Енерготехнологічне дослідження та вдосконалення виробництва залізного порошку

Ключові слова: енергетичні витрати, диспергування, карботермічне відновлення, масообмін, кінетика відновлення, тепловий баланс, піч.

Аннотация

Федоров Д.Н. “Энерготехнологическое исследование и усовершенствование производства железного порошка”.

Диссертация на соискание ученой степени кандидата технических наук по специальности 05.14.06 - техническая теплофизика и промышленная теплоэнергетика. - Институт газа НАН Украины, Киев, 2002.

Диссертация посвящена проблеме снижения удельных энергетических затрат при производстве железного порошка. В ходе работы над диссертацией выполнено энерготехнологическое исследование производства железного порошка методом распыления и восстановления. Выполнены аналитические и экспериментальные исследования процессов использования кинетической энергии струй сжатого воздуха при распылении железоуглеродистого сплава, процессов массообмена по углероду в ходе обезуглероживающего отжига. Рассчитан тепловой баланс и определены показатели энергетической эффективности вертикальной и туннельной печей карботермического восстановления. Экспериментально исследовано кинетику восстановления плоского дисперсного слоя гематитового концентрата из индийской железной руды “Blue Dust”. На основании проведенных исследований разработаны технологические мероприятия по снижению энергетических затрат в ходе производства железного порошка. Для этого модернизировали форсунку распыления, разработали новый способ обезуглероживающего отжига распыленого порошка-сырца, модернизировали печь для этого процесса. Разработан и внедрен альтернативный карботермическому способ восстановления гематитового концентрата в атмосфере диссоциированного аммиака.

Ключевые слова: энергетические затраты, распыление, карботермическое восстановление, массообмен, кинетика восстановления, тепловой баланс, печь.

Summary

Fedorov D.N. “Energotechnological study and improvement of iron powder production”

Thesis to claim award of scientific candidate degree of technical science. Specialization 05.14.06 - technical thermo physics and industrial heat power engineering. - The Gas Institute of National Academy of Science of Ukraine, Kyiv, Ukraine, 2002.

The thesis is devoted to problem of decreasing specific energy consumption of iron powder production. The purpose of study is to increase effectiveness of using energy sources to produce iron powder by method of development and implementation of new and improved technological techniques of the process. The thesis consists of six chapters, conclusions, reference list and appendix.

It is known that specific energy consumption is very important indicator of perfection of the industrial level. Iron powder production is a modern quickly developing branch of the industry. It is complicated technology including many consequent stages and using different forms of energy. It is not sufficient research study from point of view of energy saving in this field. That is why it is necessary to use method of energotechnological study of the technology. In the world there are two main technologies of iron powder production, namely by atomization of overheated carbon-iron alloy and by carbothermal reduction of iron oxides.

Both technologies have been researched with using of energotechnological method. The most energy consumption stages have been highlighted. They are preparation of carbon-iron alloy, atomization, decarbonizing annealing and carbothermal reduction. Each stage has been analytically and experimentally studied.

To improve carbon-iron alloy preparation it is proposed to use secondary cast iron with gang element content and use energy of oxidizing to save electric power.

During atomization two phenomena take place. First one is using of kinetic energy of pressurized air jets, second one is energy of CO expansion inside of liquid particles. Hence, new design of the air jets have been developed and experimentally confirmed improvement of atomization.

Mass exchange between carbon that is uniformly distributed among solid phase of dispersed flat powder layer and gaseous reagent of technological atmosphere is defined velocity of the decarbonization. Multifactor design experiment has been conducted to determinate optimal regime of the process. Three control factors have been chosen to be varied on two levels. They are temperature of the process, dew point of technological atmosphere, time of treatment under humid atmosphere. The adequate linear equations for carbon and oxygen content have been obtained.

Using results of multifactor design experiment the industrial implementation through experimental decarbonizing annealing has been done. New method of iron powder production and new design of the annealing furnace are developed.

There are two types of furnaces to embody carbothermal reduction of iron oxides. One is channel furnace (kiln) and second is vertical furnace. The energothecnological research of the technology to produce iron powder using carbothermal reduction of iron oxides in vertical furnace has been carried out. It has shown high level of specific energy consumption (49 MJ/kg). The experimental study of the furnace has been conducted. On this basis heat balance of the furnace has been calculated. The indicators of energy effectiveness, namely effective time, coefficient of reduction agent using and specific energy consumption have been calculated for both type of the furnaces. Comparing has shown that the channel type furnace in general is better then the vertical one. Coefficient of reduction agent using is 0.27 against 0.43, but specific energy consumption is 10.204 against 28.162 MJ/kg. Anyway carbothermal reduction is required following multi stages crushing and milling operations and final refining annealing under hydrogen atmosphere. To improve technology of iron powder production by reduction it has been proposed to develop an alternative process by gaseous reduction. Experimental research of kinetics of the iron ore hematite concentrate by cracked ammonia has been carried out. The kinetics provides data of reduction time depending on height of powder bed and cracked ammonia flow rate. The optimal regime has been developed and control reduction has been done. The alternative reduction technique provides only 16.7 MJ/kg energy consumption and higher output of the iron powder.

The implementation of improved and new techniques to produce iron powder by method of atomization provides 40% decreasing of energy consumption simultaneously with 27% decreasing of the cost in part of energy source.

The implementation of the alternative reduction technique of iron ore hematite concentrate by cracked ammonia provides 68.08% decreasing of specific energy consumption (from 49.14 down to 16.7 MJ/kg). Decreasing of the cost in part of energy source is 3.86% (from 525.83 down to 505.52 USD).

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