The paper shows the results of studies in searching for a binder for briquetting finely dispersed dust (FDD) of ferroalloy production of the Kazakhstan content. The fractional composition and shape of FDD particles were studied. Liquid glass and caustic soda were used as a binder. The research results showed the possibility of using liquid glass as a binder. Experimental briquettes have sufficiently high compressive strength and drop strength, which implies the possibility of their transportation and loading

Alina, A. A.

Issagulova, D. A.

Kovaleva, T. V.

Kulikov, V. Yu.

Kvon, Sv. S.

Omarova, A. E.

English

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143METALURGIJA 63 (2024) 1, 143-145D.А. ISSAGULOVA, SV.S. КVON, А.Е. ОMAROVA,  Т.V. КОVALEVA, V.YU. КULIKOV, А.А. АLINASTUDYING THE BINDER EFFECT ON THE PROPERTIES  OF BRIQUETTES OF FERROALLOY PRODUCTION WASTEReceived – Primljeno: 2023-07-06Accepted – Prihvaćeno: 2023-08-25Preliminary Note – Prethodno priopćenjeThe paper shows the results of studies in searching for a binder for briquetting finely dispersed dust (FDD) of ferroal-loy production of the Kazakhstan content. The fractional composition and shape of FDD particles were studied. Liquid glass and caustic soda were used as a binder. The research results showed the possibility of using liquid glass as a binder. Experimental briquettes have sufficiently high compressive strength and drop strength, which implies the possibility of their transportation and loading.Keywords: ferroalloy production, ferrosilicon, finely dispersed dust, briquettes, strengthISSN 0543-5846METABK 63(1) 143-145 (2024)UDC – UDK 669.168.015:669.1.782:621.762:622.788:539.4=111INTRODUCTIONThe problem of utilization of finely dispersed dust (FDD) of ferroalloy production is not new but it has not nevertheless been resolved actually in the Republic of Kazakhstan.In the process of ferroalloy production, among other anthropogenic wastes, finely dispersed dust (FDD) is necessarily formed.This dust has a dual origin: firstly, it is formed as a result of implementing the technological process itself when discharging a ferroalloy product; secondly, it is formed as a product of gas cleaning systems [1].Irrespective of the origin, FDD composition is close to that of the produced ferroalloy and can be used as a raw material for obtaining a conditioned product. At present, FDD of Kazakh ferroalloy production is active-ly exported abroad, in particular to Russia, and then im-ported to the Republic of Kazakhstan in the form of a briquetted product with a high added value.FDD itself is an environmental hazard, because it requires significant storage space, it is a source of air pollution and has significant pyrophoricity due to the developed interaction surface [1].These circumstances determine the relevance of the problem.At present, there are a sufficient number of imple-mented technologies for FDD utilization in the world, but in our country such technologies are not widely used. The problem is exacerbated by the fact that simple transfer of the FDD utilization technology is impossi-ble, because FDD of each production is characterized by certain features, such as the chemical and fractional composition, the presence of impurities, etc. This leads D.А. Issagulova, Sv.S. Кvon, А.Е. Оmarova (aidana_kartu@mail.ru), Т.V. Коvaleva, V.Yu. Кulikov, А.А. Аlina. Karaganda Technical Uni-versity named after Abylkas Saginov, Karaganda, Kazakhstanto the necessity to adapt even well-known technologies for a local product.One of the promising areas for the utilization of FDD is producing briquettes, because the use of FDD in its original form, without preliminary agglomeration, is not possible [2, 3].Finished briquettes produced on the FDD basis must meet the following requirements:• correspond in chemical composition to SS 1415-93 for this ferroalloy;• withstand the conditions of transportation, i.e. have sufficient mechanical strength;• comply with the size factor according to the rele-vant SS.One of the key points that arise during the FDD bri-quetting is the correct selection of the binder compo-nent. The binder component must provide certain plas-ticity for the formation of a briquette, mechanical strength after appropriate processing (for example, dry-ing) and not make large changes in the chemical com-position of the briquette, so that the composition of the briquette complies with the SS for a given ferroalloy.Searching for a binder and developing the composi-tion of the mixture for briquetting on the FDD basis are dealt with in a significant number of works [4-7]. In most studies, caustic soda, liquid glass, such minerals as fluo-rite or vermiculite, etc. are used as a binder. Depending on the binder, the post-treatment mode is selected to provide the necessary characteristics of the finished briquette.EXPERIMENTALThe purpose of this work is to determine the effect of some binders on the strength and hardness of the fin-ished briquette produced on the basis of Kazakh raw materials. Finely dispersed dust (FDD) from the YDD Corporation LLP was used as the main raw material.144  METALURGIJA 63 (2024) 1, 143-145D.A. ISSAGULOVA et al.: STUDYING THE BINDER EFFECT ON THE PROPERTIES OF BRIQUETTES...This enterprise specializes in the production of fer-rosilicon (FeSi), in particular, FS70 grade (SS 1415-93). The mass of dust generated during the crushing of ferroalloys and dust that is the product of gas cleaning systems, currently amounts to tens of tons and is a real problem for this enterprise.The chemical composition of the FS70 grade, ac-cording to SS 1415-93 and FDD (averaged, according to the enterprise certificate) are shown in Table 1.It is seen from the data in Table 1 that the FDD com-position corresponds to SS for FS70 and can accord-ingly be used as a raw material for producing a ferroal-loy briquette. According to SS 1415-93, ferrosilicon can be supplied in the form of ingots weighing no more than 42 kg, pieces weighing no more than 25 kg, or in the form of crushed particles, the size of which depends on the size class.To assess the fractional composition of the studied FDD, a sedimentation analysis of the product was car-ried out on an FSH-6K instrument. The results of the analysis are shown in Table 2.It is seen from the data in Table 2 that the largest mass fraction falls on particles 0,2-1,0 mm in size, the total shape of the particles, it is possible to start briquetting with relatively low pressures.Liquid glass (an aqueous alkaline solution of sodium silicates Na2O(SiO2)n and the 30 % aqueous solution of caustic soda NaOH were selected as a binder for pro-ducing briquettes using FDD.The selection of binders is based on the results of studies [5–8], in which these substances were used as binders, however, the chemical and fractional composi-tion of the FDD differed from that used in this work. Binders and moisture were added in excess of 100 %; the mass of pure FDD was taken as 100 %.Table 3 shows the composition of the charge used.All the components of the charge were thoroughly mixed within 5 minutes until a homogeneous mass was Table 1 Chemical composition of FS70 and FDD/wt. %Grade Si Fe C S P Al CrFS70 (1415-93)68,0-74,0 26-28 0,1 0,02 0,04 2 0,4FDD 71,5 26,7 0,06 0,02 0,04 1,104 0,049Table 2 Particle size distribution / mm Particle size ≤ 0,05 0,05-0,2 0,2-1,0 1,0-3,0 ≥3,0 Content 12 % 14 % 52 % 12 % 10 %fraction of particles up to 1,0 mm in size is 78 %. It is known that the finer the powder particles, the greater their specific surface area and, as a rule, the worse its compressibility [8,9]. However, strength of compacts made using fine powder is often higher than that of com-pacts made using coarse powder of the same material. This is explained by the fact that with increasing the powder specific surface, mechanical adhesion of the par-ticles increases, which, on the one hand, prevents com-paction of the powder during pressing, and on the other hand, causes the particles to jam relative to each other, which leads to increasing strength of the compacts [9].In addition to the fractional composition, the shape of powder particles also affects the process of briquette formation [9, 10].The analysis of the FDD particles shape carried out using electron microscopy, shows that the shape of the particles is closer to equiaxed one (Figure 1) according to the classification [9] but not spherical. It is believed that spherical powder particles give the maximum bulk density, i.e., the most dense packing with free filling, but they are poorly pressed and high specific pressures are required to obtain compacts of sufficient strength [9]. In this case, taking into account the non-spherical Table 3 The composition of the charge usedCharge designation Amount ofNa2O(SiO2)n / %Amount ofNaОН / % Water / %А 10 - 5В - 10 5achieved. Then, samples with the diameter of 35 mm and the height of 10 mm were made using the prepared mixture, the pressure varied from 30 to 60 kN.Raw briquettes were dried at the temperature of 60 0С within 2 hours. At the end of the drying process, the finished briquettes were tested for compressive strength and drop strength.Compressive strength was determined on an Instron machine, and drop strength was determined according to the method specified in work [4].The sample was 3 times dropped onto a steel plate 20 mm thick from the height of 2 meters. Then the test samples were sifted through 10 mm sieves. Sieves with smaller meshes were not used, because according to SS 1414-93, the smallest allowable particle size is 10 mm (size class 6), and the share of undersize product should be no more than 10 %.The weight fraction of the undersize product was used as the indicator of the drop strength: the larger the Figure 1 FDD particle shape145D.A. ISSAGULOVA et al.: STUDYING THE BINDER EFFECT ON THE PROPERTIES OF BRIQUETTES...METALURGIJA 63 (2024) 1, 143-145share of the undersize product, the lower the drop strength. Table 4 shows the results of the studies. Figure 2 shows the appearance of the samples before and after the drop test.It is seen from the data in Table 4 that the samples of series A (the binder is liquid glass) in all the respects show higher characteristics than the samples of series B. Therefore, the use of caustic soda as a binder in the briquetting of this enterprise (the YDD Corporation LLP) FDD seems less appropriate.If to consider the relationship between the pressure and the mass fraction of the undersize product (Table 4), then it can be concluded that the use of pressure be-low 50 kN is also inappropriate, because the output of the undersize product after discharge tests exceeds the allowable rate according to SS 1415-93. Such briquettes cannot be used in the future, because during transporta-tion or loading, they will increase the amount of solids emitted into the atmosphere, which in turn will lead to deterioration in technical and economic indicators, en-vironmental pollution, etc.Among the studied samples, only samples No. 3 and No. 4 are of practical interest. For sample No. 3, the share of the undersize product slightly exceeds the permissible norm but there are prospects for improving pre-treatment (drying mode), which can improve this indicator.Sample No. 4 has sufficient drop strength and meets the requirements for the dimensions of a conditioned product in accordance with SS.It should also be noted that samples No. 3 and No. 4 have sufficient compressive strength: 27 and 32 MPa, respectively. According to study [7], for transportation of briquettes, it is necessary to provide mechanical strength of at least 25 MPa.CONCLUSIONThe studies carried out in searching for a binder for briquetting fine dispersed dust of ferroalloy production show the possibility of using liquid glass as a binder. The obtained results are the basis for carrying out more detailed studies for the development of pressing and drying modes of the Kazakhstan content FDD for pro-ducing a conditioned product.In the future, it is necessary to study the chemical composition and such properties of briquettes, as poros-ity, pore size distribution, and specific surface area of pores, since these parameters of the porous structure determine electrical conductivity, thermal conductivity and interaction surface, which together with mechanical properties determine the quality of the final product.These studies were carried out in the framework of grant of the Science Committee of the Ministry of Edu-cation and Science of the Republic of Kazakhstan AP19576811 entitled “Developing the technology of obtaining a conditioned product using finely dispersed dust of ferroalloy production”.AcknowledgmentI should like to thank Sv.S. Кvon, V.Yu. Кulikov for their assistance rendered to me in writing this article.REFERENCES[1] Kostikov V.I., Varenko A.N. Industrial and environmental safety of metallurgical industries. Ecomet (2006), 388-392.[2] Ozhogin V.V. Fundamentals of the theory and technology of briquetting of crushed metallurgical raw materials // Mariu-pol: PSTU, 2012, 441p.Meghana A Patankar, Sandeep Td Experimental Investigations on Effect of Alccofines and Mi-crosilica on Durability Properties of High Performance Cocrete//|International Journal of Advanced in Managment, Technology and Engineering Sciences (2018) 8, 1-8.[3] Aubakirov D., Issagulov A., Kvon S., Kulikov V., Chsher-bakova Y., Arinova S. Modifying Effect of a New Boron-Barium Ferroalloy on the Wear Resistance of Low-Chro-mium Cast Iron. Journal Metals 12 (2022) 7, 543–546.[4] Fei Li, Zhibo Sun, Fegyun Yan The agglomeration of solid Wastes for Ferroalloy Production. Infacon XVI: Internatio-nak Ferro-Alloys Congress? Trondheim 27029 (2021), 1-7.[5] Patent RU 2398029 // Method of producing briquettes using industrial dispersed ferroalloys.[6] Patent RU 2156814 // Method of producing briquettes using dispersed and powdery wastes of ferroalloy production.[7] Protsenko E.L., Zhukovsky T.F. Experimental studies of the process of briquetting fine-grained dust produced by ferrosilicon. Vestnik of BSEU n.a. V.G. Shukhova (2014) 6. 187-191.[8] Baisanov S., Tolokonnikova V., Narikbayeva G., Korsukova I., Mukhambetgaliyev Ye. Mathematical method of phase equilibrium of binary system Cr-Si based on Bjerrum-Gug-genheim concept. Metalurgija 59 (2020) 1, 97-100.[9] Aubakirov, D.R., Issagulov, A.Z., Akberdin, A.A., Kulikov V., et al. Influence of boron- and barium-containing modi-fiers on the structure of low-chromium cast iron. Heliyon 8 (2022) 11, 87-91.Table 4 The results of the tests carried outSample number ChargePressure / kNCompression strength / МPаShare of the  undersize product ≤ 10 mm / %1А30 15 442 40 19 263 50 27 154 60 32 105В30 12 586 40 22 357 50 26 238 60 28 18Note:  Responsible for the English language is Natalya Drak,  Karaganda, Kazakhstanа) b)Figure 2 Sample: а – before testing; b – after testing

Studying the binder effect on the properties of briquettes of ferroalloy production waste

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