Role of the thermal-inertia zone in conveyer roasting machines

Bokovikov, B. A.; Брагин, В. В.; Shvydkii, V. S.

doi:10.3103/s096709121408004x

Cited by 18 publications

(6 citation statements)

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“…Iterating in this procedure the optimal values of the parameters Tg 0i , Wgi at each stage of the decomposition provides the optimal sought-after sequence {Xi (Tg 0i , Wgi)} that optimizes the drying process of the multi-layer mass of pellets throughout the horizontal grate machine [21,22].…”

Section:  mentioning

confidence: 99%

Optimization of Energy and Resource Efficiency in a Multistage Drying Process of Phosphate Pellets

Мешалкин

Бобков²,

Дли³

et al. 2019

Energies

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The roasting of phosphate pellets is an energy-intensive process the optimization of which can give rise to considerable efficiency improvements. To this purpose, the mathematical modeling and the computer-aided simulation of a multi-stage process of phosphate pellets roasting have been developed. This process includes drying, dissociation reaction of carbonates and a sintering process in a moving, dense, multilayer mass of phosphate pellets in a special horizontal grate apparatus. A theoretical model for the physical-chemical processes of a mass of phosphate pellets moving in a multistage process and subject to external operation variables (i.e., temperatures and flowrates of the drying gas at different positions of the conveyor length) has been developed. By letting these control variables vary over suitable ranges limited by technical constraints, it is possible to construct an algorithm that minimizes the overall energy consumption subject to the attainment of the required quality indicators of the pellets. Therefore, the set of constraints includes bounds on both the operational variables and quality indicators of the final product. A dynamic programming algorithm subject to suitable penalty functions for avoiding constraints violation has been used. The results obtained show that the scientifically based operation described in this paper achieves the goal of attaining considerable energy savings while assuring the quality of the finished pellets. Furthermore, the results highlight the convenience of extending the general strategy developed in this article to other chemical energy engineering processes.

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Section:  mentioning

confidence: 99%

Optimization of Energy and Resource Efficiency in a Multistage Drying Process of Phosphate Pellets

Мешалкин

Бобков²,

Дли³

et al. 2019

Energies

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show abstract

“…Fierce competition in the market for iron ore raw materials, especially pellets, forces enrichment metallurgical enterprises to reduce production costs and improve product quality [4,5]. Thermal hardening of the pellets allows to use a non-scarce fuel to improve the metallurgical properties of the pellets, to reduce fuel and energy costs in the subsequent metallurgical processing [6,7]. The next important factor is the rise of heat and electrical energy cost spent on the production of iron ore pellets, which leads to their constant rise in price.…”

Section: Introductionmentioning

confidence: 99%

Analysis of the Granulometric Composition of the Feedstock Influence on Mechanical Properties of Iron Ore Pellets

Бобков

Morgunova

2022

MSF

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The paper investigates the effect of high-temperature roasting and cooling modes of roasted iron ore pellets on their strength and porosity. These characteristics depend on the initial iron ore raw materials properties, the parameters of the raw pellets, the firing temperature, the holding time at this temperature, the heating and cooling rate, and take into account the change in these indicators in connection with the chemical and mineralogical compositions of the pellets. It has been established that the strength of iron ore pellets obtained at the optimum firing temperature depends on the characteristics of the initial finely dispersed iron ore raw material. The relationship between the content of draw rock and the strength of calcined pellets has been revealed. A significant influence of the raw pellets porosity on the strength of the calcined pellets was found. It is shown that the crushing strength of pellets cooled in air is higher than the strength of pellets cooled with water, and a decrease in the final cooling temperature leads to an increase in the strength of the pellets. It is substantiated that the heating rate should not exceed the rate of gas diffusion, and with a decrease in the size of finely dispersed iron ore raw materials, the shrinkage of the pellet layer increases during heating. It is shown that shrinkage appears at temperatures lower than the optimal calcining temperature and insignificantly affects the strength of the pellets. The results obtained can be used to substantiate resource-and-energy efficient operating modes of horizontal-grate machines in ferrous metallurgy.

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“…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]. From other side, elevation of prices for thermal and electric power, which are used for thermal preparation of iron ore raw materials, is considered as an important factor determining necessity of outing into practice the new technologies.…”

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

cisisr

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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.

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Role of the thermal-inertia zone in conveyer roasting machines

Cited by 18 publications

References 0 publications

Optimization of Energy and Resource Efficiency in a Multistage Drying Process of Phosphate Pellets

Optimization of Energy and Resource Efficiency in a Multistage Drying Process of Phosphate Pellets

Analysis of the Granulometric Composition of the Feedstock Influence on Mechanical Properties of Iron Ore Pellets

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

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