SU1076460A1 - Synthetic slag - Google Patents

Description

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The invention relates to metallurgy and can be used in the submersible heating of steel ingots and the heading under pressure treatment, in particular when heating the slag bath with a torch immersion and during casting.

In metallurgy, the processing of metals and alloys uses slags and fluxes based on salts, most often chlorides and fluorides, as well as oxides. Fluxes containing chlorides and fluorides are mainly used in the smelting of non-ferrous metals and alloys.

A synthetic spackle used in steel casting, containing blast furnace slag with alkali metal oxides, is known in the following ratio of components, all.%: Blast furnace slag 75-90J alkali metal oxides 10-25 l.

Said synthetic slag is not very suitable for heating steel ingots and billets under pressure treatment in it due to a sharp drop in viscosity with decreasing temperature (this is the so-called short batch. At low temperatures (), such slag loses mobility, at high (up to) - containing large amounts of sulfur in the milked slag (up to 2.5%) sulfur passes into the surface layers of the solid metal heated in it.

The closest to the proposed is synthetic slag 2j,. containing blast furnace slag, oxides of alkali metals and oxides of boron, in the following ratio of components, carried.%:

Blast furnace slag 75-85

Alkaline oxides

metals5-10

Oxides of boron 10-15

In this slag, the addition of boron oxides lowers the melting point and surface tension of the slag without significantly increasing the viscosity of the slag. The reduced surface tension of such a slag leads to improved wetting of the surface of the heated solid metal. But in subsequent metal processing by pressure - forging, stamping, rolling - such slag, like short, having an increased viscosity in the low-temperature region, crushes into the surface of the ingots and hardly separates from them.

The purpose of the invention is to reduce the viscosity of the slag.

The goal is achieved by the fact that synthetic slag, including blast furnace slag and oxides of alkali metals, additionally silica, and as blast furnace slag - sweet blast furnace slag in the following ratio of components, wt.%:

Sweet Slag 60-80

0 Alkali oxides

metals 10-20 Silicon dioxide 10-25 In the proposed slag, the addition of 10–20% alkali metal oxides to the blast-furnace slag causes a decrease in the softening temperature of the synthetic slag, and the addition of 10–20% silicon makes the slag longer, reducing it viscosity 0 at low temperatures ().

Synthetic slag is prepared as follows.

At the beginning, a certain amount of domain5 slag is melted with the help of a torch, then the torch is immersed in it and later melted down by a van-well using an immersion torch). Then, the additives are poured into the bath and dissolved, stirring the melt immersed in it with streams of flame.

In the process of blasting blast furnace slag when it is preheated to a high temperature (1400-1500 C), sulfur is blown out of the donkey, almost to the tracks. For example, at 5 consumption of 60 natural gas per 1 ton of blast-furnace slag, when the oxygen consumption ratio is equal to a unit of sulfur, it decreases to traces after 15-20 minutes of purging at 0 melt temperature. In addition, in the process of heating the ingots, the slag is continuously flushed with a torch, therefore the initial sulfur content in the blast furnace slag does not actually have 5 starting points - there is no sulfur in the final gatetized / slag.

Various slags are smelted when alkali metal oxides and silicon dioxide are added to the pre-sweet blast-furnace donkey.

Then, the temperature of the melting slags in the micro furnaces with a platinum heater and their fluidity at 1400 and in accordance with the standard method is measured, the length is measured

column spreading slag, poured into a spiral graphite snail,

The composition and properties of the experimental slags are given in the table.

Alkali metal oxides (No20 and) are introduced into slags by adding soda ash and silicate lump (compositions 3,4,7,9 and 10) or only soda ash (compositions 2,5,6 and 8, silica) to the charge. to slag, backfill into a mixture of silicate lump (compositions 3,4,7,9 and 10) or quartz sand (compositions 2,5,6 and c).

As can be seen from the table, long slags are obtained 2,5,8-10, which have a fluidity comparable (rather high) at 1400 and IOCPc and melting point below 1000 ° C. However, slags 2 and 5 are unsuitable for introducing heat-slag steel into them billets, as the surface of the latter is eroded in the heating process due to the increased content of alkali metal oxides. Thus, only slags 8–10 can be recommended for heat-slag heating in them of steel blanks for pressure treatment.

With the introduction of alkali metal oxides of less than 10% into synthetic slag, its melting point decreases slightly; Synthetic slag. With an alkali metal oxide content of more than 20%, it erodes billets during heating and loses an excess of thermodynamically relatively weak oxides in the blowing process. When silica is introduced in less than 10%, synthetic slag is short, i.e. its visibility is sharp

increases with decreasing temperature “l, and the introduction of more than 20% of silicon dioxide into synthetic slag makes it too viscous in the high-temperature region, which makes it impossible to move the spack well

5 flare struts.

Included in the composition of the slag oxide compounds provide a stable chemical composition of the slag melt at operating temperatures of heating

0 solid metal (llOO-1400cj.

Slag of the proposed composition has so pl. 920-990 ° C, bk. 1620-1680 ° С {viscosity at 1400s 8–15 Pa-s, at 20-30 Pa-s.

five

Examples of making slag from various materials, wt%: silicate block 20; soda ash 17j blast-furnace blast furnace slag 63 or silica sand 18; calcined soda 22; Sweet blast furnace slag 60.

Synthetic slag is prepared, for example, by fusing components into a crucible.

5 s. Using gas-oxygen torch. In the process of preparation of synthetic. Slag is removed from the blast furnace slag (sulfur is removed), therefore sulfur is not present in the finished synthetic slag.

An example of the chemical composition of synthetic slag, 38.78, AbgOz 5.86; 4.11, Ca0119, OP MgO 11.72, MhO 0.4; 15.57; tipK mixes - the rest.

five

The proposed synthetic slag longer has a lower melting point than the known. The technical effect of the use of synthetic slag is due to reduced viscosity both in low and in high altitudes of the atour region, and therefore there is less entrainment of slag dust with waste gases, improved mixing of the slag bath with torches, which intensifies heat transfer.

the dacha to the ingot, accelerates the heating of the metal, thereby saving heat (combusted natural gas). The ingots are heated more evenly, without local overheating. The initial scale is dissolved in the proposed slag better.

The economic effect from the introduction of the proposed synthetic slag according to preliminary estimates is more than 200 thousand rubles.

Claims (1)

SYNTHETIC SLAG, including blast furnace slag and alkali metal oxides, characterized in that, in order to lower the viscosity, it additionally contains silicon dioxide, and as blast furnace slag, desulfurized blast furnace slag in the following ratio, wt.%: · Desulfurized blast furnace slag 60-80 Alkaline oxides of metals 10-20 Silica 10-25