EA012637B1 - Mixture for refining and modifying steel and cast iron - Google Patents

Abstract

The invention relates to metallurgy, in particular to out-of-furnace processing of steel and cast-iron. Said invention enables to develop a reaction mixture which makes it possible to extract alkaline-earth or earth rare metals with a high recovery degree during the recovery thereof from carbonates and oxides, mainly by means of aluminium, subsequently, to form stable silicon compounds and to obtain a liquid-movable synthetic slag from calcium aluminate. The inventive mixture for refining and modifying steel and cast-iron comprises a polymetal ore containing carbonates and/or oxides of alkaline-earth metals, oxides of earth rare metals, aluminium, silicon or the alloys thereof consisting of iron whose content is equal to or less than 25 % and a datolite ore in the quantity of 30-80, 0.001-15, 5-30, 5-25 and 1-5 mass %. Said mixture cal also contain 0-15 mass % at least one type of oxide from a TiO, NbO, VO, MoOand NiO group. Said mixture makes it possible to exclude the roast processing of a main component, to produce and dry brings, when the mixture is introduced in an iron-carbon melt, to produce a liquid-movable and a highly-basic slag and to simultaneously carry out refining, modifying and micro alloying of steel and cast-iron.

Description

The invention relates to the field of metallurgy, in particular to the creation of a refining and modifying mixture for the treatment of steel and cast iron. The developed mixture can be used at metallurgical and machine-building enterprises for out-of-furnace processing of steel and cast iron in order to improve their quality.

Known refining and modifying mixture containing 50-70% of oxides and / or carbonates of barium, calcium, magnesium, 1-10% of oxides of rare-earth metals, 2-5% of borate ore, 5-20% of aluminum and 20-35% of silicon [1 ]. With the introduction of this mixture in a metallic iron-carbon melt due to the occurrence of reactions, the simultaneous formation of a modifying alloy containing active elements and a refining slag is achieved.

The disadvantage of the mixture is the toxicity and high cost of barium oxides and carbonates obtained from natural sulphate ores by complex chemical processing. In addition, the introduction of the mixture into molten steel is accompanied by a significant pyroelectric effect due to the formation of magnesium vapor, whose vapor pressure at 1600 ° С exceeds 2 MPa (20 atm).

The closest to the invention to the technical essence and the achieved effect is a briquette for deoxidation and modification of steel and cast iron [2], containing the product of burning of viterite cyanite concentrate, aluminum, ferrosilicon FS65, fluorspar and binder with the following content of components, wt.%:

The product of roasting vitertrontsianitovogo concentrate53-55

Aluminum Powder7-12

Ferrosilicon powder FS6529-32

Fluorspar2-3

Binder2-4

The disadvantage of the briquette is the low efficiency of the use of barium and strontium, recovered from vitertstritsianitovogo concentrate, due to the presence in the mixture of ferrosilicon FS65, containing up to 35% iron. Such a high content of iron increases the loss of these metals by evaporation due to their extremely low solubility in the resulting ferroalloy. The low efficiency of the mixture is also due to the absence of a calcium-containing component in it, since the highest efficiency of barium and strontium in the treatment of liquid steel is manifested only when the calcium modifier contains barium and strontium solvent.

The aim of the invention is to improve the refining and modifying capacity of the mixture.

This goal is achieved by the fact that the mixture for deoxidation and modification of steel and cast iron containing aluminum, barium-strontium-containing and silicon-containing material according to the invention additionally introduces oxides of rare-earth metals and datolite ore in the form of oxides and carbonates, and as bari-strontium-containing and silicon-containing materials use polymers respectively. containing alkaline-earth metals in the form of carbonates and / or oxides, and silicon, or its alloys, containing less than 25% iron, When the following component ratio, wt.%:

Polymetallic ore30-80

Aluminum5-30

Silicon, or its alloys, containing less than 25% iron 5-25

Oxides of rare earth metals 0,001 -15

Datolite ore1-5

Polymetallic ore in the form of carbonates and / or oxides contains barium, strontium, calcium, magnesium, silicon, potassium, sodium, iron, manganese, aluminum and titanium with the following content of components, wt.%: 10-18 Wa, 2-7 8g, 10–20 Ca, 0.4–0.7 Md, 10–16 δί, 2-3 K, 0.7–1.5 Ha, 1.5–7.0 D, 0.1–0.3 Mp , 1-4 A1 and 0.4-0.8.

Datolite ore in the form of oxides and / or carbonates contains boron, aluminum, magnesium, calcium, silicon, iron, manganese, potassium and sodium in the following ratio of components, wt.%: 2-4 V, 0.3-1.0 A1, 0.2-0.4 MD, 20-30 Ca, 15-25 δί, 2-5 Re, 0.2-2.5 Mn, 0.04-0.06 (K + Na).

In addition, the mixture for deoxidizing and modifying steel and cast iron may contain 5-15 wt.% At least one oxide from the group ΤίΟ ₂ , Li ₂ O ₅ , ν _{2 5} , MoO ₃ , N10.

The technical effect of using the invention is that the developed composition of the mixture provides a high degree of extraction of alkaline-earth and rare-earth metals when they are reduced from carbonates and oxides predominantly with aluminum, the subsequent formation of stable compounds with silicon, the formation of liquid mobile synthetic slag from calcium aluminates. With the addition of at least one of the oxides ΤίΟ ₂ , ЬЬ ₂ О ₅ , ν ₂ Ο ₅ , MoO ₃ , ΝίΟ, it allows refining, modifying and microalloying of steel and cast iron at the same time.

Alkaline earth metals calcium, barium and strontium contribute to obtaining the most favorable type of non-metallic inclusions in steel - oxides in a sulfide sheath. When combined

- 1 012637 nominal introduction of alkaline earth and rare earth metals into liquid steel, due to the low boiling point and low solubility of calcium, barium and strontium in liquid iron, these metals are consumed to a greater extent than rare earth metals whose boiling point exceeds 3000 ° WITH. These metals dissolve well in iron and are stored for subsequent interaction with harmful impurities, including nitrogen, hydrogen and non-ferrous metals, transfer them to passive forms and purify the grain boundaries during cooling and crystallization of the metal.

A decrease in the amount of polymetallic ore in the mixture below the lower limit (30%) will lead to a decrease in its refining and modifying capacity. An increase in its content of more than 80% will not lead to an increase in the modifying effect of alkaline-earth metals on the melt due to their extremely limited solubility in liquid iron. In addition, in this case, a refractory slag with low refining ability is formed.

An increase in the amount of aluminum in the mixture of more than 30% will lead to an excessively high content of aluminum oxide in the resulting slag from the mixture, an increase in the melting point of the slag and a decrease in its refining capacity. Reducing the amount of aluminum in the mixture of less than 5% will lead to insufficient recovery from the mixture of alkaline-earth and rare-earth metals and, as a consequence, a decrease in the modifying effect.

If the amount of silicon in the mixture exceeds the upper limit (more than 25%), the refining capacity of the slag formed from the mixture is reduced due to an excessively high content of silicon dioxide in it. A decrease in the amount of silicon in the mixture of less than 5% will reduce its modifying capacity due to the unsatisfactory recovery of the active elements.

The lower limit of the content of oxides of rare-earth metals in the mixture (0.001%) is due to the fact that in some cases the necessary modifying effect is achieved almost without the participation of rare-earth metals. In addition, oxides of rare earth metals are scarce and have a high cost. An increase in the amount of oxides of rare-earth metals by more than 15% is inexpedient due to the possibility of the formation of a defect in the steel macrostructure — cerium heterogeneity.

In case of an upper limit (5%) in the amount of datolite ore in the mixture, unwanted excessive microalloying with boron is possible, since the maximum effect of boron microalloying has a pronounced concentration peak (0.003-0.005%). Reducing the amount of datolite ore in a mixture of less than 1% will not provide liquid-moving slag with high refining ability.

Additional addition of at least one oxide from the group ΤίΟ ₂ , ΝΒ ₂ Ο ₅ , ν _{2 5} , MoO ₃ , N10 in the amount of 5% to the mixture in the presence of aluminum and reduced reactive elements will lead to the complete reduction of metals from the oxides of this group and microalloying they became and cast iron. When the content of one or several oxides in the mixture is less than 5%, the content of micro-alloying elements in the steel will not be enough. The increase in the number of these oxides in the mixture of more than 15% is impractical due to the fact that further improvement of the properties of the metal being treated is not very noticeable.

Example 1. Modeling of processes occurring with a mixture when it is heated to operating temperature and exposure.

The components of the mixture with a particle size of less than 2 mm after mixing are loaded into a graphite crucible, which with the mixture is heated in a Tamman furnace at a temperature of 1450 ° C for 5 minutes. Melting products are weighed and subjected to chemical analysis. The results of the experiments are given in the table.

Indicators Experience number Prototype 2 3 four five The composition of the mixture, the masses. % Polymetallic ore 85 80 55 thirty 28 - Aluminum 33 thirty 17 five 3 ten Crystal Silicon four - 15 20 - Ferrosilicon FS75 five thirty Oxides of rare earth metals 0.001 four 7 15 eight Datolite ore 2 2 3 five four Rutile concentrate (98% TU ₂ ) - five ten - - The firing product of viterstroncyanite concentrate - - - - - 54 Ferrosilicon FS65 - 30.5 Fluorspar - - - - - 2.5 Binder - - - - - 3.0 Alloy yield,% Unsatisfactory separation of metal and slag 45.7 48.5 49.3 44.0 42.7 Recovery,% barium 52.5 59.7 55.1 51.8 48.5 strontium 41,8 45.3 43.0 41.1 40.0 calcium 20.5 19.6 18.0 15.8 - rare earth metals 79.4 82.5 80.1 76.3 - titanium 94 90 - - -

- 2 012637

As can be seen from the above data, the proposed mixture allows you to increase the yield of the alloy, extracting barium and strontium from it by 3-6%, additionally extract calcium, rare earth metals and titanium.

The use of the proposed mixture in comparison with the known one allows to exclude the burning of the ore component, the briquetting of the mixture and the drying of briquettes;

to obtain an alloy containing highly active alkaline-earth metals, including calcium, rare-earth and alloying metals, as well as liquid mobile synthetic slag based on calcium aluminates;

to carry out an effective and safe treatment of iron-carbon melt, simultaneously refining, modifying and micro-alloying steel and cast iron;

replace expensive and scarce ferroalloys with raw materials.

Information sources:

1. RF patent 2192479, IPC S21S 1/00, 1/06. Bul No. 31, 2002.

2. RF patent 2023044, 15.11.2001. Bul No. 21

Claims (4)

CLAIM 1. A mixture for refining and modifying steel and cast iron, containing aluminum, barium-strontium-containing and silicon-containing material, characterized in that it additionally contains rare-earth metal oxides and datolithic ore in the form of oxides and carbonates, and polymetallic materials are used as barium-strontium-containing and silicon-containing materials containing alkaline earth metals in the form of carbonates and / or oxides, and silicon or its alloys containing less than 25% iron, in the following ratio nents, wt.%: Polymetallic ore 30-80 Aluminum 5-30 Silicon or its alloys containing less than 25% iron5-25 Rare earth oxides 0.001-15 Datolite ore1-5 2. The mixture according to claim 1, characterized in that the polymetallic ore in the form of carbonates and / or oxides contains barium, strontium, calcium, magnesium, silicon, potassium, sodium, iron, manganese, aluminum and titanium in the following components, wt. %: 10-18 Ba, 2-7 8t, 10-20 Ca, 0.4-0.7 Md, 10-16 δί, 2-3 K, 0.7-1.5 Ba, 1.5-7 , 0 Be, 0.1-0.3 MP, 1-4 A1 and 0.4-0.8 Τί. 3. The mixture according to claim 1, characterized in that the datolithic ore in the form of oxides and / or carbonates contains boron, aluminum, magnesium, calcium, silicon, iron, manganese, potassium and sodium in the following ratio, wt.%: 2- 4 V, 0.3-1.0 A1, 0.2-0.4 Md, 20-30 Ca, 15-25 81, 2-5 Be, 0.2-2.5 Mp, 0.040.06 (K + Ba). 4. The mixture according to claim 1, characterized in that it contains 5-15 wt.% At least one oxide from the group Τ1Ο2, L2O3. UzOya. MoO ₃ . N10.