Mathematical simulation of chemical and energotechnological processes and procedures of coke fines burning in agglomerated layer

Self Cite

Thermally activated chemical and metallurgical processes of lumping of fine-dispersed iron ore raw material during sintering are examined in the work. The following processes are included: moisture removal, ignition of coke fines and burn-off of carbonates, taking into account burning features of coke fines, fusion of grain charge, forming of agglomeration cake, creation of overhumidification area in sintering layer owing to condensation of water vapours in washout of heat-carrying gas. Parameters of sintering kinetics are obtained experimentally, other parameters characterizing layer shrinkage of sintering charge are presented. It was established that the temperature in the sintering area has substantial effect on shrinkage. The presented temperature relationship describes experimental data with sufficient precision. The values of power exchange coefficients in the drying area are examined. The criteria equations of heat and mass exchange are presented. The mathematical model using empiric material is proposed; it describes sintering kinetics for agglomeration charge, taking into account layer shrinkage and variation of head losses in technological areas of fusion and forming of ready agglomerate, what corresponds well with the experimental data. Multi-factor relationship between chemical and metallurgical processes (from one side) and heat and mass exchange in the sintering layer of agglomeration charge (from other side) is noted. Adequacy of mathematical models allows to use them for analysis of high-efficient conditions of agglomerate fabrication. The research was conducted under financial support of the Russian Foundation of Basic Research (RFFI within the framework of the scientific project No. 18-29-24094 МК and in accordance with the State assignment, the project No. FSWF-2020-0019.

“…Moreover, resistance values differ essentially in different layer areas [18,22]. The following relationship is true for gas dynamic resistance:…”

Section: Discussion Of Experimental and Numerical Results Obtained On The Modelsmentioning

confidence: 99%

Analysis of chemical-metallurgical agglomeration processes during charge sintering

Бобков¹,

Дли²,

Sokolov³

et al. 2020

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“…Use of reliable initial data, study and taking into account the most significant factors (which determine running of technological processes) allow to solve the problems connected with heat and mass transfer in devices at the principally new level [18]. It is recommended to advance from a labour-intensive experimental search to mathematical simulation and numerical examination of the obtained models [19].…”

Section: Preparation Of Raw Materialsmentioning

confidence: 99%

Experimental examination of the chemical-metallurgical roasting process for iron ore raw materials on the fire grate of a roasting conveyor machine

Bobkov,

Dli,

Kulyasov

2023

The results of experimental power engineering examination of operating roasting conveyor machines are presented. These machines are used for complicated energy-intensive chemical-metallurgical process of roasting of iron ore raw materials in moving dense layer with cross feed of heat-carrying gas. The studies were conducted within the temperature ranges of thermal and aerodynamic operating conditions of the existing roasting conveyor machines. The causes of insufficient power engineering efficiency of the chemical-metallurgical roasting process were revealed, qualitative analysis of thermal conditions of roasting dense layer of iron ore raw materials was carried out. The data on temperature distribution of heating gas and iron ore material in different areas of a dynamic dense layer and on a fire grate in different sections of the roasting machine were obtained. The experimental data from technological control of the roasting conveyor machine were presented, as well as the results of chemical and granulometric analyses of roasting iron ore raw materials. Essential deviations in the thermal conditions of operating roasting machine in comparison with designed parameters were found out. The data on roasting conditions of iron ore raw materials in the experimental unit -the sintering pan, which provides simulation of the roasting conditions close to designed ones, are displayed. Insufficient heating in the lower layer levels at the operating roasting machines (in comparison with the designed parameters), stipulated by low speed of heat-carrying gas sweeping in the roasting area was revealed. Temperature heterogeneity along the width of a fire grate, caused by heterogeneity of heat-carrying gas sweeping due to segregation of iron ore material by its size during its loading to the roasting conveyor machine was substantiated scientifically.

“…It is evident that these technologies can be applied with maximal efficiency in the industrial branches which are using mineral resources; concentration of iron ore ram materials can be related to such industries [4,5]. From one side, it is stipulated by strict competition at the iron ore raw material market, which makes metallurgical concentrating works to cut their production expenses and to improve quality of products [6,7]. Thermal decomposition of carbonates in roasting and sintering machines allows to use non-critical fuel for improvement of metallurgical properties of iron ore raw materials, what promotes lowering of fuel and power expenses during consequent metallurgical tech-nological stages [8,9].…”

Section: Introductionmentioning

confidence: 99%

Influence of the conditions of internal heat exchange on the process of thermal decomposition of carbonates in iron ore raw materials

Bobkov¹,

Dli²,

Rubin³

2022

This work considers influence of heating rate of iron ore raw materials on chemical and metallurgical processes of thermal dissociation of carbonates, which occur during its high-temperature roasting. The research was conducted for the temperature ranges of the existing roasting and sintering machines, taking into account macro-kinetics of calcination processes. Substantial influence of heating rate of iron ore samples on kinetics of thermal decomposition of carbonates was revealed. The cause of the effect of internal heat exchange conditions in reacting iron ore sample on macro-kinetics of dissociation reaction for carbonates was substantiated scientifically. Influence of nonisothermal properties on precision of thermal analytical investigations, which were conducted using the methods of non-isothermal kinetics with different heating rates of iron ore samples, was studied. The authors suggested the mathematical model, which allows to take into account wide range of variations of the parameters in kinetic equations and volumetric thermal and chemical-metallurgical dissociation processes for carbonates. A series of calculating experiments, aimed on reveal of the relationship between heating rate of iron ore samples and evolution of concentration fields, transformation rates and temperature gradients, was carried out using the suggested model. The obtained results can be used for development of the optimal operating conditions for sintering and roasting machines, which propose optimization of heat treatment processes for iron ore preparation, owing to intensification of heat and mass exchange processes during high-temperature roasting. These conditions are considered as optimal from the point of view of power-and resource efficiency. Forming of the above-mentioned conditions allows to decrease fuel and power expenses for thermal preparation of raw materials at metallurgical production facilities, as well as to lower total economical production charges due to use of thermal decomposition of carbonates.