SU939563A1 - Slag forming mix - Google Patents

Description

(SLAG FORMING MIXTURE

one

The invention relates to ferrous metallurgy, in particular to mixtures for the treatment of cast iron.

When processing liquid iron and steel, slag-forming mixtures are used to protect the molten metal from saturation with gases during aging and casting, to build (}) smelting from oxygen, sulfur, and remove non-metallic inclusions.

Perlite is known to treat molten iron Cl.

The disadvantage of perlite is that it does not give positive results on cleaning the melt from non-metallic inclusions and its formation (}) due to the high viscosity of the induced slag at cast iron temperatures equal to UOO-l iSO C. In furnaces and casting buckets nastils are formed that impede metal casting.

Of the known slag-forming materials, the closest in purpose and achieved to the proposed

is a slag-forming mixture containing, in wt.%:

Perlite 60-90

Thinners

Calcium or sodium oxides, fluorspar, cryolite C2 are used as thinners.

The disadvantage of the mixture is that (1) the forming slag does not have good liquid mobility and adsorption capacity with respect to non-metallic and slag inclusions of liquid iron at its casting temperatures of 1300-1A50 ° C. This is due to .J but the fact that calcium oxide, which is part of the mixture, does not possess sufficient surface-actier properties, and, therefore, cannot ensure the capture of individual slag 20 and non-metallic inclusions and their retention in the volume of slag.

The purpose of the invention is to increase the adsorption capacity of mixtures with respect to non-metallic inclusions. 39 The goal is achieved by the fact that the slag-forming mixture containing perlite and fluorides, as fluorides, contains magnesium and strontium fluorides and additionally magnesium and strontium carbonates in the following ratio of components, wt.%: Perlite 70-90 Magnesium and strontium fluorides - 15-5 Magnesium and strontium carbonates Perlite is introduced into the mixture as axial. It is a mineral of volcanic origin and contains, weightD: Silica Alumina Alkali metal oxides Volatile components (COi, etc.) 0.5-1.2 Calcium, magnesium, iron, titanium oxides Rest Perlite deficiency, as slag due to the instability of the alkali metal oxide content, fluctuations of which significantly change the viscosity of slags. Magnesium and strontium fluorides when introduced into perlite in an amount of 5-15 significantly reduce the viscosity of slags at a temperature of 1330-1400 ° С and block the influence of oxides u Christmas metals and perlite. Magnesium and strontium carbonates introduced into the mixture based on perlite decompose with carbon dioxide during heating, and the resulting oxides of magnesium and strontium, along with fluorides, give the slag mixture an increased adsorptivity with respect to non-metallic inclusions formed in the liquid cast iron, absorb them, linking them into easily removable segregations. In this case, the gaseous components released facilitate the removal of slag from the surface of the melt. The use of magnesium and strontium salts in a perlite-based slag-forming mixture improves the efficiency of metal cleaning from non-metallic inclusions, since magnesium fluoride and strontium reduce the viscosity of induced slags to a greater degree than fluorspar. Forming oxides of magnesium and strontium have high surface-active properties, and therefore, impart high adsorption capacity to the induced slag with respect to non-metallic and slag inclusions. Magnesium and strontium carbonates They are emitted with the release of carbon dioxide, which additionally screens the melt from oxygen. Best results are obtained using magnesium and strontium fluorides, as well as magnesium and strontium carbonates in equal amounts. The mixture is prepared on the basis of crushed (to a grain size of 0.2-1.0 mm) perlite, magnesium and strontium fluorides and magnesium and strontium carbonates by mixing them in runners or a screw mixer. To lay the slag, the mixture is placed on the mirror of the liquid metal directly into the furnace or ladle in the amount of 30-60 g per 1 dm of the treated surface. The limiting ratios of the components of the mixture are selected on the basis of the temperature of casting iron. At a lower temperature of the molten iron, the mixture in order to obtain slag with optimum physicochemical properties requires the introduction of a larger amount of magnesium and strontium salts. The lower the temperature of the pig iron to be treated, the more the magnesium and strontium salts are introduced into the mixture. For example, at a cast iron temperature of 1300 ° C, a mixture containing fluorides and carbonates of 15 is recommended, and at a temperature C, the amount of fluorides and carbonates can be reduced to depending on the degree of contamination of the metal and the required degree of cleaning of the iron, the mixture can be applied once or several times. Formation of buildup in furnaces and casting ladles is excluded. An example. By mixing the dosed amounts of perlite, magnesium and strontium fluorides, magnesium and strontium carbonates, mixtures 1–3 and also the prototype mixture are obtained (see table). The mixtures are used to process cast iron. The cast iron is melted in a high frequency induction furnace from a cast iron, steel scrap and ferroalloy charge.

Slag-forming mixture is applied to the metal mirror in the furnace and ladle and held for 4-5 minutes. The metal pouring temperature is 1350t10C.

To determine nonmetallic slag inclusions, special samples are poured, which are then cut and polished. The number of nonmetallic inclusions is estimated by the ratio of the area of the slag inclusions to the entire area of the ground surface in percent.

As can be seen from the data in the table, increased adsorption

properties with respect to non-metallic inclusions of the proposed mixture. cause a better degree of purification of the liquid melt and, as a consequence, a lower degree of incidence of the castings with slag inclusions. When this mixture is introduced onto the mirror of the melt, individual slag inclusions actively bind, and the resulting solid segregations are easily removed with a metal scrubber, ensuring a high purity of the metal mirror, which contributes to reducing slag casting through the slag shells. In addition, the mixture has a desulfurizing ability.

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Claims (2)

The invention of perlite 70-90 Slag-forming mixture for the treatment of magnesium and cast iron, including perlite and fluoristrontium 515 dyes, about 1.5 million tons of carbonates, with the aim of increasing the adsorption magnesium and ability with respect to nonmetal strontium. 5-15 lyric inclusions, it is an additional source of information, but contains carbonates of magnesium and strontium taken into account in the examination of qi, and fluoride as fluorides 1. Japanese patent tf + 8-270 "6, d magnesium and strontium with the following: Cl. 10 J 15, 1973. ratio of components,. 2. USSR author's certificate , weightD: №562575, cl. Since 21 Since 1973. Fluorides