CC BY
3
SRSTI 53.31.21
https://doi.org/A0.48081/NKAB8600
*P. S. Varbanov
Brno University of Technology, Czech Republic, Brno * e-mail: varbanov@fme.vutbr.cz
INVESTIGATION OF THE INFLUENCE OF VARIOUS FACTORS ON THE ELECTRICAL RESISTIVITY OF THE CHARGE DURING FERROSILICON ALUMINIUM SMELTING
This paper presents the results ofa study on the change in the electrical resistivity of charge mixtures for smelting ferrosilicon aluminum and the possibility of using iron sands in the composition of the charge. Traditionally, iron shavings, a byproduct of metal cutting, are a part of the charge mixture for producing ferrosilicon aluminium. In this paper, two charges were selectedfor comparison. The first charge was a mixture of high-ash coal, quartzite and iron shavings. The second charge was a mixture of high ash coal, quartzite and iron sand. The task set in this study was to compare the resistivity of the components of the experimental mixture consisting of high-ash coal, quartzite and iron shavings and the possibility ofobtaining ferrosilicon aluminium from the mixture based on iron shavings. The results of the research have shown the possibility of replacing steel chips with metallized iron ore sinter, which can significantly reduce the consumption of scarce steel chips in the ferroalloy industry. Iron-ore sands, in turn, are an anthropogenic waste of alumina production. Thus, their involvement in processing can also partially solve the environmental problems of Pavlodar region.
Keywords: ferroalloy, electrical resistivity, steel shavings, ash, high ash coal.
Introduction
The operation of ferroalloy furnaces depends to a large extent on the immersion depth of the electrodes in the charge [1], which improves the technical and economic performance of the processes. At high sitting electrodes the melting zone moves upwards that sharply worsens a course of process: thermal losses with head gases increase, maintenance of the overheated grate becomes difficult, the temperature of the furnace increases that creates additional difficulties at release of metal and slag, extraction of the basic elements reduces because of the raised flight. At a constant secondary voltage, the depth of immersion of electrodes depends on the total resistance of the furnace bath, which in turn depends on the nature of the ores used, the type of their preparation (sintering, pelletising, briquetting) [2], the fractional composition of the materials and the type of reducing agents.
The method of charge materials preparation, the type of pelletised materials, is reflected in the electrical resistance of the charge [3, 4]. The electrical resistance of the charge, when non-isothermal heating to high temperatures, largely depends on the
chemical and mineralogical composition of the charge, as well as on the processes of phase transformations in the sample [5].
The efficiency of the furnace depends on the working resistance of the furnace, which also depends on the resistivity of the furnace charge [6]. As a result, it is necessary to conduct research on the electrical resistance of pellet charge materials. The study of the electrical resistance of charge materials and charges was carried out by the method described in the work of Zhuchkov V. I., which allows determining the electrical resistance of materials and charges at temperatures up to 1800 °C in the bulk layer while recording the degree of their softening (shrinkage). At present, this method is used by many researchers to determine the electrical resistivity of materials and charges [7, 8].
Comparative studies on the variation of resistivity of charge mixtures for the melting of ferrosilicon aluminium were carried out. The electrical resistivity of selected components and the whole charge mixture was measured during the experiment. All factors affecting the charge resistance were monitored: temperature, aggregate state, and degree of reduction of materials. In order to explain the reasons for changes in electrical resistance, the volume of materials was monitored continuously.
When measuring the electrical resistance of the charge materials, the fractional composition of the charge materials was selected in proportion to the coarseness of the components of the charge materials used in the production conditions, the limits of which were reduced by an order of magnitude.
Materials and methods
The charge materials used were high-ash coal from the Molodezhny Coal Mine (Borly UD), and quartzite was used as charge materials. The difference between the experimental and comparative charge consisted in the use of metallized agglomerate from iron sands in the first case, and in the composition of the comparative mixture traditionally used steel chips. High ash coal in 1-5 mm fractions had the following technical composition: ash content - 56.8 %; volatile components - 17.2 %, humidity - 1.0 %. Ashes were composed of 58.9 % silica and 37.2 % aluminium oxide. The pilot charge mixture consisted of 67.8 % high ash coal, 12.3 % metallised agglomerate and 19.8 % quartzite.
The measurements were carried out on a pilot laboratory setup with the possibility of conducting experiments in the temperature range 22-1600 °C according to the method [3]. The measurements were carried out at DC voltage equal to 5 Vwith fixing of current values depending on temperature.
Results and discussions
The results of comparative studies in the form of resistivity and conductivity vs. temperature are shown in Figures 1 and 2. The plots are presented for the temperature interval 850-1200 °C, which is typical for the upper layers of the charge during melting of ferrosilicon aluminium.
Figure 1 - Temperature dependence of electrical resistivity of comparative and experimental charge mixtures for melting ferrosilicon aluminium
As can be seen from the results of measurements at temperatures up to 950 °C the electrical resistance of experimental charge with sinter is slightly lower than that of traditional charge with steel chips. This is explained by the fact that the composition of metallized sinter contains small amounts of sintered relatively fusible mixtures containing iron compounds, in particular fayalite (Fe2SiO4).
Figure 2 - Temperature dependence of specific conductivity of comparative and experimental charge mixtures for smelting ferrosilicon aluminium
Further after reduction of iron at temperatures above 1000 °C the electrical resistivity of comparative and experimental charge mixtures equalizes. This shows the principal possibility of replacing steel chips with metallized iron sinter, which can significantly reduce the consumption of scarce steel chips in the ferroalloy industry.
The presence of iron sands [4] up to 15-25 % in total oxides of silicon and aluminium in the sinter obtained from waste alumina production [9, 10, 11] will not have a significant negative impact in the smelting of FA, as they are the main components of the charge.
Сonclusions
It should be noted that steel chips contain 1.5-2.5 % of manganese, chromium and non-ferrous metals which will be completely transferred to the melted FSA. In the pilot agglomerate there are practically no impurities of these elements, so the melted ferrosilicon aluminium will be pure for these impurities.
СПИСОК ИСПОЛЬЗОВАННЫХ ИСТОЧНИКОВ
1 Dhainaut, M. Simulation of the electric field in a submerged arc furnace // Proceedings of the Tenth International Ferroalloy Congress. - 2004. - P. 605-613.
2 Tangstad, M., Leroy, D., Ringdalen, E. Behavior of agglomerates in ferromanganese production // The Twelfth International Ferroalloys Congress Sustainable Future 2010. - Р. 457-466.
3 Жучков, В. И., Розенберг, В. Л., Зельберг, Б. И. Энергетические параметры и конструкции рудовосстановительных электропечей. - Челябинск : Металл, 1994. - 192 с.
4 Miyauchi, Y., Nischi, T., Saito, K., Kizu, Y. Improvement of High Temperature Electric Characteristics of Manganese ores, INFACON X, South Africa, 2004, P. 155-162.
5 Mukhambetgaliyev, Y. E. Research of electrical resistance and temperature of the beginning of softening of charge mixtures for smelting a complex alloy, Metalurgija, 2022, 61(3-4), P. 781-784.
6 Magnussen, T. E. Basic parameters in the operation and design of submerged arc furnaces, with particular reference to production of high-silicon alloys. Journal of the Southern African Institute of Mining and Metallurgy. - 2018 - 118(6). - 631-636. - https://dx.doi.org/10.17159/2411-9717/2018/v118n6a11.
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REFERENCES
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2 Tangstad, M., Leroy, D., Ringdalen, E. Behavior of agglomerates in ferromanganese production// The Twelfth International Ferroalloys Congress Sustainable Future. - 2010. - Р. 457-466.
3 Zhuchkov, V. I., Rozenberg, V. L., Zelberg, B. I. Energeticheskie parametry i konstruktcii rudovosstanovitelnykh elektropechei [Energy parameters and designs of ore-recovery electric furnaces] - Chelyabinsk : Metal, 1994. - 192 с.
4 Miyauchi, Y., Nischi, T., Saito, K., Kizu, Y. Improvement of High Temperature Electric Characteristics of Manganese ores, INFACON X, South Africa, 2004. -P. 155-162.
5 Mukhambetgaliyev, Y. E. Research of electrical resistance and temperature of the beginning of softening of charge mixtures for smelting a complex alloy, Metalurgija, 2022. - 61 (3-4). - P. 781-784.
6 Magnussen, T. E. Basic parameters in the operation and design of submerged arc furnaces, with particular reference to production of high-silicon alloys. Journal of the Southern African Institute of Mining and Metallurgy. - 2018. - 118(6). - 631-636. https://dx.doi.org/10.17159/2411-9717/2018/v118n6a11
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Material received on 06.02.23.
*П. С. Варбанов
Брно технологияльщ университет^ Чех Республикасы, Брно к. Материал 06.02.23 баспаFа тYстi.
ФЕРРОСИЛИКОАЛЮМИНИЙД1 БАЛЦЫТУ КЕЗ1НДЕ ШИХТАНЫЦ МЕНШ1КТ1 ЭЛЕКТР КЕДЕРГ1С1НЕ ЭРТYРЛI ФАКТОРЛАРДЬЩ ЭСЕР1Н ЗЕРТТЕУ
Бул макалада ферросиликоалюминийдi балцытуга арналган шихта коспаларыныц меншiктi электр кедергктщ взгерут жэне шихта, курамында темiрлi бар кумдарды колдану мумктдшн зерттеу бойынша зерттеу нэтижелерi келтiрiлген. Дэстyрлi эд^пен ферросиликоалюминий алу ушт шихтаныц курамына темiр жоцкалары, металды кест-жонып вцдеудщ жанама внiмi кiредi. Бул жумыста салыстыру ушт ек1 влшендi тацдалды. Бiрiншi жогары кyлдi квмiр, кварцит жэне темiр жоцщларыныц крспасы болды. Екiншi влшендi-кyлi жогары квмiр, кварцит жэне курамында темiрi бар кумдардыц цоспасы. Бул зерттеуде цойылган мтдет тапшы темiр жоцкаларын алмастыру реттде усынылган кyлi жогары квмiрден, кварциттен жэне курамында темiрi бар кумдарынан туратын шихтаныц эксперименттк курамындагы компоненттердщ меншiктi кедергкт жэне курамында темiрi бар кумдарына негiзделген шихтадан ферросиликоалюминий алу мумктдшн салыстыру болды. Зерттеу нэтижелерi болат жоцкаларын металдандырылган темiр рудалы агломератка ауыстырудыц негiзгi мумктдшн кврсеттi, бул феррокорытпа внеркэЫбтде тапшы болат жоцкаларын тутынуды айтарлъщтай твмендетуi мумкт. курамында темiрi бар кумдар, вз кезегтде, алюминий тотыгын вндiрудiц техногендт калдыктары болып табылады. Осылайша, оларды кайта вцдеуге тарту Павлодар вщрШц экологиялык проблемаларын да шмара шеше алады.
Кiлттi свздер: феррокорытпа, электр кедергШ, болат жоцкалары, кул, курамында кyлi жогары квмiр.
*П. С. Варбанов
Технологического университета Брно, г. Брно, Чешская Республика Материал поступил в редакцию 06.02.23.
ИССЛЕДОВАНИЕ ВЛЯНИЯ РАЗЛИЧНЫХ ФАКТОРОВ НА УДЕЛЬНОЕ ЭЛЕКТРИЧЕСКОЕ СОПРОТИВЛЕНИЕ ШИХТЫ ПРИ ВЫПЛАВКЕ ФЕРРОСИЛИКОАЛЮМИНИЯ
В данной статье приводятся результаты исследования по изучению изменения удельного электрического сопротивления шихтовых смесей для выплавки ферросиликоалюминия и возможности применения в составе шихты, железистых песков. Традиционно в состав шихты для получения ферросиликоалюминия входит железная стружка, побочный продукт обработки металла резанием. В данной работе для сравнения были выбраны две навески шихты. Первая навеска представляла собой смесь высокозольного угля, кварцита и железной стружки. Вторая навеска - смесь высокозольного угля, кварцита и железистых песков. Задача, поставленная в данном исследовании, заключалась в сравнении удельного сопротивления компонентов экспериментального состава шихты состоящей из высокозольного угля, кварцита и железистых песков предложенных в качестве замены дефицитной железной стружки, и возможности получения ферросиликоалюминия из шихты на основе железистых песков. Результаты исследований показали принципиальную возможность замены стальной стружки на металлизованный железорудный агломерат, что может существенно снизить потребление дефицитной стальной стружки в ферросплавной отрасли. Железистые пески в свою очередь, являются техногенным отходом производства глинозема. Таким образом, вовлечение их в переработку может также частично решить и экологические проблемы Павлодарского региона.
Ключевые слова: ферросплав, удельное электрическое сопротивление, стальная стружка, зола, высокозольный уголь.
