Dissolution Kinetics Of Ulexite Research Articles

Cinética de la disolución de ulexita calcinada en soluciones de sulfato de amonio

La ulexita es uno de los minerales de boro, que incluye una cantidad considerable de agua de hidratación. Se puede usar como materia prima en la producción de compuestos de boro. Una parte del agua existente en la composición química de la ulexita puede eliminarse de la matriz sólida aplicando tratamiento de deshidratación que permite obtener una estructura porosa, que aumenta la velocidad de reacción. En el presente trabajo, se estudió el efecto de la temperatura de deshidratación sobre la cinética de disolución de ulexita en soluciones de sulfato de amonio, en un reactor discontinuo estudiando los parámetros de concentración de solución, relación sólido/líquido, velocidad de agitación y la temperatura de reacción. Se determinó que la velocidad de disolución del material calcinado aumentaba al aumentar la concentración de la solución y la temperatura de reacción y con la disminución de la relación de sólido/líquido. La velocidad de disolución más alta se alcanzó con la muestra calcinada a 150 °C. Se encontró que la velocidad de disolución se ajusta al modelo pseudohomogéneo de primer orden. La energía de activación del proceso de disolución se estimó en 42 kJ·mol-1.

Kinetic Investigation of Reaction Between Mineral Ulexite and Citric Acid

In this study, the dissolution kinetics of ulexite, a sodium-calcium-borate hydrate (Na2O·2CaO·5B2O3·16H2O) in citric acid solutions was investigated in a batch reactor. The rate of dissolution can be expressed according to surface chemical reaction controlling with changing fluid reactant concentration. The activation energy of the process was found to be 39.4 kJ/mol.

Kinetic investigation of reaction between ulexite ore and phosphoric acid

One of the most important boron minerals, ulexite, is dissolved in aqueous phosphoric acid to produce boric acid whereby sodium and calcium phosphates are formed as byproduct. The dissolution of ulexite in aqueous phosphoric acid solutions was investigated in a batch reactor employing the parameters of stirring speed, particle size, temperature, solid/liquid ratio and acid concentration. It was found that the dissolution rate increased with stirring speed and reaction temperature. However, increasing the particle size and solid/liquid ratio decreased the dissolution rate. The conversion rate increased until 0.7 mol L − 1 with increasing acid concentration and then decreased with increasing acid concentration. The dissolution kinetics of ulexite was examined according to heterogeneous and pseudo-homogeneous reaction models, and it was found that the dissolution rate was controlled by product layer (or ash layer) diffusion process. The experimental data were tested by graphical and statistical methods and it was found that the following models for two different concentration levels were best fitted to the experimental data. 1 − 3 ( 1 − x ) 2 / 3 + 2 ( 1 − x ) = [ 197.72 D − 1.74 C 0.63 ( S / L ) − 1.1 ( W ) 2.01 e − 26.17 / R T ] . t ( C ≤ 0.7 M ) 1 − 3 ( 1 − x ) 2 / 3 + 2 ( 1 − x ) = [ 46.97 D − 1.51 C − 0.37 ( S / L ) − 1 ( W ) 1.87 e − 26.17 / R T ] . t ( 0.7 M ≤ C ) where X is the conversion fraction, D is the particle size, C is the acid concentration, S/ L is the solid-to-liquid ratio, W is the stirring speed, t is the reaction time, and T is the reaction temperature. The activation energy for the process was found to be approximately 26.17 kJ mol − 1.

Dissolution kinetics of ulexite prepared under different calcination temperatures

Ulexite is one of the boron minerals used as a raw material in the production of boron compounds. It contains a substantial amount of hydration water. Using calcination methods, the B2O3 grade of ulexite can be increased. In this study, the effect of calcination temperature on dissolution kinetics of ulexite in ammonium chloride solutions was investigated in a batch reactor employing the parameters of concentration, solid-to-liquid ratio and reaction temperature. It was found that the dissolution rate increased with increasing concentration and reaction temperature and with decreasing solid-to-liquid ratio. The highest dissolution rate was obtained with the sample calcined at 413 K. It was determined that the dissolution rate fit to the second-order pseudo-homogeneous model. The activation energy of this dissolution process was found to be 64.3 kJ/moL.

Dissolution kinetics of ulexite in ammonium nitrate solutions

In this study the dissolution kinetics of the boron mineral ulexite, a sodium-calcium-borate hydrate (Na 2O·2CaO·5B 2O 3·16H 2O), in ammonium nitrate solutions was investigated in a batch reactor. The effects of solution concentration, particle size, solid/liquid ratio, and reaction temperature on the dissolution rate were determined. It was found that the dissolution rate increased with increase in ammonium nitrate concentration and reaction temperature, and with decrease in particle size and solid/liquid ratio. No effect of stirring speed was observed on the conversion. It was determined that the dissolution rate fit to the chemical reaction control model. The activation energy of this dissolution process was found to be 58.2 kJ/mol.

Dissolution kinetics of ulexite in perchloric acid solutions

The dissolution kinetics of ulexite in perchloric acid solutions was investigated. The effect of perchloric acid concentration, particle size, stirring speed and reaction temperature on the dissolution rate of ulexite was determined. It was found that the rate of dissolution increased with increasing perchloric acid concentration, stirring speed, reaction temperature and with decreasing particle size. The dissolution rate may describe the Avrami model. The activation energy was calculated 19.12 kJ mol − 1 .

Dissolution Kinetics of Ulexite in Ammonium Sulfate Solutions

The dissolution kinetics of ulexite in ammonium sulfate solutions was investigated. The effects of ammonium sulfate concentration, particle size, solid/liquid ratio, stirring speed, and reaction temperature on the dissolution rate have been evaluated. It was found that the dissolution rate increased with increasing ammonium sulfate concentration, stirring speed, and reaction temperature. However, increasing the particle size and solid/liquid ratio decreased the dissolution rate. Experimental data were examined by the heterogeneous and homogeneous models. The heterogeneous diffusion-controlled ash or product layer may describe the dissolution rate. The following mathematical model was used to represent the reaction kinetics: 1 − 3(1 − X)2/3 + 2(1 − X) = 3.9 × 107C0.64D-0.85(S/L)-1.06ω0.40e-10050/Tt, where X is the fractional conversion, C the ammonium sulfate concentration, D the particle size, S/L the solid-to-liquid ratio, ω the stirring speed, T the reaction temperature, and t the reaction time.

Dissolution kinetics of ulexite in ammonia solutions saturated with CO 2

The dissolution kinetics of ulexite in ammonia solutions saturated with carbon dioxide were investigated. Experiments investigating the following parameters: concentration of ammonia; particle size; stirring speed; solid to liquid ratio; reaction temperature; and carbon dioxide flow rate; showed that ulexite can be dissolved completely in solutions of carbonic acid at atmospheric conditions. It was found that the dissolution rate increased with increasing ammonia concentration, reaction temperature and calcination temperature, and with decreasing particle size and solid to liquid ratio. It was observed that the flow rate of carbon dioxide and stirring speed have almost no effect on the dissolution rate. It was determined that the dissolution rate of ulexite can be described by a first-order pseudo-homogeneous reaction model and an empirical equation for the process was developed: −1 n(1−X)=1.0×10 5(C A) 0.22(d) −0.92( S L ) −0.54 exp( 6600 T −t) where C A is the ammonia concentration, d the initial particle size and ( S L ) the solid to liquid ratio. The activation energy for the process was found to be approximately 55 kJ mol −1.

Dissolution Kinetics of Ulexite in CO<SUB>2</SUB>-Saturated Water

Dissolution Kinetics of Ulexite in CO<SUB>2</SUB>-Saturated Water

Dissolution Kinetics of Ulexite in CO2-Saturated Water

The dissolution kinetics of ulexite in CO2-saturated water have been investigated with respect to the effects of particle size and solution temperature. The effect of preheating the mineral up to 300°C prior to contact with the aqueous phase was also examined. The calcination of ulexite enhanced the dissolution rates which reached a maximum when ulexite was heated to 150°C. The activation energy for this dissolution reaction was determined to be 51.7 kJ mol−1. Résumé Les cinétiques de dissolution de l'ulexite dans l'eau saturée en CO2 ont été étudiées en fonction de la taille de particule et de la température de la solution. L'effet du préchauffage du mineral jusqu'é 300°C avant l'incorporation dans la phase aqueuse a aussi été analyse. La calcination de l'ulexite augmente le taux de dissolution qui atteint un maximum lorsque la température de l'ulexite est de 150°C. L'energie d'activation de cette réaction de dissolution a été évaluée a 51.7 kJ mol−1.

Dissolution kinetics of ulexite in water saturated by sulphur dioxide

AbstractThe dissolution kinetics in SO2‐saturated water of ulexite, a sodium calcium borate, have been studied. The effect of particle size, gas flow rate and temperature were determined. Ulexite dissolution rates increased with decrease in particle size, with increase in temperature and were not affected by the flow rate of SO2. The activation energy for the dissolution was calculated as 58‐01 kJ mol−1.