KINETICS OF HYDROCHLORIC ACID DECOMPOSITION OF MUSCOVITE MONOMINERAL

ABSTRACT

A method for conducting kinetic tests has been proposed for the decomposition of the muscovite monomineral using the hydrochloric acid method. The kinetic characteristics of muscovite sintering under isothermal conditions have been studied. It has been shown that the extraction of Al₂O₃ from the monomineral muscovite increases significantly with increasing temperature and sintering time. It was determined that the maximum extraction of Al₂O₃ occurs during sintering for 120 minutes and a sintering temperature of 1100°C, amounting to 91.6%. The kinetic and energy parameters of the technological process were calculated. It has been established that the kinetic curve lines characterizing the sintering of muscovite depending on the temperature and sintering time at 700 and 800°C are rectilinear; then, with an increase in temperature from 900 to 1150°C, they transform from rectilinear to parabolic.

АННОТАЦИЯ

Предложена методика проведения кинетических испытаний с целью разложения мономинерала мусковита солянокислотным способом. Изучены кинетические характеристики спекания мусковита в изотермических условиях. Показано, что извлечение Al₂O₃ из мономинерала мусковита значительно увеличивается при повышении температуры и времени спекания. Определено, что максимальное извлечение Al₂O₃ происходит при спекании в течение 120 минут и температуре спекания 1100°C, составившее 91,6%. Рассчитаны кинетические и энергетические параметры технологического процесса. Установлено, что кинетические кривые линии, характеризующие спекание мусковита в зависимости от температуры и времени спекания при 700 и 800°C являются прямолинейными, далее при увеличении температуры от 900 до 1150°C из прямолинейных переходят в параболические.

Keywords: kinetic and energy parameters, hydrochloric acid decomposition, muscovite monomineral.

Ключевые слова: кинетические и энергетические параметры, солянокислотного разложения, мономинерала мусковита.

INTRODUCTION

The problems of rational use of mineral resources, minerals [1–3], alloys [4, 5], melt [6] and raw materials [7, 8] are solved through the development of technological solutions for the extraction, analyze and processing of mineral resources, which are also environmentally friendly technologies [1–3].

The purpose of the work is to study the kinetics of the solar acid decomposition of the monomineral Muscovit to obtain useful components.

RESEARCH METHODOLOGY The methodology for the study of the decomposition of monomineral muscovit in a solar acid method covers the effects of temperature, duration of the sintering process and the mass ratio of components to increase the content of Al₂O₃ as part of the speck. Kinetic studies were carried out for hydrochloric acid extraction of aluminum oxide from muscovite-containing raw materials. The resulting kinetic line curves follow a first-order differential equation:

The equation for plotting the dependence of Lg (1-α) on decomposition time is mathematically converted into the following equation:

The kinetics of the decomposition process was studied under isothermal conditions with the exposure of the shiht in the muffle furnace for 10-50 minutes.

DISCUSSION RESULTS The kinetic curves of the line characterizing the course of this process are up to 60°C straight, and over 60°C acquire a parabolic character. For the decomposition process to proceed, the temperature region >80°C is of practical interest, in which almost complete extraction of aluminum oxide is achieved within a short period of time. Hydrochloric acid decomposition of muscovite-containing raw materials with an increase in temperature from 25 to 96°C and decomposition time to 100 minutes, Al₂O₃ recovery increases slightly, from only 2.9 to 29.9% (fig. 1).

Further kinetic studies were devoted to determining the activation energy of the hydrochloric acid decomposition process of muscovite-containing ore. For this purpose, a graph was constructed in the coordinates Lg1/(1-α) and time (τ) (fig. 2).

Figure 1. Effect of decomposition time on Al₂O₃ recovery at different decomposition temperatures

These dependence lines obtained a negative slope, which is equal to k/2.303. The values of the activation energy (E) and the pre-exponential factor (ko) in were calculated based on the Arrhenius equation and the plotted graph using the following equations: 

Figure 2. Dependencies: (a) lg (1/(1- α)) on time at different temperatures, (b) Lgk on absolute reverse temperature.

As part of the study of the kinetic parameters of the process, the dependence of the logarithm of the extraction rate constant Lgk on the absolute reverse temperature (1/T∙10³) was determined. It was shown that the calculation points make up an almost straight line, the slope of which was used to calculate the activation energy (E) of the hydrochloric acid decomposition of muscovite-containing raw materials. The value of E turned out to be 38.5 kJ/mol. According to the calculated activation energy value, it can be concluded that hydrochloric acid decomposition occurs at the boundary of the kinetic and diffusion regions (table). Also, for the hydrochloric acid decomposition of muscovite monomineral, kinetic parameters were studied, the study was carried out with variations in a wide range of parameters such as temperature in the range from 25 to 96°C, the decomposition time varied in the range of 30-45-60-75-90-105-120 minutes. For decomposition, HCl (20%) was used, taken in 100% of the stoichiometric amount from the calculation of the formation of aluminum, iron and potassium chlorides. In each experiment, kinetic curves of the lines corresponding to the recovery of aluminium oxides (Al₂O₃) and iron oxides (Fe₂O₃) from the muscovite-containing feedstock were obtained (table).

Table

Effect of temperature and time of hydrochloric acid decomposition of muscovite monomineral on Al₂O₃ and Fe₂O₃ recovery

CONCLUSIONS

The mechanisms of decomposition of individual minerals and extraction of compounds Al, Fe, Na and K into productive solutions in the form of chlorides of these chemical elements are influenced by various external factors, among which the main ones are the following – temperature and time of decomposition, HCl concentration and its dosage, these parameters often include the size of mineral particles after their grinding.

The kinetic crooked lines characterizing the sintering process of the monomineral of the muscovite from temperature are straightforward (700-800 ° C) and parabolic (900-1150 ° C). It was established that the maximum extraction of AL2O3 from the monomineral of the muscovit occurs when sintering for 120 minutes and a sintering temperature of 1100 ° C, which was 91.6%.

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