RU2485172C1 - Method of producing oxide-fuel briquettes - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing oxide-fuel briquettes, involving preparation of a briquetting mixture which contains coal fines, blast-furnace dust and/or iron dross, lime, a sulphonic acid derivative or molasses, compacting the mixture in vibration moulds and drying the briquettes, the method being characterised by that the following is used at the step of preparing the briquetting mixture, wt %: coal fines 45-64, blast-furnace dust and/or iron dross - 5-10, lime - 5-6, sulphonic acid derivative or molasses - 5-6; slag from ferromanganese production and/or manganese ore fines containing 30-60 wt % manganese oxide is added to increase content of manganese in the obtained cast iron; 20-30 wt % table salt is added, and after drying, the obtained briquettes are put into water for complete dissolution of salt and the drying process is repeated in order to form pores in the briquettes.

EFFECT: method increases strength, thermal stability and porosity of briquettes, while increasing their reactivity and efficiency of reducing manganese oxides.

1 cl, 3 ex, 1 tbl

Description

The invention relates to the technology of briquetting of minerals, secondary raw materials, industrial waste and can be used in the metallurgical and engineering industries for the smelting of cast iron.

A known method of briquetting small classes of coke [1], which includes obtaining a briquette from small fractions of coke and applying a protective coating on it, characterized in that the briquette formed from various methods of small coke of a certain shape is placed on the draws in a detachable flask into which the filling the channel is supplied with liquid melt of blast furnace or steel slag, it is cooled and a briquette covered with a layer of slag having porosity and thermal stability is removed. The invention improves the strength and heat resistance of briquetted fines of coke, as well as to increase the efficiency of using secondary materials.

The disadvantage of this method is the complexity of the process of obtaining a briquette and the need for high capital costs for the implementation of the project.

A known method of producing a metallurgical briquette [2], adopted for the prototype, comprising mixing coke or coal fines with crushed waste metallurgical production, sulfonic acid derivative and lime, briquetting the mixture, subsequent heat treatment and cooling of the briquettes, characterized in that as the waste of metallurgical production using oil-calcin-containing sludge and / or blast furnace dust and / or iron oxide with the following content of components, wt.%: oil-sludge-containing sludge and / or stake collar dust and / or iron oxide - 10-60, sulfonic acid or molasses derivative - 1-15, lime - 0.01-10.0, coke or coal fines - up to 100, briquettes are pressed at a pressure of 5 MPa and subjected to heat treatment at 250-700 ° C for at least 5 minutes, and the lime powder is introduced into the mixture or applied to the briquette in the form of a layer of a saturated aqueous solution of lime, with the addition of 5-30 wt.% derivative of sulfonic acid or molasses. The briquettes are cooled simultaneously with the application of the lime solution on the hot briquettes due to the evaporation of moisture from the solution, and the briquettes can also be cooled by mixing them with oil-sludge-containing sludge and / or coke breeze followed by briquetting.

The disadvantage of the prototype is that the resulting briquettes have low efficiency. In the prototype, recovery processes occur only on the surface of the briquette in a direct way with solid carbon:

FeO + C → Fe + CO,

Fe ₂ O ₃ + C → 2FeO + CO,

Fe ₃ O ₄ + C → 3FeO + CO.

If pores were present in the briquette, then indirect reduction using carbon monoxide II would occur in them:

FeO + CO → Fe + CO ₂ ,

Fe ₂ O ₃ + CO → 2FeO + CO ₂ ,

Fe ₃ O ₄ + CO → 3FeO + CO ₂ .

The objective of the invention is to increase the regenerative ability of briquettes due to the pores formed, as well as to improve the quality of cast iron by adding manganese oxides to the briquette.

The problem is solved as follows: in a method for producing oxide-fuel briquettes, comprising preparing a briquetting mixture containing fines of coal, blast furnace dust and / or iron oxide, lime, a sulfonic acid derivative or molasses, compacting the mixture in vibration forms and drying the briquettes, characterized in that at the stage of preparing the mixture for briquetting take, wt.%: fines of coal - 45-64, blast furnace dust and / or iron oxide - 5-10, lime - 5-6, sulfonic acid derivative or molasses - 5-6, add ferromanganese slag th production and / or fines manganese ore containing manganese oxides, wt% - 30-60 to increase the manganese content in the resulting cast iron.; table salt, wt.% - 20-30, and after drying the resulting briquettes they are placed in water to completely dissolve the salt and repeat the drying process to form pores in the briquette. Salt crystals, dissolving, leave an empty space instead, which increases the porosity of the briquette.

The mixture is compacted in vibroforms, the resulting briquette is placed in a chamber dryer at a temperature of 90-100 ° C for 10-15 minutes to give the necessary strength, after which it is placed in a water bath to completely dissolve table salt and again sent to a chamber dryer, where the briquette is 10-15 minutes at a temperature of 90-100 ° C.

Coal fines and manganese and iron oxides are added to the briquetting mixture in accordance with the stoichiometry and atomic weights of the components of the reactions of direct and indirect reduction of manganese with carbon and carbon monoxide II.

With the composition of fines of coal less than 45% and slag of ferromanganese production and / or fines of manganese ore over 60%, carbon will not be enough to completely restore manganese from its oxides. With the composition of fines of coal more than 64% and slag of ferromanganese production and / or fines of manganese ore, less than 30% of the carbon in the briquette will be in excess in excess of the amount necessary for the complete reduction of manganese from its oxides. Carbon will mostly burn, and manganese briquette performance will be minimal.

Iron oxides in the amount of 5-10% are added to the briquette as a catalyst for the reduction process of manganese oxides by direct and indirect method. When the composition of blast furnace dust is less than 5% and the slag of ferromanganese production and / or fines of manganese ore over 60%, iron oxides will not be enough as a catalyst for the complete reduction of manganese from its oxides. When the composition of blast furnace dust is more than 10% and the slag of ferromanganese production and / or fines of manganese ore less than 30% of iron oxides as a catalyst in the briquette will be in excess in excess of the amount necessary for the complete recovery of manganese from its oxides. Iron will be restored mainly, and the productivity of the briquette for manganese will be minimal.

A content of lime below 5% will lead to incomplete slagging of coal ash, and if the content of lime is above 6%, the slag will become excessively fluid and will easily leak out of the briquette and not participate in metallurgical reactions of reduction of iron and manganese.

An interval of 5-6% for a sulfonic acid derivative or molasses is associated with the strength characteristics of the briquette. If the content of the sulfonic acid derivative or molasses is less than 5% or more than 6%, the briquette strength will be insufficient.

When the salt content is less than 20% of the pores in the briquette after dissolving the salt and drying the briquettes, it will not be enough for the reactions of indirect reduction of iron and manganese to proceed:

MnO ₂ + 2CO → Mn + 2CO ₂ ,

Mn ₂ O ₇ + 7CO → 2Mn + 7CO ₂ .

MnO oxide is reduced only by direct means on the surface of the briquette by the reaction: MnO + C → Mn + CO.

When the content of table salt is above 30%, the strength of the briquette after dissolving the salt and drying the briquette drops below a technologically acceptable level.

The experiments were carried out on the cupola of the laboratory of the foundry department of the Siberian State Industrial University (Siberian State University, Novokuznetsk).

The cupola has an internal diameter of 200 mm, a useful height of 2.5 m and a pipe-in-pipe recuperator built into the mine, and is serviced by a BP-120-28 high-pressure fan with a rated capacity of Q = 4.5 · 10 ³ nm ³ / h and pressure P = 600 mm water column

Three series of experiments were carried out:

I series: metal charge (battle of heating radiators) - 200 kg; coke - 28 kg; limestone - 8 kg.

II series: metal charge - 200 kg; coke - 18.0 kg; briquettes without pores - 16.8 kg; limestone - 8 kg. The composition of the briquettes (wt.%): Fines of coal - 45; ferromanganese slag production and / or fines of manganese ore - 60; iron oxides - 10; lime - 5; molasses - 6 in excess of 100%.

III series: metal charge - 200 kg; coke - 18.0 kg; briquettes with pores - 16.8 kg, limestone - 8 kg. Briquettes had pores in an amount of 30% by volume, obtained as a result of adding table salt to the briquette charge in an amount of 25% in excess of the charge volume and dissolving it after briquetting. The composition of the briquettes (wt.%): Coal - 45; ferromanganese slag and manganese ore fines - 60; iron oxides - 10; lime - 5; molasses - 6 in excess of 100%, table salt - 25 in excess of 100%, dissolved after briquetting to form pores.

The melts were conducted at an air flow rate of 1.9 m ³ / (m ² s) for one hour. Cast iron from a cupola was poured into metal molds measuring 100 × 100 × 50 mm. The molds were knocked out after cooling, and the resulting ingots were weighed on an electronic balance with digital mass indexing.

The experimental results are shown in the table.

The percentage of manganese in the resulting molten iron from a cupola for one hour,% I series 0.35-0.40 II series 0.70-0.75 III series 0.88-0.96

The experiments showed:

In series I, the manganese content is 0.35-0.40% in the obtained molten iron due to the manganese contained in the refractory fight;

In the II series, the increased content of manganese is 0.70-0.75% in the obtained molten iron due to briquettes without pores that contain slag from ferromanganese production and / or fines of manganese ore, which are an additional source of manganese oxides. In briquettes without pores, only direct reduction reactions occur. MnO oxide is reduced only by direct means on the surface of the briquette by the reaction:

MnO + C → Mn + CO.

In series III, the increased manganese content of 0.88-0.96% in the obtained molten iron due to briquettes containing, in addition to slag, ferromanganese production and / or fines of manganese ore, pores formed by the addition of salt, which simultaneously undergo direct reduction processes reactions:

MnO + C → Mn + CO,

MnO ₂ + 2C → Mn + 2CO,

Mn ₂ O ₇ + 7C → 2Mn + 7CO.

And indirect recovery by reaction:

MnO ₂ + 2CO → Mn + 2CO ₂ ,

Mn ₂ O ₇ + 7CO → 2Mn + 7CO ₂ .

The method allows to increase the strength, heat resistance and porosity of briquettes, increasing their reactivity and efficiency of the reduction of manganese oxides.

List of sources used

1. RF patent No. 2374308. Method for briquetting small classes of coke / Selyanin I.F., Senkus V.V., Feoktistov A.V. IPC C 10 L 5/32. Claim 2008.21.04. Publ. 2009.27.11. Bull. Number 8.

2. RF application No. 97107736. Carbon-containing briquette and method for its preparation. / Luri V.G. IPC C 10 L 5/48. Claim 1997.04.08. Publ. 1999.02.27. Bull. Number 3.

Claims (1)

A method of producing oxide-fuel briquettes, comprising preparing a briquetting mixture containing fines of coal, blast furnace dust and / or iron oxide, lime, a sulfonic acid derivative or molasses, compacting the mixture in vibration forms and drying the briquettes, characterized in that at the stage of preparing the briquetting mixture take, wt.%: fines of coal - 45-64, blast furnace dust and / or iron oxide - 5-10, lime - 5-6, sulfonic acid derivative or molasses - 5-6, add ferromanganese slag and / or fines of manganese ore , sod containing manganese oxides - 30-60 wt.% to increase the manganese content in the resulting cast iron; table salt - 20-30 wt.%, and after drying the resulting briquettes they are placed in water to completely dissolve the salt and repeat the drying process to form pores in the briquette.