Experimental determination of calcite solubility and the stability of aqueous Ca– and Na–carbonate and –bicarbonate complexes at 100–160 °C and 1–50 bar pCO2 using in situ pH measurements

Bychkov, Andrew Y.; Bénézeth, Pascale; Pokrovsky, Oleg S.; Shvarov, Yu. V.; Castillo, Alain; Schott, Jacques

doi:10.1016/j.gca.2020.09.004

Cited by 7 publications

(8 citation statements)

References 73 publications

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“…At 25 °C, the retrograde solubility of calcite, K SP‑cal , is 10 –8.48 , for the reaction Ca(CO 3 ) ⇌ Ca 2+ + CO 3 2– , and decreases to ca. 10 –11.5 at 205 °C . For our synthetic multi-REE polymorphs, we will use kozoite-(Nd) and hydroxylbastnäsite-(Nd) as thermodynamic proxies (see the rationale in SI Text S3).…”

Section: Resultsmentioning

confidence: 99%

Utilization of Eggshell Waste Calcite as a Sorbent for Rare Earth Element Recovery

Rateau,

Maddin,

Szucs

et al. 2024

ACS Omega

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The green energy transition requires rare earth elements (REE) for the permanent magnets used in electric cars and wind turbines. REE extraction and beneficiation are chemically intensive and highly damaging to the environment. We investigated the use of eggshell waste as a sustainable alternative sorbent for the capture and separation of REE from aqueous solutions. Hen eggshell calcite was placed in multi-REE (La, Nd, Dy) solutions at 25 to 205 °C for up to 3 months. A pervasive diffusion of the REE inside the eggshell calcite was observed along pathways formed by the intracrystalline organic matrix and calcite crystal boundaries. At 90 °C, kozoite (REECO 3 OH, orthorhombic) spherulites precipitate on the surface of the dissolving calcite. At 165 and 205 °C, an interface-coupled dissolution−precipitation mechanism is observed, resulting in the complete dissolution of the calcite shell and its pseudomorphic replacement by polycrystalline kozoite. At 205 °C, kozoite is slowly replaced by hydroxylbastnasite (REECO 3 OH, hexagonal), the stable form of the rare earth hydroxycarbonate polymorphs. Our results demonstrate two potential applications of eggshell waste for the uptake of rare earth elements in solution: at low temperatures, as a mixed organic−inorganic adsorbent and absorbent, given sufficient sorption time; and at higher temperatures, as an efficient sacrificial template for the precipitation of rare earth hydroxycarbonates.

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Section: Resultsmentioning

confidence: 99%

Utilization of Eggshell Waste Calcite as a Sorbent for Rare Earth Element Recovery

Rateau,

Maddin,

Szucs

et al. 2024

ACS Omega

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“…In-line pH sensors, designed for continuous data measurement, have been used in the biotech and pharmaceutical industries for a number of years [48][49][50]. However, there are a limited number of electrode systems capable of providing in-situ pH measurements at temperatures greater than 100 • C and at pressures greater than saturated water pressure.…”

Section: Industrial Applications Of In-line Ph Measurement Under Chal...mentioning

confidence: 99%

pH, the Fundamentals for Milk and Dairy Processing: A Review

Aydogdu

O’Mahony

McCarthy

2023

Dairy

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The ability to measure and capture real-time unit operational data has significant benefits during dairy processing, whether it is the basics, such as measuring temperature, pressure, and flow rates, or more recent developments in the case of in-line viscosity and product-compositional measurements. This rapid data collection has helped increase profitability by reducing energy costs, minimizing product loss, and allowing automated control. Advances in technology have allowed for in-line measurements of the composition and some physical attributes such as particle size and viscosity; however, an attribute that spans both compositional and physical attributes is pH, directly influenced by composition but also environments, such as temperature and dry matter content. pH is measured for a plethora of reasons, such as a measure of milk quality (microbial spoilage), acidification of casein, cheese production, maintaining optimum conditions during protein hydrolysis, etc. However, very little is published on the fundamentals of pH and pH measurement in dairy processing; rather, it is usually a cause-and-effect phenomenon. This review visits one of the oldest analytical considerations in the dairy industry and re-examines how it is affected by product composition and processing conditions.

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Section: Solubilitymentioning

confidence: 99%

“…Beginning with Engel in 1889, many researchers have studied the solubility of calcite under different conditions [31,32]. The pKsp (298.15 K) values of calcite are reported to be around 8.40 [33,34].The saturated solution compositions of fluorite and calcite are shown in Figure 2 As illustrated in the diagrams, the main components of fluorite within the pH8-10 (conventional fluorite flotation pH range) are Ca 2+ and F − , and the main components of calcite are Ca 2+ , CO3 2− and HCO3 − .The results of solution chemistry calculations and XPS spectral analysis in several previous studies [36,37] showed that the dissolved F − and CO3 2− can adsorb on the surface of calcite and fluorite, respectively and form the corresponding calcium-containing compounds, which homogenizes the chemical properties of fluorite and calcite surfaces.…”

Section: Peer Reviewmentioning

confidence: 99%

Difficulties and Recent Achievements in Flotation Separation of Fluorite from Calcite—An Overview

Huang

Zhang

Li³

et al. 2022

Minerals

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As an important strategic non-metallic mineral resource, fluorite has been widely used in various industrial fields, such as metallurgy, optics and semiconductor manufacturing, as well as fluorine-related chemical engineering. Since the major gangue minerals of fluorite ore are silicate and carbonate ones, flotation is the main beneficiation method for the concentration. Compared with the relatively easy operation for silicate-type fluorite ore, fluorite concentration from calcite has always been the most difficult challenge in the field of mineral processing. In this review, analyses of the fundamental reasons for the difficulties of flotation separation of fluorite from calcite are performed, from the similar surface properties of both calcium minerals to the deterioration by the interference of dissolved ions in the pulp during grinding and flotation. Recent achievements in the flotation separation of fluorite from calcite as the main contents are comprehensively summarized, covering all aspects of flotation reagents of collectors, depressants and modifiers. Finally, successful examples of industrial practices forfluorite and calcite flotation separation are introduced. This overview provides a detailed and comprehensive reference source for the current research status of fluorite and calcite flotation separation, and some suggestions for future research are provided.

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Experimental determination of calcite solubility and the stability of aqueous Ca– and Na–carbonate and –bicarbonate complexes at 100–160 °C and 1–50 bar pCO2 using in situ pH measurements

Cited by 7 publications

References 73 publications

Utilization of Eggshell Waste Calcite as a Sorbent for Rare Earth Element Recovery

Utilization of Eggshell Waste Calcite as a Sorbent for Rare Earth Element Recovery

pH, the Fundamentals for Milk and Dairy Processing: A Review

Difficulties and Recent Achievements in Flotation Separation of Fluorite from Calcite—An Overview

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Experimental determination of calcite solubility and the stability of aqueous Ca– and Na–carbonate and –bicarbonate complexes at 100–160 °C and 1–50 bar pCO2 using in situ pH measurements

Cited by 7 publications

References 73 publications

Utilization of Eggshell Waste Calcite as a Sorbent for Rare Earth Element Recovery

Utilization of Eggshell Waste Calcite as a Sorbent for Rare Earth Element Recovery

pH, the Fundamentals for Milk and Dairy Processing: A Review

Difficulties and Recent Achievements in Flotation Separation of Fluorite from Calcite—An Overview

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Product

Resources

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Experimental determination of calcite solubility and the stability of aqueous Ca– and Na–carbonate and –bicarbonate complexes at 100–160 °C and 1–50 bar pCO2 using in situ pH measurements