Population balance model is crucial for improving the method of aluminum hydroxide massive crystallization and enhancing the quality of control over industrial precipitation trains. This paper presents the updated population balance model, which can be used for simulation of industrial-scale precipitation. Processes of birth-and-spread and particle breakage are considered integral parts of the precipitation process along with secondary nucleation, growth and agglomeration of particles. The conceptual difference of the proposed system of equations is its ability to reproduce the oscillatory process that occurs in precipitation circuits as a result of cyclic changes in the quality of the seed surface. It is demonstrated that self-oscillations can occur in the system without any external influence. The updated model is adjusted and verified using historical industrial data. The simulation of seed-recycle precipitation circuit showed an exact correspondence between the calculated dynamic pattern of changes in particle size distribution of aluminum hydroxide and the actual data.
Рассмотрены способы численного расчета работы вращающейся печи. Описаны особенности моделирования теплового режима работы вращающейся печи с учетом изменения температуры материала и футеровки по длине печи, запыленности газового потока.
Рассмотрены способы и возможность расчета горения газа в турбулентном потоке. Описаны основные уравнения, описывающие процесс горения, для определения длины факела и распределения температуры в факеле. Показаны программные продукты для расчета и моделирования сжигания газа.
The mathematical description of the technology of firing of lump limestone raw materials in a shaft kiln equipped with burner devices providing preliminary gas combustion is given. The model takes into account the peculiarities of the process of dissociation of carbonate component of raw materials, uses equations describing the kinetics of the drying process, conditions of counter-flow of gases and material, regularities of distribution of material and gas flows along the cross-section and height of the shaft. The developed model represents a stationary two-dimensional solution of the problem.
The results of numerical studies of aerodynamics of the dense layer and hollow regions of the shaft kiln; mechanism of material movement; kinetics of lump limestone dissociation are presented. A mathematical model of a shaft kiln with distributed parameters is developed. A computer program allowing to carry out predictive calculations of firing and to optimize mode and determining geometrical parameters of the installation is made. Proposals for modernization of operating shaft furnaces are made.
A numerical approach to solving the problem of dissociation of natural calcium carbonate represented by a piece of limestone or chalk having a spherical shape is considered. The modeling takes into account the mutual influence of thermal and mass transfer factors, as well as thermochemical kinetics of the dissociation process.
The paper describes the operation and control system of modern press filters on the example of LaroxPF filters installed in the roasting shop of Pechenganickel Combine. The main problems of improving and optimizing the operation of press filters are identified and a method of their solution is proposed by drawing up regression dependencies for the main characteristics of filter operation based on experimental data.
Recommendations on optimization and forcing of heating rates in roasting furnaces are given. Apparatuses for heat exchange intensification in rotary kilns are proposed, their advantages are shown. Constructive and operational characteristics of a high-performance compacted kiln are given.
Statistical processing of experimental data on filterability of slurries of a number of metallurgical enterprises in the CIS on filters of FPACM ( Larox PF ) type was carried out. Regression dependences of residual moisture content and volume of collected filtrate on characteristics of initial pulp and parameters of dewatering process for copper and zinc concentrates were obtained. The efficiency of pulp dewatering process at press filters is estimated and the ways of its further improvement are indicated. Optimal parameters of the combined filtration process for a number of hydrometallurgical pulps are determined and recommendations for improvement of its technical and economic efficiency are given.
The aim of this work is to improve the mathematical description and hardware design of separation processes of process water and discharge solutions of hydrometallurgical production. The paper shows that automated filter presses of FPAKM type and their improved models - LAROX OY filter presses can be used with high efficiency at modern hydrometallurgical plants, which is confirmed by the results of laboratory tests. The tests were performed on a special laboratory filter press manufactured in Finland, which allows simulating the operation of large industrial filter presses with high precision. During the experiments the samples of technological pulps of some domestic enterprises were tested. When evaluating the efficiency of separation of suspensions on filter presses it is more rational to use the method of mathematical modeling. For this purpose, the available literature on the processes of filtration of suspensions, washing and drying of the resulting sediment, hydrodynamics and heat transfer in the dispersed media has been analyzed. Based on the collected data, a generalized mathematical description of these processes is made. This model can find wide application in practice at designing, selection and adjustment of automated filter-presses, and at its inclusion into the software of the latter it will allow increasing the efficiency of their work.
The basic dependences of filtration, flow formation and drying processes given in various scientific papers are generalized. A detailed algorithm for calculating these processes has been developed, taking into account hydrodynamic and heat and mass transfer patterns of the above processes. On the basis of previously collected experimental data the possibility of application of LAROX OY filter-press for filtration of crushed ore suspension at hydrometallurgical enterprises has been substantiated. Experimental data on separation of suspensions are processed and prepared for numerical calculation.
A brief summary of the research and engineering work performed by professors, graduate students, and students of the Department of Furnaces, Control and Automation of Metallurgical Processes in 2000 is given. Two main directions of research activities were modeling of technological equipment for metal production and modeling of control systems for industrial metallurgical furnaces. In the first direction of research the following mathematical models were developed: converter conversion of smelting shop of Pechenganickel metallurgical plant; ore thermal smelting process; dissolution and liquation processes; waste water treatment using calcium hydrocarboaluminate. The technology of zinc-tin iron dust processing in a rotary kiln was also developed. A method of separating suspensions using LAROX PF press-filters was introduced. The second area of research includes works on development of spectral density method for synthesis of control systems with intermittent lag and on improvement of efficiency of manipulation of gas regimes in converters.