UA145391U - METHOD OF OBTAINING IRON-CARBON BRIQUETTES - Google Patents

Abstract

The method of obtaining iron-carbon briquettes includes mixing iron-containing and carbon components with flux and binder, homogenization of the resulting mixture, pressing and subsequent drying. The mixture of iron and carbon-containing components, before the introduction of the binder, is crushed to an average particle size of 0.048-0.1 mm, and as a binder and flux use bischofite in the amount of 9-11%, and the prepared mixture is pressed for 0.5-1, 5 years

Description

A useful model belongs to ferrous metallurgy and can be used in the metallization of iron with a solid reducing agent.

There is a known method of obtaining iron-carbon briquettes, which includes mixing prepared iron-containing waste of metallurgical production with finely ground carbon-containing material in the amount of 15-60 95 by carbon from the mass of waste and a binder, processing the resulting mixture with an aqueous solution of MagO-p5iO", pressing at 20 MPa and drying at 200 "C for 1 hour. As a binder, a mechanical mixture of natural materials - loam, clay or feldspar and sodium carbonate, taken in the following ratio, mass. 9o: sodium carbonate - up to 15; one of the named materials - the other.

At the same time, the mixture is subjected to joint grinding to a fraction of less than 0.85 mm. As iron-containing waste, rolling and forge slag, dust from gas cleaning devices, sludge from gas cleaning devices and pickling baths, welding slag from heating wells and furnaces are used, and as carbon-containing waste, graphite electrode sludge and sludge or sludge from electrolysis baths for aluminum production are used. Weight of dry briquette 0.11 kg. The degree of recovery of briquettes is 98.2 95111.

The disadvantages of this method include the use of clay materials as a binder, which reduces the content of useful components; application of low pressing pressure 20

MPa gives the briquettes insufficient strength and causes their destruction during production overloads and heating during recovery. Insufficiently fine grinding of the mixture, despite the use of finely ground carbon-containing material and a long recovery time - 1.2 g, does not ensure a high degree of recovery, which under these conditions can exceed 99 95. The degree of recovery of briquettes 98.295 is achieved by an excessive amount of carbon-containing material - up to 60 95.

There is a known method of obtaining iron-carbon briquettes, which includes mixing metal oxides with finely ground carbon-containing material in the amount of 20-50 95 by carbon from the mass of oxides and binders, pressing at a pressure of 10-25 MPa and further drying at 200-250 70 for 1.0- 2.5 hours At the same time, as a binder, a mechanical mixture consisting of sodium carbonate, dust from gas cleaning of an electric arc furnace and manganese-containing materials is used, and sand in their ratio, wt. 95: mixture - ZO, sand - other.

Before mixing, metal oxides are pre-crushed, the binder is finely ground, a mixture of oxides and binder is prepared and mixed with carbon-containing material evenly moistened with an aqueous solution of MagO-p5iO" or sulfite bar in the amount of 7-10 95 over 100 95.

Metal oxides in the form of scale, containing up to 72.5 95, are crushed to a particle size of 0.3-1.5 mm, carbon-containing material is ground to a polydisperse mixture with an upper particle size of no more than 3 mm, binder - to less than 0.85 mm . Weight of dry briquette 0.2-3.5 kg 21.

The disadvantages of this method include the increased weight of the briquettes and the excessive amount of carbon-containing material in the briquettes, which has low adhesion, as a result of which an excessive amount of binder is used, including liquid glass or sulphite bard, the components of which introduce harmful and ballast impurities. Low pressing pressure does not provide industrial briquettes with sufficient strength during delivery and loading into the furnace. Grinding the mixture is also not enough to quickly restore the briquettes.

The closest in terms of technical essence and results to the proposed useful model is the known method of obtaining iron-carbon briquettes, which includes mixing of iron-containing and carbon components with flux and binder, homogenization (that is, thorough averaging to a homogeneous composition) of the obtained mixture, pressing and further drying. At the same time, slag, finely dispersed sludge from oxygen converter filters, as well as dust from electric arc furnaces mixed with a carbon component are used as an iron-containing component. Coal or coke is used as a carbon component, and calcium carbonate and kaolite (AIg2Oz-5iO2) are used as fluxes. A polymer composite emulsified in water is used as a binder.

The briquette contains, wt. 90: iron 30-60, carbon 7-20, flux 7.5 and binder - polymer resin 10. Forming, according to one of the options, is carried out by briquetting under a pressure of 210 MPa.

Drying, which is combined with polymer curing, is carried out at 120-205 "С. Then the briquettes are mixed in an electric arc furnace for the recovery of the IZ). Fractional and chemical composition of materials, as well as briquettes, which are presented in this analogue, see the initial conditions in the table 1 and Table 2.

The disadvantages of this method include the use of expensive binders and complex polymer compositions. Drying is long and not intense, because it serves to polymerize the binder. Individual components of the binder are protected by other patents (for example, the component that is specified in the US application Mo 08/184099). The use of individual fluxes (kaolite), which also act as a hardener of the briquetting mixture, multi-stage mixing, which requires several mixers and great mixing thoroughness, as well as high pressing pressure make the process much more complicated and expensive. A large part of the mixture is not crushed, which prolongs the metallization process of the briquettes. The content of iron and carbon in individual compositions of briquettes is not enough to obtain high-quality briquettes.

The basis of a useful model is the task of developing such a method of obtaining iron-carbon briquettes, in which, due to the use of new materials and changes in the conditions of preparation of the mixture, an increase in the degree of iron metallization in the briquettes, a reduction in the duration of their recovery, and an improvement in the technical and economic indicators of the process are achieved.

The problem is solved by the fact that in the method of obtaining iron-carbon briquettes, which includes mixing the iron-containing and carbon-containing components with flux and binder, homogenization of the obtained mixture, pressing and further drying, according to a useful model, the mixture of iron- and carbon-containing components of the mixture is crushed to with an average particle size of 0.048-0.1 mm, and bischofite in the amount of 9-11 95 is used as a binder and flux, and the prepared mixture is kept for 0.5-1.5 g before pressing.

Iron-carbon briquettes intended for metallurgical processing must meet a number of requirements, in particular, have high strength, have a certain size and porosity, as well as high homogeneity (homogeneity) of the mixture and the fine size of its particles.

High strength is ensured by fine particle size, binder quality, homogeneity, pressing pressure and other factors.

A large briquette heats up longer and recovers worse, so in metallurgy, the size of pieces of raw material is 40-60 mm, pellets 10-25 mm.

Briquettes are considered high-quality if the duration of their processing is minimal. It is determined by the high speed of the reactions, which is provided by the large contact area of the reacting phases, the diffusion speed of atoms, the presence of micropores through which the reaction products are removed, as well as the temperature at which these reactions are carried out |4|.

It follows from this that the contact area of the reacting particles increases as their size decreases, so all particles must be of the minimum possible size. From the experimental dependence presented in Fig., it follows that the duration of briquette metallization is determined by the size of large particles. So, if the average size of the particles is 0.383 mm, then the briquettes at 1100 C are restored in 53.5 minutes, and if their size decreases to 0.048 mm, then the restoration is reduced to 20.8 minutes. Nanoparticles are restored almost instantly. However, obtaining them on an industrial scale using metallurgical high-performance crushing equipment is problematic. Therefore, we will limit ourselves to the micron level of particles that are provided by abrasives, mills or even runners.

Sifting out the large fractions contained in the mixture, grinding them and returning them to the process is difficult, costly and impractical, because the loose mixture must undergo compaction before pressing. In order to increase the efficiency of the grinding and compaction processes, they are combined in one device. Joint processing of iron- and carbon-containing components in the eraser provides them with the necessary size, uniformity (homogeneity) and close contact, which cannot be obtained by ordinary mixing.

As an iron-containing component corresponding to the above conditions, small and dusty iron-containing wastes, which are generated at metallurgical enterprises and require disposal, were chosen. These include steelmaking dust and sludge formed during "wet" gas cleaning, which contain more than 80 95 fractions of 0.05 mm.

Large scale is scarce and requires grinding, and thin scale-bearing sludge contains oils that are difficult to remove. Therefore, they are not considered as a permanent component of iron-carbon briquettes. Concentrate can be taken as their substitute.

Anthracite slag, which is formed during coal mining, was chosen as the carbon component. As a similar raw material, coke screening, which has properties similar to anthracite coal, and lignin, which is formed during the processing of wood into cellulose |5), which has better regenerative properties than coal and coke bi, can serve as similar raw materials.

Bischofite is used as an auxiliary material that acts as a binder and magnesium flux

Masig-bH2O. It is not in short supply, significant reserves of it are concentrated in underground lakes in

Chernihiv (reserves of 2 billion tons) and Poltava (same level of reserves) regions.

The density of dry bischofite is 1.59-1.65 g/cm3. A natural solution of bischofite with a density of 1.27 g/cm3 contains, 95 (mass): Ma "- 9.2; MosSi" 31.6; mass 6.6; Sassi»g 0.5; other salts 1.7; water - other

The thick, oily-green consistency of bischofite makes it difficult to mix it with dry iron- and carbon-containing components of briquettes. Therefore, it should be diluted with water, the amount of which is determined taking into account the moisture contained in the components of the mixture and added to the mixture before pressing.

When using a liquid binder, an important factor is the complete wettability of the particles, the extrusion of trapped air, which prevents contact between the particles and the binder, and the uniformity of its distribution throughout the volume, which is achieved by aging the finished mixture.

To determine the declared parameters of the process, raw materials and materials of the following composition and properties were used, see table 1 and table. 2.

The above starting conditions allow us to establish that the most significant, effective and easily implemented factors are: 1) general parameters of briquetting: size (size and mass) of briquettes, pressing pressure, temperature and duration of drying; 2) the size of the reacting particles; 3) the type and amount of binder, which gives the briquettes high strength and introduces a minimum amount of harmful and ballast impurities; 4) duration of exposure of the mixture prepared for briquetting.

To determine the value of the declared parameters, laboratory studies and calculations were performed, the results of which are presented below. 1. Determination of general briquetting parameters.

Briquettes were obtained as follows. The mixture with the calculated ratio of components (8595 steel-smelting dust, 1595 anthracite slag) was crushed in a scraper, bischofite was added in the amount of 0-15 95 (depending on the experiment), dissolved in water to a total moisture content of the mixture of 15-17 95, which ensures satisfactory pressing and extraction briquettes from the cells of the press, and thoroughly mixed for 6 minutes.

The mixture was kept for 0.4-3.0 hours. to determine the optimal duration of its aging and pressed on a screw mechanical press into cylindrical briquettes with a diameter of 30 mm, a height of 20 mm and a volume of 14.1 cm3.

Table 1

Granulometric composition of raw materials and materials, 90

Average zeeennntnnny od rochervoryaom ote 28.0 s 13.0-1.611.6-0.40.4-0.05) "0.05 | of particles, 3.0

MM

1. Steelmaking dust, incl. zpleptroduovihhlchey 01707756 | 6060 olom 2. Also, after grinding. d | - | - | - | 05 1 88 | 90.7 | 00475 3. Iron ore concentrate./// | - | - | - | b2 1 60.7 | 39 | 01484 4. Also, after grinding - | - | - | - / 123 | 87.7 | 00496 5. Anthracite brick. d | - 1Ш|1.91|268)| 328 324 | bl | 1233 6b. Also, after grinding | - | - | - | 05 | 11.39 | 88.2 | 00525 7. Lime quenched /-/-:/ 7777771 - | - 1 - | - 121 19791 00292

Teshe 11 1 royu (Main analogue) " (9. Iron-carbon briquette (Application) | | | | / | | bo

Table 2

Chemical composition of raw materials and metallized briquettes and 1. Steelmaking dust, in it. 2. Iron ore concentrate 650 - (252|35| 03 |od, 01-11 05 3. Anthracite ash? 11771 - 1 - |473| 189 | 46 14 |08 | - 4. Calcareous /-: 104 1 - 1 - 1713 03 657 1 | - | z06 5. Bishofites 77777771 11-11 - 103| - 104 265|04| 715 6. Iron carbon briquette 4 (main analog) 45.0 16.4) 3.6 8.8 0.3 |0.3| 9.8 7. Also restored. 729 671175|54| 08 (131,040, - 8. Iron-carbon briquette (application)! 541 | - |100| 6.91 ti2 |57| 32 |05| 65" (9. Also, restored. /6781675108)|5.3| 1, 4 |13.7| 3.9 |06| -

Notes to the table. 2: 1 - losses during firing; 2 - the content of free carbon in dust, Stor - 1.2 uv; C - the content of volatile substances in the stem - 4.4 95, carbon Shor - 82.2 Us; 4 - without taking into account the carbon content Combustion.

The shape of the briquettes is not critical for recovery and is determined by the configuration of the mold. The size of the briquettes should not be excessive, because the heating of large briquettes takes longer, which is inefficient. The optimal fraction of briquettes is 30 mm. Briquetting was carried out under a pressure of 50 MPa, which is available to the main types of common roll presses with a capacity of up to 50 t / h. 7, p. 349).

Briquettes were dried at a temperature of 2507 C for 0.5 hours, which ensures effective removal of moisture and prevents a decrease in the strength of the coal component as a result of its pyrolysis (7, p. 1731.

Restoration of briquettes was carried out in a blacksmith's furnace by heating to a given temperature the metal cups installed in it with a lid. The duration of recovery was determined by the cessation of combustion of the gas coming out from under the lid of the glass. 2. Selection of the optimal particle size.

The selection of the optimal particle size, which ensures the minimum duration of briquette recovery, was carried out on the basis of initial (table 1 and table 2), literary and calculated data, as well as experimental dependence, which are presented in table. 3.

Table C

Calculation-experimental relationship between the duration of recovery (min) and the average size of particles in briquettes o Average size of particles in briquettes, mm

Temperature, EU 770 170048 0.383 1100 1200 50 | 15 | 275 | 35 | 495 | 55 | 90 | 120

For the sake of clarity, we will present the obtained dependence graphically on the drawing, where the line -x- represents the dependence of the briquette recovery duration on the particle size at a recovery temperature of 1100 "C, and the line -y - characterizes the same dependence, but at 1200 "C.

According to the table 3 and drawing. in the table 4, the average particle size is determined, which provides the optimal duration of recovery of iron-carbon briquettes under the conditions of the claimed method.

Table 4

Determining the average particle size in the briquettes ensures the minimum recovery time

Particle size in briquettes, mm less than 0.048 from 0.048 to 0.1

Duration of recovery of briquettes Duration of recovery: . . .. - y Duration of recovery of briquettes is minimal and is less than | of briquettes is 20.5-34.5 izko increases from 35-42 min to Z h 20.5 min at 1100 "C and 15 min at min at 1100 "C and 15-27.5 min at R ko zrd d od. oh oh and more. Although it is partly 1200 "C, but the costs of 1200 "C, and the costs of . : and we s. - corresponds to the modern level, but the abrasion of the mixture increases, the abrasion of the mixture is not significant, which - will not allow to use as much, which does not lead to a decrease b . and rickets in intensive processes of production of briquettes efficiency of the method. to metallization Conclusion. The goal is ineffective. Conclusion. Purpose Conclusions. The goal is useful. and . . a useful model is not achieved. a useful model is not achieved. model is achieved.

Thus, the most effective (according to the criteria of minimum recovery time and allowable crushing costs) is the average particle size of the mixture being briquetted, which is 0.048-0.1 mm, which allows you to fully solve the problem set before the useful model. 3. Determination of the amount of binder.

According to the initial conditions, a universal and multifunctional bischofite was chosen as a binder, which also acts as a flux and a substance that removes some harmful impurities.

The amount of binder is determined experimentally based on the fact that briquettes are supposed to be regenerated in induction furnaces or in rapid heating furnaces 7, p. 3701, or use in intensive converter processes, where the load on briquettes is significantly lower than in blast furnaces.

Thus, from the practice of processing briquettes in blast furnace production, it is known that the crushing strength of briquettes is satisfactory, which is at least 250 kgf / mu, or 25.5 MPa |8, p. 2134. Taking into account the data (9, p. 25| we accept the crushing strength limit for briquettes used in steel production processes at the level of 12-15 MPa.

Briquettes were tested for strength by crushing them on an EEO-40 type testing machine with a measurement accuracy of 1 95.

The results of tests on the crushing of briquettes containing 85 95 of current steelmaking dust and 15 95 of anthracite slag, with different contents of bischofite, are presented in the table. 5.

Table 5

The composition of the mixture of the studied briquettes and their crushing strength

Experiment number

Indicator 1 | 2131 4|51|16 | 7 1. The composition of the mixture that is briquetted pi p PO PNYA I I POL 80.75 | 77.78 | 77.35 | 75.65 | 75.23 | 72.25 14.25 | 13.72 | 13.65 | 13.95 | 13.27 | 12.75 ospoluchna-bishofit 77777711 0 | 5 | 851 9 | 11 | 115 15 2. Crushing strength of briquettes dried at 250 "C, MPa 3.8 112. 12.0 | 15.0 | 15.5 | 17.8

Based on the data in the table. 5 in table. 6, we determine the maximum amount of bischofite, which provides the briquettes with a specified strength of 12-15 MPa.

Table 6

The influence of the amount of bischofite on the crushing strength of briquettes

The amount of bischofite in the mixture, which is briquetted, 95 less than 9.0 from 9.0 to 11.0 more than 11.0 o. at. Briquettes have a strength of

Briquettes have a strength of | Briquettes have a crushing strength of 15.5 MPa and a crushing strength of 11.2 MPa and a crushing strength of 12-15 MPa, i.e. . what is higher is the maximum set, less what is below is the minimum that corresponds to the set value of 15 MPa. The set level of 12 MPa also applies. with a level of 12-15 MPa! R. and and Ts and overexpenditure of bischofite, more

Conclusion. The purpose of a useful conclusion. Purpose of useful : : ineffective. Conclusion. The goal of the model is not achieved. model is achieved. . . a useful model is not achieved.

Thus, the use of bischofite in the amount of 9-11 95 allows you to fully solve the task set before the useful model. 4. Determining the duration of exposure of the briquetting mixture.

To identify the significance of the influence of the aging factor of the briquetting mixture on the strength of the briquettes, a study was conducted, the results of which for the minimum strength of the briquettes are presented in the table. 7.

Table 7

Dependence of the crushing strength of the briquettes on the length of time the prepared mixture is laid out

Number, experiment

Indicator " 1 | 21314 |5 1 6 1. Content of bischofite, 95 8090 | 90 | 90 | 90 9 2. Duration of laying of the mixture, hours 3. Crushing strength of briquettes, dried

I' 11.9. 124 | 153.01 15.2 | 13.3 | 134 at 2507 C, MPa " " " " " "

Based on the data in the table. 7 in the table. 8, we determine the optimal length of time for laying the prepared mixture, which ensures that the briquettes exceed the minimum specified strength 12

MPa

Table 8

Determining the effect of the length of exposure of the mixture on the strength of the briquettes

Duration of exposure of the mixture, hours less than 0.5 from 0.5 to 1.5 more than 1.5 o. oh Briquettes have a strength of

Briquettes have a strength of | Briquettes have strength on holes

And crushing 13.3 MPa and more, crushing 11.9 MPa and crushing 12.4-13.2 and above the specified 12 MPa. However, excessively less, which is below the specified|and MPa, which is above the specified 121). and the duration of exposure to 12 MPa increases. Conclusion. The purpose of MPa. I and 4 mixtures, which is expensive. Conclusion. The purpose of a useful model is not Conclusion. The purpose of useful useful is achieved. model is achieved. . model is not reached.

Thus, the exposure of the mixture for 0.5-1.5 hours. allows you to fully solve the task set before the useful model.

The process of obtaining self-healing iron-carbon briquettes, which corresponds to the claimed method, is as follows.

We take steelmaking dust as the starting iron ore raw material, and anthracite slag in the ratio of 85: 15 as the carbon component, the particle size and chemical compositions of which are presented in the table. 1 and 2.

The dosed components of the mixture are mixed, crushed and compacted in a scraper to an average particle size of 0.048 mm, and then mixed in a paddle mixer with the binder - bischofite in the amount of 10 95. It is supplied in the liquid form of a bischofite solution containing water in the amount of 50.4 95, which is diluted with water, taking into account the moisture contained in the raw material, to the total moisture content of the mixture of 16 95.

The resulting mixture is kept in the bunker for 1 hour to equalize the humidity throughout the volume of the mixture. The aged mixture is pressed under a pressure of 50 MPa on a roller press into briquettes of a fraction of 30 mm with a volume of 14.1 cm, and then sent to a belt oven for drying. Briquettes are dried at a temperature of 250 C for 0.5 hours, which ensures effective moisture removal. Dried hot briquettes are fed into the furnace for recovery and metallization.

The method allows to increase the degree of recovery of iron from 98.2 95 to 99.6 95 and reduce the duration of recovery from 1.2-2.0 hours. up to 0.25 hours

Sources of information: 1. Method of preparation of batch material in the form of briquettes for melting: pat. 2154680 of the Russian Federation, IPC

C228 1/243, 7/00 // B.E. Ageev, V.P. Lemyakin, G.N Elansky and others - Mo 99104430/02; statement 03/05/1999; published 20.08.2000. 2. The method of preparing the batch material in the form of briquettes for melting: pat. 2187563 of the Russian Federation, IPC

C228 1/242, 7/00 // B.E. Ageev, V.S. Antonov, V.P. Lemyakin and others - MO 2000125040/02; statement 03.10.2000; published 20.08.2002. 3. The method of extracting iron from iron-containing materials: pat. 2147617 005, IPC

C218 1/245, 7/02, B29C 47/36 // Ford George U., Lambert Richard S, Mzdsen Russell G. - Appl. 08.02.1996; published 20.04.2000. 4. Hlinka N.L. General chemistry: Textbook for universities - 21st ed., stereotyped / Ed.

Rabinovich V.A. - L.: Chemistry, 1980.-720 p. 5. Ravich B.M. Complex use of sulfur and waste / B.M. Ravych, V.P. Okladnikov,

V.N. Lhach et al. - M.: Khimiya, 1988.-288 p. 6. Iron-containing briquette for metallurgical production: pat. 80234 OA, IPC C218 1/242 //

V.V. Ozhohin, I.A. Kovalevskyi, O.V. Zherlitsyna and others. - MO a200610274; statement 09/26/2006; published

From 27.06.2007. 7. Ozhogin V.V. Fundamentals of the theory and technology of briquetting of crushed metallurgical coal: Monograph. - Mariupol, PGTU, 2010.-442 p. 8. Lurie L.A. Briquetting in black and color metallurgy / L.A. Lurie. - M.:

Metallurgizdat, 1963.-324 p. 9. Ravich B.M. Briquetting in non-ferrous and ferrous metallurgy - M.: Metallurgy, 1975. - 232 p.

Claims (1)

USEFUL MODEL FORMULA 40 The method of obtaining iron-carbon briquettes, which includes mixing iron-containing and carbon-containing components with flux and binder, homogenization of the resulting mixture, pressing and further drying, which is characterized by the fact that the mixture of iron- and carbon-containing components, before the introduction of the binder, is crushed to an average particle size of 0.048- 0.1 mm, and bischofite in the amount of 9-11 95 is used as a binder and flux, and the prepared mixture before 45 pressed and kept for 0.5-1.5 hours. 7 now the tuftnntntntnentnntnntntnntntntnentntntntntnentntntntntntntnntntnntntnntntntpnntntnntnnntntnnnitsnnikhptlnnntntnntntnntntnntntnntntnntnthnntnntnntnntnthnntnnthntnnthnntn. POSSIBLE I MOHA I NN NN NN NN P P P P P PO PO PO PO KI NAC 04 02 03 04 04 05 06 07 08 09 1 MEDTHING SHOCK