RU2404262C1 - Magnesium-containing modifying agent for converter slag and modification method of converter slag - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: modifying agent includes magnesium carbonate (MgCO₃) mixed with calcined magnesite with calcined shape of magnesium oxide (MgO), calcium oxide (CaO), iron oxide (Fe₂O₃), silicon oxide (SiO₂), carbon (C) and bonding agent. At that, there used is calcined magnesite with calcined shape of magnesium oxide (MgO) with particle size of 0.1÷1.5 mm and magnesium carbonate (MgCO₃) with particle size of 0.05÷0.1 mm, and mixture of water-repelling agent with anhydrous bonding agent is used as bonding material. Calcined magnesite with calcined shape of magnesium oxide (MgO) mixed with magnesium carbonate (MgCO₃) are taken in the following ratio, wt %: (16÷45)÷(55÷84) respectively, and water-repelling agent with anhydrous bonding agent - in the following ratio, wt %: (40÷60)÷(60÷40) respectively.

EFFECT: inventions allow increasing life time of skull layer, decreasing the number of application operations of skull layer and consumption of modifying agent, preventing formation of hydrogen in converter to avoid metal explosions and emissions, achieving reduction of losses of modifying agent with emitted dust, and providing effective neutralisation of initial slag of converter melting, and increasing service life of converter liner.

2 cl, 4 tbl, 2 dwg, 1 ex

Description

The invention relates to the field of metallurgy, in particular to modifiers of the final converter slag for protection against destruction of the periclase-carbon lining of the oxygen converter, as well as increasing its service life.

Known modifier of metallurgical slag (patent RU 2141535 C1), which consists of dolomite and iron-containing material obtained by their joint grinding and firing in a rotary kiln at a temperature of 1360 ÷ 1450 ° C. The disadvantages of the known modifier are: low MgO content, which leads to low efficiency of its use and high consumption to increase the MgO content in the final slag; high hygroscopic ability, due to the high content of CaO, which leads to the accumulation of hygroscopic moisture by the modifier during storage and transportation and the formation of hydrogen at the temperature of use of the modifier, which is dangerous in the conditions of a metallurgical unit that adversely affects the properties of the melted metal; low rate of assimilation of the calcined modifier by the final slag; high energy costs for production associated with the firing of the modifier at a temperature of 1360 ÷ 1450 ° C.

Known modifier of metallurgical slag (patent RU 2260626 C1), consisting of magnesium oxide and iron oxide in the amount (wt.%) 65,0 ÷ 97,0 and 2,0 ÷ 15,0, respectively, obtained by sintering in a rotary kiln finely ground crude magnesite and siderite. The disadvantages of the known modifier are: low rate of assimilation of the sintered modifier by the final slag; high energy consumption for the production of the modifier associated with sintering; a high content of iron oxides, which leads to a decrease in the resistance of the skull layer from the final slag modified by it.

Known modifier of metallurgical slag (patent RU 2205232 C1) containing magnesium oxide, aluminum oxide, iron oxide, silicon oxide and calcium in the following ratio (wt.%): MgO 32.0 ÷ 33.5; Al ₂ O ₃ 0.5 ÷ 0.95; Fe ₂ O ₃ 2.0 ÷ 5.0; SiO ₂ 2.5 ÷ 3.0; CaO - the rest obtained by co-firing in a rotary kiln, at a temperature of 1570 ÷ 1670 ° C, of dolomite and iron-containing material, with a ratio of dolomite to Fe ₂ O ₃ equal to 8: 1. As iron-containing material, mill scale or iron ore is used. The disadvantages of the known modifier are: low MgO content, which leads to low efficiency of its use to increase the MgO content in the final slag; high hygroscopic ability, due to the high content of CaO, which leads to the accumulation of hygroscopic moisture by the modifier during storage and transportation and the formation of hydrogen at the temperature of use of the modifier, which is dangerous in the conditions of a metallurgical unit, soluble in the smelted metal and adversely affect its properties; low rate of assimilation of the calcined modifier by the final slag; high energy costs for production associated with the firing of the modifier at a temperature of 1570 ÷ 1670 ° C.

A known method of steel smelting in a converter (RU 2327743 C2) with an additive in the converter modifier on the left slag, after the release of metal, for applying a skull layer consisting of magnesium oxide 40.0 ÷ 95.0 wt.%, Aluminum oxide 0.1 ÷ 30.0 wt.%, Calcium oxide 0.5 ÷ 45.0 wt.%, Silicon oxide 1.0 ÷ 20.0 wt.%, Iron oxide - the rest obtained by sintering in a rotary or shaft furnace (at 900 ÷ 1500 ° C) of high-magnesian materials (crude magnesite, brucite) with aluminum-containing materials (aluminous materials, aluminum slags, etc.) with the addition of iron won materials (siderite, slag, etc.). A disadvantage of the known flux is the high content of Al ₂ O ₃ (up to 30.0 wt.%) And SiO ₂ (up to 20.0 wt.%), Which leads to a decrease in the melting temperature of the modified slag, the formation of a more overheated slag melt with increased aggressiveness to refractory lining; the use of the known flux on the final slag left after metal release for applying the skull coating leads to a reduction in the life of the skull layer, an increase in the number of operations for applying the skull layer, an increase in the consumption of the modifier and a reduction in the effective time of using the converter, and a decrease in the efficiency of neutralizing the initial slag of the next melting; high energy costs for production associated with sintering at a temperature of 900 ÷ 1500 ° C of the known modifier.

Closest to the claimed is a modifier of metallurgical slag and the method of its use (patent RU 2244017 C2). The modifier contains oxides of magnesium, calcium, silicon and iron in the following proportions (wt.%): CaO 0.5 ÷ 10.0; SiO ₂ 0.5 ÷ 5.0; iron oxide 0.5 ÷ 6.0; MgO - the rest. Moreover, MgO is in carbonate and hydrate forms with their ratio in the range of 0.5 ÷ 2. The modifier may contain carbon in the range of 5 ÷ 10 wt.% (Prototype).

Obtaining a known modifier is carried out by joint dry grinding of natural magnesite and calcined magnesite, with their mass ratio in the range (30 ÷ 70) ÷ (70 ÷ 30), to a specific surface of 0.6 ÷ 12.0 m ² / g, pelletizing with a ground mixture in a granulator with the addition of water (at a moisture content of 15 ÷ 25%), after which the pelletized material is kept for 15 ÷ 40 minutes. to the formation of granules with a size of 5 ÷ 40 mm, or form briquettes with a volume of up to 70 cm ³ . Perhaps the introduction of a mixture of coke. The strength gain of the granules is due to crystallization of the magnesium hydroxide binder. The source of MgO of the known modifier is MgO, which is formed when a modifier is introduced onto the converter slag during decarbonization and dehydration of its constituent components (MgCO ₃ , Mg (OH) ₂ ), the specific surface of the resulting material reaches 30 m / g.

The disadvantages of the closest to the claimed modifier (prototype):

- the presence of magnesium hydroxide in the modifier, which leads to the formation of hydrogen at the temperature of use of the modifier, dangerous in the conditions of a metallurgical unit, soluble in the lost metal and adversely affecting its properties;

- the high hygroscopic ability of unfired hydrophilic granules from finely ground natural magnesite and caustic magnesite leads to their absorption of moisture from air during storage and transportation, which leads to the formation of hydrogen at a temperature of use of a modifier that is dangerous in a metallurgical unit that is soluble in the melted metal and adversely affects its properties;

- losses in the form of dust extractors, when using a modifier due to low strength and abrasion resistance of a water-granulated modifier, which leads to the destruction of the granules of the modifier during storage and transportation, the destructibility during storage for 30 days reaches 61.0 wt.%;

- the formation of an uneven thickness of the skull layer due to its rolling and the preservation of the lining surface partially uncovered by the skull, resulting in a greater number of operations for applying the skull layer, the consumption of the modifier increases and the effective time of using the converter is reduced.

The objective of the proposed technical solution is to develop a modifier composition that provides an increase in the life of the skull layer, a decrease in the number of operations for applying the skull layer and consumption of the modifier, and an increase in the effective operating time of the converter; preventing the formation of hydrogen in the converter to prevent explosions and metal emissions, reducing the loss of the modifier with dust collector, increasing its hydrophobicity, strength and abrasion resistance of the granules during transportation and storage of the modifier, as well as providing effective neutralization of the initial slag of converter melting and increasing the life of the converter lining.

The problem is achieved in that the magnesia modifier for converter slag, containing a mixture of magnesium carbonate (MgCO ₃ ) and calcined magnesite with a calcined form of magnesium oxide (MgO), calcium oxide (CaO), iron oxide (Fe ₂ O ₃ ), silicon oxide (SiO ₂ ), carbon (C) and a binder, using calcined magnesite with a calcined form of magnesium oxide (MgO) fraction 0.1 ÷ 1.5 mm and magnesium carbonate (MgCO ₃ ) fraction 0.05 ÷ 0.1 mm , a mixture of a water repellent with an anhydrous binder was used as a binder in the following relation oshenie components, wt.%:

MgCO ₃ 41.0 ÷ 78.5 MgO 15,5 ÷ 34,0 CaO 1,5 ÷ 5,0 SiO ₂ 1,0 ÷ 4,5 Fe ₂ O ₃ 0.5 ÷ 4.5 FROM 0.5 ÷ 4.0 Water repellent mixture with anhydrous binder 2.5 ÷ 7.0

the calcined magnesite with the calcined form of magnesium oxide (MgO) and magnesium carbonate (MgCO ₃ ) in the mixture are taken in the ratio, wt.%: (16 ÷ 45) ÷ (55 ÷ 84), respectively, and the water-repellent agent with an anhydrous binder in the ratio , wt.%: (40 ÷ 60) ÷ (60 ÷ 40), respectively.

The task is also achieved by the fact that in the method of modifying the converter slag, a modifier is applied to the final converter slag at a temperature of 1450 ÷ 1600 ° C, in an amount based on one ton of slag, determined by the formula:

where X _MgO is the initial content of magnesium oxide in the final converter slag (wt.%), X _CaO is the content of calcium oxide in the final converter slag (wt.%), X _SiO2 is the content of silicon oxide in the final converter slag (wt.%), ρ _MgO is the density of magnesium oxide (t / m ³ ), ρ of _slag is the density of the final converter slag (t / m ³ ), A and B are empirical coefficients depending on the temperature of the final converter slag, which vary in the range A = 16.63 ÷ 41.66; B = 10.45 ÷ 27.25 in the temperature range 1450 ÷ 1600 ° C, wt.%. 0.52 is an empirical coefficient with a dimension of wt.%.

The inventive modifier and method of its use can increase the life of the skull layer, reduce the number of operations applying the skull layer and consumption of the modifier, increase the efficiency of the converter; to prevent the formation of hydrogen in the converter to prevent explosions and metal emissions, to reduce the loss of the modifier with dust collector, increase its hydrophobicity, strength and abrasion resistance of the granules during transportation and storage of the modifier, as well as provide effective neutralization of the initial slag of converter melting and increase the life of the converter lining.

It is possible to introduce a modifier directly during converter smelting, including the initial slag to neutralize the slag and increase the concentration of MgO in it, in quantities that do not reduce the refining ability of the slag during the smelting process.

Mineral and petroleum oils were used as a water repellent agent (GOST 20799-88. Industrial oils. Technical conditions), a phenolic binder (GOST 4806-79), shale phenolic resin, formaldehyde resin (TU 2257-005-05761778-2002) )

Raw materials: TU 1515-021-00190495-2002. Raw crushed magnesite (Specifications), GOST 1216-87. Caustic magnesite powders (Specifications), GOST 10360-85. Sintered periclase powders for the manufacture of products (Specifications), GOST 24862-81. Periclase and periclase-lime powders for steelmaking (Technical conditions), GOST 3213-91. Electrode pitch coke (Specifications), GOST 3340-88. Coal foundry coke (Specifications), GOST 22898-78. Low-sulfur petroleum coke (Specifications), GOST 5279-74. Crystalline foundry graphite (Specifications), GOST 5420-74. Cryptocrystalline graphite (Technical conditions).

Obtaining a modifier includes crushing and grinding natural magnesite MgCO ₃ to a fraction of 0.05–0.1 mm, mixing with calcined magnesite MgO fractions of 0.1–1.5 mm in the claimed ratio, introducing a mixture of a hydrophobizing agent and an anhydrous binder, carbon in the form of coke or graphite, followed by granulation and / or briquetting.

The source of MgO is the calcined form of MgO fraction 0.1 ÷ 1.5 mm and natural magnesite fraction 0.05 ÷ 0.10 mm, in a mass ratio of 0.2 ÷ 0.8, which ensures the formation of a polydisperse slag suspension with a high MgO content at constant viscosity.

The use of a water repellent prevents moisture from reaching the surface of natural and calcined magnesite fractions, the interaction of an anhydrous binder with the mineral component of the modifier leads to the formation of hydrophobic phenolates of calcium and magnesium, which ensures the hydrophobicity of the modifier granules. The increase in strength and abrasion resistance of the modifier granules occurs due to the polymerization of an anhydrous binder during heat treatment.

The introduction of carbon optimizes the viscosity of the slag suspension by reducing the concentration of oxidized forms of iron.

A decrease in the content of magnesium carbonate in the modifier less than 41.0 wt.% Leads to a decrease in the concentration of MgO in the modified slag and a decrease in the efficiency of the use of the modifier. An increase in the content of magnesium carbonate in the modifier of more than 78.5 wt.% Leads to a significant increase in heat consumption for decarbonization and assimilation of slag modifier. A decrease in the ratio of the calcined form of the MgO fraction of 0.1 ÷ 1.5 mm to magnesium carbonate fraction of 0.05 ÷ 0.1 mm is lower than 15.5: 78.5 or an increase in the ratio of the calcined form of the MgO fraction of 0.1 ÷ 1.5 mm to magnesium carbonate fractions of 0.05 ÷ 0.1 mm above 41.0: 34.0 leads to a significant increase in the viscosity of the slag suspension formed when using the modifier. An increase in the carbon content in the modifier above 4.0 wt.% Leads to a significant cooling effect of the slag suspension and an increase in its viscosity, which makes it difficult to apply a skull layer from it. A decrease in the carbon content in the modifier below 0.5 wt.% Leads to the formation of a slag suspension with a low viscosity and the formation of a thin skull layer. The content in the composition of the modifier of the mixture of water repellent with an anhydrous binder of less than 2.5 wt.% Does not provide satisfactory strength, abrasion resistance and hydratability during storage of the modifier; and does not increase the strength, abrasion resistance of hydration and destructibility during storage of the modifier. The increase in the content of impurities: CaO more than 5.0 wt.%, SiO ₂ more than 4.5 wt.%, Fe ₂ O ₃ more than 4.5 wt. % in the modifier leads to a decrease in the concentration of MgO and MgCO ₃ and a decrease in the efficiency of using the modifier to increase the concentration of MgO in the final slag.

The claimed technical solution provides: reducing the number of operations for applying the skull layer and modifier consumption, increasing the effective time of the converter by increasing the resource of the skull layer formed from slag suspension with a high MgO content with optimized viscosity and applying a continuous uniform skull layer with a high MgO content from it ; neutralization of primary converter slag and increase of the lining resource due to the application of a skull layer with a high MgO content; preventing the formation of hydrogen in the metallurgical unit when using the modifier, due to the exclusion of hydrated forms of MgO from the composition of the modifier, as well as by eliminating the accumulation of hygroscopic moisture during transportation and storage of the modifier; reduction of losses in the form of dust extractor when using a modifier, due to increased strength and resistance to abrasion of modifier granules.

According to the polymer model of silicate melts, silicate slags are solutions that contain polymer silicate anions of different sizes and complexity, depending on the nature of cations and concentrations of basic oxides [Paderin SN, Filippov VV Theory and calculations of metallurgical systems and processes. - M .: MISSIS, 2002. - 334 p.]. Polymer silicate anions consist of SiO ₄ ^-4 , where silicon atoms are connected by bonding oxygen atoms, an increase in the concentration of metal cations (for example, Ca ⁺² , Mg ⁺² , Fe ⁺² ) leads to the progressive destruction of oxygen bonds of polymer anions and the formation of oxygen ions, Connective Function (NBO) [Kenneth C. The Influence of Structure on the Physico-chemical Properties of Slags // ISIJ International. Vol. 33 No. 1, 1993. pp. 148-155.]. Silicate slag melt simultaneously contains various polymer anionic associations existing in the form of chains, plates and rings, the introduction of lattice-breaking metal cations does not change the nature of polymer anionic associations, but affects their quantitative content, towards shorter and less massive anions [Kenneth C. The Influence of Structure on the Physico-chemical Properties of Slags // ISIJ International. Vol. 33 No. 1, 1993. pp. 148-155]. Cations with a shorter radius and greater valency contribute to the formation of a more depolymerized melt, while tri- and tetra- and pentavalent cations, such as Al ⁺³ , Fe ⁺³ , B ⁺³ , Ti ⁺⁴ , P ⁺⁵ , contribute to the polymerization of the melt [Kenneth C The Influence of Structure on the Physico-chemical Properties of Slags // ISIJ International. Vol. 33 No. 1, 1993. pp. 148-155].

To assess the degree of melt depolymerization, the ratio of the molar fractions of oxygen ions that do not have a connecting function to the oxygen atoms involved in the formation of polymer anions - (NBO / T) is used. It was experimentally established that the viscosity of the slag melt decreases with increasing depolymerization, and vice versa, sharply increases when (NBO / T) approaches 0, the parameter (NBO / T) is determined by the chemical composition of the slag melt and is calculated by the formula [Kenneth C. The Influence of Structure on the Physico-chemical Properties of Slags // ISIJ International. Vol. 33 No. 1, 1993. pp. 148-155]:

x (i) is the mole fraction of the i-th component. Thus, an increase in the concentration of oxides SiO ₂ , Al ₂ O ₃ , TiO ₂ , P ₂ O ₅ , Fe ₂ O ₃ , etc. leads to an increase in the viscosity of slag melt, and an increase in the concentration of oxides CaO, MgO, FeO, Na ₂ O, K ₂ O, etc. (having a more ionic character) leads to a decrease in its viscosity. Acidic slag becomes fluid (viscosity about 1 Pa · s) only at temperatures well above their melting point, for example, the most low-melting slag in the ternary system CaO-Al ₂ O ₃ -SiO ₂ : SiO ₂ 62.0 wt.%, Al ₂ O ₃ 14.8 wt.%, CaO 23.2 wt% (triple eutectic CaO · SiO ₂ - SiO ₂ - CaO · Al ₂ O ₃ · SiO ₂ ) melts at 1155 ° C, and a viscosity of the order of 1 Pa · s acquires at 1600 ° C [Romanenko A.G. Metallurgical slag. - M.: Metallurgy, 1977. - 190 p.]. An increase in the basicity of slag, that is, an increase in the concentration of CaO and MgO in it, causes a decrease in its viscosity, but only to a certain limit, highly basic slag rich in CaO and MgO are inactive [Romanenko A.G. Metallurgical slag. - M .: Metallurgy, 1977. - 190 pp.], Since when the concentration of basic oxides exceeds the solubility limit, the viscosity of the slag increases due to the dispersion of insoluble highly refractory phases in it and the formation of a suspension. The viscosity of the suspension is higher than the viscosity of its liquid dispersion medium and increases with increasing volumetric filling of it with a solid phase.

Disperse systems (tv - g.) (Suspensions) can be divided [Reiner M. Rheology, per. from English Malinina N.I., ed. Grigolyuk E.I. - M .: Nauka, 1965. - 224 p.] At:

- sols, which are a dispersion of a solid in a liquid medium at low volumetric filling, behave like liquids;

- gels, which are a dispersion of a solid in a liquid dispersion medium, characterized by the presence of a continuous structural network of dispersed particles.

- jellies, the solid phase is continuous throughout the entire volume (percolated), such a structure is close in properties to solids.

With an increase in the volume concentration of the solid phase, there is a transition from sol to gel, and then, with its percolation, to jelly.

The relative viscosity of sols is determined by Einstein’s formula [Reiner M. Rheology, per. from English Malinina N.I., ed. Grigolyuk E.I. - M.: Nauka, 1965. - 224 p., Uryev N.B., Potanin A.A. The fluidity of suspensions and powders. - M .: Chemistry, 1992. - 247 p.]:

where η ^* is the viscosity of the sol, η _m is the viscosity of the dispersion medium, Cν is the volumetric filling of the dispersed phase. This formula is valid with a volumetric filling of less than 3%. The general expression for calculating the viscosity of the gels has a polynomial form [1]:

для кубической плотнейшей упаковки и 0,74 для гексагональной. Соответственно граничными условиями для решения задачи (7) являются следующие выражения:At low values of the volumetric filling of the suspension (Cν) with a third, fourth, etc. the terms of the polynomial can be neglected, as a result of which we obtain Einstein's formula (1), where α ₁ = 2.5. With an increase in volumetric filling, the gel viscosity continuously increases, tending to infinity during percolation of the solid phase (transition from gel to jelly). The minimum volumetric filling of the solid phase, sufficient for its percolation, is

for cubic tight packing and 0.74 for hexagonal. Accordingly, the boundary conditions for solving problem (7) are the following expressions:

One of the solutions to problem (7), taking into account the boundary conditions (8) and (9), is the Mooney formula:

which gives good agreement with experimental measurements of the viscosity of suspensions for a wide range of sizes of dispersed particles of the solid phase, when empirically determining the coefficient K [Reiner M. Rheology, trans. from English Malinina N.I., ed. Grigolyuk E.I. - M .: Nauka, 1965. - 224 p.]. K = 1.35 ÷ 1.91.

приведена на Фиг.1.In the case of a polydisperse suspension, where the dispersed solid phase is represented by two fractions with a size difference of at least an order of magnitude, a suspension of a fine fraction in a dispersion medium can be represented as a dispersion medium for a large fraction [Reiner M. Rheology, trans. from English Malinina N.I., ed. Grigolyuk E.I. - M .: Nauka, 1965. - 224 p.]. The calculated dependence of the relative viscosity of the polydisperse suspension on volumetric filling, at different volume ratios of coarse and fine fractions

shown in Fig.1.

, находящимся в пределах 0,7-1,5, смотри Фиг.2. The introduction of the polydispersity factor, with equal volumetric filling, leads to a decrease in the viscosity of the suspension, and its minimum values are achieved when

between 0.7-1.5, see FIG. 2.

Accordingly, the introduction into the suspension of a dispersed filler in the form of 2 fractions will allow to achieve a higher concentration of the solid phase, compared with monodisperse filling, with a constant viscosity.

A significant difference of the proposed technical solution lies in the formation of a volume ratio of the calcined form of MgO of the coarse fraction to the fine fraction of MgO obtained by decomposition of magnesium carbonate in the range 0.4–1.8, providing a decrease in viscosity and an increased MgO content in the modified slag suspension; reducing modifier hydration during storage and transportation, eliminating the formation of hydrogen when using a modifier, increasing the strength and abrasion resistance of the modifier through the use of a mixture of water repellent and anhydrous binder.

The novelty of the claimed technical solution consists in the fact that a converter slag modifier is proposed, containing a calcined form of MgO in the form of large grains and magnesium carbonate in the form of small grains, a mixture of water repellent with an anhydrous binder, in the claimed ratio, introduced per ton of final slag, in an amount determined by the formula (1).

Thus, the proposed technical solution is new, has an inventive step and is industrially applicable.

An example embodiment of the invention:

according to claim 1

Natural magnesite fraction 0.05 ÷ 0.1 mm is mixed in a mixer with calcined magnesite fraction 0.1 ÷ 1.5 mm, with a mixture of water repellent and anhydrous binder (mineral or petroleum oil and phenolic binder in a mass ratio of 1: 1), s coke, in the ratio shown in table 1.

The composition of the modifiers is given in table 2.

The properties of the modifiers are presented in table 3.

according to claim 2

The amount of modifier introduced per 1 ton of final converter slag is given in table 4.

Thus, the claimed technical solution provides: reducing the number of operations for applying the skull layer and the consumption of the modifier, increasing the effective time of the converter by increasing the resource of the skull layer formed from slag suspension with a high MgO content with optimized viscosity and applying a continuous uniform skull layer from it high MgO content; preventing the formation of hydrogen in the metallurgical unit when using a modifier, due to the exclusion of the hydrated form of MgO from the composition of the modifier, as well as by eliminating the accumulation of hygroscopic moisture during transportation and storage of the modifier; reduction of losses in the form of dust collector when using a modifier, by increasing the strength and abrasion resistance of the modifier granules.

Table 1 The composition of the modifiers for converter slag, wt.% No. Natural Calcined coke mixture magnesite magnesite water repellent and anhydrous binder one 48.6 40.4 ¹ 4.0 7.0 ⁴ 2 52.3 37.7 ¹ 4.0 6.0 ⁴ 3 58.1 31.9 ¹ 4.0 6.0 ⁴ four 61,4 30.1 ² 3,5 5.0 ⁵ 5 68.3 24.2 ² 2.5 5.0 ⁵ 6 74.8 19.2 ³ 2.0 4.0 ⁵ 7 81.0 16.0 ³ 0.5 2.5 ⁴ prototype 42.0 48.0 10.0 - ¹ - caustic magnesite powder according to GOST 1216-87 ² - periclase powder for steelmaking in accordance with GOST 24862-81 ³ - periclase sintered powder according to GOST 10360-85 ⁴ - a mixture of mineral oil and TFP ⁵ - a mixture of petroleum oil and TFP

table 2 The composition of the modifiers for converter slag, wt.% No. MgCO ₃ MgO Cao SiO ₂ Fe ₂ O ₃ FROM a mixture of water repellent and anhydrous binder one 41.0 34.0 5,0 4,5 4,5 4.0 7.0 2 45.0 32,5 4,5 4.0 4.0 4.0 6.0 3 50,0 27.5 4,5 4.0 4.0 4.0 6.0 four 55.0 27.0 2.5 3,5 3,5 3,5 5,0 5 62.0 22.0 2.5 3,5 2.5 2.5 5,0 6 70.0 18.0 2.0 2.5 1,5 2.0 4.0 7 78.5 15,5 1,5 1,0 0.5 0.5 2.5 prototype - 80.0 ÷ 99.5 0.5 ÷ 10.0 0.5 ÷ 5.0 0.5 ÷ 6.0 5.0 ÷ 10.0 -

Table 3 Comparative properties of the claimed modifier and prototype compositions hydration (set
mass when stored in air), wt.%, no more the presence of Mg (OH) ₂ in the composition the content of the dust fraction after 30 days of storage, wt.% average relative viscosity of the final slag modified for applying the skull (η) the average MgO content in the skull layer, wt.% * one 1.80 ÷ <1.0 3.0 26.3 2 1.75 ÷ <1.0 2,8 24.8 3 1.74 ÷ <1.0 2.7 23.5 four 1.70 ÷ <1.0 2.6 22.4 5 1,67 ÷ <1.0 2.5 21.5 6 1,58 ÷ <1.0 2.7 20.8 7 1,50 ÷ <1.0 3.0 20.3 prototype not less than 15 + up to 61.0 5,0 no more 15.0 * - increased MgO content increases the stability of the skull layer, determines the effective neutralization of the initial converter slag.

Table 4 The amount of modifier (t) introduced per 1 ton of final converter slag according to the formula 1 * initial MgO content in the final slag, wt.% final slag basicity amount of modifier (t), per 1 t of final slag MgO content in modified slag 14.0 2.5 0.190 26,4 14.0 2.6 0.160 24.4 14.0 2.7 0.130 22.5 14.0 2,8 0,100 20.5 14.0 2.9 0,070 18.5 14.0 3.0 0,040 16.5 14.0 3,1 0.009 14.5 10.0 2.5 0.260 26,4 10.0 2.6 0.230 24.4 10.0 2.7 0,200 22.5 10.0 2,8 0.170 20.5 10.0 2.9 0.136 18.5 10.0 3.0 0.104 16.5 10.0 3,1 0,073 14.5 10.0 3.2 0,040 12.6 10.0 3.3 0.009 10.6 * - A = 30.68; B = 19.80; temperature 1550 ° С

Claims (2)

1. Magnesium composition modifier for converter slag, containing a mixture of magnesium carbonate (MgCO ₃ ) and calcined magnesite with a calcined form of magnesium oxide (MgO), calcium oxide (CaO), iron oxide (Fe ₂ O ₃ ), silicon oxide (SiO ₂ ) , carbon (C) and a binder, characterized in that calcined magnesite with a calcined form of magnesium oxide (MgO) fraction 0.1 ÷ 1.5 mm and magnesium carbonate (MgCO ₃ ) fraction 0.05 ÷ 0.1 mm are used, in as a binder, a mixture of water repellent with an anhydrous binder was used in the following ratio of components, ma from.%:
MgCO ₃ 41.0 ÷ 78.5 MgO 15,5 ÷ 34,0 CaO 1,5 ÷ 5,0 SiO ₂ 1,0 ÷ 4,5 Fe ₂ O ₃ 0.5 ÷ 4.5 FROM 0.5 ÷ 4.0 water repellent mixture with anhydrous binder 2.5 ÷ 7.0
the calcined magnesite with the calcined form of magnesium oxide (MgO) and magnesium carbonate (MgCO ₃ ) in the mixture are taken in the ratio, wt.%: (16 ÷ 45) ÷ (55 ÷ 84), respectively, and the water-repellent agent with an anhydrous binder in the ratio, wt.%: (40 ÷ 60) ÷ (60 ÷ 40), respectively. 2. A method of modifying converter slag, characterized in that the modifier according to claim 1 is applied to the final converter slag at a temperature of 1450-1600 ° C, in an amount based on one ton of slag, determined by the formula:

where X _MgO is the initial content of magnesium oxide in the final Converter slag, wt.%,
X _Cao - the content of calcium oxide in the final Converter slag, wt.%,

- the content of silicon oxide in the final Converter slag, wt.%,
ρ _MgO is the density of magnesium oxide, t / m ³ ,
ρ _slag is the density of the final Converter slag, t / m ³ ,
A and B are coefficients depending on the temperature of the final converter slag, which vary in the range A equal to 16.63 ÷ 41.66;
In, equal to 10.45 ÷ 27.25, in the temperature range 1450 ÷ 1600 ° C.

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