JPS58133844A - Operating method of magnetic separator - Google Patents

Abstract

PURPOSE:To reduce the rising time of exciting current, and to make a separator compact and light, in the separator which excites by detecting an inclusion of magnetic pieces, by exciting with small electric power in ordinary running and exciting with large power when said piece is detected. CONSTITUTION:An exciting coil of a magnetic separator 12 is ordinarily excited by a small electric power kept within a range where a temperature rise of said coil is kept from exceeding an allowable temperature i.e. a preparation voltage VS, and an exciting current IS is supplied. When a magnetic piece mixed in raw materials on a moving conveyor 10 passes through a detecting means 24, a detecting signal S1 is transmitted to a controlling device to convert the voltage VS into an exciting voltage VF enough to attract the magnetic piece. Then the exciting current increases from the value IS in an ordinary state toward the IF corresponding to the voltage VF at the time of attracting state, and corresponding to said change, the value of magnetic field also increases from HS to HF. Thus the rises are curved as shown by real lines in the figure because of the delays caused by said increases. Accordingly, the attraction takes place after a short time t1 from the time the signal S1 is outputted, when the lower limit of magnetic field necessary for attracting the magnetic piece is put HL, and the current value necessary for exciting of HL is put IL.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention detects the presence of magnetic particles in raw materials using a magnetic particle detection means such as a metal eluator, and operates the excitation coil of a magnetic separator in response to this detection signal to remove the magnetic particles. Regarding the method of operating a magnetic separation device that separates pieces by suction, the device can be made smaller and lighter as a whole, and can be used in narrow spaces such as the inside of an unloader used when unloading cargoes of raw materials such as coal and ore from ships. The present invention provides a method for operating a magnetic separation apparatus of the type described above, which allows it to be easily installed in a large space.

Unloaders are used when unloading raw materials such as coal and ore from ships. The raw materials unloaded by the unloader are placed on the ground and sent to the yard by a telephoto conveyor. At this time, if foreign substances such as iron pieces are mixed in the raw materials, it often causes tears in the conveyor belt of the conveyor or damages the conveyor mechanism.

The economic loss associated with the failure of this conveyor is large.
This not only increases the ship's time on board, but also has a significant impact on related systems. Therefore, the magnetic pieces in the raw material are required to be completely separated in an unloader before the conveyor.

This problem can be solved by (1) installing a magnetic separator on the in-machine conveyor installed in the unloader or at a suitable location in the machine, and magnetically attracting and separating the magnetic pieces.

On the other hand, unloading requires extremely high unloading capacity for economic reasons such as improving work efficiency and shortening ship time. For this reason, a magnetic separator that removes magnetic contaminants mixed in cargo handling and conveyance is also required to have a large processing capacity. The processing partner of this magnetic separator is determined by the attraction capacity of the electromagnet, which is its main component, and the requirement for high magnetic attraction capacity leads to the electromagnet becoming large.

On the other hand, existing unloaders do not have enough space to accommodate a magnetic separator with a huge electromagnet, and there is not enough strength to support it, and even newly installed unloaders lack structural strength and capacity. Planning something that satisfies these requirements will inevitably lead to an increase in the size of the unloader, and this increase in size will lead to an increase in the size of the unloader (which is difficult to implement considering changes to peripheral equipment and systems).

For these reasons, it is desirable to miniaturize the electromagnet, which is the main component of magnetic separation*, as much as possible to reduce the overall size. However, there is a limit to miniaturization when considering the temperature rise of the electromagnet due to heat generated by the excitation coil.

Therefore, as a means to suppress the temperature rise while maintaining the attraction ability, it is possible to cool the excitation coil by an appropriate method.Also, as an alternative method, it is possible to reduce the load factor by energizing only when magnetic pieces are mixed. Furthermore, it is conceivable to use both of these in combination to further enhance the effect.

The method of reducing the load factor by exciting the electromagnet of the separator only when magnetic pieces are present has the following problems when it is actually applied.

That is, an electromagnet with a large attraction capacity used for magnetic separation has an extremely large inductance, which causes a significant time delay in the rise of the excitation current. Therefore, even if a signal is received from a magnetic piece detection means such as a metal detector, the desired magnetic attraction force cannot be exerted immediately.

For this reason, it is necessary to install the magnetic piece detection means at a predetermined distance from the magnetic separator, taking into account this time delay and the speed of the conveyor belt through which the raw materials are transported. In other words, the length of the belt conveyor should be sufficiently long (and the distance between the magnetic piece detection means on the conveyor and the magnetic separator should be sufficient), and after the magnetic piece detection means detects the presence of the magnetic piece, the magnetic piece is removed. It is necessary to make the time required for the excitation current to reach the magnetic separator longer than the rise time of the excitation current.

It is impossible to secure such a space, that is, a sufficient space between the magnetic piece detection means and the magnetic separator, in the case of the in-machine conveyor of the unloader, which has a high-density structure. It is.

The purpose of the present invention is to solve the problem 11 in the prior art, to achieve a reduction in size and weight of a magnetic separation device, and to improve the operation of the magnetic separation device so that it can be mounted even in a narrow place such as the above-mentioned unloader. The purpose is to provide a method.

The feature of the present invention is that the excitation coil is constantly excited with a small power within a range that does not exceed the allowable rise value, and only when a mixed magnetic piece signal is received, the large power necessary for attracting the magnetic piece is supplied to the excitation coil. Therefore, it is possible to shorten the rise time of the excitation current and to make the magnetic heat separation device smaller and lighter.

That is, according to the present invention, a method for operating a magnetic separator that detects the presence of magnetic pieces in a raw material by means of a magnetic piece detection means, and operates an excitation coil of a magnetic separator based on this detection to attract and separate the magnetic pieces. 2, the excitation coil is constantly excited with a small electric power within a range that does not exceed the allowable value for temperature rise, and when receiving a signal of mixed magnetic pieces from the magnetic piece detection means, the magnetic field strength necessary to attract the magnetic pieces is set. A method of operating a magnetic separation device is provided, which is characterized by exciting with a large electric power that generates a magnetic separator.

The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a diagram illustrating a simplified structure of an unloader suitable for applying the method of operating a magnetic separation apparatus of the present invention, and a mantrolley type unloader is illustrated.

The i-loader is a rail 1 installed on land along the quay.
．． A pedestal 3.3 that can run on 1 via rolling wheels 2.2
and a crossbeam 4 that is supported by these pillars and extends to the sea, and the crossbeam 4 is equipped with an i-trolley type crane hoisting device (hereinafter referred to as a hoisting device) that can run via a trolley 17. (referred to as the device) 6 is deployed. A pedestal 7 is provided at a height that does not hinder the movement of the hoisting device 6 of the fuselage 5, a receiving hopper 8 is arranged near the sea-side end of the mosquito pedestal, and a receiving hopper 8 is disposed near the sea-side end of the mosquito pedestal. Delivery hoppers 9 (two in the illustrated example) are arranged.

In addition, the receiving hopper 8 and the delivery '
An in-machine conveyor 10 is installed to connect the hopper 9 and the hopper 9. These receiving hopper 8, sending hopper 9, and in-machine conveyor 10 constitute a raw material feeding device 11 within the unloader. .

There is a magnetic separator 12 in the middle of the in-flight conveyor 10! The magnetic separator has an oil-filled electromagnet 13 that forms a magnetic field on the bottom surface.
(See M in Figures 2 and 3). The magnetic valve @912 is supported by the pedestal 7 or the body of the in-machine conveyor 100 via a suitable support member, and is attached to the horizontal inner conveyor 1.
It is suspended above 0.

The pedestal 7 is provided with an insulating oil circulation device 14, which forcibly circulates cooling insulating oil into an oil tank in which the excitation coil of the magnetic separator 12 is immersed.

Further, a feeder 15 is provided at the lower end of the receiving hopper 8.
is connected to the receiving hopper, and the next raw material is fed into the machine onto the conveyor 10 through this feeder 15. The raw materials conveyed by the in-machine conveyor 1o and inputted into the delivery hopper 9.9 are supplied from these delivery hoppers onto the ground transport: ff7bene 716.16,
The nuclear transport conveyor sends it to the yard.

The hoisting device 6 is supported so as to be able to travel along the crossbeam 4 from the point 1:r 1717 K, and is located between the sea side position indicated by the solid line in FIG. 1 and the land position indicated by the two-dot chain line. After going back and forth, it became 5 to 5. A raw material loading/unloading machine such as a grab bucket 18 is connected to the rope end of the bagging f16. Therefore, the raw materials on the docked ship are scooped up in fixed amounts by the hoisting device 6, fed into the hind leg receiving hopper which is moved onto the receiving hopper 8 by running the trolley 17, and passed through the feeder 15 at a predetermined delivery speed. It is supplied to the in-machine conveyor 10. In-flight conveyor 1
0 raw materials are discharged and fed through the hopper 9.9 to the conveyor 18.16 and fed to the yard.

FIGS. 2 and 3 are diagrams showing details of an in-machine conveyor 10 and a magnetic separator 12 suitable for carrying out the present invention. In FIGS. 2 and 3, parts corresponding to each sK in FIG. The excitation coil of the oil-filled electromagnet 13, which has a magnetically active surface 20 on its lower surface to apply a magnetic field toward the magnetic field, is immersed in an oil tank containing insulating oil. An endless belt 21 is stretched around the electromagnet 13 and rotates along the magnetically active surface 20 in the direction indicated by the arrow in FIG. A long endless belt is stretched along the driving pulley 22 and the driven pulley 23. The magnetic separator 12 having such a configuration is an in-flight comparator 1.
At an appropriate position between 0 and 0,
It is hung on the horizontal frame.

The electromagnet 13 is constantly excited with a small excitation power within a range where the rise in Il due to continuous operation does not exceed a permissible value, and when magnetic contaminants mixed in the raw materials on the in-machine conveyor are detected, the power as described below is turned on. A magnetic piece detection means 24 of a metal detector ring is installed at an intermediate position between the magnetic separator 12 and the feeder 15 of the in-machine conveyor 10 to attract and separate magnetic pieces under control.
The passage of a magnetic piece such as an iron piece on 9 is detected.

The insulating oil circulation device 14 installed on the pedestal 7 is connected to the radiator 2
5. Consists of an oil feed pump 26 and other fluid control elements (not shown), connected to the electromagnet 13 of the magnetic separator 12 through pipes 27 and 27, and insulating oil for cooling in the oil tank of the electromagnet. is configured to forcefully circulate.

At a position after the endless belt 21 of the magnetic separator 12 has passed through the conveyor belt 19, a chute 28 is provided for removing magnetic pieces attracted to the surface of the endless belt while the endless belt 21 is being conveyed. It is being In addition, a second magnetic piece detection means 29 such as a metal detector is arranged on this chute 28 to confirm the magnetic piece separation effect of the magnetic separator 12, and based on the signal from this, the magnetic separator 12 It is designed to control the timing of return to normal.

The method of operating the pneumatic magnetic separator is explained above and shown in Fig. 4 (AJ-
This will be explained below with reference to each figure including (b).

The whll coil with magnetic separation of $12 is constantly energized with a small power within the range where the rise does not exceed the allowable value, that is, the preparation voltage v8 in Figure 4 (J3), and even during regular operation, the
C) excitation current in! S is supplied.

When magnetic pieces mixed in the raw materials moving on the in-machine conveyor 10 pass through the magnetic piece detection means 24f, the magnetic piece detection means detects this and generates the detection signal S shown in Figure (4). . This signal S is provided separately and sent to a control device (not shown), and the control device changes the excitation voltage vB in the normal state to an excitation voltage VF (in Fig. 4) sufficient to attract the mixed magnetic pieces. converted.

When the voltage increases to vJIil and vy, the excitation current returns to the normal value of 1.5 as shown in FIG. 4(C). The attraction dark voltage v
Value 1 for F. increase towards. Corresponding to this increase in the excitation current, as shown in FIG. 4), the value of the magnetic field also increases from the normal state value H8 toward the attraction state value H1.

However, such an increase in the excitation current and magnetic field causes a delay in the conversion of the excitation voltage due to the intuffance of the excitation coil, and as shown in Fig. 4(C) and Fig. 4).
The rise characteristic is curved as shown by the solid line.

Therefore, the lower limit of the magnetic field required to attract mixed magnetic pieces is set to <HL as shown in the figure, and the current value required for HLo excitation is set to 1. Then, the mixed magnetic piece is W, (Fig. 4(C) and Fig. 4)
As shown in (), the magnetic piece is attracted after a time tl after the magnetic piece detection means 24 emits the signal S.

By the way, when the preparation voltage, that is, the excitation voltage VB in the normal state is not applied, the excitation current and magnetic field change as shown by the dots in FIG. 4 (C> and FIG. 4D), and the detection signal S, The time tt from when the magnetic piece is attracted until the magnetic piece is attracted
is significantly thicker than the time t when the voltage is applied. In other words, if the preparatory voltage Vat- is not applied and the excitation voltage in the normal state is set to zero, the FJJJVBt current will rise from zero. Therefore, the time delay until suction is
? However, if the predetermined excitation voltage v8 is constantly applied as in the present invention, the time delay tl until the attraction occurs can be reduced.
can be made significantly smaller. To give specific figures, a conveyor pipe with a belt width of 1.8% is used, and the conveyance speed is 70fi/min for ore and 140WLZ for coal.
The electromagnet specifications when operating in minutes are as follows.
The excitation (preparation) voltage V8 during normal operation is 200 V DC and its power is 11.6 KW, the excitation voltage V during attraction is 350 ■ and its power is 35.5 KW, and the value of the excitation current at this time is always n< Preparation) At 1. =58A.

Ir=101A during suction. The rise time in this case is t,=3 seconds, and t when no preparation voltage is used.
, it was shortened to a large width from -7 seconds.

The magnetic pieces drawn onto the endless bell 21 by the magnetic separator 12 are successively introduced into the chute 28 and discharged. When the removal of the magnetic pieces by the magnetic separator 12 is completed in this way, the magnetic pieces are removed by the second magnetic particle detection means 2.
9 V (therefore, it is detected and the detection signal Bat shown in Fig. 4 (4) is generated. Based on this signal Sm, the control device returns the excitation pressure to the value vy at the time of suction to the normal value 8. ζ
At the same time, the values of the excitation current and the magnetic field also return to the normal state values of -L and 8 and H, respectively, with a slight delay.

In the illustrated example, the second magnetic piece detection means 29 is used and its signal output 8W returns the magnetic separator 12 to the normal state. Signal output of the magnetic piece detection means 24 on the conveyor belt 19 according to the time signal6. It is also possible to apply the attraction voltage Vv to the electromagnet 13 for a predetermined period of time after receiving the voltage. However, as shown in the figure, the second magnetic piece detection means 29
It is preferable to control the vJWi voltage while ensuring that the removal of the magnetic pieces is completed by V, since the separation of the magnetic pieces can be reliably performed with minimum power.

In addition, the magnetic valve ms uses a suspended type electromagnet 13 having a removal mechanism using an endless belt 21, but other types of electromagnets may be used depending on the structure, unloading capacity, and mounting location of the unloader. You can also. For example, it is possible to adopt a method of installing a rotating drum type magnetic separator at the outlet of the receiving hopper 8, or a method of using an electromagnetic pulley as the terminal pulley of the horizontal conveyor 10.

As is clear from the above description, according to the present invention, the excited coin is always excited with a predetermined small electric power, and when a magnetic piece mixed signal is received, the power necessary for attracting the magnetic piece is supplied to the magnet. Since the separator is operated, the rise time of the excitation current can be shortened, thereby reducing the distance between the magnetic piece detection means and the magnetic separator, thereby achieving a reduction in size and weight of the entire apparatus. is obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram illustrating the structure of an unloader suitable for carrying out the method of operating a magnetic separation apparatus of the present invention, and FIG. Figure 1 is a partially enlarged explanatory diagram showing the in-machine conveyor part; Figures 3 and 3 are cross-sectional views taken along the line drawing -■ in Figure 2;
(A), (B), (0 and (2)) are graphs illustrating the change characteristics of the magnetic piece detection signal, excitation voltage, excitation current, and magnetic field when implementing the operating method of the magnetic separation device of the present invention. 5. Unloader body, 6. Hoisting device, 7.
, frame, 8... receiving hopper, 9. ... Delivery hopper, lO ... In-machine conveyor, 12 ... Magnetic separator, 13 ... Magnet, 14 ... Disconnected oil circulation device, 1
9... Conveyor belt, 20... Magnetic action surface, 21
...Endless belt, 24...Magnetic piece detection means,
28... Chute (for removing magnetic pieces), 29... Second magnetic piece detection means. Agent: Tatsuyuki Unuma (and 2 others) '・ 1 Figure 21゛1 °3 111 'Continued from Figure 4, page 1 ■Applicant Kanetsu Kogyo Co., Ltd. 1111 Uedawara, Ueda City, Ueda City

Claims (2)

[Claims] (1) In the method of operating a magnetic separator, the magnetic piece detection means detects the presence of magnetic pieces in the raw material, and the detection signal activates the excitation coil of the magnetic separator to attract and separate the magnetic pieces. The excitation coil is constantly excited with a small electric power within a range that does not exceed the allowable value for temperature rise, and when a signal of mixed magnetic pieces is received from the magnetic piece detection means, the magnetic %' store necessary for attracting the magnetic pieces is activated. A method of operating a magnetic separation device characterized by excitation with a large generated electric power. (2) A second magnetic piece detection means is provided in the sending rod path of the magnetic pieces separated by suction from the raw material, and the excitation filter of the magnetic separator is returned to a normal state by a magnetic piece passage signal from the detection means. A method for operating a magnetic separator according to item (1) of Patent No.