RU2401869C1 - Slag forming mixture for steel refining (versions) and briquette out of slag forming mixture (versions) - Google Patents

Abstract

FIELD: metallurgy. ^ SUBSTANCE: slag forming mixture includes components containing aluminium oxide Al2O3 in wt % 3099. Also, components in its composition are chosen depending on percent contents of Al2O3 at the following ratio in wt %: 535 of Al2O3 >90; 3070 AI2O3 from 55 to 90; the rest - Al2O360 of fractions<1 mm, 1020 of fractions 110 mm, the rest - of fractions from 10 to 30 mm. With introduction of pure aluminium into the composition of mixture composition of components does not exceed 5 mm. The briquette out of slag forming mixture contains binding at ratio in wt % 14 and compressed particles including aluminium oxide in wt %: 3099 or aluminium oxide Al2O3 and aluminium in wt %: 3099 and 120 correspondingly. Notably, components are chosen depending on contents of Al2O3 at the following ratios in wt %: 535 Al2O3>90; 3070 Al2O3 from 55 to 90; the rest -Al2O360 of fractions 01 mm; 60>25 of fractions 13 mm; the rest - of fractions 35 mm. Volume of a briquette is 4070 cm3, its volume density is 72.0 g/cm3, briquette humidity is within ranges of 15%, while its volume is 4070 cm3. ^ EFFECT: ensuring quality of refined steel and prevention of contact zone of lining and slag from destruction. ^ 12 cl, 2 tbl

Description

The invention relates to the field of metallurgy and can be used in aggregates for complex processing of steel (AKOS) when slag-forming mixtures are introduced into a ladle furnace to accelerate the production of refining slags on the surface of a liquid melt and neutralize their destructive effect on the lining by forming in the zone of interaction of slag with magnesia lining bucket protective spinel.

Slag usually covers the surface of a liquid metal in metallurgical processes: smelting raw materials, processing molten intermediates and refining liquid melts. Slag is an alloy of oxides of variable composition; The main components of the slag are acid oxide SiO ₂ and alkaline oxides CaO, FeO, MgO, as well as neutral oxides Al ₂ O ₃ . During the chemical reaction that occurs when the steel is treated with slag containing Al, and called deoxidation, the product of deoxidation Al ₂ O ₃ remains, which is removed during subsequent refining of the product. CaF ₂ fluorspar is usually used for this purpose. Side effects from its use include the release of fluorine, the removal of which is associated with additional costs for ventilation and treatment equipment and intensive destruction of the lining of the bucket in the zone of contact with slag.

Steel refining is also carried out by adding to the slag melt mixtures having absorbing properties with respect to Al ₂ O ₃ , prepared, for example, on the basis of alumina. However, due to the fine structure of alumina, its introduction into the ladle furnace is impossible without preliminary processing. Therefore, there is a need for the preparation of synthetic slag of a given composition by fusing its components in a melting furnace, which leads to a sharp rise in the cost of the product.

Known slag-forming heat-insulating mixture for liquid melt [description of the patent of the Russian Federation No. 2320451, publ. March 27, 2008], including organic and mineral components, characterized in that the mineral component has the following composition, wt.%: Basic oxides CaO, MgO - 53.00-65.00, acid oxide SiO ₂ - not more than 50.00, bauxite Al ₂ O ₃ - not more than 36.00 or basic oxides CaO, MgO - 53.00-65.00, acid oxide SiO ₂ - not more than 50.00 - not more than 36.00 or basic oxides CaO, MgO - 53 , 00-65.00, bauxite Al ₂ O ₃ - not more than 36.00, while the organic and mineral components are taken in the following ratio, wt.%: Organic component 5-25, mineral component 75-95.

The disadvantage of this mixture is that it does not ensure the removal of Al ₂ O ₃ from the melt and does not protect the contact zone of the lining and slag from destruction.

The aim of the invention is the creation of a slag-forming mixture that improves the quality of steel refining and provides protection of the contact zone of the lining and slag from destruction, with a significant - up to 25%, reducing its cost.

This goal is achieved through the use of combinations of primary and secondary alumina, corundum materials, scrap and waste high alumina refractories, while the slag-forming mixture for refining steel, including components containing aluminum oxide (Al ₂ O ₃ ), includes components containing oxide aluminum in an amount of 30 ÷ 99 wt.% in the following ratio in the mixture, wt.%:

components with Al ₂ O ₃ > 90 content 5 ÷ 35 components with Al ₂ O ₃ content from 55 to 90 30 ÷ 70 components with the content of Al ₂ About ₃ <55 rest.

The composition of the mixture may also include aluminum waste, such as aluminum shavings. In this case, the slag-forming mixture for refining steel, including components containing aluminum oxide (Al ₂ O ₃ ) and aluminum, includes components with an aluminum oxide content of 30–99 wt.% And aluminum in an amount of 1–20 wt.% , the ratio of components containing aluminum oxide in the mixture is, wt.%:

components with Al ₂ O ₃ > 90 content 5 ÷ 35 components with Al ₂ O ₃ content from 55 to 90 30 ÷ 70 components with the content of Al ₂ About ₃ <55 rest.

The list of materials used as components with different percentages of Al ₂ O ₃ and Al is shown in Table 1.

Table 1 The content of Al ₂ About ₃ (%%) Components and content of Al ₂ O ₃ (%%) and Al more than 90 White aluminum oxide - 99 Scrap corundum lightweight - 99 Alumina - 98 from 55 to 90 High alumina cement - 70 High alumina scrap 65 ÷ 85 (scrap of mullite-corundum wall (MKS-72, MMKN-90) and mullite-corundum (MMKB) bricks, mullite aggregate MMK-88) less than 55 Alumina cement - 50 Chamotte scrap 30 ÷ 35 Clay (Kaolin) - 35 Clay (PHB) - 30 Pure Al Aluminum shavings - 99

Variants of the composition of the mixture are shown in Table 2.

table 2 Content Components (%%) Al ₂ O ₃ (%%) I option II option III option More than 90 White aluminum oxide - 30 Alumina - 10 Alumina - 10 (scrap of corundum light weight) White aluminum oxide - 15 White aluminum oxide - 10 (scrap of corundum light weight) (scrap of corundum light weight) from 55 to 90 Alumina and / or high alumina cement - 7 Alumina and / or high alumina cement - 7 Alumina and / or high alumina cement - 7 High alumina scrap - 26 High alumina scrap - 37 High alumina scrap - 43 less than 55 Chamotte scrap -37 Clay (kaolin) - 13 Chamotte scrap - 30 Pure al - Aluminum shavings - 18 -

Achieving the required technical result in terms of quality and cost of the steel refining process, as well as in protecting against destruction of the contact area of the lining of the ladle and slag, is due to the composition of the slag-forming mixture and the method of its introduction into the ladle furnace.

For the fastest possible formation of a slag layer on the melt mirror, a protective spinel in the zone of contact between the slag and the ladle lining, as well as ensuring a generally constant reaction rate for steel refining due to uniform dissolution of the slag-forming mixture for steel refining, including components containing aluminum oxide ( Al ₂ O ₃ ), includes components with an aluminum oxide content of 30 ÷ 99 wt.% In the following ratio in the mixture, wt.%:

components with the content of Al ₂ About ₃ > 90 5 ÷ 35 components with Al ₂ O ₃ content from 55 to 90 30 ÷ 70 components with the content of Al ₂ About ₃ <55 rest,

while the slag-forming mixture has the following fractional composition, wt.%:

components with a fraction of 0 ÷ 1 mm > 60 components with a fraction of 1 ÷ 10 mm 10 ÷ 20 components with a fraction of 10 to 30 mm rest.

When pure aluminum Al is introduced into the mixture in the form, for example, of aluminum production waste, their fractional composition does not exceed 5 mm. In this embodiment, a slag-forming mixture for refining steel, including components containing aluminum oxide (Al ₂ O ₃ ) and aluminum, includes components with an aluminum oxide content of 30–99 wt.% And aluminum in an amount of 1–20 wt.%, Moreover the ratio of components containing alumina in the mixture is, wt.%:

components with the content of Al ₂ About ₃ > 90 5 ÷ 35 components with Al ₂ O ₃ content from 55 to 90 30 ÷ 70 components with the content of Al ₂ About ₃ <55 rest,

while the slag-forming mixture has the following fractional composition, wt.%:

components with a fraction of 0 ÷ 1 mm > 60 components with a fraction of 1 ÷ 10 mm 10 ÷ 20 components with a fraction of 10 to 30 mm rest.

However, in the process of introducing the manufactured mixture with the specified fractional composition into the ladle furnace, losses of the main fractional component (<1 mm) are inevitable, which primarily affects the rate of formation of the slag layer and the protective spinel. Losses are caused by the presence in the transportation and loading zone of intense air currents that are characteristic and inherent in metallurgical shops. This problem can be solved, for example, by briquetting fractions of the mixture, subject to blowing. In addition, briquetting of fine fractions of the mixture ensures maximum accuracy of its dosage, excluding spontaneous descent from the hopper into the ladle furnace.

A known briquette for steelmaking [description of the invention to the patent of the Russian Federation No. 2304175, IPC С22В 1/243 (2006.01), publ. 08/10/2007]. The briquette contains scale of ferrous metals, blast furnace dust, gas treatment dust from electric steelmaking and cement as a binder. The ratio of the components in the briquette is as follows, wt.%: Gas cleaning dust from electric steelmaking production 10-60, blast furnace dust 0.5-15, dross of ferrous metals 35-80, cement 1-4.5.

Also known is a briquette for steelmaking [description of the invention to the patent of the Russian Federation No. 2298584,

IPC С22В 1/243 (2006.01), publ. 05/10/2007]. The briquette contains iron-containing waste from metallurgical production, including blast furnace dust 1-40 wt.%, Pulverized dolomite 5-30 wt.%, Cement as a binder 1-5 wt.% And gas cleaning dust from electric steelmaking 40-80 wt.%.

Closest to the proposed is a briquette for deoxidation and refining of steel [description of the invention to the patent of the Russian Federation No. 2226556, IPC С21С 7/06, publ. 04/10/2004], made in the form of compressed particles consisting of aluminum and aluminum oxide, while the particles forming it are aluminum shavings 1-2 mm thick coated with a shell of aluminum oxide, while the bulk density of the briquette is 0.85-0 , 95 chip density, and the ratio by weight of aluminum and aluminum oxide is in the range (100: 6) - (100: 13).

The main disadvantage of this briquette is its high cost.

The aim of the invention is the elimination of losses of the slag-forming mixture and ensuring the accuracy of its dosage when reaching maximum values of the rates of formation of the liquid slag phase and the specified quality indicators of steel after refining at a reduced cost of production of briquettes.

To achieve this goal, a briquette from a slag-forming mixture for steel refining, including compressed particles of components containing aluminum oxide (Al ₂ O ₃ ), includes a binder that defragments the briquette into fractions, in an amount of 1 ÷ 4 wt.%, And components that include oxide aluminum, contain aluminum oxide in them in an amount of 30 ÷ 99 wt.% in the following ratio in the mixture, wt.%:

components with the content of Al ₂ About ₃ > 90 5 ÷ 35 components with Al ₂ O ₃ content from 55 to 90 30 ÷ 70 components with the content of Al ₂ About ₃ <55 rest,

while these components have the following fractional composition, wt.%:

components with a fraction of 0 ÷ 1 mm > 60 components with a fraction of 1 ÷ 3 mm from 25 to 60 components with a fraction of 3 ÷ 5 mm rest,

moreover, the bulk density of the briquette is 1.7 ÷ 2.0 g / cm ³ , the humidity is 1 ÷ 5%, and the melting or burning temperature of the binder is 550 ÷ 650 ° C.

In an embodiment of a briquette from a slag-forming mixture for refining steel, including compressed particles of components containing aluminum oxide (Al ₂ O ₃ ) and aluminum, the briquette includes a binder that defragments the briquette into fractions, in an amount of 1 ÷ 4 wt.%, And the components including aluminum oxide and aluminum, contain aluminum oxide in them 30 ÷ 99 wt.% and aluminum in an amount of 1 ÷ 20 wt.%, and the ratio of components containing alumina in the mixture is, wt.%:

components with the content of Al ₂ About ₃ > 90 5 ÷ 35 components with Al ₂ O ₃ content from 55 to 90 30 ÷ 70 components with the content of Al ₂ About ₃ <55 rest,

while these components have the following fractional composition, wt.%:

components with a fraction of 0 ÷ 1 mm > 60 components with a fraction of 1 ÷ 3 mm from 25 to 60 components with a fraction of 3 ÷ 5 mm rest.

As in the first embodiment, the bulk density of the briquette is 1.7 ÷ 2.0 g / cm ³ , humidity is 1 ÷ 5%, and the melting or burning temperature of the binder is 550 ÷ 650 ° C.

In both versions, either an inorganic binder, for example building cement, and / or alumina cement, and / or high alumina cement, or an organic binder, for example lignosulfonate (LST), and / or PVA glue, and / or molasses, can be used as a binder, and / or starch. It is allowed to use both independently inorganic or organic binders, and their various combinations. The main requirement for ligaments is their melting or burning temperature, which ensures defragmentation of the briquette into fractions in the temperature range 550 ÷ 650 ° С. The briquette has a volume of 40 ÷ 70 cm ³ .

In one embodiment, the briquette is made, in general, in the form of a cube with the size of any of the ribs no more than 45 mm by pressing the mixture with a binder introduced into its composition. Pressing is carried out in special forms on a roller press with a small pressure of the rolls or on a vibrating table. Then the mixture in the molds is dried and, after cooling, unloaded from the molds.

Storage and transportation of briquettes is carried out in waterproof packaging.

The use of combinations of primary and secondary alumina, corundum materials, scrap and waste of high-alumina refractories makes it possible to reduce the cost of the mixture and bring it closer to fluorspar, and the use of the proposed briquettes from slag-forming mixture avoids losses of its main fractional component (<1 mm) and reaches the maximum the accuracy of the dosage of the mixture, to ensure the specified quality indicators of the steel after its refining.

Claims (12)

1. Slag-forming mixture for refining steel, comprising components containing aluminum oxide (Al ₂ O ₃ ), characterized in that the slag-forming mixture includes components with an aluminum oxide content of 30-99 wt.% In the following ratio in the mixture, wt.%:
components with the content of Al ₂ About ₃ > 90 5-35 components with Al ₂ O ₃ content from 55 to 90 30-70 components with the content of Al ₂ About ₃ <55 rest 2. Slag-forming mixture for refining steel, including components containing aluminum oxide (Al ₂ O ₃ ) and aluminum, characterized in that the slag-forming mixture includes components with an aluminum oxide content of 30-99 wt.% And aluminum in an amount of 1 -20 wt.%, While the ratio of components containing alumina in the mixture is, wt.%:
components with the content of Al ₂ About ₃ > 90 5-35 components with Al ₂ O ₃ content from 55 to 90 30-70 components with the content of Al ₂ About ₃ <55 rest 3. Slag-forming mixture for refining steel, including components containing aluminum oxide (Al ₂ O ₃ ), characterized in that the slag-forming mixture includes components with an aluminum oxide content of 30-99 wt.% In the following ratio in the mixture, wt. %:
components with the content of Al ₂ About ₃ > 90 5-35 components with Al ₂ O ₃ content from 55 to 90 30-70 components with the content of Al ₂ About ₃ <55 rest,
while the slag-forming mixture has the following fractional composition, wt.%:
components with a fraction of 0-1 mm > 60 components with a fraction of 1-10 mm 10-20 components with a fraction of 10 to 30 mm rest 4. Slag-forming mixture for refining steel, including components containing aluminum oxide (Al ₂ O ₃ ) and aluminum, characterized in that the slag-forming mixture includes components with an aluminum oxide content of 30-99 wt.% And aluminum in an amount of 1-20 wt.%, while the ratio of components containing alumina in the mixture is, wt.%:
components with the content of Al ₂ About ₃ > 90 5-35 components with Al ₂ O ₃ content from 55 to 90 30-70 components with the content of Al ₂ About ₃ <55 rest,
while the slag-forming mixture has the following fractional composition, wt.%:
components with a fraction of 0-1 mm > 60 components with a fraction of 1-10 mm 10-20 components with a fraction of 10 to 30 mm rest 5. A briquette from a slag-forming mixture for refining steel, comprising compressed particles of components containing aluminum oxide (Al ₂ O ₃ ), characterized in that the briquette includes a binder to defragment the briquette into fractions, in an amount of 1-4 wt.%, And the components including aluminum oxide, contain aluminum oxide in them in an amount of 30-99 wt.% in the following ratio in the mixture, wt.%:
components with the content of Al ₂ About ₃ > 90 5-35 components with Al ₂ O ₃ content from 55 to 90 30-70 components with the content of Al ₂ About ₃ <55 rest,
while these components have the following fractional composition, wt.%:
components with a fraction of 0-1 mm > 60 components with a fraction of 1-3 mm from 25 to 60 components with a fraction of 3-5 mm rest,
moreover, the bulk density of the briquette is 1.7-2.0 g / cm ³ , humidity -1-5%, and the melting or burning temperature of the binder is 550-650 ° C. 6. The briquette according to claim 5, characterized in that an inorganic binder is used as a binder, for example, building cement and / or alumina cement, and / or high alumina cement. 7. The briquette according to claim 5, characterized in that the binder used is an organic binder, for example, lignosulfonate and / or PVA glue, and / or molasses, and / or starch. 8. The briquette according to claim 5, characterized in that the briquette has a volume of 40-70 cm ³ . 9. A briquette from a slag-forming mixture for refining steel, comprising compressed particles of components containing aluminum oxide (Al ₂ O ₃ ) and aluminum, characterized in that the briquette includes a binder to defragment the briquette into fractions, in an amount of 1-4 wt.%, and components including aluminum oxide and aluminum, contain aluminum oxide in them 30-99 wt.% and aluminum in an amount of 1-20 wt.%, while the ratio of components containing alumina in the mixture is, wt.%:
components with the content of Al ₂ About ₃ > 90 5-35 components with Al ₂ O ₃ content from 55 to 90 30-70 components with the content of Al ₂ About ₃ <55 rest,
while these components have the following fractional composition, wt.%:
components with a fraction of 0-1 mm > 60 components with a fraction of 1-3 mm from 25 to 60 components with a fraction of 3-5 mm rest,
moreover, the bulk density of the briquette is 1.7-2.0 g / cm ³ , humidity -1-5%, and the melting or burning temperature of the binder is 550-650 ° C. 10. The briquette according to claim 9, characterized in that an inorganic binder, for example, building cement and / or alumina cement, and / or high alumina cement, is used as a binder. 11. The briquette according to claim 9, characterized in that an organic binder, for example, lignosulfonate and / or PVA glue, and / or molasses, and / or starch, is used as a binder. 12. The briquette according to claim 9, characterized in that the briquette has a volume of 40-70 cm ³ .