Refractory brick processing method

Abstract

To provide a processing method of a refractory brick capable of effectively separating a slag deposited on a surface of a refractory brick while maintaining yield of the refractory brick.SOLUTION: In a processing method of a refractory brick with its surface deposited with a slag, a slag is separated from the refractory brick after allowing the refractory brick to take in water, followed by repeating freeze and thaw multiple times.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for treating refractory bricks. [Background technology]

[0002] In recent years, as part of efforts to improve recycling efficiency in steelmaking, it has been proposed to reuse refractory bricks used in the ironmaking process, such as torpedo bricks and converter bricks.

[0003] Generally, iron and slag adhere to the working surface of a refractory brick (the surface that comes into contact with molten steel and slag) through the pores in the refractory, and mortar may adhere to some other surfaces. When recycling such refractory bricks, if the above-mentioned deposits are mixed in, the durability of the recycled product as a refractory material will be significantly reduced, making it unusable. Therefore, when recycling refractory bricks, it is necessary to remove the above-mentioned deposits, such as slag.

[0004] The current method for recycling refractory bricks involves manually striking each refractory brick to remove the slag adhering to its surface, followed by crushing. This method allows only a portion of the refractory bricks to be reused, and is not entirely satisfactory in terms of work efficiency and running costs. Therefore, in order to efficiently recycle refractory bricks, it is desirable to automate the separation of slag and other adhering materials from the refractory brick surface on a large scale.

[0005] In response to this, for example, Patent Document 1 proposes a water jet type scraping device that performs scraping treatment (treatment for removing material adhering to the surface) by spraying water from a jet nozzle onto a workpiece being transported. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-009390 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the device described in Patent Document 1 mentioned above not only cleans the surface but also scrapes the base material itself due to the high-speed water spraying. In other words, the above device has the problem of reducing yield.

[0008] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for treating refractory bricks that can effectively separate slag adhering to the surfaces of the refractory bricks while ensuring the yield of the refractory bricks. [Means for solving the problem]

[0009] As a result of intensive research conducted by the present inventors to solve the above-mentioned problems, they discovered that by soaking refractory bricks in water and repeatedly freezing and thawing them multiple times, gaps are formed between the refractory bricks and the slag, making it easier for the slag to peel off, which led to the present invention.

[0010] The gist and configuration of the present invention are as follows.

[0011] [1] A method for treating refractory bricks having slag attached to their surfaces, comprising: A method for treating refractory bricks, characterized in that water is taken up into the refractory bricks, and then freezing and thawing are repeated multiple times to remove slag from the refractory bricks.

[0012] [2] The method for treating a refractory brick according to [1], wherein the freezing temperature is −20° C. or lower.

[0013] [3] The method for treating a refractory brick according to [1] or [2], wherein the total treatment time for the repeated freezing and thawing is 1 hour or more.

[0014] [4] The method for treating a refractory brick according to any one of [1] to [3], wherein the number of repetitions of freezing and thawing is four or more. [Effects of the Invention]

[0015] According to the method for treating refractory bricks of the present invention, it is possible to effectively separate slag adhering to the surfaces of the refractory bricks while ensuring the yield of the refractory bricks. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic diagram of a processing flow according to an embodiment of the processing method of the present invention. [Figure 2] 1 is a schematic diagram showing an effect of the processing method of the present invention. [Figure 3] 1 is a graph plotting the crushing strength and slag content of slag remaining on the surface of refractory bricks after treatment in Examples in relation to the treatment time (number of repetitions) of freezing and thawing. DETAILED DESCRIPTION OF THE INVENTION

[0017] A method for treating refractory bricks according to one embodiment of the present invention (sometimes referred to as the "treatment method of this embodiment") will be described below. Note that the following description shows one embodiment or a preferred aspect of the present invention, and does not limit the present invention in any way.

[0018] The treatment method of this embodiment is a method for treating refractory bricks having slag attached to their surfaces, and is characterized in that water is introduced into the refractory bricks, and then the slag is separated from the refractory bricks by repeatedly freezing and thawing the refractory bricks multiple times.

[0019] More specifically, the treatment method of this embodiment includes a step of taking in water into refractory bricks having slag attached to their surfaces (hereinafter, sometimes referred to as "refractory bricks with slag") (water taking in step), a subsequent step of freezing the refractory bricks (freezing step), and a subsequent step of thawing the refractory bricks (thawing step), and requires repeating the above-mentioned freezing step and thawing step multiple times.

[0020] 1 is a schematic diagram of a processing flow according to this embodiment. Each step will be described in detail below with reference to FIG.

[0021] (Water intake process) In the water intake step, water 5 is taken into the refractory brick 1 with the slag 2 attached thereto, as shown in FIG. 1A. This water intake step is performed to facilitate the detachment of the slag 2 in the subsequent freezing and drying steps. Furthermore, in this water intake step, it is preferable that moisture penetrate between the refractory brick 1 and the surface-adhered slag 2, in order to facilitate the detachment of the slag 2, as described above. Specifically, the water intake step is preferably performed by immersing the refractory brick 1 with the slag 2 attached thereto in water 5 stored in a water tank 4, as shown in FIG. 1A. The immersion time in this case is preferably 8 seconds or more to achieve the desired effect, and preferably 20 seconds or less from the viewpoint of processing efficiency. In addition, the method of spraying water onto the surface of the refractory bricks, for example, using a spray, may result in water being difficult to penetrate or not penetrating at all between the refractory bricks 1 and the surface-adhering slag 2 (i.e., water may not be absorbed into the refractory bricks).

[0022] (freezing process) Next, in the freezing step, as shown in FIG. 1B, the refractory brick 1 with the slag 2 after the water intake step is frozen using a freezer 6 or the like. In this freezing step, the water 5 that has penetrated between the refractory brick 1 and the surface-adhered slag 2 freezes to form ice 5', and its volume expands. The freezing temperature is preferably −15°C or lower, more preferably −20°C or lower, and even more preferably −25°C or lower, from the viewpoint of ultimately making the slag 2 more easily detachable from the refractory brick 1. On the other hand, the freezing temperature is preferably −30°C or higher, more preferably −28°C or higher, from the viewpoint of sufficiently causing volume expansion of the water (avoiding rapid freezing). The freezing time is not particularly limited, but can be about 10 to 30 minutes.

[0023] (Thaw process) Next, in the thawing step, the refractory brick 1 with the slag 2 after the freezing step is thawed. The thawing is preferably performed by natural thawing, as shown in Fig. 1(C). In the case of natural thawing, the time required for thawing is about 5 to 15 minutes.

[0024] (Repeated freezing and thawing) The treatment method of this embodiment requires that the above-described freezing and thawing steps be repeated multiple times. By repeating the freezing and thawing steps multiple times, the water 5 that has penetrated between the refractory brick 1 and the surface-adhered slag 2 turns into ice 5', resulting in repeated volume expansion (see FIG. 2). Furthermore, by repeating the freezing and thawing steps multiple times, the strength of the slag 2 that has adhered to the surface of the refractory brick 1 decreases. As a result, the slag 2 becomes more easily peeled off from the refractory brick 1 (so-called freeze peeling). In this way, the slag 2 that has adhered to the surface of the refractory brick 1 can be effectively peeled off. Specifically, the treatment method of this embodiment also makes it possible to achieve a slag content of 2.7% by mass or less (a target value set based on the requirements of a specific recycling destination) in the refractory brick.

[0025] The timing for transition from the thawing process to the freezing process can be when the ice on the surface of the refractory bricks 1 melts and turns back into water.

[0026] The total time for the repeated freezing and thawing is not particularly limited, but is preferably 1 hour or more. In this case, the slag adhering to the surface of the refractory brick can be more effectively removed. From the same viewpoint, the total time for the repeated freezing and thawing is more preferably 3 hours or more, and even more preferably 4 hours or more. On the other hand, if the total processing time is too long, the amount of slag removed will saturate, so it is preferable that the total processing time be 7 hours or less.

[0027] Although a certain degree of effect can be achieved by repeating the freezing and thawing process multiple times (two or more times), four or more times is particularly preferable. In this case, the slag adhering to the surface of the refractory brick can be more effectively removed. From the same viewpoint, the number of times the freezing and thawing is repeated is more preferably six or more times, and even more preferably nine or more times. On the other hand, since an excessively high number of times the amount of slag removed becomes saturated, it is preferable that the number of times the freezing and thawing is repeated is 14 or less.

[0028] (sieving process) In the treatment method of this embodiment, after repeated freezing and thawing steps, the treated material (refractory bricks 1 and slag 2) can be passed through a sieve 8 and separated into a plurality of different fractions for recovery, as shown in Fig. 1(D). For example, by using a sieve 8 with a mesh size of 40 mm, refractory bricks 1 of 40 mm or larger remain on the sieve 8, which allows separation from other substances, including flaked slag 2, that fall below the sieve 8, and ultimately recovery of the treated refractory bricks 1.

[0029] The treatment method of this embodiment does not require crushing or grinding the refractory bricks, which has the following advantages: the labor required for crushing is eliminated; the refractory bricks 1 can be easily separated from the exfoliated slag 2 by sieving; and the yield of the refractory bricks 1 during sieving can be ensured. Specifically, the treatment method of this embodiment can achieve a refractory brick yield of 90% or more. [Example]

[0030] Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples.

[0031] In the following, the peeling ability of slag adhering to the surface of refractory bricks was compared by changing the freezing and thawing processing time (number of repetitions) and the freezing temperature.

[0032] (1) Evaluation of freezing and thawing processing time (number of repetitions) Refractory bricks with slag (slag content: approximately 16% by mass) were prepared and immersed in water for approximately 10 seconds. Next, freezing (freezing temperature: -20°C, freezing time: 20 minutes) and thawing (natural thawing, thawing time: 10 minutes) were combined into one set (total of 30 minutes), and freezing and thawing (repeated) were performed in sets ranging from 0 (no freezing) to 14 (total of 7 hours) (15 cases in total). For each example of refractory brick after repeated freezing and thawing, the crushing strength (MPa) of the slag remaining on the surface was measured using a rebound hammer. Furthermore, for each example of refractory brick after repeated freezing and thawing, the slag content (mass%) was also measured using a rebound hammer. A graph plotting these results is shown in Figure 3. In all examples, the yield of the refractory brick was nearly 100%.

[0033] Figure 3 shows that the strength of the surface slag decreases with the number of repeated freezing and thawing cycles, and that by repeating freezing and thawing cycles sufficiently, the slag adhering to the surface undergoes freezing and peeling, and is eventually completely peeled off from the refractory brick.

[0034] (2) Evaluation of freezing temperature Refractory bricks with slag (slag content: approximately 16% by mass) were prepared and immersed in water for approximately 10 seconds. The freezing temperature was then varied between -5°C, -10°C, -15°C, -20°C, -25°C, and -30°C. Each set consisted of a 20-minute freezing period and a 10-minute natural thawing period, with each set representing a total of 30 minutes. Up to 20 sets of freezing and thawing were performed (a total of 10 hours) (six examples in total). In each example, the time when the slag content of the refractory bricks reached 2.7% by mass or less (a target value set based on the requirements of a specific recycling destination) was considered to be the completion of freeze stripping. This time is shown in Table 1. In each example, the yield of the refractory bricks was nearly 100%.

[0035] [Table 1]

[0036] Table 1 shows that the slag content of the refractory bricks was reduced to the target value in the shortest time when the freezing temperature was -25°C. When the freezing temperature was -30°C, the time to complete freezing and peeling was slightly longer, but this is thought to be because the temperature was lowered too much, causing rapid freezing and making it difficult for the volume expansion of the water to proceed.

[0037] As described above, the method for treating refractory bricks of the present invention can effectively separate slag adhering to the surfaces of the refractory bricks while ensuring a high yield of the refractory bricks. In particular, the present invention is expected to achieve a slag content of 2.7% by mass or less remaining in the refractory bricks and a refractory brick yield of 90% or more, which were not possible with conventional methods. [Explanation of symbols]

[0038] 1: Refractory bricks 2: Slag 4: Aquarium 5:Water 5': Ice 6: Freezer 8: Sieve

Claims

1. A method for treating refractory bricks having slag attached to their surfaces, comprising: A method for treating refractory bricks, characterized in that water is taken up into the refractory bricks, and then freezing and thawing are repeated multiple times to remove slag from the refractory bricks.

2. 2. The method for treating refractory bricks according to claim 1, wherein the freezing temperature is −20° C. or lower.

3. 3. The method for treating a refractory brick according to claim 1, wherein the total treatment time for the repeated freezing and thawing is one hour or more.

4. 3. The method for treating refractory bricks according to claim 1, wherein the number of times the freezing and thawing is repeated is four or more.

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