JPH0154404B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is produced by coarsely pulverizing an iron powder cake with a primary granulator, re-pulverizing it with a secondary granulator, and then classifying it. The present invention relates to a method for processing over powder, and particularly to a method that can improve the recovery efficiency of over powder as product iron powder and improve the overall yield.

[Conventional technology]

Generally, iron powder that has been reduced in a reduction furnace is extracted as a solidified plate-shaped iron powder cake, so it is first coarsely pulverized by a primary granulator, and then coarsely granulated by a secondary granulator. After being finely pulverized, it is passed through a vibrating sieve and sifted into under powder and over powder. Then, the under powder is recovered as product iron powder, and the over powder is re-disintegrated by a re-pulverizing machine, and the under powder is recovered after being sieved by a vibrating sieve.

[Problem that the invention seeks to solve]

By the way, the above-mentioned re-pulverizer uses the same model as the feather mill that is conventionally used as a secondary crusher, but since the feather mill can only change the lost mesh, it is difficult to meet the requirements of the product iron powder. It is difficult to control product quality according to coating density and particle size distribution. For example, if you install a re-crushing machine that can handle over-sized powder when the required apparent density is high, the re-crushing function will not be sufficient for over-sized iron powder when the required apparent density is high. There is a problem that it is difficult to obtain underpowder even after re-pulverization, and the yield is low.

The present invention has been made in order to solve the problems of the conventional apparatus described above, and it is possible to re-disintegrate the product iron powder according to the required apparent density, and to process over-powder that can improve the yield of under-powder. The purpose is to provide a method.

[Means for solving problems]

The present invention provides a method for processing over-powder in which the over-powder is re-pulverized in an iron powder disintegrating equipment that sieves the iron powder cake into under-powder and over-powder after primary and secondary disintegration. As a re-crushing machine for oversized powder, a crushing hammer is swingably attached to a rotor that is disposed in a casing so that it can be driven at variable speed, and the oversized powder is removed by the impact energy of the crushing hammer caused by the rotation of the rotor. A variable speed rotary hammer-type granulator for re-pulverizing is adopted, and the above-mentioned pulverizer is rotated at a higher speed as the required apparent density of the product iron powder in the secondary crusher is higher, and at a lower speed as the density is lower. The feature is that the over-sized powder is re-disintegrated.

Here, in the method of the present invention, for example, the apparent density required for the product iron powder that has passed through the secondary disintegrator, and the rotation speed of the disintegrating hammer of the re-disintegrator that can realize the required apparent density. A characteristic curve representing the relationship is determined in advance through experiments, and a map calculation is performed to determine the speed of the disintegration hammer that can achieve the required apparent density using this characteristic curve.
It is desirable to control the speed of the regranulator with this speed as a target.

In addition, the re-crushing machine of the present invention is a variable speed rotary hammer type re-crackling machine, since it is a method of re-crackling the over-sized powder using the impact energy generated by the rotation of the crushing hammer, as described above. It is necessary to adopt a granulator. However, the type and structure of the primary and secondary granulators prior to re-granulation are selected appropriately depending on the properties of the iron powder cake, the required apparent density of the product iron powder, etc., and are subject to limitations. do not have to.

[Effect]

According to the over-powder processing method in iron powder disintegration equipment according to the present invention, the rotation speed of the re-granulator is changed according to the required apparent density of the product iron powder.
The over powder can be re-pulverized using rotational energy that corresponds to the particle size of the over powder that is generated, making it easy to adjust the degree of disintegration for high, medium, and low density over powder, and as a result, the yield of under powder can be improved. .

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIGS. 1 to 4 are diagrams for explaining an over-powder processing method in an iron powder crushing facility according to an embodiment of the present invention.

In the figure, reference numeral 1 denotes a primary crushing equipment for coarsely granulating a solid iron powder cake that has been subjected to reduction treatment in a reduction furnace (not shown) and is conveyed by a steel belt 2. A variable speed granulator 4 as a primary granulator is provided at the lower part of a chute 3 disposed in the granulator 4, a horizontal transfer lift 5 extending horizontally to a discharge chute 4a of the granulator 4, and a vertical transfer lift extending vertically upward. 6 are connected in sequence.

7 is a secondary disintegration equipment for finely disintegrating and classifying the coarsely disintegrated iron powder. A buffer hopper 10 is connected to the lower part of the buffer hopper 10 via a bellows-type expansion joint 9, and a vibration feeder 11 is disposed at the lower part of the buffer hopper 10 via an expansion joint 9. A vibrating sieve 13 is connected to the lower part of the feather mill 12 via an expansion joint 9.

In addition, the upper sieve tub 1 of the vibrating sieve machine 13
A 90-mesh screen is installed between 3a and the lower sieve tub 13b. An over powder collection pipe 14a is connected to the upper sieve tub 13a, the lower end of the collection pipe 14a is connected to an over powder vibrating conveyor 15, and an under powder collection pipe 14b is connected to the lower sieve tub 13b. The lower end of the collection pipe 14b is connected to the under powder vibrating conveyor 16. Note that 20 is a recovery hopper for recovering the sifted under powder.

Reference numeral 21 denotes a first re-crushing device for re-crushing the over-powder, which includes a buffer hopper 10 that accommodates the over-powder collected by the over-powder vibrating conveyor 15 and the vertical transfer lift 6a.
a, a vibrating feeder 11a connected to the buffer hopper 10a, a variable speed re-pulverizer 23 for re-pulverizing the oversized powder conveyed by the feeder 11a, and a vibrating feeder 11a connected to the buffer hopper 10a; It is composed of a vibrating sieve machine 13.

The variable speed re-granulating machine 23 has a rotational speed of 30 to 100 m/sec, and is a high peripheral speed disintegrating machine in which a knife-edge or stirrup-type disintegrating hammer is attached to the rotor. be. In addition, the drive device 27 of this variable speed granulator 23 includes:
A hammer speed control device 28 is connected, and this control device 28 is configured to control the rotation of the rotor at a higher speed as the required apparent density S of the product iron powder in the secondary crusher 12 increases. . That is, the control device 28 stores apparent density S-rotational speed V maps shown in FIGS. is mapped and the speed of the drive device 27 is controlled based on this map.

Here, the map shown in Fig. 4 above was obtained in advance through an experiment, and this experiment was conducted using two different types of steel.
For types of over-sized powder (X, Y), knife edge type and stirrup type crushing hammers were adopted as the crushing hammer of the variable speed crusher 23, and while changing the rotation speed, the screen of the crusher was set to 1 mm.
Particles were disintegrated using a hole diameter of φ or 2 mmφ.

FIG. 4a shows the case where the oversized powder X is re-milled, and FIG. 4b shows the case where the oversized powder Y is re-milled. In the figure, ○ and ● symbols indicate the case where a knife edge type hammer is used, and △ and ▲ symbols indicate the case where a stirrup type hammer is used. Furthermore, the black symbols in both of the above symbols indicate the case where the sample was passed through a 1 mmφ screen, and the white symbols indicate the case where the sample was passed through a 2 mmφ screen.

Further, a flow rate detector 29 is provided downstream of the variable speed granulator 23, and the detected flow rate is inputted to a flow rate control device (not shown). This flow rate control device controls the vibrating feeder 11 so that the detected flow rate becomes a flow rate corresponding to the sieving capacity of the vibrating sieve machine 13.
It is configured to control the transport speed frequency of a.

Furthermore, an over powder collection pipe 14a is connected to the upper sieve tub 13a of the vibrating sieve 13,
The recovery pipe 14a is branched into a vertical transfer lift 6a and an over powder recovery conveyor 25 by a switching damper 24. The recovery conveyor 25 is connected to a second re-pulverizing device 22 that further re-pulverizes the oversized powder from the first re-pulverizing device 21.
This second re-grilling device 22 is for crushing the over powder into product iron powder for another purpose, but its configuration is almost the same as the first re-grinding device 21, and the buffer hopper is 10b, a variable speed high-speed granulator 23a, a vibrating sieve 13d, etc.

Next, a case will be described in which the method of this embodiment is implemented using the above-mentioned apparatus.

The iron powder cake conveyed by the steel belt 2 is coarsely pulverized by a primary pulverizer 4, stored in a buffer hopper 10 by transfer lifts 5 and 6 and a vibrating conveyor 8, and then subjected to secondary pulverization by a vibrating feeder 11. After being transported to a feather mill 12 as a granulator and re-pulverized there, it is sieved by a vibrating sieve 13 into under powder and over powder, and this under powder is collected in a recovery hopper 20 as product iron powder.

Further, the overflour collected by the overflour vibrating conveyor 15 is transferred to the buffer hopper 10a by the vertical transfer lift 6a, and the overflour accommodated in the hopper 10a is supplied to the variable speed re-granulator 23. The rotational speed V of this regranulator 23 is controlled by a control device 28 at a variable speed according to the apparent density S of the product iron powder. For example, when a stirrup type hammer and a 2 mmφ screen are used, the steel type is Y and the apparent density S of the product iron powder is 2.8.
In the case of g/cc, the rotational speed V=60 m/s is read from the map shown in FIG. 4b, and control is performed at this speed as well. Further, as the apparent density S further decreases, the rotational speed V is lowered, and as the apparent density S becomes larger, the rotational speed V is increased. As a result, the desired underpowder can be obtained.

Furthermore, the iron powder from the re-granulator 23 is passed through a vibrating sieve 13, and the sieved under powder is transferred to the collection hopper 20, and the over powder is transferred to the second re-granulator 22, where it is transferred to the second re-granulator 22. It is further re-cracked at a rotation speed suitable for the target product iron powder.

As described above, according to the method of this embodiment, the over-sized powder from the secondary disintegration equipment 7 is processed by the first re-disintegration equipment 21 at a rotation speed corresponding to the required apparent density and particle size distribution of the product iron powder. Since re-disintegration is carried out, the degree of disintegration of the over-powder can be easily adjusted, and as a result, the re-collection of the under-powder can be greatly improved, and the yield of product iron powder can be improved.

In addition, in this embodiment, since the over powder from the first re-pulverizing device 21 is further re-pulverized, the over powder, which was conventionally disposed of, can be used for secondary purposes as product iron powder, such as cores for welding rods. Can be used as a line,
The overall yield can be improved.

In addition, in the above embodiment, the oversized powder from the secondary disintegration equipment was re-disintegrated twice by the first and second re-disintegrators 21 and 22, but in the present invention, it is not necessarily necessary to disintegrate it twice. No, just once is fine.

〔Effect of the invention〕

As described above, according to the over-powder processing method in the iron powder disintegrating equipment according to the present invention, the over-powder after being classified is processed by the variable speed re-granulator at a rotation speed according to the required apparent density of the product iron powder. Since the over powder is re-disintegrated, the degree of disintegration of the over powder can be easily adjusted according to the required apparent density, and the yield of the under powder can be improved.

[Brief explanation of drawings]

Fig. 1 is an overall configuration diagram of iron powder disintegration equipment for explaining an over-powder processing method according to an embodiment of the present invention, and Fig. 2 shows its primary and secondary disintegrators and first re-disintegrator parts. Fig. 3 is a block diagram of the first regranulation device, Fig. 4a and Fig. 4b.
is a characteristic diagram showing the relationship between the rotational speed and apparent density of the variable speed disintegrator. In the figure, 4 is a variable speed granulator (primary granulator);
12 is a feather mill (secondary crusher), and 23 is a variable speed re-granulator.

Claims (1)

[Claims] 1 After the plate-shaped iron powder cake solidified in the iron powder reduction furnace is first and secondly pulverized by the first and second pulverizers, it is divided into under powder with a smaller diameter than a predetermined particle size and over powder with a larger diameter than the predetermined particle size. In an iron powder disintegrating equipment that sieves into powder, the above-mentioned over-ground powder is re-disintegrated by a re-disintegrator, and the above-mentioned re-disintegrator is installed in a casing. A variable speed rotary hammer type re-granulation system that re-granulates the oversized powder using the impact energy of the pelletizing hammer, which is generated by rotating the rotor and uses the impact energy of the pelletizing hammer, which is generated by rotating the rotor. The pulverizing hammer is rotated at a variable speed such that the required apparent density of the product iron powder in the secondary pulverizer is higher as the density is higher and lower as the density is lower. A method for processing over-powder in iron powder granulation equipment, characterized by the following.