JPH0749343A - Method of measuring amount of wear and tear of refractory material - Google Patents

Abstract

PURPOSE:To easily measure an amount of wear and tear of a molded refractory material by a method wherein the molded refractory material is thrown in a molten material housed in a molten metal smelting furnace or a holding vessel and after withdrawing it, dimension before throwing and after withdrawing are compared with each other. CONSTITUTION:A molded refractory material like a mug carbon refractory material is cut off to a prescribed shape and the surfaces are treated with an abrasive process. After that, a length of each side is measured up to two digits below the decimal point by 5mm interval. After molten iron is housed in a converter, in order to avoid heat spalling in an initial period of time after throwing, the molded refractory material, which is wrapped as a whole by about 5mm sized corrugated board for forming a packing carton, is thrown in the converter from a sublance opening of an entrance section thereof. After prescribed blowing is applied in the furnace, it is inclined to discharge the slag and to withdraw the refractory material. And the refractory material is cooled in the graphite powder to be measured again so that an amount of wear and tear of the refractory material is obtained from the difference between initial dimension before throwing and the measured dimension. In addition, the speed of wear and tear is calculated from the amount of wear and tear, slag and the residence time of the molten iron. At that time, the amount of wear and tear is measured by the accuracy of 0.01mm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to measurement of a wear rate of a refractory due to slag and / or molten metal when the molten metal is retained in a molten metal refining furnace or a molten metal holding container.

[0002]

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

As a method of measuring the wear rate of bricks, a laboratory study using the following simulated test is used instead of the actual furnace. (3) Slag erosion test As a method of knowing the wear rate of bricks and refractories, there are rotary slag erosion test furnaces, bricks by high-frequency induction furnace, and refractory partitioning tests. The rotary slag erosion test furnace is divided into test drums or refractory linings in a cylindrical drum, and the slag is melted by heating with a burner or an electrode in this drum to react the slag with bricks or refractories. Examine the degree of erosion by. In addition, in the test using a high-frequency induction furnace, the lining of the induction furnace is divided with test bricks or refractories to melt the metal and slag,
Examine the refractory wear of the molten metal and bricks at the 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 only the brick cannot be accurately measured. Further, according to the AGA device, an error is likely to occur in the setting of the reference point, so that it is impossible to measure in millimeters.

Further, in the furnace dismantling investigation method, the average amount of wear and the average wear rate through the furnace cost can be obtained, but it is not possible to know the wear rate under the steelmaking conditions such as the temperature, the slag composition and the blowing condition for each treatment. Can not.

Further, in the simulated test method, the treatment atmosphere, slag component, slag amount, molten iron amount, stirring condition, etc. are limited to a certain range, so that the damage environment in the actual furnace or the molten metal holding container can be accurately simulated. It cannot be said that there is. Therefore, it is not possible to immediately determine the wear rate in the actual furnace from these laboratory studies.

The present invention has been made in view of the above circumstances, and wear due to differences between charging in an actual furnace and various refining conditions, that is, temperature, temperature change, slag component, component change, stirring strength, etc. It is an object of the present invention to provide a method for measuring the amount of wear of a refractory material, which can appropriately grasp changes in the amount of refractory materials.

[0008]

DISCLOSURE OF THE INVENTION The inventors of the present invention have made various investigations on the obstacles for putting a brick into an actual furnace or a molten metal holding container to measure the wear rate after recovery. As a result, the following findings (a) to (d) were obtained. (B) The bricks put into the furnace are cracked by the heat spall generated when the bricks and refractory are put into the furnace, and it is impossible to maintain the predetermined brick shape. (B) The environment in which the bricks and refractory that are thrown in are exposed is more severe than the bricks lined in the furnace body, and there is a concern that they will be completely worn and disappear. (C) The bricks and refractories put in are 1200 ° C to 1600 ° C.
It is generally not easy and dangerous work to get into the slag and recover the brick and refractory from the viewpoint of the temperature being extremely high. (D) It is not easy to find small bricks in a large amount of molten slag.

As a result of intensive studies based on these findings, the inventors 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 refractory materials having a shape to be put into the furnace or the holding container are collectively referred to as “molded refractory materials”.

The method for measuring the amount of refractory wear according to the present invention is
A step of measuring the initial dimensions of the molded refractory, a step of charging the molded refractory into the molten metal contained in a molten metal refining furnace or a molten metal holding container, and the molded refractory charged from the melt The method is characterized by including a step of collecting, a step of measuring the size of the collected molded refractory, and a step of calculating the amount of wear of the molded refractory based on the measured size and the initial size. [Molding of refractory material] The shape of the molded refractory material is determined in consideration of spall resistance, and is required to be a shape that does not impair the refining ability in the refining furnace. In order to improve the accuracy of measuring the amount of wear, the surface of the molded refractory must be smooth. Further, in a molded refractory having a characteristic structure, it is necessary to specify the direction in which the pressing force is applied during molding. Further, it is possible to change the apparent specific gravity of the formed refractory by determining which of the amount of wear of the refractory at the slag, the molten metal, or the interface between the slag and the molten metal is obtained. [Size of Molded Refractory] The volume of the molded refractory must satisfy the following inequality (1).

[0011] ^{1cm 3 <V <90000cm 3 ...} (1) However, V represents the volume of the molded refractory [cm ^3]. If the volume V exceeds 90,000 cm ³ , the thermal stress generated inside the molded refractory becomes excessive, and spalling causes cracks in the molded refractory. By the way, if the spall resistance of the molded refractory is improved and the volume V is larger than 90,000 cm ³ , the heat capacity of the refractory becomes too large, and heat is taken from the surrounding slag and the molten metal immediately after charging to the refractory surface. Since a solidified slag or a metal film is formed, if the solidified slag or the like does not immediately dissolve, the amount of refractory wear 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 material needs to satisfy the following inequality (2) in order to maintain the environment in which the normal lining refractory material 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 holding container.

Here, the maximum outer diameter L of the molding refractory to be charged
Is larger than (1/3) D, refining is hindered in the case of a refining furnace, or the environment is different from the environment in which the refractory lining is placed. On the other hand, when the maximum outer diameter L of the molded refractory is smaller than (1/400) D, it becomes difficult to recover the molded refractory. [Surface grinding] By grinding the parallel surface facing at least one surface, it is possible to easily measure the amount of wear of the molded refractory. Further, in order to investigate the microscopic wear rate of the surface of the formed refractory, it is possible to grind at least one surface and observe the microscope to determine the wear rate of the aggregate and matrix of the refractory structure. [Method of identifying molded refractory and directionality during manufacturing] The following methods (1) to (4) are effective for identifying molded refractory by material or pretreatment of refractory. . (1) The molded refractory can be specified for each material or each pretreatment by changing the length of the molded refractory in a specific direction to a certain interval. For example, the maximum length is 400m
380 mm, 390 to identify m refractory
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 material
The molded refractory can be specified in the same manner by obliquely changing the angle and cutting. (3) In mag-carbon refractory, generally, the wear rate of the refractory surface tends to differ depending on the orientation direction of the scaly graphite in the refractory. The orientation direction of this graphite depends on the forming (pressurizing) direction when manufacturing the refractory, and the following method can be considered to identify the surface of the magcarbon refractory having such a graphite orientation.

Each side (a, b,
The pressure surface at the time of molding is specified by defining c) as in the following expression (3) and specifying each surface. a <b <c (3) By changing the lengths of these sides, the material of the molded refractory and the history of each heat treatment can be specified even after the collection. (4) Furthermore, in addition to the above (3), the molding surface of the molded refractory is similarly specified by cutting the longitudinal edges (edges) of the rectangular parallelepiped molded refractory at oblique angles. be able to. [Change of Density of Molded Refractory] By changing the apparent density of the molded refractory, the molded refractory can be positioned at any level in the depth direction of the slag layer. For example, if the apparent specific gravity is reduced by providing a cavity inside the molded refractory and the molded refractory is always positioned on the upper surface of the slag layer, the slag splashes on the slag surface, wear due to rocking, and the furnace atmosphere. It is possible to investigate the wear caused by.
Also, by embedding a dense substance 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 fire resistance The reaction between an object and a molten metal can be investigated. Furthermore, by adjusting the apparent specific gravity of the molded refractory material between the slag and the molten metal, the wear rate in the coexistence of the slag and the molten metal can be investigated. [Measurement of dimensions of molded refractory] Normal calipers and the like are used for measurement of dimensions of molded refractory. However, for refractory materials with a slow wear rate, a device capable of measuring at least two digits after the decimal point is required. When heat-treating a refractory, it is necessary to measure the refractory size again after the heat treatment. [Heat Treatment of Molded Refractory] In the case of an unfired refractory, for example, a magcarbon refractory, a heat treatment is performed in a temperature range of about 300 ° C. when manufacturing the refractory. When such a molded refractory material is charged into the furnace, the binder agent such as phenol resin is gasified, and the refractory material in the furnace may be adversely affected. In particular, caution is required 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, if there is such a risk, it is necessary to heat-treat the molded refractory material 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 breeze or in a non-oxidizing gas atmosphere. In addition, when the binder agent or the like forms a hydrate like alumina cement, it is possible to remove free water and crystallization water in advance by heat treatment, and it is possible to prevent explosion of the molded refractory.

When the heat treatment is performed, there is a high possibility that the dimensions of the molded refractory will change, so it is necessary to measure the dimensions after the heat treatment. In addition, if a compound or the like is newly formed in the molded refractory due to the heat treatment and this may react with moisture in the atmosphere, it is necessary to block the molded refractory from the surrounding atmosphere. is there. Particularly in the case of magcarbon refractory, carbonization of additives in the refractory during heat treatment causes reaction with moisture in the air at room temperature to cause digestive 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 in a dry atmosphere until use.

[0016]

[Action]

[Timing of charging into the furnace] In the case of a refining furnace, the wear rate of the refractory can be obtained in any period until recovery by charging the molded refractory into the furnace before and during refining at any time. be able to. [Measures for avoiding heat spalling] A molded refractory is wrapped in a member that exhibits heat insulation properties such as cardboard for a certain period of time, and when it is present, it is used as heat insulation for a certain time Prevents rapid heating of molded refractories in the initial stage. This is because when a 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. In order to prevent such heat spalling, a heat-insulating layer is required on the surface of the molded refractory, and if it is removed from the refractory surface after achieving the purpose of preventing cracking at the time of injection, it will The amount of material loss can be measured without disintegration due to thermal spalling when the refractory is charged. [Recovery of molded refractory material] Although it is extremely difficult to recover the molded refractory material, the recovery efficiency is improved by the most suitable method among the following methods in view of the size of the furnace and the specific gravity of the refractory material. (A) 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 recovered with a scoop-shaped jig. If the apparent specific gravity of the molded refractory is larger than the specific gravity of the slag and smaller than the specific gravity of the molten metal, gently slag the slag in small amounts and collect the final molded refractory just before it is discharged. can do. However, when the workers use human power to collect, the furnace and holding container must be small. In this case, it is desirable to use a remote-control dedicated recovery machine that has high safety and a high recovery rate, and that can also recover from a large furnace and a molten metal holding container. (B) Discharge with slag and collect in slag yard If the specific gravity of the refractory is smaller than that of the molten metal, after discharging the molten metal, the molded refractory is discharged together with the slag into the slag pot (slag pan) to remove slag. Wastes are collected from the slag pot at the yard (slag treatment plant) and collected. At this time, when the slag is discharged from the slag pot to the slag yard, the slag is discharged through a steel net (plow) to improve the refractory recovery efficiency. (C) When slag is discharged, it is recovered by the refractory collection receiver under the furnace. If the apparent specific gravity of the formed refractory is smaller than the specific gravity of the molten metal, after discharging the molten metal, the slag from the furnace and the molten metal holding container is removed. When discharged, the molded refractory is recovered by discharging it through a steel net (plow). (D) A small amount of slag is left and recovered under the furnace together with the refractory having a high specific gravity. If the apparent specific gravity of the molded refractory is between the slag specific gravity and the molten metal specific gravity, after the molten metal is discharged from the tapping port. , The remaining slag is gently discharged little by little, and the molded refractory finally discharged is discharged under the furnace together with the remaining slag, and the molded refractory is recovered from it. Alternatively, in the case of the molten metal holding container, it may be discharged to another position and the molded refractory material may be recovered from it. (E) Collect a small amount of slag and collect it under the furnace together with a refractory with a heavy specific gravity. If the apparent specific gravity of the molded refractory is higher than the specific gravity of the molten metal, gently discharge the molten metal after discharging the slag as much as possible. The last remaining molded refractory is discharged together with the remaining slag under the furnace or in the case of a molten metal holding container to another position, and the molded refractory is recovered from it. [Cooling of collected refractory material] In the case of carbon-containing refractory material (such as mag carbon refractory material), cooling the molded refractory material in graphite can prevent the carbon in the refractory material from being consumed by oxidation. In this case, it is important to insert the molded refractory into graphite as soon as possible after recovery. In the method of preventing oxidation, a carbon source other than graphite may be used in order to prevent oxidation of the contained carbon, and since air is shut off, cooling under vacuum, reduced pressure, or in an inert atmosphere is also effective. Is recognized.

On the other hand, even in oxide-based refractory materials, refractory materials having poor spall resistance require gradual cooling. By cooling in graphite powder or magnesia powder, or in a container lined with a heat insulating material. It is possible to prevent cracking of refractory due to cooling. In this case, it is important to put the molded refractory into powder or an insulating box as soon as possible after collection. [Measurement of Amount of Wear] The collected refractory material is cut, and the dimensions of the cut surface are measured. The amount of wear of the refractory is calculated from the difference between the initial size before charging and the measured size, and the rate of wear is calculated from the amount of the 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.

For refractories having a small amount of wear, the wear amount of the refractory aggregate and the matrix can be known by investigating the refractory working surface by microscopic observation. In addition,
By microscope SEM observation of the refractory working 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 in which a refractory is added.

(A) Wear rate for each furnace treatment (for each charge) (b) Effect of smelting and refining conditions (temperature, slag component, basicity, time) on wear rate (c) During furnace treatment Change of wear rate (for example, change the timing of refractory input in the early, middle, and late stages of processing to understand the wear state at each time) (d) Effect on wear rate of refractory material (e) Wear rate of aggregate and matrix in refractory (f) Difference in wear rate depending on molding direction of refractory

[0020]

EXAMPLES Various examples of the present invention will be described below with reference to the accompanying drawings with reference to the accompanying drawings. Example 1 In order to determine the wear of refractory during blowing of a refining furnace with an inner diameter of 1.6 m, 6 kinds of magcarbon refractory, one each, were charged before the start of refining and recovered after blowing. I looked it up. As shown in FIG. 1, the length of each side of the cast 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, each molded refractory side a,
The lengths of b were fixed to 90 mm and 110 mm, respectively, so that the pressing surface at the time of working the magcarbon refractory material was the 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. The other planes are a.
They are referred to as -b plane and ac plane. ) And, in 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 a range of 0 mm.

The six types of molded refractories, which were molded in advance by an oil press as shown in Table 1 depending on the amount of graphite and the type of aggregate, were cut into a predetermined shape leaving a machining allowance. In order to make the surface of the refractory parallel and the surface of the refractory smooth, a JIS
It is processed to the surface roughness triangular symbol ▽▽ by the standard display. The final thickness of each refractory after processing, a, b, and c is below the decimal point 2
Up to the digit, the length was measured every 5 mm using a caliper.

Each molded refractory was wrapped all over with a cardboard paper for making a 5 mm thick packaging box in order to avoid thermal spalls in the initial stage. Molded refractories, after containing molten iron in the converter,
It was charged into the furnace through the sublance opening of the furnace entrance. After the charging, predetermined blowing was performed. Fifty-seven minutes later, upon completion of blowing, the furnace was tilted and the slag was gradually discharged, and at the end of the slag discharge, the molded refractories were manually collected one by one from the front of the furnace. The recovered refractory was glowing red and was immediately placed in graphite powder and cooled to prevent oxidation. Here, all 6 molded refractories were successfully recovered.

Since the slag is attached to the surface of the molded refractory that has cooled to room temperature, the remaining thickness cannot be measured immediately. Therefore, after measuring the length in the direction of side c and ranking the lengths of the eight molded refractories to identify the molded refractory, the molded refractory is cut at the center of the refractory parallel to the b-c plane. The molded refractory is normally used in accordance with ab surface and ac surface.
The wear with the surface could be obtained.

As a result of the observation of the cut surface, the recovered refractory did not show cracks, flakes, or cracks due to the heat spall. The dimensions of the side b and the side c after collection were measured every 5 mm. The corners of the refractory wear more markedly than other parts due to heating on the three sides and reaction with the 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-cut part where the degree of wear is stable, the remaining dimension (the thickness in the side b direction) of the part of the length c of the side c with the center of the side c as the center ) Was made into the typical value of the refractory material. This residual size was subtracted from the size before the refractory was added to obtain the amount of wear, and the wear rate was divided by the residence time in the furnace to obtain the wear rate. This is shown in Table 2.

As a result, in the influence of the refractory material,
We were able to clarify the effects of the type of aggregate and the content of graphite. Based on this result, it is possible to improve the life of the furnace by improving the refractory material in this furnace with an appropriate graphite composition,
It was improved by selecting the magnesia raw material. Comparative Example 1 Under the same conditions as in Example 1, molded refractory B and molded refractory C having a length of 560 mm and 600 mm respectively wrapped with cardboard paper, and a length of 580 m not wrapped with cardboard paper
Two pieces of molded refractory B and molded refractory C having a size of m and 620 mm were respectively charged, but immediately after the charging, the two molded refractories which were not wrapped in the corrugated cardboard were cracked at a half position in the long side direction. The remaining two molded refractories have a minimum radius of 1.6 m, so the refractory is always located in the center of the furnace, and the oxygen jet from the lance located in the center of the furnace is the direct refractory. In addition to inhibiting the refining reaction, a considerable decarburized layer of the recovered magcarbon refractory was observed. It was judged that such a situation was unsuitable for the evaluation of refractories used for furnace walls. Comparative Example 2 A molded refractory having a rectangular parallelepiped shape as shown in FIG. 1 was used. The dimensions of the molded refractory were set to 200 × 400 × 1200 mm. This was heat-treated at 1100 ° C. in a coke breeze. After the heat treatment, the dimensions were measured, and the pieces were wrapped in cardboard paper for packing, and then the amount of wear due to the addition of the refractory was measured under the same conditions as in Example 1. After the charging, the molded refractory gradually began to adhere to the surrounding slag in the slag, grew and developed into large lumps, and became suspended on the slag. As a result, the refining operations fell into a state where they could not be satisfied. It is presumed that this molded refractory had 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 treatments. In order to improve the refining conditions by investigating the influence of refining treatment on the mag carbon refractory used in this refining furnace on refractories, and improving the refining conditions during the early, middle, and late wear during the treatment The wear rate was determined by changing the timing of adding medium refractory.

As the molded refractory, three types of each of the shapes shown in FIGS. 1 to 3 were prepared up to the first to third series. The first series of molded refractory is to be put in at the initial stage of the treatment, has the rectangular parallelepiped shown in FIG. 1, and has the length of each side a, b, c (where a <b <c) shown in Table 3. The lengths of the sides a and b of the molded refractories are fixed and the length of the side c is changed. The molded refractories of the second and third series are introduced at the middle and final stages of the treatment, respectively, and the end face of the maximum side c is changed in angle as shown in FIGS. 2 and 3. did. This makes it possible to specify the injection time of the molded refractory and the molded refractory collected after refining.

The magcarbon refractory has a side a and a side b so that the pressing direction at the time of molding is the ac plane and the pressing direction is specified so that the difference in wear becomes clear. It is fixed to the size of (a <b). The molded refractory used here was a magcarbon refractory (brick C) containing 20% by weight of graphite used in the slag line of the furnace, 50% by weight of electrofused magnesia, and 50% by weight of sintered magnesia. After cutting into a predetermined shape while leaving a machining allowance, the surface of the refractory was ground using a surface grinding machine until the surface roughness became a triangle symbol ▽▽ on the JIS standard display. Molded refractory is 1000 ℃ in advance
Heat treatment was performed in a coke breeze to remove the volatile components from the binder of the refractory and prevent the refractory from collapsing due to the expansion of volatile gas due to the rapid heat when the refractory was charged. After treatment,
The thickness b of each molded refractory was measured up to two digits after the decimal point using a caliper every 5 mm in the length direction.

5 mm to avoid thermal spall at the initial stage of charging
The entire surface of each refractory was wrapped in cardboard for work in a thick packaging box. Molded refractory is charged before the refining of each refining process,
During the middle and end of the period, it was charged into the furnace through the sublance opening in the upper part of the furnace. The method of collecting the shaped refractory is as follows: after blowing and after tapping, the furnace is tilted and the slag is gradually discharged to the slag pan, and at the end of the slag slag discharge, the "plow" installed under the furnace is charged. The molded refractory was collected. As a result, 6 out of 9 pieces in the refining treatment A and 7 out of 9 pieces in the refining treatment B could be recovered. It is considered that the remaining formed refractories were discharged to the slag pan at the early stage of slag, together with the slag. Since the recovered refractory material on the "plow" was red-hot, it was immediately put into a box containing graphite in graphite powder prepared in advance to prevent oxidation.

After the forming refractory is specified by the angle and the dimension, first, the forming refractory is cut in half in parallel with the ab plane in order to obtain the amount of wear in the pressing direction and the direction perpendicular thereto. did. Each of the half-cut formed refractory materials was cut at a right angle to the a-c plane and a right angle to the b-c plane at the central portions of the sides a and b. Thus, the remaining dimensions of the sides a and b after the collection were measured. The corners of the molded refractory are worn out more than other parts due to heating on three sides and reaction with slag, so remove this part, and remove the part in the longitudinal and c-direction, that is, from the first half-cut position to the 2 / 6c position. The average thickness was defined as the residual dimension. First, subtract the remaining size from the size before loading, and divide the product by the respective residence time in the furnace because the residence time in the furnace varies depending on the molded refractory, and then divide by 2 to obtain the wear rate on one side. It shows in Table 4.

Wear rate = (initial size-remaining size) / 2
As a result, in the refining process A, which was considered to have a large effect on the initial wear of the refining process, the wear hardly progressed in both the first and second stages of the refining process, and in the other refining process B, The wear rate was 0.8 mm / hour, which was larger than that of the former, and the wear rate in the previous period was 1.4 from the difference in the amount of wear of refractory materials thrown in the process.
It was found that the wear was extremely large in the previous period of mm.
Regarding the wear rate in the previous term, it was found that the slag control was poor and slag slag formation was poor, and the wear rate of the molded refractories increased. By improving this, the overall wear rate could be reduced to half, 0.4 mm / hour. It was also found that in the case of the magcarbon refractory, a surface perpendicular to the pressure surface is used as the operating surface, and the wear rate of this surface is about 20% better than the wear rate of the pressure surface.

On the basis of this result, in this furnace, the refining temperature was raised in refining treatment A with a small wear rate,
The total smelting time was reduced to 8
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 an inner diameter of 6.5 m is mainly used for decarburizing steel. In order to obtain the influence of the end temperature on the magcarbon refractory used in this refining furnace and the difference in refractory materials, the wear rate by the refractory charging method was obtained.

The molding refractory to be charged before the treatment has a rectangular parallelepiped shape shown in FIG. 1, and the sides a, b and c are shown in Table 5, respectively. The molded refractory used here was 20% by weight of graphite used for the furnace slag line, and sintered magnesia 10
There are two types of refractory (brick C) of magnesia magcarbon consisting of 0% by weight of magcarbon refractory (refractory A), 50% by weight of electro-melted magnesia, and the rest consisting of sintered magnesia.

After cutting into a predetermined shape while leaving a machining allowance, the surface roughness of the refractory is measured by a surface grinding machine using a surface grinding machine.
Grind until the triangle symbol ▽▽ is displayed on the S standard display. The molded refractory was heat-treated in advance in a coke breeze to 1000 ° C. to remove volatile components from the binder of the molded refractory and prevent collapse of the molded refractory due to expansion of volatile gas due to rapid heat when the refractory was charged. The thickness b of each molded refractory was measured up to two digits after the decimal point using a caliper every 5 mm in the length direction. In order to avoid heat spall at the initial stage of charging, the entire surface of each molded refractory was wrapped with cardboard paper having a thickness of 5 mm. The molded refractory was put into the furnace through the sublance opening in the upper part of the furnace before the decarburization treatment was started. The test was repeated three times with the end temperature changed. The method of collecting the molded refractory is as follows:
After 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 slag, which was dropped under the furnace. The slag was moved to a safe position with a bulltozer, and the molded refractory was recovered from this slag.

Since the recovered refractory was red-hot, it was immediately put into a box containing graphite prepared in advance to prevent oxidation. Then, in order to obtain the amount of wear in the pressurizing direction and the direction perpendicular thereto, the center part of the side a is cut in parallel with the bc plane, and the length of the side b is increased by 5 mm in the side c direction. It was measured. It is assumed that the corners of the refractory will be more worn out than the other parts due to heating on three sides and reaction with slag, so remove this part (part from 1 / 6c from the end) and center it in the direction of side c. / 3c was taken as the residual dimension.

Wear rate = (initial size-remaining size) / 2
/ Residence time in the furnace is shown in Table 6. From this, it can be seen that the higher the end point temperature, the greater the influence on the wear of the refractory. Further, the difference in the material appears as the difference in the amount of wear as the temperature rises. The working surface of the refractory at 1600 ° C, which causes almost no wear, was polished with abrasive paper and diamond paste, and photographed 10 times and 100 times.
From the double-time micrograph, although the coarse-grained portions remained, the amount of wear of the refractory matrix was about 3 times different between refractory A and refractory C, and refractory C was better. Differences in the wear of the refractory matrix that did not appear from the residual dimensions were also revealed by microscopic observation. From these results, it was found that it is important to keep the end point temperature at least 1640 ° C from the viewpoint of reducing the amount of refractory wear, and by suppressing the temperature rise at the end of the refining process as much as possible, the life of the furnace body is improved by about 30%. I was able to do it. Example 4 Generally, when a magcarbon refractory is exposed to a high temperature of 1000 ° C. or higher, a metal such as Al added as an antioxidant in the refractory reacts with graphite in the refractory and carbonizes to form a carbide. To do. If this is left in the atmosphere after cooling,
The moisture in the air reacts with this carbide, causing digestive swelling.

In the above-mentioned Example 3, the heat-treated magcarbon refractory was made of a non-permeable bag in which all of the heat-treated molded refractories were subjected to heat treatment in order to prevent digestive expansion during the storage period until the loading test. It was vacuum sealed in.

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

Molded refractory material is 20% by weight of graphite,
A magcarbon refractory (brick A) containing 100% by weight of sintered magnesia was used. The molding refractory to be added before processing is shown in Fig. 1.
The rectangular parallelepiped shape shown in FIG. 7 and each side a, b, c is shown in Table 7. After cutting with a machining allowance into a predetermined shape, it was ground using a surface grinding machine until the surface roughness became a triangle symbol ▽▽ on the JIS standard display. Four of the molded refractories were heat-treated in advance in a coke breeze to 1000 ° C. to remove volatile components contained in the binder agent. In order to avoid the heat spall at the initial stage of charging, the entire surface of the molded refractory was wrapped with cardboard paper for making a packaging box having a thickness of 5 mm.

A total of eight refractory materials which had not been heat-treated and which had been heat-treated were charged into the furnace through the sublance opening at the top of the furnace at the start of the decarburization treatment. After blowing and hot water, tilt the furnace and discharge all the slag to the slag pan, transport the slag to the slag yard, discharge the slag from the slag pan to a small amount, move the remaining slag to a new location, Molded refractory was collected from the slag and the slag. The recovered refractory material was immediately placed in a box containing graphite in graphite powder prepared in advance in order to prevent oxidation.

Therefore, in order to determine the amount of wear in the pressing direction and in the direction perpendicular thereto, the central portion of the side a was cut in parallel with the bc plane. When observing the cross section of the molded refractory, three of the four molded refractories that have not been subjected to the heat treatment have cracks but have not yet collapsed, and it is possible to measure the side b in the side c direction. there were. However, as shown in Table 8, it was found that the residual dimension was larger than the dimension of the molded refractory before charging, which corresponds to the residual linear expansion due to heating of the molded refractory. Therefore, if a refractory that has not been heat-treated is added, the number of molded refractories that have the possibility of collapsing is large, and the residual linear expansion and contraction are measured in advance so that the refractory does not have to be heat-treated. It was confirmed that it was possible to measure the amount of wear due to the input. Comparative Example 3 In Example 4, when the molded refractory material was recovered, after the completion of blowing and tapping, the furnace was tilted, all the slag was discharged to the slag pan, the slag was transported to the slag yard, and then the slag of the slag pan was slag. The slag that had left a small amount was discarded, and the remaining slag was moved to a new location and tried to be removed. Has solidified with the molding refractory in the slag pan. Attempts were made to recover it using a breaker, but the slag was stuck to the molded refractory and could not be taken out as it was. Therefore, the probability of recovery in this recovery method often takes time from the waste from the converter to the recovery, and is not necessarily higher than that of refractory recovery under the furnace. Example 5 A molten metal holding container having an inner diameter of 3.5 m is used as a container for transporting from a refining furnace to a continuous casting facility and also as a holding container when processing is performed by 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 material in this holding container. The wear rate under this condition was determined by charging the refractory material, and the material was examined.

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

In the case of the magcarbon refractory, the pressing direction at the time of molding was specified so as to be the b-c surface and the difference in wear was clearly defined. The molded refractory used in the test was a magcarbon refractory (13% by weight, sintered magnesia), an alumina-spinel castable, and an alumina castable precast in the shape of Table 9 to form a block. Among them, Mag carbon refractory,
Grinding was performed using a surface grinding machine until the surface roughness became a triangle symbol ▽▽ on the JIS standard display. Mag carbon refractory is heat-treated in advance in coke breeze up to 1000 ℃,
Volatile components from the binder in the refractory were removed, and collapse of the molded refractory due to expansion of volatile gas due to rapid heat when the refractory was charged was prevented. In addition, the precast block has a heating curve that considers the removal of free water and crystal water up to 1100 ° C.
It was heated in a box-type electric furnace.

After the treatment, the thicknesses a and b of each molded refractory were measured up to two digits after the decimal point using a caliper every 5 mm in the length direction. The entire surface was wrapped with cardboard paper for making a 5 mm-thick packing box to avoid refractory and precastable from the heat spall at the initial stage of charging. The refractory and the like were charged from the front of the furnace before the start of treatment with the arc type heating device. As a method of recovery after the treatment, the holding container was tilted, and the molded refractory was scraped off together with the slag by the slag drager.

The recovered magcarbon refractory was immediately put into a box containing graphite in graphite powder prepared in advance in order to prevent oxidation. The castables were allowed to cool in an iron box lined with a heat insulating material to prevent spalls during cooling. For refractory and precast blocks after cooling to room temperature, measure the length in the direction of side c,
After the block was specified, the refractory was half-cut 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 worn than other parts due to heating on the three sides and reaction with the slag.
The average remaining thickness of ⅔ of the side c was determined centering on the central portion in the direction. 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 magcarbon refractory was overwhelmingly smaller than that of the castable block, and the magcarbon refractory was specified as the material of the slag line of the holding container, and detailed examination of the material was carried out. Example 6 The minimum distance of the slag line part of the tundish for continuous casting is 1.5 m. This tundish is a so-called hot tundish, in which the slag in the tundish is discharged hot and the tundish is used without being repaired without being cooled to room temperature. In order to discharge all the slag from the tundish, a slag modifier that lowers the viscosity of the slag is used. The slag whose viscosity is reduced by this modifier has an extremely high erosion ability. Therefore, conventional slag line materials (high alumina refractory, 8
5 wt% Al ₂ O ₃ ), magnesia refractory (95 wt%
The difference due to this modified slag between MgO) and magcarbon refractory (20 wt% C) was examined.

The shape of the refractory material is as shown in FIG. 1, and the size of each molded refractory material is shown in Table 11. The refractory is heat-treated beforehand at 1100 ° C in a reducing atmosphere for the magcarbon refractory,
The oxide refractory was heat-treated at 1100 ° C. in an air atmosphere. The temperature in the tundish is 1500 ° C, which is lower than the temperature of the refining furnace, and the thermal shock given to the refractory is small.
Further, since the slag in the tundish is less agitated than in the refining furnace, the entire surface of the refractory is not wrapped with the cardboard paper at the time of charging described in Examples 1 to 6, but the cardboard is carbonized as it is and the refractory surface is used. It was put into the tundish as it was, and the dissolution rate was investigated. For refractory collection, insert a steel plow when tilting the tundish,
Only mag carbon refractory is cooled in graphite,
The other refractories were left to cool on an iron plate.

The ratio of erosion rates was 5: 2: 1 for the high alumina refractory, the magnesia refractory and the magcarbon refractory. Furthermore, the thickness of the slag infiltration layer is 10: 4: 1, and the infiltration of oxide refractory is outstanding. From this, it was found that mag carbon refractory was superior as the slag line material. Example 7 In Example 6, the reactivity and durability of a magcarbon refractory having a possibility of carburizing molten steel to molten steel were examined. In order to control the specific gravity of refractory, W
C spheres were embedded in a refractory material, the refractory material was submerged in molten steel, and was collected using a plow at the time of slag waste. The material and heat treatment, recovery, and cooling method of the magcarbon refractory material are the same as in Example 6. The infiltration of molten steel into the refractory was observed in the presence of graphite on the surface of the magcarbon refractory, but the molten steel stopped at a position 3 mm from the refractory operating surface. No macroscopic wear of the refractory was observed. Example 8 The inner diameter of the high frequency induction furnace that melts 500 kg is 400 mm.
Is. Under the condition that hot metal and dephosphorized slag coexist in the induction furnace which is the experimental facility, the durability of Al ₂ O ₃ -SiC-C refractory, which is a slag line material for hot metal pretreatment, was examined. 7% by weight of SiC and 11% of carbon
In order to investigate the effect of aggregates by fixing with the weight%, refractory material G
Alumina was used as the aggregate, and refractory H was replaced with alumina by spinel aggregate.

The shape of the refractory is shown in FIG. 1 and the lengths of the sides are shown in Table 12. The refractory is specified. The refractory is heat-treated in advance in a coke breeze at 1200 ° C. It was measured. Refractory shape is 25 × 35 ×
Since it is as small as (45-60) mm, cracks due to spalls at the time of charging do not occur. Therefore, it was charged into the induction furnace as it was without providing a heat insulating layer. The refractory was held in the induction furnace for 2 hours. The hot metal temperature at this time is 1400 ° C,
CaO / SiO ₂ was 3.6, and Na ₂ O was 4 wt% slag. The refractory was scissored from the upper part of the induction furnace and cooled in graphite.

The average amounts of wear of the refractories of refractory G and refractory H are 1.5 mm / hour and 1.0 mm / hour, respectively.
It was time, and it was obtained that the spinel aggregate containing the magnesia content showed better corrosion resistance to Na ₂ O in the slag than the alumina aggregate. Example 9 It is known that the thermal spray repair method using an oxygen-propane flame has considerably higher corrosion resistance than the conventional hot repair method by spraying, from the observation of the residual amount in an actual furnace. But,
The wear rate of individual thermal spray bodies is not as easy to measure as with refractories. In the case of hot spray repair, slag adheres to the refractory surface of the furnace, and the spray material adheres to the refractory through the slag. Therefore, first, in order to adhere slag to the surface of the refractory, insert the molded refractory into the furnace, collect it, spray the sprayed material onto the surface of the refractory, and then insert it again into the furnace to determine the wear rate of the sprayed layer. It was measured.

In Example 2, at the end of the refining process A in which the wear of the magcarbon refractory material was extremely small, a total of eight magcarbon refractory materials (refractory material C) shown in Table 13 were added. The heat treatment of the refractory other than the shape of the refractory, the charging method, the collecting method, the cooling method, and the like are all the same as in the second embodiment. Six out of eight refractories could be recovered.
The collected refractory with the slag adhered in a gas furnace at 1300
It was heated to ℃, and two types of thermal spray materials of alumina-chromium system and magnesia-slag system were sprayed on the surface of the slag on which the refractory was adhered. After measuring the dimensions of the sides a, b, and c, the sides a, b, and c were wrapped and wrapped in a corrugated cardboard paper, and this time, they were charged again into the furnace at the beginning of the refining process B in which the wear rate was high. The charging and collecting methods were the same as in Example 2. The molded refractories that could be recovered were 4 out of 6.

From the wear rate of the sprayed layer obtained from the cross section by the same method as in Example 2, the wear rate of the magnesia-slag system was larger than that of the alumina-chromium sprayed material, and the difference in the corrosion resistance was magnesia-slag system sprayed. It is assumed that this is due to the amount of slag in the material, and thereafter, the alumina-chrome thermal spray material was used for the hot repair performed after the 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]

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to easily measure the amount of wear of the refractory due to the slag and / or the molten metal during the molten metal retention in the molten metal refining furnace and the molten metal holding container using the refractory. It is possible to properly operate and operate the furnace and holding vessel and select refractories.

[Brief description of drawings]

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

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

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

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hisaki Kato 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Steel Pipe Co., Ltd.

Claims (6)

[Claims] 1. A step of measuring an initial dimension of a molded refractory, a step of introducing the molded refractory into a molten material contained in a molten metal refining furnace or a molten metal holding container, and And a step of measuring the size of the recovered molded refractory, and a step of calculating the amount of wear of the molded refractory based on the measured size and the initial size. A method for measuring the amount of refractory wear. 2. The method for measuring the amount of wear of a refractory according to claim 1, further comprising a step of removing volatile components, free water, or crystal water of the binder contained in the molded refractory. 3. The method for measuring the amount of refractory wear according to claim 1, further comprising a step of wrapping the molded refractory with a heat insulating member before charging. 4. The method for measuring the amount of wear of a refractory material according to claim 1, further comprising the step of reducing the molded refractory material recovered from the melt or cooling it in an inert atmosphere. 5. A refractory to be turned on, claim characterized by having the following formula: 1cm ³ <V <90000cm ³ However, V is shows the volume of the refractory [cm ^3], satisfying the volume 2 5. The method for measuring the amount of wear of a refractory according to any one of 1 to 4. 6. The refractory to be charged has the following formula (1/400) D <L <(1/3) D, where L is the maximum outer diameter [cm] of the refractory, and D is a furnace or Indicates the minimum diameter or distance [cm] of the holding container,
The method for measuring the amount of refractory wear according to claim 5, wherein the method has a shape that satisfies the above condition.