N. V. Kochetkova

Interaction of basalt with hydrochloric acid

Physicochemical modeling and experimental investigations are performed to study the interaction of basalt with hydrochloric acid. The equilibrium compositions of the liquid and solid phases of the basalt-hydrogen chloride-water system are calculated. The effects of the hydrochloric acid concentration and solid-to-liquid weight ratio on the phase composition of reaction products are quantified, and the degrees of extraction of iron, aluminum, calcium, sodium, and silicon into liquid are determined. The results of physicochemical modeling are compared with the experimental data. Conditions for selective extraction of the basalt components into solution are estimated.

Basalt leaching with orthophosphoric acid

Basalt leaching with orthophosphoric acid is studied by the method of isothermal dissolution. The total degree of dissolution of basalt and degrees of extraction into solution of separate elements as a function of temperature (20, 100°C), acid concentration (5–40%), and liquid-to-solid ratio are determined. Through the control of leaching conditions, it is possible to vary the coefficient of acidity of the basalt charge, decreasing the content of separate components. The possibility, in principle, of using this process for the optimization of charge composition in the manufacture of basalt-fiber materials and cast stone products is shown.

Interaction of basalt with orthophosphoric acid

Physicochemical modeling is used to study the decomposition of basalt by orthophosphoric acid. The equilibrium compositions of the liquid and solid phases of the Al-Fe-Ca-Mg-Na-Si-P-O-H system are calculated. The effects of the acid concentration and solid-to-liquid ratio on the composition of reaction products and the degrees of extraction of iron, aluminum, magnesium, calcium, sodium, and silicon into solution are determined. Conditions for selective extraction of the components into liquid phase are estimated.

Solubility of α-and β-gypsum in aqueous solutions of calcium, magnesium, and sodium chlorides

The interaction of multicomponent water-salt systems including calcium, magnesium, and sodium chlorides, gypsum, air, and water were studied by the methods of thermodynamic modeling. The solubility of α-CaSO4 · 2H2O and β-CaSO4 · 2H2O were determined in aqueous solutions of calcium, magnesium, and sodium chlorides and their mixtures at 25°C and carbon dioxide partial pressure of 10−1.53 kPa, metal chloride concentrations of 10−4 to 1.0 mol/kg H2O, and their molar ratio of 1: 1.

Physicochemical modeling of precipitating and dissolving of gypsum in chloride solutions

Physicochemical modeling is used to study the isolation of sulfate ions as α (β)-CaSO4 · 2H2O from aqueous solutions. The equilibrium compositions of liquid, solid, and gas phases of the NA2SO4-CaCl2-CO2-H2O system are calculated at 25°C, CO2 partial pressures of 10−1.53 kPa, CaCl2/Na2SO4 molar ratios of 0.2–3.0, and CaCl2 concentrations from 0.01 to 0.15 mol/kgH2O. The Gibbs energies of formation for α(β)-gypsum were determined from experimental solubility data on the α(β)-gypsum-air-water system by solving the inverse problem of physicochemical modeling. The data obtained are ΔG°f298 (α-CaSO4 · 2H2O) = −1796.446 kJ/mol and G°f298 (β-CaSO4 · 2H2)) = −1797.317 kJ/mol.

Physicochemical simulation and experimental study of interactions in the Si-Al-Ca-Mg-Fe-Na-Cr-Cl-H-O system

The interactions in the SiO2-Al2O3-CaO-MgO-Fe2O3-FeO-Na2O-Cr2O3-CaCl2-HCl-H2O system were studied by physicochemical simulation methods. Conditions for the most complete extraction of chromium into hydrochloric acid solutions were estimated. The equilibrium compositions of reaction products were calculated. The effect of calcium chloride on the solubility of chromium-containing minerals in hydrochloric acid was determined.

Physicochemical modeling and experimental study of the interaction in the Si-Al-Ca-Mg-Fe-Na-K-V-Cl-H-O system

Physicochemical modeling is used to study the interaction in the SiO2-Al2O3-CaO-MgO-Fe3O4-Na2O-V2O3(V2O5)-HCl-H2O system. The regions of formation of calcium (magnesium, iron) vanadates and various vanadium oxides are determined. The conditions for the most complete extraction of vanadium into hydrochloric acid solutions are estimated. The data obtained can be used to develop the procedure a the extraction of vanadium during the leaching of basalt with hydrochloric acid.

Simulation of the precipitation of calcium phosphates, sulfates, and carbonates from aqueous solutions of complex composition

The isothermal evaporation of aqueous solutions containing calcium, magnesium, and sodium carbonates, phosphates, sulfates, and chlorides was studied by physiochemical simulation methods. The equilibrium composition of the Ca(HCO3)2-Mg(HCO)2-H3PO4-H2SO4-NaCl-CO2-H2O system was calculated for T = 25°C, pCO2 = 10−1 − 103 Pa, pH 7.7–9.4, solution concentration factors of 1–10, H2SO4 concentrations of 10−4−9 × 10−4 mol/(kg H2O), an H3PO4 concentration of 2 × 10−5 mol/(kg H2O), and a NaCl concentration of 10−3 mol/(kg H2O). Conditions were determined for calcium precipitation as calcite, dolomite, gypsum, and hydroxylapatite. The results of simulation were used in the development of commercial-scale methods for stabilizing cooling solutions in circulating water supply systems.

Physicochemical principles of the decontamination and utilization of arsenic-containing waste

Thermodynamic computer simulation of heterogeneous multicomponent systems containing arsenic(III), arsenic(V), and calcium chlorides, hydrochloric acid, nitric acid, hydrogen peroxide, and oxygen is carried out for temperatures of 25–100‡C. The solute state of arsenic is found to influence the fugacities of arsenic trichloride and hydrogen chloride. Arsenic(III) oxidation in chloride solutions and distillation of arsenic-containing solutions in the presence of oxidants are studied experimentally to determine conditions for a rapid and virtually complete oxidation of arsenic in chloride solutions by nitric acid, ammonium nitrate, and hydrogen peroxide.