One of the problems to be solved in the course of exsolution of crystal sediments is to re-ceive products with desired technological properties. Two fundamentally different approaches can be applied for its resolution depending on method of supersaturation and requirements to the crystal sediments quality. In case of high supersaturation growth centers arise spontaneously and their number determines the properties of the final product to a large degree. The crystallization in the metastable region of solutions prevents spontaneous crystal nucleation and an introduc-tion of the seed phase becomes inevitable in this case. The nature of this phase determines the properties of the final product to some extent. During the real process there are mechanisms that disrupt the normal growth of crystals, causing distortion, leading to heterogeneous nucleation and recrystallization with degradation of seed material even. The line between these trends is the limiting supersaturation value, attrib-uted to the unit of phase interface. In this case the development of appropriate growth mecha-nisms is proportional to the deviation of the specific supersaturation of the solution from its value limit. The traditional source of heterogeneous nucleation is the mechanical interaction of the particles. The interaction probability is proportional to their concentration. Particles’ mass and their size becomes the most significant heterogeneous nucleation factor for seed particles of the same nature and morphology at the conditions of reproducible stream turbulence. Mathe-matical description of these trends has allowed to establish the dependence of the final particles’ size on the seed concentration in the feed pulp and to show the existence of a minimum number of particles of the final product. Experimental study of the of chemical sediments’ properties that depend on the seed amount, was carried out in relation to the breaking-up of aluminate solutions of alumina production. The process of selection of aluminum hydroxide has allowed to establish the amount of the seed aluminum hydrox-ide, resulting in a product of maximum size, and thus to confirm the theoretical conclusions.
The article analyses the results of an opinion survey of first-year students of the Chemistry and metallurgy department of the Mining University. The attention was concentrated on their reasons for entering the university, factors affecting their choice, academic activities and the studying conditions contentment, their views on future jobs and employment possibilities. Some recommendations for attracting attention of a greater number of potential applicants were given.
Materials of the kinetic analysis of multistage mass-transfer process at decomposition of aluminate solutions in alumina production are presented. It is shown that in the mass-transfer equation concentration indicators which take into consideration distribution of reagents and products in a diffusive layer can play a role of effective concentration. Results of experimental researches of crystallization streams on a various fraction structure are resulted.
На основании ранее полученной модели процесса декомпозиции в аппарате периодического действия составлена математическая модель процесса декомпозиции в проточном реакторе полного перемешивания с учетом ввода затравки в питание. На основе полученной модели процесса декомпозиции в проточном реакторе составлена модель процесса декомпозиции в каскаде из 14 реакторов проточного типа. Модели составлены в среде программного комплекса ReactOp. Решение уравнения модели выполнялось методом стационирования с использованием метода LSODA для решения обыкновенных дифференциальных уравнений.
The decomposition process of aluminate solution is briefly characterized. The main para-meters and reactions of the process are described. A mathematical model of the process is created taking into account the coarseness and its particle size distribution. Modeling of the decomposition process was carried out using the software package ReactOp.