DE2412126A1 - MELTING PROCESS FOR SOLID IRON IN A GAS FIRED KUPOLE FURNACE - Google Patents

Description

p <.--! ■■; · / · :. R. U.:ykcn

PensensKij Kompressornyj zavod

March 13, 197 ^

Penza / USSR. ^{P 53}

L / Br

MELTING PROCESS FOR SOLID IRON IM GAS FIRED CUPOL OVEN

The invention relates to metallurgy and

refers in particular - - - - - :: to fusion processes for solid pig iron in gas-fired cupola furnaces.

At present, a temperature is set in the shaft of the latter for melting solid pig iron in the gas-fired cupola generated, which is above the melting temperature of the pig iron, whereupon the cupola furnace with the insert, which is made of solid Pig iron and flux, is charged

The charging of the cupola furnace is carried out continuously, whereby a constant bed height of the cupola furnace charge is maintained.

The temperature which is used to guide the pig iron

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• ir "

Process is required by the heat of gases generated, which are burned in a gas burner, which is arranged in the lower part of the cupola shaft.

Under the influence of the heat of the gas, the lower charge layer becomes melted; the molten cast iron is continuously withdrawn from the cupola.

However, the known method has a significant disadvantage: in the lower part of the shaft at the end of the Melting process, when the loading is stopped, a metallic crust, which consists of metals and their oxides. This crust contains up to 10% of the solid pig iron charge and forms waste. It also complicates the crust the gas flow through the cupola shaft and reduces the melting int ens i ν it ät and the furnace throughput.

Therefore ^mu ^ ^ ^ie ^ Kr * s ⁰ where the lining which surrounds the above-mentioned crust, is destroyed to be removed when preparing the cupola for the next following melt, ·

The aim of the present invention is to eliminate the drawbacks mentioned.

The invention is based on the object of such

_Develop process after <3 βπι solid pig iron melted

the

without the formation of crusts, as a result of which metal losses maximally reduced during the melt and the repair of the cupola furnace lining before the start of each melt

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can be avoided

This object is achieved in that when solid pig iron is melted in a cupola furnace according to the invention Completion of the loading of the cupola with solid pig iron in the cupola given such an amount of refractory material

covering
how to create a layer on the surface of the

molten cast iron is required.

The thickness of the refractory material layer is expedient at least equal to 0.3 of the diameter of the cupola shaft.

The inventive method enables the formation to avoid crusts and consequently also to reduce losses of pig iron when it is smelted. In addition, κ ir-d

• It is possible several times thanks to the method according to the invention, solid

Melting pig iron in the cupola without the cupola lining Touch up before each melt.

! ■ The following is the melting process for solid pig iron imj gas-fired cupola, the advantages of the present invention being apparent will"

He f ind, according to - method consists in that the gas-fired cupola, which is at a temperature above the melting point the temperature of the pig iron is heated, is continuously fed with an insert made of W Pig iron and fluxes. The rate of loading is so great that in the cupola it is constant

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Feed level is maintained. By, the warmth of Gases in the gas burner, which is located in the lower part of the cupola, are burned, the lower charge layer will melt. According to the invention upon completion of loading the cupola, such amount of refractory material abandoned, which is enough. to be on the

■ cover.cover.end
Send surface to generate a layer. The thickness of this layer is expediently equal to 0.3 of the diameter of the cupola shaft. Melting pig iron according to this process makes it possible to avoid the formation of crusts.

It was found that the formation of crusts in the known smelting processes for pig iron can be explained by the fact that after the loading of the cupola furnace with the insert the heat-conducting Q _ase ^ ie gradually diminishing charge layer break through, whereby the even distribution of the Hot gas heat is interrupted over the cross section of the cupola shaft and dead zones are created,

.a

in which the metal deposit is not melted, but crusts forms. Accordingly, they form on the shoulders (in the gas-fired cupola with shoulders in the shaft) and on the grids (in the gas-fired cupola with grates in the shaft) or on the shaft hearth (in the gas-fired cupola with outside relocated overheating chamber) metal crusts.

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It has been found that the formation of crusts is avoided by creating a counter pressure for the gases which break through can be. This is achieved according to the invention in that, after completion, the loading of the cupola furnace with the use of refractory material, for example chamotte or high alumina refractory material, is abandoned, its Layer now generating the required back pressure ensures. The hot gas evenly heats the remaining insert part and melts it without creating any dead zones develop.

After the charge has completely melted partially melted the refractory material that adhered to the cupola walls flows down and solidifies, causing the cupola lining, which was partially melted off during the high iron smelting process restored and its thickness is increased.

The method can be used in any construction gas-fired cupola, such as a gas-fired one Cupola furnace with grates in the shaft. Enclosed Drawing shows the construction of such a cupola. Before the start of Schmeis, a burner 1 is ignited and the cupola lining 2 is heated to a temperature which is above the melting temperature of the pig iron, after which the cupola shaft 3 is charged with an insert consisting of solid pig iron and flux. The Metallfeatz will retained on water-cooled grids 4 of the cupola furnace,

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where it is melted. The molten cast iron drips down into an overheating chamber 5, is additionally overheated and flows through a forehearth 6 into a ladle Iber. Of the Cupola furnace is continuously charged with the insert. To When the loading is terminated with the insert, the loading height in the Eupolo furnace shaft 3 »gradually decreases, as a result of which the counter pressure for the gases in the Überhit tion chamber 5 is reduced and unblown zones arise in which the melted Metal cools down and forms a metal crust. Ss is about the emergence of non-blown zones and the forming to avoid a metal crust at the end of the melting process

a

a refractory material is placed on the metal set in the melting zone, whose basicity corresponds approximately to the basicity of the cupola lining. The height of the refractory layer should be at least equal to 0.3 of the diameter of the shaft { be the cupola melting zone 7. The size of the refractory pieces should be about the same as the size of the pieces of the

a
The presence of refractory material on the surface of the metal etch makes it possible to generate a counterpressure in the metal zone 7, to distribute the hot gases evenly over the cupola cross section in the melting zone 7, to eliminate the dead zones Avoid losses from unmelted metal. In addition, after the metal charge has melted, the refractory material begins to melt,

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7 -

which flows down the walls of the shaft 3, solidifies and here in the warm state the lining of the overheating chamber 5 repairs. After switching off the gas burner 1 and blowing the cupola shaft 5 ^ i * air solidifies the melted refractory layer on the lining

Lining the overheating chamber 5 and forms with her a monolithic schoa The stated ratio of the height of the refractory layer to the shaft diameter in the melting zone 7 is an optimum value this ratio, because a reduction in the refractory layer (to a value smaller than 0.2 of the diameter of the Shaft in the melting zone is) a reduction of the back pressure in the melting zone and a smaller effect for Consequence.

The basicity of the related refractory should be approximately the same as the basicity of the refractory cupola lining as a change in the basicity causes the lining of the cupola walls to erode.

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Claims (2)

March 13, 1974 L / Br PATENT CLAIMS: 1. Melting process for solid pig iron in a gas-fired cupola furnace, characterized in that after finishing charging the cupola with solid pig iron to be melted into the cupola such an amount of refractory material is given up as for E covering
witness a layer on the surface of the melted Cast iron is required. 2. melting process for pig iron according to claim 1, d adurch marked the thickness of the Refractory layer at least equal to 0.3 of the diameter of the cupola shaft is 409840/0749 ORIGINAL INSPECTED