JPS6221053B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for efficiently recovering high-concentration iron-containing abrasive material from the granulated slag by suctioning and removing the slag floating above the hot metal and molten steel in the treatment process. It is something. Various methods have been considered to separate and remove or recover iron from slag. That is, there are magnetic beneficiation, wind classification, etc., but in either case, the operations and processes are complicated or the separation is insufficient. Moreover, since the recovered granular iron is recovered in granular form, it is unsuitable as an abrasive material for use in removing scales and the like. Therefore, the iron-containing materials recovered from, for example, converter slag are usually only used for reuse as sintering raw materials or for remelting. The present invention separates slag and iron to increase the iron concentration, and also uses the granular iron as an abrasive to break it into a required shape and recover it. That is, the present invention adopts a method of crushing slag with a roll crusher and classifying it with a screen, which solves the problems of conventional methods such as only being able to recover rounded granulated iron or having a low Fe concentration. The purpose of the present invention is to provide a method for recovering high value-added abrasive material from iron-containing slag. In recent years, split refining technology has been developed in the steel manufacturing process. In other words, in order to reduce the load of converter refining, for example, the steps of removing Si, S, and P at the hot metal stage are
It has been practiced to carry out one or more types.
The slag generated from the processing agent used in each treatment step must be sufficiently removed before proceeding to the next treatment step, and conventionally a method such as slag scraping has been adopted. However, in recent years, a slag removal method has been developed in which this fluid slag is removed by suction and then rapidly cooled to form granular slag. This quenched slag usually contains
It contains less than 20% T.Fe, and this iron is in granular form. Moreover, the slag component is hard and brittle due to the quenching effect. The present invention focuses on the above-mentioned rapidly cooled slag, uses this slag as a starting material, dissociates the adhering slag to increase the iron concentration, and processes the granulated iron with a roll crusher to give the surface an acute angle. Moreover, it is intended to be collected efficiently. The present invention will be explained below. In order to recover iron from quenched slag containing granular iron, the slag must first be crushed to release the slag particles and iron particles. Fortunately, this quenched slag is hard and brittle due to the quenching effect, and can be easily turned into fine powder. It can be broken into pieces. Furthermore, in order to remove the slag attached to the granular iron, if it is broken and dissociated into granular iron and slag, and at the same time transformed into granular iron with acute angles, the iron particles and slag can be used as an abrasive material. It was found that these can be easily separated by sieve classification. Therefore, the present invention aims to reduce the amount of pulverization in the next step and improve the pulverization efficiency by removing slag with a low iron content by magnetic separation before pulverizing and classifying the slag. Then, it is crushed by a roll crusher and classified into three to four levels of particle size. The slag is then further crushed and classified to separate it into slag containing a high concentration of iron and a slag containing a low concentration of iron.
During this process, the grained iron is deformed at the same time. However, the particle size of iron is 0.3 to 2 m/m, and the concentration is high (T.
Iron granules with sharp edges containing iron (90% or more, especially 93% or more) are recovered. Next, a specific embodiment of the method of the present invention will be described based on the steps shown in the separate drawings. Since the rapidly cooled slag is granular, only the magnetic separator 1 with a high magnetic field strength of about 2000 Gauss is used to roughly separate the slag from the iron and slag containing iron. Next, the slag containing iron is subjected to primary crushing 2 using a roll crusher 2 to crush it to, for example, an average particle size of about 0.7 m/m. Slag is more easily crushed than granulated iron. Then, it is subjected to primary classification 3 using a 2- to 3-stage screen. For example, classified fine powder of 0.3 m/m or less is removed as slag with low iron content.
The iron and iron-containing slag remaining on each sieve are subjected to secondary crushing 4 for each particle size to further release iron and slag. The released mixture of iron and slag is subjected to secondary classification5 through 2 to 3 stages of screens, and in the same way as above, fine particles of 0.3 m/m or less are removed as slag with low iron content, and then placed on each sieve. If the remaining particles are collected, a high concentration of granulated iron can be recovered. To explain the above process in a little more detail, the magnetic separator 1 that removes the slag that does not contain iron is preferably a tangential magnetic separator with a magnetic field of about 2000 Gauss in order to avoid wasting iron as much as possible. In addition, the average particle size of iron particles in the supplied granular slag is 0.7m/m.
Therefore, after the first crushing 2, parts below 0.3m/m are cut. This is because it is known that the pulverization efficiency is better if the pulverized fine powder slag is removed. Furthermore, since it is more effective for pulverization to have a particle size within as narrow a range as possible, it is preferable for classification to be performed in 3 to 4 stages between 0.3 and 1.0 m/m. Secondary pulverization 4 is performed for each particle size classified 3, and this is classified 5. In the secondary classification class, the number of screens varies depending on the required particle size of the product. The iron particles thus obtained on the sieve are given a deformation suitable for use as an abrasive mainly by secondary crushing 4 using a roll crusher, and have a high iron concentration.
Furthermore, the following cases can be considered for the primary and secondary crushing means.

[Table] That is, in this example, a roll crusher is always used in the secondary crushing 4 in order to stably and effectively deform the granulated iron as an abrasive material. The present invention utilizes the characteristics of rapidly cooled slag as described above to efficiently recover granulated iron that has been deformed into an acute-angled shape with high-grade iron. Since the simple substances are removed, the amount of grinding is reduced, and less energy is required for grinding. In addition, in separation using a magnetic field, slag is mixed in and the Fe concentration is low, but in the present invention, high-grade granulated iron with 90% or more T.Fe, especially 93% or more, is recovered, and the slag content in the granulated iron is small. Therefore, high quality abrasive material can be obtained. In addition, grinding is performed to break up the adhered slag, but at least in the final grinding stage, a roll crusher is used to simultaneously deform the granulated iron and transform it into granulated iron with acute angles on the surface. It can produce greater effects as a material. Next, specific examples will be shown. Example 1 T.
Approximately 1000 kg of granular slag containing 17% Fe was
Approximately 400 kg of iron-containing slag, which has been subjected to rough magnetic separation using a magnetic separator with a Gaussian magnetic field to remove the simple slag content, is crushed using a roll crusher (press crushing with a roll spacing of 0 m/m).
Grind. This is screen 1m/m, 0.5m/
When classified at m, 0.3m/m, each T.Fe is 96%, 81
%, containing 53%. Low Fe concentration
The iron-containing slag on the 0.5m/m and 0.3m/m sieves is further crushed using a roll crusher (press crushing with a roll spacing of 0m/m), and then the iron-containing slag on the sieves of 0.5m/m and 0.3
When classified by m/m, the final recovered granulated pig iron is granulated iron with a high concentration of sharp edges, as shown in Table 1, and the Vickers hardness of this granulated pig iron is high even without heat treatment such as carburizing, quenching and tempering. It was also 600 to 700 HV, higher than the 450 to 500 HV of normal abrasives.

[Table] *marked is an example of use as an abrasive material 2 Using the same sample as Example 1, approximately 400 kg of iron-containing slag from which the simple slag was removed by magnetic separation, 11.5 kg of iron balls of 20ψ were placed in a vibrating ball mill. Pour 0.5 kg of sample into the container and crush for 20 minutes. The crushed slag is screened at 1m/m, 0.5m/
When classified at 0.3 m/m, each T.Fe is 86% and 94
%, containing 94%. The iron-containing slag on each sieve is further crushed using a roll crusher (press crushing with a roll spacing of 0 m/m) and then classified using screens of 1 m/m, 0.5 m/m, and 0.3 m/m to obtain the final recovered particles. As shown in Table 2, the iron was recovered as granular iron with a high concentration of sharp edges, and its hardness was the same as in Example 1.

[Table] *marked is used as abrasive material As shown above, the granulated iron recovered by the method of the present invention has sharp edges and has a high concentration of iron, so it can be used, for example, for removing rust from steel materials and for surface polishing. This opens up new uses as a grid for slag, etc., and greatly contributes to the effective use of iron contained in slag.

[Brief explanation of the drawing]

The figure shows an example of the steps of the method of the present invention.

Claims (1)

[Claims] 1. A first step in which rapidly cooled slag containing iron particles is separated into plain slag and iron-containing slag by magnetic separation, and at least in the final step, the iron-containing slag is crushed using a roll crusher and classified using a screen. Repeating the operation once or twice or more to dissociate into granular iron and slag, and classifying into granular iron and slag, and
The second process of transforming granular iron into abrasive material and T.Fe90
A method for recovering an abrasive material from quenched slag, comprising a third step of recovering an abrasive material containing a high concentration of iron of % or more.