ANALYSIS OF PHASE EQUILIBRIA IN THE FOUR-COMPONENT SYSTEM CASO₄ - CACO₃ - CAF₂ - H₂O FOR OPTIMIZATION OF INDUSTRIAL WASTEWATER
Rubrics: 1. CHEMISTRY
Authors:
1.
Tadzhikskiy gosudarstvennyy pedagogicheskiy universitet im. S. Ayni, Dushanbe, Respublika Tadzhikistan
2.
Tadzhikskiy gosudarstvennyy pedagogicheskiy universitet im. S. Ayni, Dushanbe, Respublika Tadzhikistan
3.
Tadzhikskiy gosudarstvennyy pedagogicheskiy universitet im. S. Ayni, Dushanbe, Respublika Tadzhikistan
4.
Tadzhikskiy gosudarstvennyy pedagogicheskiy universitet im. S. Ayni, Dushanbe, Respublika Tadzhikistan
Type:
Article
Pages:
from 31
to 36
Status:
Published
Received:
22.10.2025
Accepted:
11.02.2026
Published:
26.02.2026
Language:
Russian
Keywords:
PHASE EQUILIBRIA, SOLUBILITY, CRYSTALLIZATION, CASO4, CACO3, CAF2, INDUSTRIAL WASTEWATER, WASTE DISPOSAL, ALUMINUM PRODUCTION, PHASE DIAGRAM
Abstract:
This paper presents an analysis of phase equilibria in the four-component system CaSO₄ - CaCO₃ - CaF₂ - H₂O, essential for optimizing industrial wastewater treatment. The system is considered within the context of the six-component system Na, Ca // SO₄, CO₃, HCO₃, F - H₂O, studied to develop waste disposal methods for large industrial facilities, such as the Tajik Aluminum Plant. The wastewater from such plants contains complex compounds of fluorides, carbonates, and calcium sulfates, interacting within a multi-component system. This requires a detailed study of phase equilibria to ensure control over crystallization and dissolution processes for effective chemical management of the water composition. The solubility method used in this study enabled the identification of key parameters influencing the crystallization of solid phases in the CaSO₄ - CaCO₃ - CaF₂ system at 50°C, focusing on the impact of concentration and temperature on crystal formation. The system's invariant points, where co-crystallization of gypsum (CaSO₄·2H₂O), calcite (CaCO₃), and fluorite (CaF₂) is possible, were identified. The constructed solubility diagram shows the crystallization field boundaries, allowing predictions of component behavior under production conditions and an assessment of their stability. The study's results indicate the effectiveness of the solubility method for analyzing such systems where fluorides, carbonates, and sulfates interact in saturated solutions. New methods for precipitating fluorides and carbonates are proposed, which may be applied to purify wastewater from aluminum plants. Thus, the findings contribute to developing more environmentally friendly technologies and enhance the overall sustainability of processes for removing harmful impurities from water.
This paper presents an analysis of phase equilibria in the four-component system CaSO₄ - CaCO₃ - CaF₂ - H₂O, essential for optimizing industrial wastewater treatment. The system is considered within the context of the six-component system Na, Ca // SO₄, CO₃, HCO₃, F - H₂O, studied to develop waste disposal methods for large industrial facilities, such as the Tajik Aluminum Plant. The wastewater from such plants contains complex compounds of fluorides, carbonates, and calcium sulfates, interacting within a multi-component system. This requires a detailed study of phase equilibria to ensure control over crystallization and dissolution processes for effective chemical management of the water composition. The solubility method used in this study enabled the identification of key parameters influencing the crystallization of solid phases in the CaSO₄ - CaCO₃ - CaF₂ system at 50°C, focusing on the impact of concentration and temperature on crystal formation. The system's invariant points, where co-crystallization of gypsum (CaSO₄·2H₂O), calcite (CaCO₃), and fluorite (CaF₂) is possible, were identified. The constructed solubility diagram shows the crystallization field boundaries, allowing predictions of component behavior under production conditions and an assessment of their stability. The study's results indicate the effectiveness of the solubility method for analyzing such systems where fluorides, carbonates, and sulfates interact in saturated solutions. New methods for precipitating fluorides and carbonates are proposed, which may be applied to purify wastewater from aluminum plants. Thus, the findings contribute to developing more environmentally friendly technologies and enhance the overall sustainability of processes for removing harmful impurities from water.
Keywords:
PHASE EQUILIBRIA, SOLUBILITY, CRYSTALLIZATION, CASO4, CACO3, CAF2, INDUSTRIAL WASTEWATER, WASTE DISPOSAL, ALUMINUM PRODUCTION, PHASE DIAGRAM
PHASE EQUILIBRIA, SOLUBILITY, CRYSTALLIZATION, CASO4, CACO3, CAF2, INDUSTRIAL WASTEWATER, WASTE DISPOSAL, ALUMINUM PRODUCTION, PHASE DIAGRAM
