Practical Multiphase Models for Aqueous Process Solutions

Abstract

Multicomponent equilibrium models for aqueous salt solutions have been developed with the novel ChemSheet program. The calculations are based on the minimization of the Gibbs free energy of the reaction mixtures. For the excess Gibbs energies of the solute species, the Pitzer interaction model with temperature-dependent parameters was used. The results of the ChemSheet multiphase calculations have been verified with experimental or reference data. With the presented modeling technique, reaction kinetics can also be taken into account for specific systems using the Gibbs energy approach. These methods have been applied to the aqueous chemistry of calcium carbonate and sulfate in the wet-end solutions of papermaking. ChemSheet models are applicable in spreadsheets and can be customized for the needs of an industrial user.

Environmental aspects of metals removal from waters and gold recovery

“…The proposed process was modelled using ChemSheet for thermodynamic modelling of chemically reactive systems including hydrometallurgical separation of metals from water. The software is a thermodynamically rigorous computation platform based on the minimization of the Gibbs energy of multiphase and multicomponent systems.…”

Oxygen Solubility in Industrial Process Development

“…The results of the Gibbs energy minimization yield the equilibrium compositions at given temperature and total pressure according to a functional description of the ideal and excess Gibbs energy terms. The modern calculation techniques allow the user to choose the model for excess Gibbs energy 3,4 like the Debye-Hu ¨ckel and Pitzer models for aqueous salt solutions. The selection of the activity coefficient model depends on the validity of the model in different temperature, pressure, and composition ranges.…”

“…Dissolved gases are commonly used as reactive chemical agents in processes in atmospheric conditions as well as in elevated pressures. The experimental and modeling results in gas solubility phenomena are important in many metallurgical and pulp and paper processes. − The processes are commonly controlled by the partial pressure of the reactive gas, temperature, and chemical composition of the reactive solution. Both measurements and simulations are needed to yield sufficient information for practical applications. − Modern computer-aided calculation methods extend the possibilities of using chemical thermodynamics for industrially important systems, which often involve dynamic reactive multiphase and multicomponent solutions.…”

“…The experimental and modeling results in gas solubility phenomena are important in many metallurgical and pulp and paper processes. [1][2][3] The processes are commonly controlled by the partial pressure of the reactive gas, temperature, and chemical composition of the reactive solution. Both measurements and simulations are needed to yield sufficient information for practical applications.…”

Gibbs energy approach for aqueous processes with HF, HNO3, and CO2CaCO3

“…Calcium carbonate is used as a filler in making fine paper grades. Recycling of calcium‐containing paper influences the acid–base chemistry of the papermaking process (Koukkari et al, 2001). Carbon dioxide (CO 2 ) gas can be used as an alternative reactive acidifying chemical instead of sulfuric acid at the wet end of a paper machine in calcite‐buffered solutions typically including 1–2 wt % of fibers (Pakarinen and Leino, 2000).…”