Thermodynamic and kinetic study of CaS in aqueous systems

Tamm, Kadriann; Uibu, Mai; Kallas, Juha; Kallaste, Priit; Velts-Jänes, Olga; Kuusik, Rein

doi:10.1016/j.fuproc.2015.10.029

Cited by 7 publications

(3 citation statements)

References 25 publications

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“…The variability in sulfide concentrations is largely due to uncertainties in the experimentally determined solubility of pure CaS. In our previous work [29], the CaS solubility was determined after three hours of dissolution under both an inert atmosphere (2.29 × 10 -3 mol/L) and atmospheric conditions (2.74 × 10 -3 mol/L). The experimental results show a Fig.…”

Section: Solubility Resultsmentioning

confidence: 99%

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Leaching Thermodynamics and Kinetics of Oil Shale Waste Key Components

Tamm¹,

Kallaste²,

Uibu³

et al. 2016

Oil Shale

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Estonia is strongly dependent on locally mined oil shale which is the main fuel for power and oil production. Vast amounts of solid wastes are formed from circulating fluidized bed (CFB), pulverized firing (PF), and solid heat carrier (SHC) technologies, and are currently wet deposited in open-air fields. Both the utilization of newly produced ash and the management of historical deposits require an accurate thermodynamic modelling of complex mixtures. The authors investigated the leaching of the main water-soluble Ca-compounds from three types of oil shale mineral waste and developed a kinetic model that was used to determine the equilibrium constants and kinetic parameters of dissolution reactions for all three ash-water systems over a wide range of solid-to-liquid (S/L) ratio. For this, we prepared binary (Ca(OH) 2-CaSO 4 •2H 2 O-H 2 O) and ternary (Ca(OH) 2-CaSO 4 •2H 2 O-CaSH 2 O) model systems that reflect the composition of the three different ashes, and measured the kinetics of dissolution for both the model systems and industrial ash. Thermodynamic calculations were performed using HsC Chemistry ® 7.1 and Aspen Plus V8.6 while the leaching kinetics was simulated employing the MODEST 6.1 software package. By comparing the results obtained for our model systems with those obtained for industrial oil shale ash-water systems the authors were able to both verify that the model results coincided to a satisfactory degree with simulation data, and also propose models that may aid one to design shale ash processing technologies.

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Section: Solubility Resultsmentioning

confidence: 99%

“…The dissolution kinetics of Ca(OH) 2 [34,35] together with the mechanism of CaS dissolution [29,31,32,36] has been described by several authors. In our previous studies [22,37,38], the main characteristics of the Ca dissolution process for OS ash were established on the basis of mass transfer mechanisms.…”

Section: Dissolution Kinetics In Os Ash-water Systemsmentioning

confidence: 99%

Leaching Thermodynamics and Kinetics of Oil Shale Waste Key Components

Tamm¹,

Kallaste²,

Uibu³

et al. 2016

Oil Shale

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“…The main characteristics of the Ca dissolution process for OS ashes and the dissolution kinetics of main water-soluble Ca-compounds together with the dissolution mechanism has been described in previous studies [12], [24], [25].…”

Section: Dissolution Kinetics In Ash-solvent Systemsmentioning

confidence: 95%

Calcium Extraction From Estonian Industrial Wastes Based on Ammonium Solvents

Tamm¹,

Viires²,

Kuusik³

et al. 2017

WIT Transactions on Ecology and the Environment

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In Estonia electricity production is based mainly on local oil shale, the latter has been the country's most important mineral resources throughout the last century, up to today. In addition, the municipal solid waste incineration (MSWI) based heat and power production has developed rapidly. Industrial wastes from combustion processes are often rich in calcium and could be used as raw materials for CO2 sequestration and calcium carbonate production. Batch dissolution experiments were carried out to investigate Ca extraction from industrial wastes using ammonium salt solvents (NH4Cl, NH4NO3 and CH3COONH4). The dissolution equilibrium and dynamics of the main species was studied from the aspects of Ca extraction selectivity and environmental safety. Conductivity and pH change in the studied systems depends mainly on the solvent (its electrolyte ionic strength and ion mobility), addition of ashes basifies the systems. Test results indicated that Ca 2 + ion extraction was noticeably enhanced by ammonium salts as compared to water systems, using NH4NO3 solution gave the best results (extraction degree up to 95%). A simplified leaching mechanism for ash-solvent systems was presented, the latter can be used for future theoretical calculations. The study was focused on recovering of Ca from Estonian waste ashes, development of calcium carbonate as a commercial by-product will be the next step.

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