Indirect Mineral Carbonation Research Articles

CO2 sequestration by indirect mineral carbonation of serpentine with (NH4)2SO4 as a recyclable extractant

Mineral carbonation with serpentine can offer a sustainable and safe process option for simultaneous CO2 emission reduction and utilization of nature mineral. In this study, a sustainable process for CO2 mineral sequestration was proposed by using serpentine and ammonium sulfate as feedstocks. The mixture of feedstocks was subjected to roasting with temperature ranging from 390°C to 480°C, converting magnesium into the corresponding sulfate. Then, water leaching was employed to dissolve the magnesium sulfate from the roasted samples. Finally, through a mineralization reaction, the corresponding magnesium bicarbonate was generated after sequestrating CO2. Under the optimal roasting-leaching conditions, i.e. roasting temperature of 420ºC, roasting time of 2 hours, and mass ratio of ammonium sulfate/serpentine of 3; leaching temperature of 80ºC, leaching time of 1 hour, and a liquid-to-solid ratio of 1, the magnesium extraction efficiency reached 76 %. Thermodynamics and experimental results demonstrated that during the sulfation roasting process, the products generated during roasting, magnesium sulfate and silicon dioxide, adhered to the surface of the serpentine, thus inhibiting the mass transfer process and impeding the progress of the reaction. However, the liquid-solid reaction facilitated by molten ammonium sulfate and the gas-solid reaction provided by the decomposition of ammonium salts into SO2 played a promoting role in the sulfation roasting reaction. The carbonation of sulfated serpentine results indicated that the optimal CO2 storage capacity can reach 204 kg/t serpentine.

Enhancing the potential application of food-waste biochar as a sustainable bio-solid fuel: Analysis of post-treatment and combustion behavior

Food-waste biochar holds significant potential as a bio-solid fuel for achieving carbon neutrality; however, its high content of sodium (Na), potassium (K), calcium (Ca), chlorine (Cl), and nitrogen, inhibits its potential use. This study explored the effects of post-treatment with ascorbic, acetic, citric, and iminodiacetic acids on the properties of food-waste biochar and volatile ionic substances to establish a foundation for assessing both the environmental impact and practical use of food waste. Post-treatment with organic acids achieved 92% Cl-removal efficiency and induced deformation of the functional groups of food-waste biochar surfaces, leading to the re-adsorption of alkali and alkaline earth metals. This re-adsorption of alkali metal ions showed a distinct correlation with NOx mitigation. The amount of re-adsorbed Na and K varied based on the types of organic acids, resulting in different NOx emission reduction effects. Iminodiacetic acid was particularly effective in alleviating Ca and PO4 volatilization, whereas citric acid exhibited the highest Ca elution performance, and the Ca-contained leachate is a potential source of CO2 storage through indirect mineral carbonation. Acetic acid is the most feasible alternative, considering both economic and environmental aspects. The findings suggest that the post-treatment of food-waste biochar effectively mitigates air pollutants during combustion and is beneficial for sustainable biosolid fuel production and bio-waste management.

Experimental study on indirect mineral carbonation using five types of slag for production of high-purity calcium carbonate

Experimental study on indirect mineral carbonation using five types of slag for production of high-purity calcium carbonate

Indirect mineral carbonation of recycled concrete aggregate: Enhancing calcium extraction using a packed bed reactor

Mineral carbonation of industrial residues is gaining increasing interest, with the first pilot and industrial-scale applications being implemented. The process offers a low-risk, easily available solution for permanent carbon dioxide storage while concurrently valorising industrial wastes. This work investigates the indirect mineral carbonation of recycled concrete aggregate (RCA), in which calcium is first leached from the RCA into an aqueous ammonium nitrate (AN) solution, followed by carbonation to yield high-purity precipitated calcium carbonate. The study focuses on the first step, calcium dissolution, which traditionally takes place in a stirred batch reactor (SBR). However, SBRs often encounter solubility constraints, leading to low calcium extraction yields. In this investigation, we explore the application of a packed bed reactor (PBR) and demonstrate its superior performance, resulting in a calcium extraction enhancement of 27% to 55% relative to SBRs, across AN concentrations ranging from 0.25 to 2.0 mol/kg, at 25 °C and atmospheric pressure. The PBR’s superior performance can be attributed to the more compact design, enabling longer dissolution times, and to the continuous supply of fresh solvent, effectively reducing solubility limitations. The impact of key operating parameters (AN concentration, liquid flow rate and extraction time) are systemically assessed experimentally, accurately modelled using a shrinking-core model, and illustrated in process performance maps. Furthermore, this research highlights the significance of ammonium nitrate recovery from the wet solids after filtration to ensure the process’s environmental viability. The packed bed reactor (PBR) functions as an integrated filter, facilitating the straightforward recovery of 80% of the trapped ammonium nitrate solution through simple water flushing. In conclusion, the utilisation of PBRs in indirect mineral carbonation presents an innovative and efficient approach for enhancing calcium extraction while addressing environmental concerns through ammonium nitrate recovery. The applicability of PBRs extends beyond recycled concrete aggregates, and could also be successfully applied for other coarse industrial residues such as steel slags.

Elution of Divalent Cations from Iron Ore Mining Waste in an Indirect Aqueous Mineral Carbonation for Carbon Capture and Storage

Mining waste is generated in vast quantities globally, which can have negative environmental consequences. This study highlights the utilization of iron ore mining waste as feedstock material in the preparatory step of an indirect aqueous mineral carbonation for carbon sequestration. The role of reactive cations (Ca2+, Mg2+, and Fe2+) was investigated in view of their elution behavior to improve carbonation efficiency. An elution experiment was carried out for the divalent cations using different acids (oxalic, HCl, acetic, and formic acid) at different concentration solutions (up to 1.5 M) and times (up to 100 min) at ambient temperature. The initial analysis confirmed the presence of divalent cations in the sample. The elution approach at ambient temperature resulted in the elution efficiency of Fe2+ (30.4%), Mg2+ (54%) using oxalic acid, and Ca2+ (98%) using HCl at a relatively short time between 50 and 100 min. It was found that for the iron ore mining waste, oxalic acid and HCl were best suited as elution agents for the Fe2+ and Mg2+, and Ca2+, respectively. The CO2 sequestration potential was calculated to be 131.58 g CO2/kg residue. A further carbonation step using a complexing agent (1,10 phenanthroline) confirmed the formation of siderite and magnesite along with phenanthroline hydrates. Findings have shown that the indirect mineral carbonation of the iron mining waste with complexing agent might improve carbonation efficiency, thus indicating that this material is useful for long-term carbon capture and storage applications.

Industrial demonstration of indirect mineral carbonation in the cement and concrete sector

This paper reports on the successful construction, commissioning and operation of a mobile indirect mineral carbonation (IMC) pilot plant in the concrete sector. This work confirms the technical feasibility of IMC at large scale, while producing precipitated calcium carbonate (PCC) and leached recycled concrete aggregate (RCA) as useful products. The plant is capable of handling industrial flue gas or pure CO2 as carbon feedstock, while processing around 80 kg/h of RCA as calcium feedstock, and storing around 0.9 kg/hr of CO2. Good recyclability of the aqueous ammonium nitrate mother liquor is suggested, although small changes occurred over time, with only small effects on the operation. Importantly, some CaCO3 precipitates in the dissolution reactor, especially at high CO2 feed rates; this does not decrease the CO2 storage rate, but it reduces the PCC production rate. The plant may be operated at a variety of operating conditions and it responds to them as expected from thermodynamic considerations. Similarly, the trade-offs in terms of performance parameters also change as expected. The observed calcium extraction efficiency is rather low due to the thermodynamic nature of the batch dissolution step. Also, the ammonium nitrate losses are rather high due to the plant not having a solvent recovery step integrated. Potentially alternative reactor concepts for the dissolution section can improve the calcium extraction efficiency while including a washing step, thus alleviating the main limitation. Material tests with the products of the process suggest that leached RCA is as good as, or even better than fresh RCA for use as aggregate in concrete; ground PCC performs similar as ground limestone in cement, however it is not the most attractive use of fine PCC, as higher value applications exist. Although improvements to the plant design are necessary to make the process economically and environmentally viable, this work represents an important steppingstone towards industrial implementation of IMC, and confirms its technical feasibility in the concrete sector.

Batchwise Leaching of Calcium from Demolition Concrete Fines in an Aqueous Ammonium Nitrate Solution: Part 2 Modeling

This article addresses the application of the indirect mineral carbonation process to recycled concrete aggregates (RCA). In such a process, calcium is first leached from the RCA feedstock into an aqueous ammonium nitrate solution and then it is carbonated to precipitate calcium carbonate. The calcium leaching step is modeled in this contribution, whereas it was investigated experimentally in part 1 of this series, where the focus was more on thermodynamic aspects than on kinetics. In this part 2 paper, kinetics aspects are also included by modeling them using two different approaches. In the first approach, the reaction–diffusion model is implemented, accounting for the congruent dissolution of the calcium hydroxide phase and the incongruent dissolution of the calcium silicate hydrate components of concrete fines. In the second approach, a double-shrinking-core model is used, which for the sake of simplicity assumes congruent dissolution of calcium silicate hydrates as well, infinitely fast reaction/dissolution kinetics, and pseudo-steady-state diffusion. The model parameters have been either determined through targeted experiments or estimated by fitting measurements obtained in experiments with two different materials, both in the size range of up to a diameter of 4 mm. Both models exhibit satisfactory accuracy in describing the experimental data; particularly for particles larger than about 0.1 mm in diameter, the two models calculate a nearly identical evolution of the calcium concentration in solution. The simplifications of the double-shrinking-core model lead to a loss of resolution in characterizing the evolution of leaching inside the particles, whereas they enable faster computations. The latter feature makes such a model a convenient tool for studying process performance, namely, productivity, calcium recovery, and solvent efficiency, through parametric analysis; this has been demonstrated as reported in the last part of the article.

Batchwise Leaching of Calcium from Demolished Concrete Fines in an Aqueous Ammonium Nitrate Solution: Part 1 Experimental Study

In this work, the dissolution step of the indirect mineral carbonation process was investigated; first, a process-relevant thermodynamic framework is introduced, and then, an extensive experimental campaign with aqueous ammonium nitrate (AN) as the solvent is presented. Steady-state experiments after 24 h of leaching under different solvent concentrations and cement dosing were studied, confirming the applicability of the developed thermodynamic framework and its mathematical description. Afterward, batch experiments were performed to study the kinetic leaching behavior from different particle sizes, at different temperatures, and under a variety of industrially relevant conditions. Smaller particles release more calcium faster than larger particles as their calcium content is higher, and they have more specific surface available and less intraparticle diffusion limitations. Between temperatures of 5 and 35 °C, a 20% increase in dissolution performance was observed, which is due to an increase in reaction kinetics and/or diffusivity. Experiments under industrially relevant conditions reveal that increasing both the AN concentration and the solid to liquid ratio increases the amount of calcium in solution but has contradicting effects on extraction efficiency. For the typical conditions of a solid to liquid ratio of 0.2 and an AN concentration of 0.5 M, about 32% of the available calcium was leached after 20 min, resulting in a calcium concentration of 0.065 M; thereafter, this leaching process slows down sharply. The knowledge developed in this work forms a solid foundation for future modeling and scaling up of the indirect mineral carbonation process.

Understanding the acid dissolution of Serpentinites (Tailings and waste rock) for use in indirect mineral carbonation

Solid carbonates can be formed by indirect mineral carbonation using the pH swing method for CO2 storage. It occurs at low temperatures and pressures in four stages: acid dissolution, purification, carbonation, and recovery. Although acid dissolution requires short reaction time that favors the extraction of reactive metals, lack of knowledge about the effects of temperature, acid concentration and particle size on metal extraction reveals that it is a critical stage of indirect mineral carbonation. In order to employ mining waste for indirect mineral carbonation, acid dissolution of serpentinites, tailings (SERP-GO) and waste rock (SERP-MG) were investigated, and their performances were compared. A Taguchi experiment design was used to assess the parameters that influence the acid dissolution process. Hydrochloric acid was used in acid dissolution for Mg and Fe extraction from both, SERP-GO and SERP-MG, and the process parameters (temperature, acid concentration, particle size and excess acid) were evaluated for 2 h of reaction. According to signal-to-noise ratio analysis of the Taguchi method, the optimized condition for Mg extraction of both samples was at 70 °C, 4 M HCl, 69 μm and twice the excess acid. The results indicated that of Mg and Fe extraction from de samples was more efficient for SERP-GO (71% and 85%) than SERP-MG (33% and 31%). Based on these findings, it was possible to have a better understanding of the factors affecting the dissolution of serpentinite tailings, to develop a more effective process for the use of mining waste in the indirect mineral carbonation process.

3-D Geological Mapping of Rocks Potentially Suitable for Capturing Carbon Dioxide from the Atmosphere

Rapid increase of the Anthropocene ambient air CO2 concentration value is the main cause of the 1.2 o C global temperature rise creating the recent adverse climate and weather changes. Promising new methods to capture CO2 from the air are being developed but remain too expensive for worldwide applications. Mantle-derived rocks, primarily basalts, peridotites and serpentinites are likely to play an important role in future CO2 reduction because of relatively rapid disintegration of minerals (including olivine and serpentine) in these rocks potentially resulting in widespread CO2 capture. Examples to be discussed include artificially enhanced carbonization of water emitted from ophiolites, and acid dissolution of serpentinites resulting in indirect mineral carbonation by optimizing temperature and pressure conditions. Reconstruction of a large cone-shaped body of serpentinite situated within the Mount Albert peridotite intrusion in Québec is presented as an example of the rôle 3-D geologic mapping can play in future CO2 reduction efforts.

Aqueous mineral carbonation of Fe rich olivine by cation complexation using 2,2′-bipidine; concept validation and parameters optimization

Mineral Carbonation can significantly reduce GHG emissions and it is one of the most promising methods to sequester postcombustion CO2 emissions. In this work, a novel pH-swing indirect mineral carbonation approach by cation complexation using 2,2′-bipyridine has been developed. A mining residue mainly composed of Fe (II)-rich olivine was used as a feedstock. The leaching of the mining residue was performed using NH4HSO4 as solvent (pH 2–3), at 61 °C with 250 rpm of stirring during 2 h of reaction time. A total of 28 and 41 wt% of iron and magnesium was leached respectively. Then, the iron leachate was stabilized as [Fe(bipy)3]2+ complex using 2,2′-bipyridine avoiding iron hydroxide precipitation when the solution pH is raised using NaOH. Finally, the mineral carbonation reaction was performed, using a CO2 gas stream into the solution at alkaline pH. Different parameters such as the temperature, the pH, the reaction time and the vol% CO2 gas injected were optimized in batch mode reactions. This innovative approach allows the use of mild temperature and pressure conditions to obtain iron carbonates. The best results shows that 50 wt% of the CO2 gas stream have been removed from the gas phase giving a ratio of 0.11 kg of CO2 sequestered per kg of residues, which represent an important improvement regarding past studies on Fayalite.

Feasibility of a Mineral Carbonation Technique Using Iron-Silicate Mining Waste by Direct Flue Gas CO2 Capture and Cation Complexation Using 2,2′-Bipyridine

Mineral carbonation is gaining increasing attention for its ability to sequester CO2. The main challenge is doing it economically and energy-efficiently. Recently, many studies have focused on the aqueous reaction of carbon dioxide with the alkaline earth minerals such as serpentine, Mg-rich olivine and wollastonite. Nevertheless, Fe-rich olivines have been poorly studied because of their high energy demand, which make them unfeasible for industrial implementation. This article describes the feasibility of an indirect mineral carbonation process using silicic, Fe-rich mining waste with direct flue gas CO2 via iron complexation using 2,2′-bipyridine. The overall process was performed in three main steps: leaching, iron complexation, and aqueous mineral carbonation reactions. The preferential parameters resulted in a recirculation scenario, where 38% of Fe cations were leached, complexed, and reacted under mild conditions. CO2 uptake of 57.3% was achieved, obtaining a Fe-rich carbonate. These results are promising for the application of mineral carbonation to reduce CO2 emissions. Furthermore, the greenhouse gas balance had a global vision of the overall reaction’s feasibility. The results showed a positive balance in CO2 removal, with an estimated 130 kg CO2/ton of residue. Although an exhaustive study should be done, the new and innovative mineral carbonation CO2 sequestration approach in this study is promising.

Mineral carbonation of a pulp and paper industry waste for CO2 sequestration

This study focuses on the mineral carbonation to capture CO2 using an alkaline industrial waste, the grits, formed during the kraft pulp production process. An indirect mineral carbonation route was adopted, composed by two steps: first the extraction of calcium from the grits and second the precipitation of calcium carbonate. Firstly, four solvents were analyzed (HNO3, CH3COOH, NaOH and NH4Cl). Only HNO3 and CH3COOH have shown significant extraction efficiencies of 79.4 and 73.2 %, respectively, after 2 h at 30 °C. Kinetic tests demonstrated that equilibrium conditions are reached after 60 min. Since the nitric acid is a corrosive acid and with high associated costs, the acetic acid was selected for the dissolution of grits and extraction of calcium. The optimal conditions determined were an acetic acid concentration of 2 M, solid/liquid ratio of 30 g/L and temperature of 45 °C with an efficiency approximately of 77 %. In the second step, carbonation experiments were performed contacting the Ca-rich liquor, obtained from the extraction step, with a flux of pure CO2 gaseous in a stainless inox reactor. The optimal conditions determined were 30 °C and 30 bar, reaching a carbonation efficiency of 74 %, corresponding a CO2 sequestration capacity of 460 kg CO2/ton of grits.

Indirect mineral carbonation of phosphogypsum for CO2 sequestration

Abstract An indirect mineral carbonation of phosphogypsum with NaCl and NH4OH was proposed. The effect of different process conditions on the extracting process of CaSO4·2H2O in phosphogypsum, the carbonation ratio of Ca2+ in the CaSO4·2H2O lixivium, and the crystal phase and morphology of the product during the carbonation process were systematically discussed. NaCl was tried to be reused. Impacts of NaCl recycling number on the carbonation reaction efficiency and the crystal phase of the carbonated products were also studied. The leaching rate of Ca2+ in phosphogypsum was 49.42% under the optimized conditions. The carbonation ratio was 96.31%. The carbonated product composed of pure calcite, or vaterite and calcite was successfully prepared by adjusting the reaction conditions and NaCl cycle number. The performance of the obtained product met the Chinese standard requirements of HG/T 2226–2010. The proposed PG carbonation strategy showed potential prospect of application.

Simulating Continuous Counter-Current Leaching Process for Indirect Mineral Carbonation Under Microwave Irradiation

Mineral carbonation is a promising avenue to realize a deep reduction in carbon dioxide emissions. Though many methods were studied to improve the leaching ratio of mineral leached by ammonium salt, little attention has been received to the problem that the calcium leaching ratio increases while its concentration drops rapidly with the liquid-solid ratio increasing. The continuous counter-current leaching for mineral carbonation process under microwave irradiation is proposed in this study, and the results show that the simulating continuous counter-current leaching process in this article not only is beneficial to improve the leaching ratio and concentration of calcium ions in solution at the same time, but also increases the relative purity of calcium in leached solution. And the produced calcium carbonate products meet the requirements of industrial precipitation of calcium carbonate.

A Review of Mineral Carbonation from Industrial Waste

For relieving CO2 emissions and climate change, carbon sequestration and storage has been paid more attention. Mineral carbonation technology is a process that the calcium and/or magnesium-containing minerals react with CO2 to form stable carbonate precipitation, which in turn fixes CO2. It originates from natural rock weathering process that calcium and magnesium-containing rocks react with CO2 dissolved in rain water to form carbonate minerals. The source of mineral carbonation is the solid containing calcium and magnesium compound. The classification of mineral carbonation including direct and indirect mineral carbonation is indicated, and the descriptions of extraction by different extract agent have been given. The pretreatments, operation conditions and reaction kinetics are also discussed. Furthermore, the different processes by carbonizing from industrial waste are reviewed and the energy loss and cost are also described.

The Indirect Mineral Carbonation of Electric Arc Furnace Slag Under Microwave Irradiation

The indirect mineral carbonation of industrial residues is one of the potential technologies for CO2 sequestration. In this paper, the leaching and carbonation of electric arc furnace (EAF) slag under microwave irradiation was investigated. The experimental results show that the main reactive calcium-containing phase in the EAF slag carbonation process is calcium silicate, and the final leaching ratio of larger particles is lower than that of smaller particles due to the silica layer produced on the surface of the calcium silicate. The Drozdov equation with a self-impeding coefficient can describe EAF slag leaching kinetics under microwave irradiation. The explosive homogeneous nucleation phenomenon under microwave irradiation contributes to the thinning and narrowing of crystals. Microwave irradiation can inhibit the crystaltype transformation of vaterite.

Combined synthesis of Li4SiO4 sorbent with high CO2 uptake in the indirect carbonation of blast furnace slag process

Carbon capture, utilization and storage (CCUS) is one of the most important technological options to mitigate the effect of greenhouse gases on the global climate. A process for indirect mineral carbonation of blast furnace slag (BFS) with (NH4)2SO4 as a recyclable reagent has been proposed recently. Preparation of high-performance and high-value-added products from its by-products would further improve economy of the process. In this study, Li4SiO4, a lithium-based high temperature CO2 sorbent, was prepared using Li2CO3 or LiOH·H2O and the silica gel derived from the indirect carbonation process. As a comparison, two other silicon sources were also used in the synthesis. The sorbents thus-prepared were compared for their CO2 uptake performances. The results show that the sorbent synthesized with Li2CO3 and the BFS-derived silica gel at Li/Si molar ratio of 4 (Li2CO3-BFS-4) possesses the best CO2 uptake performance with a sorption capacity of 0.329 (g CO2/g sorbent) within 20 min. The replacement of Li+ in the Li4SiO4 crystal lattice by the impurity metal ions, Ti4+ and Al3+, entrained in the silica gel through co-precipitation during the mineralization process, enhanced the diffusion of Li+ and O2−, which might be responsible for the excellent CO2 uptake performance. The effect of absorption temperature, Li/Si ratio, CO2 concentration and the CO2 sorption/desorption cycling stability were also investigated systematically. Compared with other existing synthesis methods, the method presented in this work for high temperature CO2 sorbent of Li4SiO4 through mineral carbonation of blast furnace slag is more environment-friendly and economically attractive, thus with promise in industrial application.

Indirect mineral carbonation of chlorinated tailing derived from Ti‐bearing blast‐furnace slag coupled with simultaneous dechlorination and recovery of multiple value‐added products

AbstractThe chlorinated tailing (CT) generated during titanium extraction from Ti‐bearing blast‐furnace slag contains 3–5 wt% chlorides, which are hazardous to the environment. In this paper, a process for simultaneous CO2 mineralization, dechlorination, and recovery of multiple value‐added products was proposed to fully utilize the CT. In this process, Ti, Al, Mg, and Ca are extracted in the form of their sulfates via roasting with recyclable (NH4)2SO4 followed by leaching with dilute H2SO4. Their extraction ratios are 83.1%, 87.4%, 89.4%, and 92.1%, respectively. The chlorides are simultaneously removed from the CT as gaseous HCl with a dechlorination ratio of 98.5%. Subsequently, 89.5% of the Al and 97.5% of the Ti in the leaching liquor are successively recovered as NH4Al(SO4)2·12H2O with a purity of 99 wt% and titanium‐rich material with TiO2 of 62.5 wt%. The CaSO4‐rich leaching residue and MgSO4‐rich leachate, after complete depletion of the Al and Ti, are separately carbonated with a mixed gas of CO2 and NH3 with total CO2 capacity up to 279.8 kg CO2 per tonne CT. The preliminary economic evaluation shows that income from selling products after the deduction of the cost of primary raw materials reaches 200 $/tonne CT. The proposed route therefore provides a cost‐efficient alternative for comprehensive utilization of the polluting CT. © 2018 Society of Chemical Industry and John Wiley & Sons, Ltd.

Optimising the recovery of high-value-added ammonium alum during mineral carbonation of blast furnace slag

A route for the indirect mineral carbonation of blast furnace slag (BFS) with (NH4)2SO4 as a recyclable reagent has been proposed recently. To improve the economy of the process, an improved recovery route was put forward herein, guided by thermodynamic studies and phase diagrams. A purer, and thus higher-value-added byproduct, ammonium alum, can be obtained during the mineral carbonation of BFS. The effects of parameters such as roasting temperature and time, mass ratio of liquid to solid during leaching, and crystallisation temperature were investigated systematically. The results showed that the extraction reaction of BFS with ammonium sulfate occurred not only in the roasting stage but also in the leaching stage. The purity and recovery of aluminium as NH4Al(SO4)2·12H2O can reach 99.6% and 73%, respectively, at the optimal conditions. A preliminary economic evaluation predicted that this route can achieve 2.5 times the profit of the original process.