RU1836617C - Lining of steel melting arc furnace bath - Google Patents

Abstract

SUMMARY OF THE INVENTION: The lining of a bathtub of a steelmaking arc furnace comprises masonry and a printed part of several layers of periclase powder. The melt contacting layer has a thickness of 150-180 mm and is made of a periclase-based refractory composition capable of hardening at a temperature of 350-500 ° C. Lower than the temperature of the molten metal before being discharged from the furnace. 1 tablet, 1 ill.

Description

The invention relates to the metallurgical industry and can be used to manufacture the lining of an arc heated steel furnace.

The aim of the invention is to increase the operational reliability of the lining by strengthening its working area.

The objective of the claimed technical solution is to increase the productivity of the furnace by reducing the downtime of the furnace for repair.

The essence of the proposal is as follows. The implementation of the lining of the lining, which is in contact with the molten metal, from a refractory periclase composition, hardening at a temperature of 350-500 ° C below the temperature of the molten metal, ensures the formation of the working zone of the lining of considerable thickness already during the first melting. It has been established from practice that the thickness of the formed hardened layer is 150-180 mm, sufficient to avoid the destruction of the lining by mechanical damage when loading scrap metal.

Stuffed, part of the lining is made of periclase powder. The strengthening of the lining layer in contact with the molten metal is achieved by the presence of known additives in it, for example, based on sodium borosilicate or iron-containing components in an amount determined by the equilibrium state diagram of a multiphase system. Due to additives, the temperature of the passage of liquid-phase and solid-phase processes at the boundaries of periclase grains is reduced, which determines the strengthening of the bonds between the grains and provides a strong and dense structure of the working area of the lining.

The layer following the hardened layer is made only of periclase powder. It is a buffer that compensates for thermomechanical stresses arising in the working area of the lining during furnace operation.

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In addition, this layer prevents the passage of molten metal to the furnace casing when a crack forms in the working area.

As the hardened layer wears out and the melting reagents migrate through it, the part of the buffer layer facing the working surface undergoes physical and chemical changes after several melts and also hardens. The strengthening of the buffer layer proceeds gradually due to the prolonged exposure to high temperatures. Thus, the formation of a strong working layer is ensured as the printed part of the lining is worn.

If the temperature difference between the molten metal and the hardening of the packing layer in contact with the molten metal is more than 500 ° C (a decrease in the temperature of hardening is below the specified limit), then in this case, the lining is destroyed due to its washing out by molten metal, because refractory lining contains a lot of low temperature glass phase.

If the temperature difference between the molten metal and the hardening of the packed layer is less than 350 ° C, i.e. if the hardening temperature is higher than the declared upper limit, then the thickness of the hardened layer during the first melting period will be less than 100 mm and there will be a decrease in the reliability of the lining. °

When analyzing the sources of scientific, technical, and patent information, the lining of the steel-smelting arc furnace was not found to be similar to the claimed design, which allows us to conclude that the differences are significant.

The proposal is illustrated by an example of a specific implementation.

The drawing shows a furnace section.

It contains a metal casing of the furnace 1, brickwork 2. a layer of the printed part of the lining of periclase powder 3 (buffer layer); a layer of the stuffed part of the lining based on periclase powder, hardening at a temperature of 350-500 ° C below the temperature of the molten metal, melting space 5.

The manufacturing techniques of the proposed multilayer lining of an electric steel furnace are as follows.

On the casing 1 of the furnace, brickwork 2 is made in the form of a bottom made of periclase brick (in three rows per die or on an edge) with obligatory spilling of seams from the eliminated periclase powder. After the brickwork 2 is completed, a packed layer 3 (buffer) with a thickness of 420 mm in the bottom and 520 mm in the slopes by backfilling and vibration compaction

recyclable powder. Next, a layer 4 is made of a packed mass hardened at a temperature of 350-500 ° C below the temperature of the molten metal. The printed part of the slopes is made using

steel ring patterns of various diameters, gradually increasing the height of the lining by backfilling the refractory powder between the template and brickwork 2. An auxiliary template is used to demarcate the buffer layer 3 and the reinforcing layer 4. For the manufacture of the buffer layer 3, periclase powder is poured between the brickwork 2 and the auxiliary template, for the manufacture of a hardening layer 4 in the space between the auxiliary template and the template with a diameter corresponding to the diameter of the furnace bath in this section of the lining, periclase powder with the additive is filled, then removed The auxiliary template is sealed and the filled granular mass is compacted by vibration sealing. Next, build up the next part of the template and pour refractory powder in the same sequence. Thus, the entire lining of the furnace is carried out. The formation of the working area of the lining is carried out by loading scrap metal into the furnace, melting it and holding

molten metal 1650-1700 ° C in a furnace 2.0-2.5 hours ca.

In order to determine the strength of the working layer of a lining made of a number of refractory compositions capable of hardening at temperatures below the temperature of molten metal I (1700 ° C), samples with a diameter of 36 mm and a height of 50 mm were made. Samples were fired at temperatures of 1200, 1350 and 1500 ° C

and their compressive strength was determined (GOST 4071-80).

The test results are shown in the table.

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Claims (1)

The claims The lining of the bathtub of a steelmaking arc furnace, including brickwork and two layers of periclase powder, one of which is in contact with molten metal, has a thickness of 150-180 mm, characterized in that the lining layer in contact with the molten metal is made of a refractory composition based on periclase powder, which has the ability to harden at a temperature of 350-500 ° C lower temperatures of molten metal before being discharged from the furnace.