Use and Enhancing Gel Formation through Carbonation

Alkali activated materials (AAMs) offer significant advantages over traditional materials like Portland cement, but require the use of strong alkaline solutions, which can have negative environmental impacts. This study investigates the synthesis of AAMs using metakaolin and wollastonite, aiming to reduce environmental impact by eliminating sodium silicate and using only sodium hydroxide as an activator. The hypothesis is that wollastonite can provide the necessary silicon for the reaction, with calcium from wollastonite potentially balancing the negative charges usually countered by sodium in the alkaline solution. This study compares raw and carbonated wollastonite (AAM-W and AAM-CW) systems, with raw materials carefully characterized and binding networks analyzed using TGA, FT-IR, and XRD. The results show that while wollastonite can reduce the amount of sodium hydroxide needed, this reduction cannot exceed 50%, as higher substitution levels lead to an insufficiently alkaline environment for the reactions. The carbonation of wollastonite enhances the availability of silicon and calcium, promoting the formation of both N-A-S-H and C-A-S-H gels.

Effect of surface water on wollastonite carbonation: Activated dissolution and mass transfer

Carbonation of non-hydraulic calcium silicate to produce cement represents a crucial strategy for mitigating carbon emissions in the cement industry. However, the dissolution rate of Ca2+ is the main constraint on the reaction kinetics. In this study, the carbonation of wollastonite (CS) was investigated, with an emphasis on the role of water in the Ca2+ dissolution process. Firstly, we investigated carbonation performance of CS and its influencing factors. Results revealed a significant impact of the water-to-solid (w-s) ratio on carbonation. In the carbonate products, we observed that the dissolution of Ca2+ adsorbed on the particle surface, referred to as “pseudocrystalline replacement”, which can serve as supplementary cementitious material. Additionally, this observation signifies the accordance of Ca2+ dissolution with the electric double layer (EDL) theory. Subsequently, we quantitatively assessed the influence of w-s ratio on carbonation using kinetic models. Based on EDL theory and the kinetic model, we categorized water film effect into three stages and determined the influence of water film thickness on the rate-determining factors of CS carbonation. This provides theoretical support for preparation of CS-based cement. Interestingly, we found that reaction rate constant varies with changes in the w-s ratio, indicating a catalytic role of water. Further analysis using density functional theory demonstrated that the free water combined with the O/Ca sites on CS to form hydroxylated surfaces, thereby decreasing and increasing the abilities of the local and neighboring sites, respectively, to absorb H2CO3. These findings provide a theoretical foundation for the curing method of low-carbon cements and offer a methodology for the preparation of supplementary cementitious materials.

Mechanochemical formation of highly stable amorphous calcium carbonate in calcium silicates: Potential long-term storage of CO2 in cement

We have investigated mechanochemical reactions with the calcium silicate wollastonite to probe potential mechanisms of sequestration and long-term storage of CO2 as mineral carbonates in cement pastes. Wollastonite, CaSiO3, was milled under ambient and 13C enriched CO2 atmospheres. Milling induced a structure change from monoclinic wollastonite−2M to triclinic−1T, consistent with high pressure treatment. The results from solid-state 13C nuclear magnetic resonance (NMR) spectroscopy shows this process forms an extraordinarily stable amorphous calcium carbonate (ACC) phase that remains despite a high temperature dehydration treatment (130 °C) and persists in the same form after 3 yrs. of storage at ambient conditions. Thermogravimetric analysis (TGA) of these samples indicates that ACC is produced at the similar solid concentrations in both CO2-enriched and ambient atmospheres. The observation of meta-stable ACC due to wollastonite carbonation may play an important role in further exploration and optimization of mineral carbonation reactions for CO2 capturing cement formulations.

Mineral carbonation as a design project for green chemical engineering education

Accelerated mineral carbonation is a promising CO2 sequestration technology that is strongly linked to concepts of sustainability and Green Chemistry, and its process requirements apply principles of reaction kinetics, transport phenomena, and materials characterization. The present work aimed to develop educational tools for including accelerated mineral carbonation in chemical engineering curricula. To this end, an experimental investigation laboratory procedure and a design project outline have been conceived. As a way to further engage students in this learning experience, the process conditions for the laboratory work are varied between groups of students, and the experimental data obtained are pooled to be used by every group for the subsequent design exercise. This is meant to give students motivation to generate accurate data that they knew would be useful for the entire class and, at the same time, provide students with the opportunity to use data generated by colleagues, much in the same way the design work is done in the industry. In the design project, students use the experimental data obtained by themselves and classmates on the accelerated mineral carbonation of wollastonite, to determine if this is a feasible process for industry to sequester carbon dioxide, in view of mitigating climate change. Also, they use the experimental data, acquired using a range of process conditions, to study the effect of the process variables (CO2 pressure and mixing rate) on the carbonation kinetics and mass transfer rate. The focus of our previously published article was on the experimental investigation, while the focus of this conference paper is on the design project.

Amino acids as performance-controlling additives in carbonation-activated cementitious materials

This article presents an investigation on the application of amino acids to control the CaCO3 crystallization in carbonation cured wollastonite composites. It was observed that wollastonite carbonated without any amino acid formed calcite as the primary polymorph of CaCO3. In contrast, the use of amino acids as admixtures resulted in the formation of stable amorphous calcium carbonate (ACC), vaterite, and aragonite during the carbonation of wollastonite. The carbonated composites produced with amino acids were observed to have a lower critical pore size, but a higher total porosity, compared to the control batch. Additionally, the utilization of amino acids was observed to increase the flexural strength and compressive strength of the composites up to 106% and 48%, respectively, compared to the control batch. Such performance enhancement of the carbonated composites in the presence of amino acids was attributed to the reduced critical pore size and the formation of organic-inorganic hybrid phases in the matrix.

Carbonation of Natural Wollastonite at Non-Ambient Conditions Relevant for CCS—the Possible Use as Cementitious Material in Wellbores

The reaction of wollastonite with CO2 accompanied by SO2 and NO2 in the presence of a chloride-rich brine (230 g/L NaCl, 15 g/L CaCl2, 5 g/L MgCl2) at temperatures relevant to injection conditions (333 K) in carbon capture and storage (CCS) were investigated within the joint BMWi (Federal Ministry for Economic Affairs and Energy) research project CLUSTER. The reaction which describes the formation of wollastonite during metamorphism is reversed and shows a strong temperature dependence. Wollastonite reacts in the presence of CO2 ( C ¯ ) in aqueous conditions to form calcium carbonate and amorphous silicon oxide. At 333 K and 2 MPa the carbonation reaction of wollastonite ( C ¯ C S ) is fast (<24 h). To determine the conversion rate of the reaction quantitatively different methods were used and compared: Powder X-ray diffraction (PXRD) with the Rietveld method and differential scanning calorimetry with thermogravimetry, coupled with a mass spectrometer (DSC-TG/MS) for quantitative phase analysis and for determination of the carbonation. The carbonation (CO2 accompanied by SO2 and NO2) of natural wollastonite at 333 K in presence of chloride-rich brine was rather fast (almost complete after 24 h reaction time).

Mathematical modelling and experimental study of carbonation of wollastonite in the aqueous media

Wollastonite (CaSiO3) is considered as one of the most suitable naturally occurring minerals for carbon dioxide (CO2) sequestration because of its high Calcium (Ca) content, which has an enormous potential to form stable carbonates. However, carbonation of CaSiO3 is a complex three–phase reaction involving CaSiO3, an aqueous solution, and gaseous CO2. The reaction mechanism gets complicated further due to the formation of undissolved silica and product layers on the surface of CaSiO3 particles. The formation of these layers is caused by incongruent dissolution of CaSiO3 and precipitation of the carbonate occurring simultaneously. In this study, a mathematical model was developed to understand the mechanism of dissolution and precipitation of the mineral components. The model functioned under various temperatures, pressures, S/L ratios and particle size fractions. The model was then validated using experimental data obtained by conducting experiments on the carbonation of CaSiO3. It utilized the experimental results to eventually calculate the Damkohler number (Da) to understand the rate controlling mechanism of the reaction.

Energy-efficient mineral carbonation of CaSO4 derived from wollastonite via a roasting-leaching route

Mineral carbonation is an important technique for the sequestration of carbon dioxide (CO2) on a large scale. In this article, indirect carbonation of abundant wollastonite [CaSiO3] mineral combined with the use of a CO2 mineralization cell (CMC) for the recovery of mineralization energy has been proposed. The results of thermodynamic analysis reveal that the described process consumes 73% less energy than that required for the route, in which serpentine is utilized as the mineralization agent. During this process, calcium sulfate (CaSO4) was first derived with recyclable ammonium sulfate (AS) via a roasting-leaching route. The gaseous ammonia produced during the roasting stage was used to capture CO2 from a mixture of flue gases and simultaneously generate ammonium bicarbonate (NH4HCO3) and electricity by the CMC. The obtained NH4HCO3 solution reacted directly with the leaching slurry to mineralize CO2 and regenerate AS at the same time. In this study, process parameters of this route were investigated in detail, and the related extraction mechanism was discussed. It was found that 94.5% of calcium species in wollastonite was converted into CaSO4, 94.8% of which was subsequently carbonated. The extraction efficiency of the roasting stage did not exceed 39% due to its low mass transfer rate resulting from the high viscosity of liquid ammonium bisulfate and presence of silicon dioxide (SiO2) and CaSO4 species on the surface of unreacted wollastonite. Preliminary energy analysis showed that a net reduction of CO2 emission of about 347 kg could be achieved for the mineralization of 1000 kg of CO2.

The Carbonation of Wollastonite: A Model Reaction to Test Natural and Biomimetic Catalysts for Enhanced CO2 Sequestration

One of the most promising strategies for the safe and permanent disposal of anthropogenic CO2 is its conversion into carbonate minerals via the carbonation of calcium and magnesium silicates. However, the mechanism of such a reaction is not well constrained, and its slow kinetics is a handicap for the implementation of silicate mineral carbonation as an effective method for CO2 capture and storage (CCS). Here, we studied the different steps of wollastonite (CaSiO3) carbonation (silicate dissolution → carbonate precipitation) as a model CCS system for the screening of natural and biomimetic catalysts for this reaction. Tested catalysts included carbonic anhydrase (CA), a natural enzyme that catalyzes the reversible hydration of CO2(aq), and biomimetic metal-organic frameworks (MOFs). Our results show that dissolution is the rate-limiting step for wollastonite carbonation. The overall reaction progresses anisotropically along different [hkl] directions via a pseudomorphic interface-coupled dissolution–precipitation mechanism, leading to partial passivation via secondary surface precipitation of amorphous silica and calcite, which in both cases is anisotropic (i.e., (hkl)-specific). CA accelerates the final carbonate precipitation step but hinders the overall carbonation of wollastonite. Remarkably, one of the tested Zr-based MOFs accelerates the dissolution of the silicate. The use of MOFs for enhanced silicate dissolution alone or in combination with other natural or biomimetic catalysts for accelerated carbonation could represent a potentially effective strategy for enhanced mineral CCS.

Wollastonite carbonation in water-bearing supercritical CO2: Effects of water saturation conditions, temperature, and pressure

Abstract The carbonation of silicates in water-bearing supercritical CO2 (scCO2) can affect the performance of CO2-enhanced subsurface operation. This study investigated the effects of water, temperature, and pressure on the carbonation of wollastonite (CaSiO3) in water-bearing scCO2 at 35–93 °C, 25–125 bar, and from dry conditions to 140 times more water than needed for saturation (140 × Sw). The extent of reaction increased with more water, higher pressure, and interestingly, lower temperature. In addition, for the first time, we report on water-bearing scCO2–silicate reactions for samples with varying prior histories of water saturation conditions, temperature, and pressure. For a sample initially reacted at 100% water saturation (1 × Sw) and then with 45 × Sw, the final reaction extent was smaller than the sample reacted only with 45 × Sw. Similarly, for a sample initially reacted at 60 °C and then at 35 °C, the reaction extent was smaller than for a sample reacted only at 35 °C. In contrast, for a sample initially reacted at 50 bar and then at 100 bar, the reaction extent was the same as for a sample reacted only at 100 bar. The amorphous silica layers formed on the particle surfaces are more permeable with more water and lower temperature, and are not affected by pressure. These findings provide new insights into the extent to which water-bearing scCO2–silicates reactions depend on environmental conditions and the reactions' impacts on subsurface CO2 injection.

Wollastonite Carbonation in Water-Bearing Supercritical CO2: Effects of Particle Size.

The performance of geologic CO2 sequestration (GCS) can be affected by CO2 mineralization and changes in the permeability of geologic formations resulting from interactions between water-bearing supercritical CO2 (scCO2) and silicates in reservoir rocks. However, without an understanding of the size effects, the findings in previous studies using nanometer- or micrometer-size particles cannot be applied to the bulk rock in field sites. In this study, we report the effects of particle sizes on the carbonation of wollastonite (CaSiO3) at 60 °C and 100 bar in water-bearing scCO2. After normalization by the surface area, the thickness of the reacted wollastonite layer on the surfaces was independent of particle sizes. After 20 h, the reaction was not controlled by the kinetics of surface reactions but by the diffusion of water-bearing scCO2 across the product layer on wollastonite surfaces. Among the products of reaction, amorphous silica, rather than calcite, covered the wollastonite surface and acted as a diffusion barrier to water-bearing scCO2. The product layer was not highly porous, with a specific surface area 10 times smaller than that of the altered amorphous silica formed at the wollastonite surface in aqueous solution. These findings can help us evaluate the impacts of mineral carbonation in water-bearing scCO2.

Feasibility of Carbonation Reactions to Control Permeability in the Deep Subsurface

Abstract Injection and subsequent carbonation of calcium and magnesium silicate particles are proposed here as a novel strategy to grout fractures or pores and decrease fluid conductivity in the deep subsurface by taking advantage of favorable reaction kinetics. This approach could be used to manage legacy environmental risks from energy extraction techniques such as hydraulic fracturing of shale formations. To evaluate this approach, we studied the carbonation of wollastonite (CaSiO3) in the presence of ground shale under temperature and pressure (T/P) conditions broadly representative of the gas-producing regions of the Marcellus formation in the eastern United States. Effect of calcite (CaCO3) precipitation on shale particle morphology and interparticle pore structures was investigated and impacts on permeability were evaluated using batch and column experiments. Formation T/P were positively correlated with extent of carbonation. Side reactions involving calcium ions and passivation by amorphous silic...

Modified wollastonite sequestrating CO2and exploratory application of the carbonation products

The feasibility of wollastonite carbonation for CO2 sequestration was systematically investigated, and the recovery of the by-products (SiO2, NH4Cl) in the carbonation process, the controllable preparation of carbonation product (CaCO3) with different polymorph and morphology during the carbonation process, and the application of the carbonation product were evaluated. The ammonia dosage and volume of the Ca2+ leaching solution showed a prominent effect on the wollastonite carbonation ratio. The synthesis of the carbonation product (CaCO3) with different polymorphs and morphologies was successfully realized by controlling the temperature and ammonia dosage during the carbonation process. A reaction mechanism of wollastonite carbonation was also proposed by thermodynamic research of the gas–liquid–solid reaction. The carbonation ratio could reach up to 93%, and 1 ton wollastonite could sequester 350 kg of CO2 under optimized conditions. The crystalline phase of the as-obtained CaCO3 was spherical vaterite and cubic calcite, which could meet the relevant standards for the industrial precipitated calcium carbonate CaCO3 (HG/T 2226-2010). The physical properties of the corresponding PP/CaCO3 composites were very close. The cost of wollastonite carbonation was estimated to be 120 $ per t without industrial scale experiment. The wollastonite carbonation strategy showed potential application for CO2 sequestration.

Aqueous carbonation of the potassium-depleted residue from potassium feldspar–CaCl2 calcination for CO2 fixation

Based on the academic thought of carbon capture and utilization, a novel process to integrate the potassium extraction from the insoluble potassium feldspar, industrial waste utilization, and the subsequent CO2 fixation using the resultant potassium-depleted residue was proposed in our previous studies. The potassium-depleted residue comprises several Ca-bearing phases, namely wollastonite (CaSiO3), pseudowollastonite (Ca3Si3O9), Cl-mayenite (Ca12Al14O32Cl2), and anorthite (CaAl2Si2O8), which are potential materials for fixation of CO2 via carbonation. In this study, carbonation of the residue was examined with focuses on the effects of reaction temperature, initial CO2 pressure, particle size of the residue, and reaction duration on the carbonation of these Ca-bearing phases. The results demonstrated that both the temperature and CO2 pressure significantly affect the carbonation, while the residue particle size has only minor influence. At 1 MPa CO2 pressure, the carbonation of these components was dominant at different reaction temperatures. Almost complete carbonation of the pseudowollastonite could be achieved at 75 °C, while significant carbonation of the wollastonite takes place above 100 °C. However, the Cl-mayenite and anorthite are incapable of carbonation even at 200 °C. Increasing the CO2 pressure to 4 MPa can lead to a distinct carbonation of the Cl-mayenite at 150 °C but the anorthite remains untouched. At 1.5 MPa CO2 pressure and 150 °C, with the increasing reaction time, the following Ca-bearing species were successively carbonated: first the pseudowollastonite in 5 min after the reaction started, the wollastonite in 5–15 min, and then simultaneously the wollastonite and the pseudowollastonite in 15–45 min, while the carbonation of Cl-mayenite do not begin even after 120 min. A priority sequence of carbonation of these Ca-bearing minerals was determined as follows: pseudowollastonite > wollastonite > Cl-mayenite > anorthite. The trend is in agreement with the results of thermodynamic calculation. Compared to the carbonation of natural wollastonite, the synthesized wollastonite contained in the potassium-depleted residue seems to be more active in carbonation.

Carbonation of wollastonite(001) competing hydration: microscopic insights from ion spectroscopy and density functional theory.

In this paper, we report about the influence of the chemical potential of water on the carbonation reaction of wollastonite (CaSiO3) as a model surface of cement and concrete. Total energy calculations based on density functional theory combined with kinetic barrier predictions based on nudge elastic band method show that the exposure of the water-free wollastonite surface to CO2 results in a barrier-less carbonation. CO2 reacts with the surface oxygen and forms carbonate (CO3(2-)) complexes together with a major reconstruction of the surface. The reaction comes to a standstill after one carbonate monolayer has been formed. In case one water monolayer is covering the wollastonite surface, the carbonation is no more barrier-less, yet ending in a localized monolayer. Covered with multilayers of water, the thermodynamic ground state of the wollastonite completely changes due to a metal-proton exchange reaction (also called early stage hydration) and Ca(2+) ions are partially removed from solid phase into the H2O/wollastonite interface. Mobile Ca(2+) reacts again with CO2 and forms carbonate complexes, ending in a delocalized layer. By means of high-resolution time-of-flight secondary-ion mass spectrometry images, we confirm that hydration can lead to a partially delocalization of Ca(2+) ions on wollastonite surfaces. Finally, we evaluate the impact of our model surface results by the meaning of low-energy ion-scattering spectroscopy combined with careful discussion about the competing reactions of carbonation vs hydration.

CO2 mineral sequestration by wollastonite carbonation

In this paper, we demonstrated a new approach to CO2 mineral sequestration using wollastonite carbonation assisted by sulfuric acid and ammonia. Samples were characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and 29Si nuclear magnetic resonance. The change in Gibbs free energy from −223 kJ/mol for the leaching reaction of wollastonite to −101 kJ/mol for the carbonation reaction indicated that these two reactions can proceed spontaneously. The leached and carbonated wollastonite showed fibrous bassanite and granular calcium carbonate, respectively, while the crystal structure of pristine wollastonite was destroyed and the majority of the Ca2+ in pristine wollastonite leached. The chemical changes in the phases were monitored during the whole process. A high carbonation rate of 91.1 % could be obtained under the action of sulfuric acid and ammonia at 30 °C at normal atmospheric pressure, indicating its potential use for CO2 sequestration.

CO2 Sequestration from flue gas by direct aqueous mineral carbonation of wollastonite

Emission of carbon dioxide is considered to be the main cause of the greenhouse effect. Mineral carbonation, an important part of the CCS technology, is an attractive option for long-term CO2 sequestration. In this study, wollastonite was chosen as the feedstock and the feasibility of direct aqueous mineral carbonation in the simulated flue gas was investigated via a series of experimental studies carried in a stirred reactor. X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), ion chromatography (IC) and thermal decomposition were used to determine the carbonation conversion. The influences of various factors, including reaction temperature, reaction pressure, solution composition, heat-treatment and particle size, were discussed. Concurrently, the effects of SO2 and NO presented in simulated flue gas were also investigated and a possible mechanism was used to explain the results. Experimental results show that reaction temperature, reaction pressure and particle size can effectively improve the carbonation reaction. Addition of 0.6 M NaHCO3 was also proved to be beneficial to the reaction and heat-treatment is not needed for wollastonite to get a higher carbonation conversion. Compared with carbonation in purified CO2 gas, CO2 sequestration directly from simulated flue gas by mineral carbonation is suggested to have a certain degree of economic feasibility in the conditions of medium and low-pressure. A highest carbonation conversion of 35.9% is gained on the condition of T=150°C, P=40 bar and PS <30 μm in distilled water for 1 h.

Insights into silicate carbonation processes in water-bearing supercritical CO2 fluids

Subsurface injection of CO2 is commonplace in certain industries, yet deployment at the scale required for emission reduction is unprecedented and therefore requires a high degree of predictability. Accurate modeling of subsurface geochemical processes related to geologic carbon sequestration requires experimentally derived data for mineral reactions. Most work in this area has focused on aqueous-dominated systems in which dissolved CO2 reacts to form crystalline carbonate minerals. Comparatively little laboratory research has been conducted on reactions occurring between minerals in the host rock and the wet supercritical fluid phase. We studied the carbonation of wollastonite [CaSiO3] exposed to variably hydrated supercritical CO2 (scCO2) at 50, 55 and 70°C and 90, 120 and 160bar. Reactions were followed by three novel in situ high pressure techniques, which demonstrated increased dissolved water concentrations in the scCO2 resulted in increased wollastonite carbonation approaching ∼50wt.%. Overall, the X-ray diffraction and infrared and magic angle nuclear magnetic resonance spectroscopies experiments conducted in this study allow detailed examination of mechanisms impacting carbonation rates. These include the development of amorphous passivating layers, thin liquid water films, and amorphous hydrated carbonate phases. Collectively, these results emphasize the importance of understanding geochemical processes occurring in wet scCO2 fluids.

ワラストナイト系晶析型脱リン材におけるリン除去メカニズムに関する研究

Wollastonite consolidated by carbonation is one of promising materials as a crystallization-type phosphorous adsorbent. The detailed crystallization mechanism of phosphorous, however, has not been clarified yet. In this study, the crystallization of calcium phosphate on the surface of the consolidated body of wollastonite was examined in detail by SEM, EDX and XRD in order to clarify the detailed mechanism of phosphorous removal by crystallization.It was found that the crystallization of calcium phosphate occurred to a depth of 100μm from the surface of the wollastonite consolidated body, which was the region fully carbonated and mainly composed SiO2 gel-like compound and CaCO3 (calcite and aragonite). Further investigation of crystallization of calcium phosphate using SiO2 gel and CaCO3 powders consolidated by gypsum revealed that a crystallization site of calcium phosphate was probably the surface of CaCO3 crystals generated by the carbonation of wollastonite. Moreover, it was found from the investigation using calcite and aragonite single crystals that the crystallization of calcium phosphate occurred on the surfaces of both crystals and that the surface of aragonite was slightly advantageous for crystallization. XRD analysis showed that Ca-deficient hydroxylapatite (Ca9(HPO4)(PO4)5OH, d-HAP) and dicalcium phosphate dehydrate (CaHPO4·2H2O, DCPD) were mainly crystallized on the surfaces of aragonite and calcite, respectively.

A Novel Indirect Wollastonite Carbonation Route for CO2 Sequestration

AbstractA new CO2 sequestration approach through indirect wollastonite carbonation is proposed to mitigate anthropogenic CO2 emissions from fossil fuel combustion. The wollastonite carbonation process includes three steps: (1) dissolution of wollastonite in hydrochloric acid to leach Ca2+ from mineral matrix; (2) reaction of the resulting CaCl2 solution with CO2 in triisooctylamine (TIOA) at low temperature, producing CaCO3 and an amino acid complex; (3) regeneration of the extractant and acid by backextraction through a temperature swing process and recycling to the dissolution and carbonation steps. It was found that the wollastonite dissolution rate was accelerated by hydrochloric acid and a maximum Ca2+ dissolution extent of 95 % was obtained.