JP2743783B2 - How to measure refractory wear - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to measurement of the rate of wear of refractories by slag and / or molten metal when the molten metal stays in a molten metal smelting furnace or a molten metal holding vessel.

[0002]

2. Description of the Related Art The following methods are available for measuring the wear rate of a furnace body and a holding vessel. (1) Furnace body measurement by laser (AGA) Japanese Utility Model Publication No. 60-27924 discloses a furnace body measurement using a laser beam to determine the size of the remaining brick for each treatment or refining, and based on this, determines the wear rate of the refractory. The required AGA device is disclosed. (2) Furnace body dismantling survey After the furnace body is used, the remaining brick dimensions are investigated, and the brick wear rate is determined from the difference between this and the brick dimensions before use.

As a method of measuring the wear rate of a brick, a laboratory study using the following simulation test instead of an actual furnace is performed. (3) Slag erosion test As a method of knowing the wear rate of bricks and refractories, there are a rotary slag erosion test furnace, a brick using a high-frequency induction furnace, and a refractory separation test. The rotary slag erosion test furnace separates test bricks or refractory as lining in a cylindrical drum and heats it with a burner or an electrode in this drum to melt the slag and react the slag with the brick or refractory. Investigate the degree of erosion due to In the test using a high-frequency induction furnace, the lining of the induction furnace is separated by a test brick or a refractory to melt the metal and slag.
Investigate the refractory wear of the brick at the molten metal, slag-molten metal interface.

[0004]

However, in the AGA apparatus, since the thickness of the slag attached to the brick surface is measured together with the brick thickness, the wear rate of the brick alone cannot be accurately measured. Further, according to the AGA apparatus, an error easily occurs in the setting of the reference point, so that measurement in millimeter units is impossible.

[0005] Further, in the furnace body dismantling inspection method, the average amount of wear and the average wear rate through the furnace allowance can be obtained. However, it is not possible to know the wear rate under steelmaking conditions such as temperature, slag composition, and blowing conditions for each treatment. Can not.

Further, in the simulation test method, since the treatment atmosphere, slag components, slag amount, molten iron amount, stirring conditions, and the like are limited to certain ranges, the damage environment in an actual furnace or a molten metal holding container is accurately simulated. I can't say that. Therefore, it is not possible to immediately determine the wear rate in the actual furnace from these laboratory studies.

[0007] The present invention has been made in view of the above circumstances, and between charging in the actual furnace, and various refining conditions, such as temperature, temperature change, slag component, melt component change, stirring intensity and the like. Accurately understand changes in wear due to differences
An object of the present invention is to provide a method for measuring the amount of wear of a refractory which can be used for controlling the rate of wear of a refractory of an actual furnace .

[0008]

Means for Solving the Problems The inventors of the present invention have examined various points which are obstacles for putting a brick into an actual furnace or a molten metal holding container and measuring the wear rate after recovery. As a result, the following findings (a) to (d) were obtained. (A) A crack is generated in the injected brick due to a heat spall generated when the brick and refractory are charged into the furnace, and a predetermined brick shape cannot be maintained. (B) The environment to which the injected bricks and refractories are exposed is more severe than the bricks lined in the furnace body, and there is a concern that the bricks are completely worn out and disappear. (C) The bricks and refractories charged are 1200 ° C to 1600 ° C.
It is generally not easy and dangerous work to enter the slag and collect the bricks and refractories because of the extremely high temperature. (D) It is not easy to find small bricks in a large amount of molten slag.

Based on these findings, the inventors have conducted intensive studies and, as a result, have found a method of easily knowing the wear rate of the refractory in the furnace by a simple operation of charging bricks. Hereinafter, bricks and refractories having a shape to be put into a furnace or a holding vessel are collectively referred to as “molded refractories”.

[0010] The method for measuring the amount of refractory wear according to the present invention is as follows.
Volatile content of binder contained in molded refractories, free water,
Or a step of removing water of crystallization, a step of measuring the initial dimensions of the molded refractory, and a step of charging the molded refractory into a molten metal smelting furnace or a molten metal held in a molten metal holding container in a metal production process. And a step of recovering the injected molded refractory from the melt, a step of measuring the dimensions of the collected molded refractory, and calculating the amount of wear of the molded refractory based on the measured dimensions and the initial dimensions. And a step. Refractories near the slag line are molten
In the laboratory due to complex damage from slag and molten steel
The simulation test alone can estimate the refractory wear behavior of a real furnace.
It is difficult. Therefore, in the present invention,
Process, initial dimension measurement process, input process, recovery process, calculation of wear amount
By performing the discharge process every time the actual furnace is operated,
The amount of wear of refractories in
I have to. In particular, the binder contained in molded refractories
-Remove volatile matter and moisture from molded refractories before
By doing so, the molded refractory will be partially
Is prevented from being lost or completely destroyed,
Highly accurate measurement of refractory wear due to erosion
And the molded refractory can be reliably removed from the melt.
Can be recovered.

[0011] ^{1cm 3 <V <90000cm 3 ...} (1) However, V represents the volume of the molded refractory [cm ^3]. When the volume V exceeds 90000 cm ³ , the thermal stress generated inside the molded refractory becomes excessive, and cracks occur in the molded refractory due to spalling. By the way, when the spall resistance of the molded refractory is improved and the volume V is larger than 90000 cm ³ , the heat capacity of the refractory becomes too large, and immediately after the refractory, heat is taken from the surrounding slag or molten metal and the refractory surface is removed. Since a solidified slag or metal film is formed, if the solidified slag or the like does not dissolve immediately, the amount of wear of the refractory cannot be accurately measured. On the other hand, when the volume V is less than 1 cm ³ , the molded refractory cannot maintain the refractory structure as a structure.

Further, the maximum outer diameter L of the molded refractory must satisfy the following inequality (2) in order to maintain an environment in which a normal lining refractory is placed. (1/400) D <L <(1/3) D (2) where L represents the maximum outer diameter [cm] of the molded refractory, and D
Indicates the minimum diameter or distance [cm] of the furnace or the holding container.

Here, the maximum outer diameter L of the molded refractory to be charged is
If the ratio is larger than (1/3) D, in the case of a refining furnace, refining will be hindered, or it will be different from the environment where the refractory lining is placed. On the other hand, if the maximum outer diameter L of the molded refractory is smaller than (1/400) D, it becomes difficult to collect the molded refractory. [Surface Grinding] By grinding a parallel surface facing at least one or more surfaces, the amount of wear of the molded refractory can be easily measured. Further, in order to examine the microscopic wear rate of the surface of the formed refractory, it is possible to grind at least one surface and determine the wear rate of the aggregate and matrix of the refractory structure by microscopic observation. [Method of specifying molded refractories and specifying directionality during manufacturing] The following methods (1) to (4) are effective for specifying molded refractories for each material or for each pretreatment of refractories. . (1) By changing the length of the shaped refractory in a specific direction to a certain interval, the shaped refractory can be specified for each material or for each pretreatment. For example, the maximum length is 400m
m, 390 mm, 390 mm
The length is changed by 10 mm, such as mm and 400 mm. (2) In addition, the end (corner part) of a rectangular parallelepiped shaped refractory
By changing the angle obliquely, the molded refractory can be similarly specified. (3) In the case of the mag-carbon refractory, generally, the wear rate of the refractory surface tends to be different depending on the orientation direction of the flaky graphite in the refractory. The orientation direction of the graphite depends on the molding (pressing) direction when producing the refractory, and the following method can be considered to specify the surface of the magcarbon refractory having such a graphite orientation.

[0014] Each side (a, b,
c) is defined as in the following equation (3), and by specifying each surface, a pressing surface during molding is specified. a <b <c (3) By changing the length of these sides, the material of the molded refractory and the history of each heat treatment can be specified even after the collection. (4) In addition to the above (3), by similarly cutting the longitudinal end (edge portion) of the rectangular parallelepiped shaped refractory at an oblique angle to specify the molding surface of the molded refractory. be able to. [Change in Density of Molded Refractory] By changing the apparent density of the molded refractory, the molded refractory can be positioned at an arbitrary level in the depth direction of the slag layer. For example, the apparent specific gravity is reduced by providing a cavity inside the molded refractory, and if the molded refractory is always located on the upper surface of the slag layer, slag splash on the slag surface, wear due to rocking, furnace atmosphere Can be checked for wear.
Also, by embedding a high-density material such as tungsten carbide inside the molded refractory, the apparent specific gravity of the molded refractory is made larger than that of the molten metal, and when the molded refractory is immersed in the molten metal, The reaction between the object and the molten metal can be examined. Further, by adjusting the apparent specific gravity of the molded refractory to an intermediate value between the slag and the molten metal, the wear rate in the presence of the slag and the molten metal can be examined. [Measurement of Dimension of Molded Refractory] A normal caliper or the like is used to measure the dimension of the molded refractory. However, for refractories with slow wear rates, equipment that can measure at least up to two decimal places is required. When the refractory is heat-treated, it is necessary to measure the refractory dimensions again after the heat treatment. [Heat treatment of molded refractory] In the case of unfired refractory, for example, magcarbon refractory, heat treatment is performed in a temperature range of about 300 ° C. at the time of manufacturing the refractory. When such a molded refractory is charged into a furnace, a binder agent such as a phenol resin is gasified, which may adversely affect the refractory in the furnace. In particular, care must be taken because the amount of gas generated increases as the size of the molded refractory increases, and the refractory in the furnace may be greatly damaged. Therefore, when there is such a danger, it is necessary to heat-treat the molded refractory in advance so that no gas is generated. The heat treatment is performed by a method suitable for the molded refractory. For example, in the case of a mag-carbon refractory, heat treatment is performed in a coke breather or in a non-oxidizing gas atmosphere. In addition, in the case where the binder agent or the like forms a hydrate such as alumina cement, crystallization water including free water can be removed in advance by heat treatment, and explosion of the molded refractory can be prevented.

[0015] When the heat treatment is performed, the dimensions of the molded refractory are very likely to change, so it is necessary to measure the dimensions after the heat treatment. In addition, if a compound or the like is newly generated in the molded refractory due to the heat treatment and may react with moisture in the atmosphere, it is necessary to shut off the molded refractory after the heat treatment from the surrounding atmosphere. is there. Particularly, in the case of the mag-carbon refractory, the additive in the refractory is carbonized by the heat treatment, so that it reacts with moisture in the air at normal temperature to cause digestion and expansion. Therefore, in this case, the heat-treated refractory is vacuum-sealed in a gas-impermeable bag to prevent digestion, or the heat-treated refractory is stored under vacuum and in a dry atmosphere until use.

[0016]

[Action]

[Timing of injection into furnace] In the case of a smelting furnace, a molded refractory is charged into the furnace at an arbitrary time before and during refining, and the wear rate of the refractory is determined in an arbitrary period until recovery. be able to. [Measures for avoiding thermal spalling] The molded refractory is wrapped with a member that has been in the furnace for a certain period of time, such as cardboard, and that exhibits heat insulation when it is present. Prevents rapid heating of the molded refractory in the initial stage. When the refractory is rapidly heated, a compressive stress acts on the surface and a tensile stress acts on the inside, and a refractory which is generally weak against the tensile stress easily cracks easily. In order to prevent such thermal spalling, a heat insulating layer is required on the surface of the molded refractory, and if it is removed from the surface of the refractory after achieving the purpose of preventing cracking at the time of injection, the refractory is The amount of wear of the object can be measured without collapse due to thermal spalling when the refractory is charged. [Recovery of molded refractory] Although recovery of molded refractory is extremely difficult, the recovery efficiency is improved by performing the most suitable method among the following methods in view of the size of the furnace, the specific gravity of the refractory, and the like. (B) Recovery from the front of the furnace If the apparent specific gravity of the molded refractory is lighter than that of the slag, the molded refractory floating on the slag can be collected with a scoop-shaped jig. If the apparent specific gravity of the molded refractory is greater than the specific gravity of the slag and less than the specific gravity of the molten metal, the slag is gently discharged in small quantities, and the final discharged molded refractory is collected immediately before its discharge. can do. However, if the worker uses human power for recovery, the furnace and holding container need to be small. In this case, it is desirable to use a dedicated remote-controlled recovery machine that has high safety, a high recovery rate, and can recover from inside a large furnace and a molten metal holding container. (B) Discharge together with the slag and collect at the slag yard If the specific gravity of the refractory is smaller than the molten metal, after discharging the molten metal, the formed refractory is discharged together with the slag into a slag pot (slag pan), and the slag is discharged. Waste is collected from the slag pot in the yard (slag processing plant). At this time, when waste is discharged from the slag pot to the slag yard, the waste is discharged through a steel net (plow), thereby improving the efficiency of refractory material recovery. (C) At the time of slag discharge, recover by the refractory collection receiver under the furnace. If the apparent specific gravity of the molded refractory is smaller than the specific gravity of the molten metal, after discharging the molten metal, remove the slag from the furnace and the molten metal holding container. Upon discharge, the formed refractory is recovered by discharging through a steel net (plow). (D) Leave a small amount of slag and collect it with the refractory having a higher specific gravity under the furnace. If the apparent specific gravity of the molded refractory is between the slag specific gravity and the molten metal specific gravity, the molten metal is discharged from the tapping hole. Then, the remaining slag is gently discharged little by little, and the molded refractory discharged at the end is discharged under the furnace together with the remaining slag, and the molded refractory is recovered from the waste. Alternatively, in the case of a molten metal holding container, the waste may be discharged to another position and the molded refractory may be recovered from the waste. (E) Leave a small amount of slag and collect it with the refractory having a high specific gravity under the furnace. If the apparent specific gravity of the molded refractory is greater than the specific gravity of the molten metal, discharge the slag as much as possible in advance and then gently discharge the molten metal. Then, the last molded refractory is discharged together with the remaining slag in the furnace or at another position in the case of a molten metal holding container, and the molded refractory is recovered therefrom. [Cooling of Recovered Refractory] In the case of a carbon-containing refractory (mag-carbon refractory or the like), by cooling the molded refractory in graphite, the oxidative consumption of carbon in the refractory can be prevented. In this case, it is important to put the molded refractory into graphite as soon as possible after collection. In the method of preventing oxidation, a carbon source other than graphite may be used to prevent oxidation of the contained carbon, and since the air is shut off, cooling under vacuum, reduced pressure, or an inert atmosphere is also effective. Is recognized.

On the other hand, refractories having poor spall resistance also need to be gradually cooled even in oxide refractories, and can be cooled in graphite powder or magnesia powder, or in a vessel lined with a heat insulating material. In addition, cracking due to cooling of the refractory can be prevented. In this case, it is important to put the molded refractory into powder or a heat insulating box as soon as possible after collection. [Measurement of wear amount] Cut the collected refractory and measure the dimensions of the cut surface. The amount of wear of the refractory is determined from the difference between the initial size before the introduction and the measured size, and the wear rate is calculated from the amount of wear of the refractory, the slag of the refractory, and the residence time in the molten metal. In this case, the amount of wear of the refractory can be measured with an accuracy of 0.01 mm.

With respect to the refractory having a small amount of wear, the amount of wear of the aggregate and matrix of the refractory can be known by observing the operating surface of the refractory by microscopic observation. In addition,
By microscopic SEM observation of the refractory operating surface of the recovered refractory,
The reaction mechanism between the refractory and the slag can be determined. [Items that can be measured] The following items (a) to (f) can be measured using a method based on refractory charge.

(A) Wear rate per furnace treatment (per charge) (b) Influence of smelting and refining conditions (temperature, slag component, basicity, time) on wear rate (c) During furnace treatment Changes in wear rate (for example, changing the refractory input timing variously in the first, middle, and late stages of processing to grasp the wear state at each time) (d) Effect on the wear rate of refractory material (e) Wear rate of aggregate and matrix in refractory (f) Difference in wear rate depending on refractory forming direction

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Various embodiments of the present invention will be described below with reference to the accompanying drawings by way of comparative examples. Example 1 In order to determine wear of refractories during blowing of a refining furnace having a furnace inner diameter of 1.6 m, six types of magcarbon refractories, one of each, were introduced before the start of refining and recovered after blowing. I checked. As shown in FIG. 1, the length of each side of the injected refractory is a,
It is a rectangular parallelepiped of b and c. As shown in Table 1, the lengths of the sides a, b, and c of the six molded refractories satisfy the inequality a <b <c. In this case, the sides a,
The length of b was fixed to 90 mm and 110 mm, respectively, so that the pressurized surface during the operation of the magcarbon refractory was a surface formed by the bc side. (Hereinafter, a plane formed by the sides b and c and a plane parallel to the plane are referred to as a bc plane.
They are called -b plane and ac plane. ) And the longitudinal direction of the molded refractory, that is, the length of the maximum side c is 160 mm to 26 mm.
Six types of molded refractories were distinguished by changing every 20 mm within the range of 0 mm.

The six types of molded refractories were previously formed by an oil press as shown in Table 1 depending on the amount of graphite and the type of aggregate, and were cut into a predetermined shape while leaving a processing margin. In order to smooth the parallelism between the surfaces of the refractory and the surface of the refractory, the surface of the refractory is surface-ground using a JIS.
The surface was machined up to the triangular symbol ア ラ on the standard display. The final thicknesses a, b, and c of each refractory after processing are 2 decimal places.
It was measured every 5 mm in the length direction using calipers up to the digit.

Each of the molded refractories was wrapped with a cardboard paper for preparing a packing box having a thickness of 5 mm in order to avoid a thermal spall in the initial stage. The molded refractory, after containing molten iron in the converter,
The furnace was charged into the furnace from the opening of the sublance. After the introduction, predetermined blowing was performed. 57 minutes later, after the end of blowing, the furnace was tilted and slag was gradually discharged, and at the end of slag discharge, molded refractories were collected one by one manually from the furnace. The recovered refractory was red hot and was immediately placed in graphite powder for cooling to prevent oxidation. Here, all six molded refractories were successfully collected.

Since the slag adheres to the surface of the molded refractory cooled to about room temperature, the residual thickness cannot be measured immediately. Then, after measuring the length in the side c direction and ranking the length of the eight molded refractories and specifying the molded refractory, the molded refractory is cut in parallel with the bc plane at the central part of the refractory. A-b and a-c surfaces where refractories are usually used
Wear on the surface could be obtained.

As a result of observation of the cut surface, no crack was generated, peeled off, or cracked in the recovered refractory due to the hot spall. The dimensions of the sides b and c after collection were measured every 5 mm. The corners of the refractory are more heavily worn than other parts due to heating on three sides and reaction with slag. Further, the length in the side c direction is the longest side in the rectangle, and it is difficult to measure due to the adhesion of slag. Of the remaining dimension distance in the side b direction of the half-section where the degree of wear is stable, the remaining dimension (thickness in the direction of the side b) of a portion ２ of the length of the side c around the center of the side c ) Is the representative value of the refractory. The residual size was determined by subtracting the remaining dimension from the dimension before the refractory was charged, and this was divided by the residence time in the furnace to determine the wear rate. This is shown in Table 2.

As a result, in the influence of the refractory material,
The effect of the type of aggregate and the content of graphite were clarified. Based on this result, the improvement of the life of the furnace by the improvement of refractory in this furnace, appropriate graphite blending,
It was improved by selecting the magnesia raw material. Comparative Example 1 Molded refractories B and C of 560 mm and 600 mm in length wrapped in cardboard paper and 580 m in length not wrapped in corrugated paper under the same conditions as in Example 1.
A total of two molded refractories B and C of m and 620 mm, respectively, were charged. Immediately after the insertion, the two molded refractories that were not wrapped in cardboard were broken at half the length in the long side direction. In addition, since the remaining two molded refractories have a minimum furnace volume of 1.6 m, the refractory is always located at the center of the furnace, and the oxygen jet from the lance located at the center of the furnace is directly refractory. At the same time, not only the refining reaction was hindered, but also a considerable decarburized layer of the recovered magcarbon refractory was recognized. Such a situation was judged to be unsuitable for evaluation of refractories used for furnace walls. Comparative Example 2 A rectangular parallelepiped shaped refractory as shown in FIG. 1 was used. The dimensions of the molded refractory were 200 × 400 × 1200 mm. This was heat-treated at 1100 ° C. in a coke breeze. After the heat treatment, dimensions were measured and wrapped with cardboard paper for packing, and then measurement of the amount of wear due to refractory charge was attempted under the same conditions as in Example 1. After the introduction, the formed refractory gradually became attached to the surrounding slag in the slag, grew and developed into a large lump, and floated on the slag. As a result, the refining operation fell into an unsatisfactory state. This is presumably because the molded refractory has a large heat capacity, so that the surrounding slag solidified and adhered to the surface and gradually grew. Example 2 A refining furnace having a furnace inner diameter of 4.8 m alternately performs two types of refining processes. Investigation of the effect of refractory on the mag-carbon refractories used in this refining furnace on refractories, and inspection of the early, middle, and late stages of wear during processing to improve refining conditions. The wear rate was determined at different times when medium refractories were charged.

As the molded refractories, three types of first to third series were prepared for each of the shapes shown in FIGS. The molded refractory of the first series is to be thrown in at the beginning of the treatment, and has a rectangular parallelepiped shape as shown in FIG. 1 and the length of each side a, b, c (where a <b <c) shown in Table 3 is set. The length of the sides a and b of each molded refractory is fixed, and the length of the side c is changed. The molded refractories of the second and third series are put in the middle and the last stages of the treatment, respectively, and the end face of the maximum side c is obliquely changed in angle as shown in FIG. 2 and FIG. did. This makes it possible to specify the charging timing of the molded refractory collected after refining and the molded refractory, respectively.

The pressing direction at the time of molding of the mag-carbon refractory is set to the ac plane, and the sides a and b are set in order to specify the pressing direction so that the difference in wear becomes clear. (A <b). The molded refractory used here is a mag-carbon refractory (brick C) of 20% by weight of graphite used for the slag line of the furnace, 50% by weight of fused magnesia, and 50% by weight of sintered magnesia. After cutting, leaving a processing allowance in a predetermined shape, the refractory surface was ground using a surface grinding machine until the surface roughness became a triangle symbol で in JIS standard display. Molded refractories are 1000 ° C in advance
Heat treatment was performed in a coke breeze until volatile matter was removed from the binder of the refractory to prevent collapse of the refractory due to expansion of volatile gas due to rapid heating when the refractory was charged. After treatment,
The thickness b of each molded refractory was measured every 5 mm in the length direction using calipers to two decimal places.

5 mm to avoid heat spall at the beginning of injection
The entire surface of each refractory was wrapped in a thick cardboard box for work. Injection of molded refractories before starting refining in each refining process
In the middle and late stages, they were charged into the furnace through the sublance opening at the top of the furnace. The method of recovering the molded refractory is as follows: after blowing, after tapping, the furnace is tilted and the slag is gradually discharged to the slag pan, and the `` suki '' provided under the furnace at the end of the slag discharge is charged. The molded refractory was recovered. As a result, in the refining process A, six out of nine pieces were recovered, and in the refining process B, seven out of nine pieces were recovered. It is considered that the remaining molded refractories flowed out to the slag pan together with the slag in the early stage of the slag discharge. The refractory recovered on the "plow" was placed in a box containing graphite in graphite powder prepared in advance in order to prevent oxidation because it was red hot.

After specifying the molded refractory based on the angle and dimensions, in order to determine the amount of wear in the pressing direction and the direction perpendicular thereto, first, the molded refractory was cut in half in parallel with the a-b plane to the c side. did. Each of the molded refractories cut in half was cut at a right angle to the a-c plane and at a right angle to the bc plane at the center of the sides a and b. Thereby, the remaining dimensions of the sides a and b after the collection were measured. The corners of the molded refractory are more severely damaged than the other parts due to three-sided heating and reaction with the slag, so remove this part and remove it from the center in the longitudinal direction and c direction, that is, from the first half cut to the 2 / 6c position. Was determined as the residual size. First, the remaining dimensions are subtracted from the dimensions before charging, and the residence time in the furnace differs depending on the molded refractory. Therefore, the remaining time in the furnace is divided by the residence time in the furnace, and the wear rate obtained by dividing by 2 to obtain the wear rate on one side is further calculated. It is shown in Table 4.

Wear rate = (initial dimension−remaining dimension) / 2
As a result, in the refining process A, which was considered to greatly affect the initial wear in the refining process, the wear hardly progressed in the first and second stages of the refining process, and in the other refining process B, The wear rate is larger than that of the former, and the refining treatment is 0.8 mm / hour. The wear rate in the previous period was 1.4 based on the difference in the amount of wear of the refractory introduced during the treatment.
mm, the wear was extremely large in the previous period.
As for the wear rate in the first half period, it was found that the slag control was not good, the slag was poorly formed, and the wear rate of the molded refractory was increased. By improving this, the overall wear rate could be reduced by half to 0.4 mm / hour. In addition, in the case of the mag-carbon refractory, the surface perpendicular to the pressurized surface is used as the operating surface, and it has been found that the wear rate of this surface is about 20% better than that of the pressurized surface.

Based on this result, in this furnace, the refining temperature is increased in the refining process A having a low wear rate,
In the previous period, the total refining time was reduced by 8% by optimizing slag slag, which caused a large rate of wear.
Thus, the amount of wear of the molded refractory can be reduced, and the life of the furnace can be improved by about 20%. Example 3 A converter having a furnace inner diameter of 6.5 m mainly performs a decarburization treatment of steel. The effect of the end point temperature on the mag-carbon refractories used in this refining furnace and the wear rate by the refractory charging method were determined in order to obtain the difference in refractory materials.

The molded refractory to be charged before the treatment had a rectangular parallelepiped shape shown in FIG. 1, and each side a, b and c is shown in Table 5. The molded refractory used here was 20% by weight of graphite used in the slag line of the furnace, and was composed of sintered magnesia 10%.
There are two types: a refractory of mag-carbon (0% by weight) (refractory A) and a refractory of magnesia-mag-carbon (brick C) of 50% by weight of electrofused magnesia and the remainder of sintered magnesia.

After cutting, leaving a machining allowance in a predetermined shape, the surface of the refractory is processed to a surface roughness JI using a surface grinding machine.
Grinding was performed until the triangle mark で was displayed on the S standard display. The molded refractory was previously heat-treated in a coke breeze to 1000 ° C. to remove volatiles from the binder of the molded refractory, and to prevent collapse of the molded refractory due to expansion of volatile gas due to rapid heating when the refractory was charged. The thickness b of each molded refractory was measured every 5 mm in the length direction using calipers to two decimal places. Each molded refractory was wrapped in a packing box acting cardboard paper having a thickness of 5 mm in order to avoid thermal spall at the initial stage of charging. Prior to the start of the decarburization treatment, the molded refractory was introduced into the furnace through a sub-lance opening in the upper part of the furnace. The test was performed three times at different end point temperatures. The method of collecting molded refractories is as follows:
After the tapping, the furnace was tilted and the slag was gradually discharged into a slag pan, leaving a small amount of slag at the end of the slag discharge and dropping it under the furnace. The slag was moved to a safe position with a bulltozer, and the molded refractory was recovered from the slag.

Since the recovered refractory was red-hot, it was immediately placed in a box containing graphite prepared in advance to prevent oxidation. Then, in order to determine the amount of wear in the pressing direction and the direction perpendicular thereto, the center of the side a is cut parallel to the bc plane, and the length of the side b is changed in the direction of the side c every 5 mm. It was measured. Since it is assumed that the corners of the refractory are more worn out than the other parts due to the three-sided heating and the reaction with the slag, this part (the part 1 / 6c from the end) is removed, and the center part in the side c direction is removed. / 3c was taken as the remaining dimension.

Wear rate = (initial dimension−remaining dimension) / 2
Table 6 shows the results. This shows that the higher the end point temperature is, the more the refractory is worn. Further, the difference in the material appears as the difference in the amount of wear as the temperature increases. The operating surface of the refractory at 1600 ° C. that hardly causes wear was polished with abrasive paper and diamond paste, and photographed at 10 × and 100 ×.
From the micrograph at × 2, the coarse particles remained, but the amount of wear of the refractory matrix was about three times different between refractory A and refractory C, and refractory C was better. Microscopic observations also revealed differences in wear of the refractory matrix that did not appear from the residual dimensions. From these results, it is understood that it is important to keep the end point temperature at least 1640 ° C. from the viewpoint of reducing the amount of wear of the refractory. By minimizing the temperature rise at the end of the refining process, the life of the furnace body is improved by about 30%. I was able to. Example 4 In general, when exposed to a high temperature of 1000 ° C. or more, a metal such as Al added as an antioxidant to a mag carbon refractory reacts with graphite in the refractory and carbonizes to form a carbide. I do. If this is left in the air after cooling,
This carbide reacts with moisture in the air, causing digestion and swelling.

In Example 3 described above, all the molded refractories after heat treatment were impermeable bags to prevent digestion and expansion of the heat-treated magcarbon refractories during the storage period before the loading test. Was sealed in a vacuum.

Since these operations are complicated, Example 3 was carried out in order to confirm the difference in collapse of the molded refractory due to expansion of volatile gas due to rapid heating of the molded refractory with and without heat treatment.
Under the same conditions as described above, a charging test was conducted during the decarburization treatment at an end point temperature of 1600 ° C., and examined.

The molded refractory is 20% by weight of graphite,
Magnesium refractory (brick A) containing 100% by weight of sintered magnesia was used. The molded refractory to be charged before the treatment is shown in FIG.
The sides a, b, and c are shown in Table 7 below. After cutting to a predetermined shape while leaving a processing allowance, the surface was ground using a surface grinding machine until the surface roughness became a triangle symbol で in JIS standard display. Four of the molded refractories were previously heat-treated in a coke breather to 1000 ° C. to remove volatile components contained in the binder. The entire surface of the molded refractory was wrapped with a cardboard paper for preparing a packing box having a thickness of 5 mm in order to avoid a thermal spall at the initial stage of charging.

A total of eight refractories, including unheated and heat-treated molded refractories, were charged into the furnace from the sublance opening at the top of the furnace at the start of the decarburization treatment. After blowing, after tapping, the furnace was tilted and all the slag was discharged to the slag pan.After transporting the slag to the slag yard, the slag in the slag pan was drained to a small amount, and the remaining slag was relocated. The slag was discharged and the molded refractory was recovered from the slag. The recovered refractory was immediately put into a box containing graphite in graphite powder prepared in advance to prevent oxidation.

Therefore, in order to determine the amount of wear in the pressing direction and the direction perpendicular thereto, the center of the side a was cut parallel to the bc plane. Observing the cross-section of the molded refractory, three of the four untreated heat-treated molded refractories have cracks but have not yet collapsed, and the side b can be measured in the direction of side c. there were. However, as shown in Table 8, it was found that the residual dimensions were larger than the dimensions of the molded refractory before charging, which corresponded to residual linear expansion due to heating of the molded refractory. Therefore, when a refractory that has not been heat-treated is added, a large number of molded refractories may be collapsed, and the residual linear expansion and shrinkage are measured in advance. It was confirmed that the measurement of the amount of wear caused by charging was possible. Comparative Example 3 In Example 4, when the molded refractory was recovered, after blowing was completed and the hot water was discharged, the furnace was tilted, all the slag was discharged to a slag pan, the slag was transported to a slag yard, and the slag of the slag pan was recovered. Waste was removed to a small amount, the remaining slag was relocated, and the waste was tried.However, the moving of the railroad car did not work well, and it took too much time until the waste was removed. Solidified with the molded refractory in the slag pan. Recovery was attempted using a breaker, but the slag adhered to the molded refractory and could not be removed as it was. Therefore, the recovery probability in this recovery method often takes a long time from the discharge from the converter to the recovery, and is not necessarily higher than the refractory recovery under the furnace. Example 5 A molten metal holding container having a furnace inner diameter of 3.5 m is used to transport from a smelting furnace to a continuous casting facility, and is also used as a holding container when processing with an arc-type heating device as refining outside the furnace.
The heat treatment in this arc type heating device determines the life of the refractory of the holding container, and the wear rate under this condition was determined by charging the refractory, and the material was examined.

The molded refractory thus introduced has a rectangular parallelepiped shape as shown in FIG. 1 and has the length of each side a, b, c (where a <b <c) as shown in Table 9, and each molded refractory. The lengths of the sides a and b of the object and the precastable were fixed, and the length of the maximum side c was changed.

In the case of a mag-carbon refractory, the pressing direction at the time of molding was specified so as to be on the bc plane, and the pressing direction was specified so that the difference in wear was clear. The molded refractory used in the test was a mag-carbon refractory (13% by weight, sintered magnesia), an alumina-spinel castable, and an alumina castable, which were precast in the form shown in Table 9 and then blocked. Of these, Mag Carbon refractories are
The surface was ground using a surface grinding machine until the surface roughness became a triangle symbol で in JIS standard display. Mag carbon refractories are heat treated in advance in a coke breeze to 1000 ° C,
Volatile components from the binder in the refractory were removed to prevent collapse of the molded refractory due to expansion of volatile gas due to rapid heat when the refractory was charged. In addition, the precast block has a heating curve up to 1100 ° C in consideration of removal of free water and crystallization water,
It was heated in a box-type electric furnace.

After the treatment, the thicknesses a and b of each molded refractory were measured to the second decimal place at every 5 mm in the length direction using calipers. The entire surface was wrapped with a cardboard paper for preparing a packing box having a thickness of 5 mm in order to avoid refractories and pre-castables from the heat spall in the initial stage of charging. The refractory and the like were charged from the front of the furnace before the treatment with the arc heating device was started. In the recovery method after the treatment, the holding container was inclined, and the formed refractory was scraped off together with the slag by the slag dragger.

The recovered mag-carbon refractories were immediately put into a box containing graphite in graphite powder prepared in advance to prevent oxidation. The castables were allowed to cool in an iron box lined with heat insulating material to prevent spall during cooling. Refractory after cooling to room temperature, precast block, measure the length in the side c direction, refractory,
After specifying the block, the refractory was cut in half on the side a in parallel with the bc plane, and the dimension of the side b after recovery was measured. The corners of the molded refractory are more severely damaged than other parts due to three-sided heating and reaction with the slag, so remove this part, and remove it in the longitudinal direction, side c
The average remaining thickness of ／ of the side c was determined with the center in the direction as the center. Table 10 shows the wear rate obtained by dividing this by the residence time in the container. As a result, the amount of wear of the mag-carbon refractories was overwhelmingly smaller than that of the castable block, and the mag-carbon refractories were specified as the material of the slag line of the holding container, and the detailed examination of the material was started. Example 6 The minimum distance of the slag line portion of the tundish for continuous casting is 1.5 m. The tundish is a so-called hot tundish in which the slag in the tundish is discharged hot, and the tundish is used without being cooled to room temperature without repair. In order to discharge all the slag from the tundish, a slag modifier for lowering the viscosity of the slag is used, and the slag reduced in viscosity by this modifier has an extremely high erosion ability. Therefore, conventional slag line materials (high alumina refractories, 8
5% by weight Al ₂ O ₃ ), magnesia refractory (95% by weight)
(MgO) and mag-carbon refractory (20% by weight C) were examined for differences due to the modified slag.

The shape of the refractory is shown in FIG. 1 and the size of each molded refractory is shown in Table 11. Magcarbon refractories are heat treated in advance at 1100 ° C in a reducing atmosphere,
The oxide refractory was heat-treated at 1100 ° C. in the air atmosphere. The temperature inside the tundish is 1500 ° C, which is lower than the temperature of the smelting furnace, and the thermal shock given to the refractory is small.
In addition, since the slag in the tundish is less stirred than in the refining furnace, the entire refractory is not wrapped with the cardboard paper at the time of loading described in Examples 1 to 6, and the cardboard is carbonized as it is and the surface of the refractory is changed. In order to avoid such a phenomenon, the material was put into a tundish as it was, and the melting speed was examined. To collect refractories, insert a steel plow when tilting the tundish,
Only Mag Carbon refractories are cooled in graphite,
Other refractories were allowed to cool on the iron plate.

The ratio of the erosion rate is high alumina refractory,
Shear refractory, Mag carbon refractory at a ratio of 5: 2: 1
there were. Furthermore, the thickness of the slag infiltration layer is 10: 4: 1 and acid
The infiltration of the refractory material is remarkable. From this, slag
Mag carbon refractory is superior as a line material
I understood. Example 7 In Example 6, there was a possibility that magcas could be carburized into molten steel.
Of the refractory properties of molten carbon steel to molten steel and its durability.
Was. In order to control the specific gravity of refractories,MoldingDuring refractory manufacturing
ToTungsten carbide (W
C)SphereMoldingEmbedded in refractory,The specific gravity of molded refractories
Adjusting to various things, these moldingsRefractory is deposited in molten steel
At the time of waste disposal, it was collected using a plow. Mag carbon resistant
The material of the fire and the heat treatment, recovery, and cooling methods were the same as in Example 6.
Is the same. Mag carbon refractory is graphite on the surface
Of molten steel into refractory in the presence of
However, the molten steel stops at a position 3 mm from the refractory operating surface.
Was. No macro wear of the refractory was observed.Comparative Example 4 Several types of components are placed in a high-frequency induction furnace that can melt 500 kg.
An experiment was conducted in which the refractory was charged and the amount of wear was measured.
This was designated as Comparative Example 4. The inner diameter of the induction furnace is 40
0 mm. In this experimental facility, an induction furnace,
Under the condition where de-rinsing slag coexists, the slurry
Al which is a gline material_Two O_Three -SiC-C refractories
The durability was studied. 7% by weight of SiC, carbon amount
Was fixed at 11% by weight, and to examine the effect of aggregate,
Refractory G uses alumina as an aggregate, and refractory H uses aluminum
Spinel aggregate was used in place of the na.

The shape of the refractory is shown in FIG. 1, the length of each side is as shown in Table 12, the refractory is specified, and the refractory is previously heat-treated at 1200 ° C. in a coke breeze. It was measured. Refractory shape is 25 × 35 ×
Since it was as small as (45 to 60) mm, cracking due to spall did not occur at the time of charging, so that it was directly charged into the induction furnace without providing a heat insulating layer. The refractory was kept in the induction furnace for 2 hours. The hot metal temperature at this time was 1400 ° C,
A slag of 3.6% by CaO / SiO ₂ and 4% by weight as Na ₂ O was used. The refractory was scissored from the upper part of the induction furnace and cooled in graphite.

The average amount of wear of the refractories G and H was 1.5 mm / hour and 1.0 mm / hour, respectively.
Time was reached, and the result was obtained that the spinel aggregate containing magnesia showed better corrosion resistance to Na ₂ O in the slag than the alumina aggregate. Example 9 It has been found that the thermal spray repair method using oxygen-propane flame has considerably higher corrosion resistance than the conventional hot repair method using spraying, from observation of the remaining amount in an actual furnace. But,
The wear rate of each sprayed body is not easy to measure as in the case of refractories. In the case of hot spray repair, slag adheres to the surface of the refractory of the furnace, and the thermal spray material adheres to the refractory via the slag. Therefore, first, the molded refractory is put into the furnace to deposit slag on the surface of the refractory, and after collecting, the sprayed material is sprayed on the surface of the refractory and then put back into the furnace to reduce the wear rate of the sprayed layer. It was measured.

In Example 2, at the end of the refining treatment A in which the wear of the magcarbon refractory was extremely small, a total of eight magcarbon refractories (refractory C) having the shapes shown in Table 13 were charged. The heat treatment, the charging method, the recovery method, the cooling method, and the like of the refractory other than the shape of the refractory are all the same as those in the second embodiment. Six out of eight molded refractories were recovered.
The recovered refractory to which the slag has adhered is placed in a gas furnace at 1300 m.
C. and sprayed two types of thermal spraying materials of alumina-chromium type and magnesia-slag type on the surface of the slag to which the refractory was adhered. After measuring the dimensions of each side a, b, and c, it was wrapped in cardboard paper for packing, and then put into the furnace again at the beginning of the refining process B having a high wear rate. The method of charging and collecting was the same as in Example 2. Four out of six molded refractories could be recovered.

From the wear rate of the sprayed layer determined from the cross section in the same manner as in Example 2, the magnesia-slag system has a larger wear rate than the alumina-chromium spray material, and the difference in corrosion resistance is due to the magnesia-slag system spray. It is assumed that it depends on the amount of slag in the material, and thereafter, alumina chromium sprayed material was used for hot repair performed after refining treatment A.

[0051]

[Table 1]

[0052]

[Table 2]

[0053]

[Table 3]

[0054]

[Table 4]

[0055]

[Table 5]

[0056]

[Table 6]

[0057]

[Table 7]

[0058]

[Table 8]

[0059]

[Table 9]

[0060]

[Table 10]

[0061]

[Table 11]

[0062]

[Table 12]

[0063]

[Table 13]

[0064]

According to the present invention, it is possible to easily measure the amount of wear of a refractory due to slag and / or molten metal in a molten metal refining furnace and a molten metal holding vessel using a refractory while the molten metal stays. , precise <br/> operation of the furnace and holding vessel can be performed selection of operational and refractories, actual furnace
The rate of wear of refractories in the real world
Can be. In particular, binder contained in molded refractories
Remove volatile matter and water from the refractory
This allows the molded refractory to be partially
Loss or complete destruction is prevented and the original measurement
Highly accurate measurement of the amount of refractory wear due to erosion
And the molded refractory can be reliably removed from the melt.
Can be recovered.

[Brief description of the drawings]

FIG. 1 is a perspective view schematically showing a molded refractory.

FIG. 2 is a perspective view schematically showing another molded refractory.

FIG. 3 is a perspective view schematically showing another molded refractory.

Continuation of the front page (72) Inventor Hisaki Kato 1-2-2 Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan Co., Ltd. (56) References JP-A-62-259060 (JP, A)

Claims (5)

(57) [Claims] (1)Volatilization of binder contained in molded refractories
Minute, free water, or a step of removing water of crystallization,  Measuring the initial dimensions of the molded refractory;In metal manufacturing process Molten metal smelting furnace or molten gold
The molded refractory is cast into the molten material contained in the metal holding container.
And recovering the injected molded refractory from the melt.
Measuring the dimensions of the collected refractory; and determining the loss of the molded refractory based on the measured dimensions and the initial dimensions.
Calculating a wear amount.
How to measure material wear. Further, the surface of the molded refractory is melted before being charged.
2. The method according to claim 1, further comprising the step of covering with a radiation material.
The method for measuring the amount of refractory wear described above. 3. The method according to claim 1, further comprising the step of wrapping the molded refractory with a heat insulating member before charging. 4. Furthermore, the first to third aspects refractory wear amount measuring method, wherein further comprising the step of cooling the molded refractory recovered from the melt-reducing or in an inert atmosphere. Further, the specific gravity of the molded refractory is adjusted before charging.
Of the specific gravity adjusting member for adjustment in the molded refractory
In the melt of the molded refractory after being charged
5. The depth position is controlled.
The method for measuring the amount of refractory wear described above.