JP5041682B2 - Agglomeration method of roll grinding powder - Google Patents

Description

  The present invention relates to a method for agglomerating roll grinding powder generated during grinding of a metal working roll such as a hot rolling roll or a cold rolling roll of steel.

  The metal working roll as described above is periodically ground to maintain a good surface state. The roll grinding powder generated at this time is a valuable material containing chromium, tungsten, vanadium, etc., but because the particle size is as fine as 500 μm or less, it is not easy to handle as metal scrap and is not effectively used. Is the actual situation.

  In Patent Document 1, in order to recycle granular or cotton-like metal processing waste, after drying and curing the metal processing waste, waste plastic is added as a binder and agglomerated by a roll molding machine or a screw extruder. A method is disclosed. However, this method has a problem that raw material preparation is not easy because it requires waste plastic, which is difficult to obtain at an iron factory. In addition, patent documents of the same applicant that sieving and forced cooling are necessary to remove the powder because the agglomerated molded product collapses and pulverizes, and there is a possibility of fire due to self-heating. It is pointed out in 2 and there is a problem that a large amount of equipment costs are required.

  Furthermore, metal processing waste contains a large amount of moisture and oil, but when using waste plastic as a binder, if the moisture content is less than 5%, the binder effect cannot be obtained, and if there is a lot of oil. It is pointed out in Patent Document 3 of the same applicant that a pre-dehydration / deoiling process is required because the strength of the molded article is reduced and the powder is easily pulverized.

Further, Patent Document 4 describes that cutting scraps of the same metal material are mixed with polishing sludge such as aluminum and compressed to form briquettes. However, in the case of a metal working roll, it is difficult for a user to obtain cutting scraps of the same material as that, and the technique of Patent Document 4 cannot be employed. As described above, various problems remain in order to obtain a lump-shaped molded article that can easily use fine metal scraps such as roll grinding powder.
JP 2000-17344 A JP 2000-256755 A JP 2000-119758 A (paragraphs 0007 to 0013) JP 2003-277842 A

  Accordingly, an object of the present invention is to stably collect lump powder generated during grinding of a metal processing roll without using a binder such as waste plastic, and without requiring complicated processes and large equipment costs. It is to provide a technology that can be formed.

This invention made in order to solve said subject passes the prior spin-drying | dehydration process the mixture which added 10% or more of metal cutting waste to the roll grinding powder generated when grinding the rolling roll of an iron mill. And a method of agglomerating roll grinding powder that is compression-molded with a compressive force of 10 MPa or more, and the metal cutting waste is 30 to 80 mm long in advance when the metal cutting waste generated when the slab surface is cut It is what was cut | disconnected by this.
The roll grinding powder has a particle size of 500 μm or less that is generated when grinding a roll for rolling steel material, and the cut metal scrap has a curl degree represented by (actual length−maximum major axis) / actual length is 0. It is preferable that it is below 0.4. Moreover, it is more preferable to mix 40% or more of metal cutting waste with the roll grinding powder.

  According to the present invention, 10% or more of metal cutting scraps cut into a length of 30 to 80 mm in advance is mixed with roll grinding powder, and agglomeration is performed without using a binder by applying a compressive force of 10 MPa or more and solidifying. Can be Moreover, due to this high pressure, the moisture adhering to the roll grinding powder is dehydrated to 5% or less, and no prior dehydration step is required. In addition, when the curl degree represented by (actual length−maximum major axis) / actual length is 0.4 or less as the cut metal scrap, the metal scrap exhibits a bridging effect and is strong. A compression molded product is obtained.

  Further, in the present invention, the agglomeration is performed at a high pressure of 10 MPa or more together with the metal cutting waste, so that it is possible to obtain a compression molded product having a high strength and no risk of powdering. For this reason, since there is no risk of fire due to self-heating, sieving and forced cooling are unnecessary. Even when the compression molded product is recycled to a blast furnace, a converter, a hot metal pretreatment furnace, an electric furnace, a cupola, etc., it can be efficiently recycled without being pulverized at a connecting point of the conveyor.

Hereinafter, a preferred embodiment of the present invention will be described with reference to FIG.
In the present invention, roll grinding powder generated during grinding of a metal working roll is collected for recycling as an iron source. Here, as a roll for metal processing, a roll for hot rolling of steel, a roll for cold rolling, etc. are typical, and the material is usually tool steel. Since these are periodically ground, a large amount of roll grinding powder is generated. As described above, the particle size is 500 μm or less and is difficult to handle as it is.

  In addition, moisture and oil are attached to the roll grinding powder, and even if it is compressed without using a binder, a strong compression molded product cannot be obtained, and there is a risk of powdering. Therefore, in the present invention, metal cutting waste is mixed with the roll grinding powder at a mass ratio of 10% or more. This metal cutting scrap is preferably a linear or ribbon-like one that can be a skeleton of a compression molded product. In this embodiment, a ribbon-shaped metal cutting scrap generated when the surface of a cast piece such as a slab is cut is used. Such metal cutting waste has a length of about 100 to 200 mm, but is usually curled because it is curled, and is difficult to supply to a compression molding machine as it is.

  So, in this invention, metal cutting waste is cut | disconnected to 30-80 mm with crushing machines, such as a rotary hammer mark lasher. FIG. 2 is a graph showing the relationship between the average length of metal cutting waste and the strength of the compression molded product, and the vertical axis represents the weight of the maximum solid matter / initial weight by dropping the compression molded product onto the concrete floor from a height of 3 m. It is the solid substance residual weight rate calculated | required by the type | formula. When the average length of the metal cutting waste is less than 30 mm, the strength of the compression molded product is rapidly reduced. This is because the bridging effect is reduced. On the other hand, when it exceeds 80 mm, the mixing property with the roll grinding powder deteriorates, and the strength of the compression molded product also decreases.

  Further, metal cutting scraps are often strongly curled as shown in FIG. 3, and a preferable bridging effect can be obtained as it is even if the length (actual length) when extended is in the range of 30 to 80 mm. There is no tendency. Therefore, it is preferable that the curl is extended at the time of cutting so that the curl degree expressed by (actual length−maximum major axis) / actual length is 0.4 or less. Such stretching can be performed simultaneously with cutting by a crusher such as a rotary hammer mark lasher. The metal cutting waste having a curl degree of less than 0.4 is small in itself and hardly functions as a skeleton material for the roll grinding powder.

  The mixing ratio of the roll grinding powder and the metal cutting waste greatly affects the strength of the compression molded product. FIG. 4 is a graph showing the results. It is shown that the strength sharply increases when the mixing ratio of the metal cutting scraps exceeds 10% and further increases when the mixing ratio exceeds 40%. Accordingly, the mixing ratio of metal cutting scraps (metal cutting scrap weight / compression molded product weight) needs to be 10% or more, and more preferably 40% or more.

  Next, the mixture of roll grinding powder and metal cutting waste is hardened by applying a compressive force of 10 MPa or more by a compression molding machine to form a compression molded product. This compression-molded product is not simply compression-molded of roll grinding powder, but contains metal cutting scraps that become a skeleton inside, and therefore has sufficient strength for handling. Since this compression molded product has no fear of pulverization, conventional sieving and forced cooling are unnecessary, and a large equipment cost is unnecessary.

  Moreover, when such a high pressure is applied, the moisture adhering to the roll grinding powder and the metal cutting waste is pushed out and drops to a level of 5% or less. A compression molded product with high strength can be obtained. For this reason, it is possible to further reduce equipment costs. However, when the pressure is less than 10 MPa, the amount of water remaining in the compression molded product increases, the strength decreases, and a problem in storage of the compression molded product is likely to occur.

  As the compression molding machine, it is preferable to use a type in which the material supplied into the cylinder is compression molded by a hydraulically driven piston. As described above, if the metal cutting waste is crushed in advance by a crusher such as a rotary hammer crusher and then mixed with the roll grinding powder, the supply into the cylinder is facilitated.

  The obtained compression molded product is thrown into the blast furnace, converter, hot metal pretreatment furnace, electric furnace, cupola, etc. as an iron source and recycled. Conventionally, since roll grinding powder has not been used, the present invention can reduce the cost and, of course, can be sold as an iron source. In addition, since the compression molded product has sufficient strength, it is not broken or pulverized by vibration in the conveying process.

  Roll grinding powder generated when grinding a hot rolling roll of an iron factory and metal cutting waste generated when cutting a slab surface of ordinary steel were mixed in a mass ratio of 50%. In addition, 30% of water | moisture content and 8% of oil content adhered to the roll grinding powder of the hot rolling roll. Since the metal cutting waste is curled and has a low bulk density and is not easy to handle as it is, the average length is 50 to 60 mm by a rotary hammer crusher, and the curl degree expressed by (actual length−maximum major axis) / actual length is 0.01. The mixture was crushed so as to be 0.2, and mixed with roll grinding powder.

  This mixture was supplied to a hydraulic reciprocating piston compressor and compressed at a pressure of 100 MPa to produce a compression molded product having a diameter of 90 mm and a thickness of 50 mm. This compression-molded product is hardly destroyed even when dropped onto a concrete floor from a height of 3 m, and the residual solid weight ratio exceeds 90%. The moisture content in the compression-molded product was analyzed and found to be 2.8%, and it was confirmed that there was a sufficient dehydrating effect without performing preliminary drying. However, the oil content was 6% and was not reduced as much as the water content. The compression molded product thus obtained was put into a converter and reused as an iron source.

  Roll grinding powder generated when grinding cold rolling rolls in steel mills and metal cutting waste generated when cutting the slab surface of ordinary steel were mixed at a mass ratio of 60%: 40%. . The roll grinding powder had 47% moisture and 3% oil. As in Example 1, the metal cutting waste was crushed so that the average length was 50 to 60 mm and the curl degree represented by (actual length−maximum major axis) / actual length was 0.01 to 0.2, and the roll grinding powder Mixed with.

  This mixture was supplied to a hydraulic reciprocating piston compressor and compressed at a pressure of 100 MPa to produce a compression molded product having a diameter of 90 mm and a thickness of 50 mm. This compression-molded product had a solid residual weight ratio of 60% when dropped onto a concrete floor from a height of 3 m, and had strength that did not hinder handling. The moisture content in the compression-molded product was analyzed and found to be 3.8%, and it was confirmed that there was a sufficient dehydrating effect without performing preliminary drying. The oil content was 2.5% and was not reduced much. The compression molded product thus obtained was put into a hot metal pretreatment furnace and reused as an iron source.

It is a block diagram which shows embodiment of this invention. It is a graph which shows the relationship between the average length of metal cutting waste, and a solid substance residual weight ratio. It is explanatory drawing of the curl degree of metal cutting waste. It is a graph which shows the relationship between the mixing ratio of a metal cutting waste, and a solid substance residual weight ratio.

Claims (4)

Roll grinding powder that compresses and forms a mixture of roll grinding powder generated when grinding mill rolls in steelworks with 10% or more of metal cutting waste with a compressive force of 10 MPa or more without going through a prior dehydration process. Roll agglomeration method, characterized in that the metal cutting waste is obtained by cutting the metal cutting waste generated when cutting the slab surface into a length of 30 to 80 mm in advance. Powder agglomeration method.   2. The method for agglomerating roll grinding powder according to claim 1, wherein the roll grinding powder has a particle size of 500 [mu] m or less generated during grinding of a rolling roll for steel.   2. The method for agglomerating roll grinding powder according to claim 1, wherein the cut metal scrap has a curl degree represented by (actual length−maximum major axis) / actual length of 0.4 or less. .   The method for agglomerating roll grinding powder according to claim 1, wherein 40% or more of metal cutting waste is mixed with the roll grinding powder.

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