Metallurgical briquette and method of its production

Abstract

FIELD: metallurgical industry.SUBSTANCE: invention concerns a method for producing a metallurgical briquette, including preparing a dry mixture, preparing a binder based on lignosulfonate and molasses, mixing the dry mixture with the binder, briquetting and drying. Moreover, the binder additionally contains graphite, water and an alkaline agent, in the following ratio, by weight of the dry mixture: lignosulfonate 1.5-7.0; molasses 2.0-7.0; graphite 0.5-2.5; alkaline agent - calcium hydroxide 0.5-3.0; water 5.0-15.0. After drying, the briquettes are calcined at a temperature of 400-700 °C in an inert atmosphere. The strength of the resulting briquettes (CBS) is not less than 65%. The invention also relates to a metallurgical briquette obtained in accordance with the above method.EFFECT: creation of a product with high mechanical strength, heat resistance and the required metallurgical properties, as well as the expansion of the raw material base due to the utilization of man-made waste, including sludge and dust from gas cleaning systems with a high content of iron and zinc oxides.15 cl, 2 dwg, 5 tbl, 4 ex

Description

[0001] The present invention relates to the metallurgical industry, in particular to the technology of preparing charge materials and recycling man-made waste, and can be used to produce composite briquettes used as a reducing agent, deoxidizer, and alloying additive in the smelting of cast iron, steel, and ferroalloys. The invention can also be used for the recycling and return to the metallurgical cycle of highly dispersed metal-containing waste, such as blast furnace gas cleaning sludge, electric smelting unit gas cleaning dust, zinc-containing dust, and other man-made products, the briquetting of which is difficult or ineffective by traditional methods.

[0002] For use in metallurgy, fine crushed screenings must be pre-agglomerated or briquetted. The main challenge in producing briquetted ferroalloys from dispersed fractions is the correct choice of binder type and briquette hardening technology. Many recommended binders not only fail to provide the required briquette quality but also impart undesirable properties. For example, organic binders recommended for briquetting, such as sulfite liquor, phenolic, urea, and other resinous binders, do not provide the briquettes with the necessary thermal stability, and they disintegrate and become dispersed when loaded into smelting units or heated pouring ladles.Inorganic binders recommended for briquetting, such as construction cements, although providing briquettes with high strength properties, are characterized by a long hardening period and may introduce impurities in the form of sulfur, which are harmful to metals. Hardened ferroalloy briquettes with liquid glass tend to undergo reversibility, i.e., to weaken during prolonged storage in a humid atmosphere or upon contact with water. (Georgadze A.G., Elashvili M.I., Pletnev A.N., Nikiforov P.A. Improving the quality of briquetted ferrosilicon. Casting and Metallurgy. 2013; (1): 22-25).

[0003] A fuel briquette is known from the prior art based on a heat-treated mixture of crushed carbon fuel and a binder - lignosulfonate or molasses and oil refining residue, where, as an oil refining residue, it contains an oil sintering additive with a softening temperature of 140-170 or >250°C with the following ratio of components, wt. %:

[0004] Oil sintering additive 1-10 Lignosulfonate or molasses 1-10

[0005] Carbon fuel selected from coal, coke, carbon electrode waste or mixtures thereof - Up to 100. (Russian Federation patent for invention RU 2181752, C1, published 04 / 27 / 2002).

[0006] The main disadvantages of the known solution are: the use of toxic petroleum residues as a binder, which is unacceptable for metallurgical applications; low heat resistance of the resulting briquettes; and the inability to use metal-containing powder waste for briquetting.

[0007] A known method for producing briquettes from fine-grained waste from ferroalloy production in the form of ferrosilicon manganese or ferrosilicon is characterized by the fact that the said waste is dosed, a plasticizer is introduced, mixed with liquid glass, the resulting mixture is pressed into briquettes, the briquettes are strengthened by neutralizing an alkaline element in the liquid glass and the briquettes are dried, wherein a liquid-plastic substance with an acidic medium is used as a plasticizer, which is applied to the surface of particles of the said waste in the form of films while stirring the mixture before mixing with liquid glass, the briquettes are strengthened by neutralizing the alkaline element in the liquid glass due to a chemical reaction between the liquid glass upon contact with a plasticizing film of the plasticizer, consisting of molasses, pre-treated with acid-containing additives, (RU patent for invention RU 2600775, C2, published 27.10.2016).

[0008] The disadvantages of this method are the tendency of liquid glass briquettes to weaken when stored in a humid atmosphere, as well as the possibility of introducing unwanted impurities into the batch.

[0009] The task set in the creation of the proposed metallurgical briquette and the method for its production is to eliminate the above-mentioned shortcomings.

[0010] The technical result is the creation of a method for producing metallurgical briquettes, ensuring the production of a product with high mechanical strength, heat resistance and the required metallurgical properties, as well as the expansion of the raw material base due to the utilization of man-made waste, including sludge and dust from gas cleaning systems with a high content of iron and zinc oxides.

[0011] The technical result is achieved by the method of producing a metallurgical briquette, which includes preparing a dry mixture, preparing a binder based on lignosulfonate and molasses, mixing the dry mixture with the binder, briquetting and drying, at the same time, the binder additionally contains graphite and an alkaline agent, and after drying, calcining the briquettes at a temperature of 400-700°C in an inert atmosphere, while the strength of the resulting briquettes (CBS) is at least 65%.

[0012] The metallurgical briquette and its production method are explained by the following drawings.

[0013] Fig. 1 shows a graph of the influence of binder composition on the compressive strength of briquettes (CBS).

[0014] Fig. 2 shows a graph of the effect of heat treatment temperature on the compressive strength (CBS) of briquettes obtained by the claimed method.

[0015] The method for producing metallurgical briquettes is carried out as follows and contains the following steps.

[0016] The preparation stage involves dosing and mixing the dry mix components according to one of the stated recipe options, for example, using coke, semi-coke, and / or anthracite fines. Examples of carbon raw materials used include quartz sand, quartzite, anthracite, microsilica, thermal power plant ash, dusty metallurgical waste such as FeSi, FeMn, FeCr, SiMn, Fe2O3, Fe3O4, FeSiMn, blast furnace gas cleaning sludge, electric smelting unit gas cleaning dust, zinc-containing dust, etc., or mixtures thereof, as well as quicklime (CaO). Calcium hydroxide can also be used as an alternative source of calcium oxide, followed by dehydration during calcination. The dry component fraction does not exceed 3.0 mm, and the moisture content is no more than 12%. In a preferred embodiment, the dry mixture is prepared in the following wt.% ratio:

[0017] quartz sand 60-70 anthracite 20-25 iron oxide 5-10 calcium oxide (quicklime) 2-8

[0018] There is an option when the dry mixture is prepared in the following ratio, wt.%:

[0019] quartz sand 70-80 anthracite 20-30 calcium oxide (quicklime) 2-3

[0020] There is an option when a dry mixture is prepared on the basis of dusty waste from the metallurgical production of calcium oxide (quicklime), while the dry mixture does not contain anthracite and iron oxide.

[0021] There is an option when a dry mixture is prepared on the basis of dusty waste from the metallurgical production of calcium oxide (quicklime), in the following ratio, wt.%:

[0022] dusty waste from metallurgical production 90-98 calcium oxide (quicklime) 2-10

[0023] There is also an option when a dry mixture is prepared on the basis of dusty waste from metallurgical production and anthracite, for example in the following ratio, wt.%:

[0024] dusty waste from metallurgical production 30-50 anthracite 40-60 calcium oxide (quicklime) 2-8

[0025] There is an option when ferrosilicon manganese (FeSiMn) dust is used in a dry mixture as dust-like waste from metallurgical production.

[0026] A step for preparing a composite binder, where the components (technical lignosulfonate, lignosulfonate), beet molasses, cane molasses, or treacle, graphite, water, and an alkaline agent) are sequentially mixed to form a suspension. Mixing is continued until a homogeneous suspension with a pH of 10-12 is obtained. It should be noted that sodium hydroxide or calcium hydroxide can be used as the alkaline agent. In a preferred embodiment, the binder contains the following ratio, by weight of the dry mixture:

[0027] lignosulfonate 1,5-7,0 molasses 2,0-7,0 graphite 0,5-2,5 alkaline agent (calcium hydroxide) 0,5-3,0 water 5,0-15,0

[0028] The stages of preparation and manufacturing of composite binder can be carried out either sequentially or in parallel.

[0029] The mixing stage where the prepared dry mix and binder are fed into an intensive mixer where they are mixed for 5-20 minutes until a homogeneous semi-dry consistency is achieved.

[0030] Briquetting stage, where the resulting mass is compacted on a roller briquette press, hydraulic press or extruder under a pressure of 300-500 kgf / cm 2 with the formation of briquettes of a given shape, for example, in a spherical shape (“nut”) or in a cylindrical shape (“tablet”), or another, depending on the purpose of the briquettes.

[0031] Drying stage where the raw briquettes are dried at 150-200°C for 1-3 hours to remove free moisture.

[0032] A heat treatment step in which the dried briquettes are placed in a calcination furnace with a controlled inert atmosphere (e.g., nitrogen or argon) and maintained at a temperature of 400-700°C for 1.5-2.5 hours. The heating rate does not exceed 5°C / min.

[0033] The cooling stage, where the finished metallurgical briquettes are cooled to ambient temperature. They are then sent for packaging and storage.

[0034] The metallurgical briquette contains the following components, in wt.%:

[0035]

[0036] It should be noted that the presented example of the claimed metallurgical briquette and the method for its production does not limit possible changes and modifications using solutions of the known prior art within the scope and essence of the attached claims.

[0037] Quartz sand in the briquette is the main source of SiO2, while the addition of anthracite reduces ash content, and quicklime lowers the slag melting point. The use of lignosulfonate and molasses in the binder reduces water absorption by up to 5% and increases briquette strength through polymerization during heat treatment. The use of graphite, which has a thermally stable crystal lattice, ensures denser particle packing during pressing and strengthens the briquette matrix.

[0038] Calcium hydroxide (slaked lime) Ca(OH)2 can also be added to the dry mix as a source of calcium oxide (flux), making it easier to handle during dosing and mixing. During subsequent calcination of the briquettes at 400-700°C, the calcium hydroxide dehydrates, forming active calcium oxide (quicklime) CaO directly within the briquette structure according to the reaction: Ca(OH)2 → CaO + H2O.

[0039] The following are examples of the implementation of the claimed invention.

[0040] Example 1. Metallurgical briquette for foundry production, contains the following components, in wt.%:

[0041]

[0042] At the heat treatment stage, the dried briquettes are placed in a calcination furnace with a controlled inert atmosphere (N2) and maintained at a temperature of 600°C for 2.0 hours.

[0043] The metallurgical briquette for foundry production, obtained by the stated method, allows achieving the following parameters:

[0044]

[0045] Example 2. Metallurgical briquette for ferroalloy production, including the following components, in wt.%:

[0046]

[0047]

[0048] At the heat treatment stage, the dried briquettes are placed in a calcination furnace with a controlled inert atmosphere (N2) and maintained at a temperature of 650°C for 1.5 hours.

[0049] Metallurgical briquette for ferroalloy production allows achieving the following parameters:

[0050]

[0051] Example 3. Metallurgical briquette for recycling ferroalloy dust containing the following components, in wt.%:

[0052]

[0053] At the heat treatment stage, the dried briquettes are placed in a calcination furnace with a controlled inert atmosphere (Ag) and maintained at a temperature of 500°C for 2.0 hours.

[0054] Metallurgical briquette for recycling ferroalloy dust allows achieving the following parameters:

[0055]

[0056]

[0057] Example 4. Metallurgical briquette for the disposal of sludge and dust from gas cleaning, including the following components, in wt.%:

[0058]

[0059] At the heat treatment stage, the dried briquettes are placed in a calcination furnace with a controlled inert atmosphere (N2) and maintained at a temperature of 550°C for 2.0 hours.

[0060] Metallurgical briquette for the disposal of sludge and dust from gas cleaning allows achieving the following parameters:

[0061]

[0062] As can be clearly seen, the declared composition of the metallurgical briquette and its variants, as well as the method of its production, make it possible to achieve the declared technical result, namely, to obtain a product with high mechanical strength, heat resistance and the required metallurgical properties, to expand the raw material base due to the utilization of man-made waste, including sludge and dust from gas cleaning with a high content of iron and zinc oxides.

[0063] The metallurgical briquette obtained by the stated method allows achieving the following parameters:

[0064]

[0065] .

Claims

1. A method for producing a metallurgical briquette, including preparing a dry mixture, preparing a binder based on lignosulfonate and molasses, mixing the dry mixture with the binder, briquetting and drying, characterized in that the binder additionally contains graphite, water and an alkaline agent in the following ratio, wt.% of the weight of the dry mixture: lignosulfonate 1,5-7,0 molasses 2,0-7,0 graphite 0,5-2,5 alkaline agent - calcium hydroxide 0,5-3,0 water 5,0-15,0, and after drying, the briquettes are calcined at a temperature of 400-700°C in an inert atmosphere, with the strength of the resulting briquettes (CBS) being at least 65%.

2. The method according to paragraph 1, characterized in that nitrogen or argon is used as an inert atmosphere during calcination.

3. The method according to paragraph 1, characterized in that the heating rate during calcination is no more than 5°C / min.

4. The method according to paragraph 1, characterized in that the dry mixture is prepared with the following composition, wt.%: quartz sand 60-70 anthracite 20-25 iron oxide 5-10 calcium oxide (quicklime) 2-8 5. The method according to paragraph 1, characterized in that the dry mixture is prepared with the following composition, wt.%: quartz sand 70-80 anthracite 20-30 calcium oxide (quicklime) 2-3 6. The method according to paragraph 1, characterized in that coke, semi-coke and / or anthracite fines are used as the carbon raw material for the dry mixture.

7. The method according to paragraph 1, characterized in that the dry mixture is prepared on the basis of dusty waste from metallurgical production and calcium oxide - quicklime, while the dry mixture does not contain anthracite and iron oxide.

8. The method according to paragraph 7, characterized in that the dry mixture is prepared with the following composition, wt.%: dusty waste from metallurgical production 90-98 calcium oxide (quicklime) 2-10 9. The method according to paragraph 7, characterized in that ferrosilicon dust, ferrochrome dust, or blast furnace gas cleaning sludge are used as dust-like waste from metallurgical production.

10. The method according to paragraph 1, characterized in that the dry mixture is prepared on the basis of dusty waste from metallurgical production and anthracite.

11. The method according to paragraph 9, characterized in that the dry mixture is prepared with the following composition, wt.%: dusty waste from metallurgical production 30-50 anthracite 40-60 calcium oxide (quicklime) 2-8 12. The method according to paragraph 10, characterized in that ferrosilicon manganese (FeSiMn) dust is used as dust-like waste from metallurgical production.

13. The method according to paragraph 1, characterized in that the dry mixture used is sludge from blast furnace gas cleaning and / or dust from electric smelting units gas cleaning, and / or zinc-containing dust.

14. The method according to paragraph 1, characterized in that briquetting is carried out on a roller briquette press, a hydraulic press, or an extruder.

15. A metallurgical briquette obtained according to any of paragraphs 1-14.

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