JPS6127107B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention detects the presence of magnetic pieces (iron pieces, etc.) in raw materials using a magnetic piece detection means such as a metal detector, and uses this detection signal to excite the excitation coil of the magnetic separator. Regarding the operating method and operating device of the magnetic separator that attracts and separates the magnetic pieces, in particular, the entire device can be made smaller and lighter, and the unloader used when unloading a cargo of raw materials such as coal or ore from a ship. The object of the present invention is to provide a method of operating a magnetic separation device of the type described above, which can reduce the size and weight of the device so that it can be easily installed in a narrow space such as inside an aircraft, and the device.

Unloaders are used when unloading raw materials such as coal and ore from ships. The raw materials unloaded by the unloader are sent to the yard by a conveyor installed on the ground. At this time, if the raw materials contain impurities from iron scraping,
Tears in the conveyor belt of the conveyor or damage to the conveyor mechanism often occur.

The economic loss associated with a failure of this conveyor is large, and not only does the ship's time on board become longer, but it 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 installing a magnetic separator on an in-machine conveyor installed in the unloader or at a suitable location in the machine to magnetically attract and separate the magnetic pieces.

On the other hand, extremely high unloading capacity is required for economical reasons such as improving the efficiency of unloading operations and shortening shipboard time. For this reason,
Large throughput is also required for magnetic separators that remove magnetic contaminants mixed in cargo handling and conveyance. The processing capacity of this magnetic separator is determined by the suction capacity of the electromagnet that forms its main part, and the requirement for high suction capacity leads to the electromagnet becoming large.

On the other hand, existing unloaders do not have enough space to accommodate a huge working magnet or sufficient strength to support it, and even new unloaders do not have sufficient structural strength and capacity to accommodate them. Planning for this will inevitably lead to an increase in the size of the unloader, and it will be extremely difficult to implement this plan, considering the changes to peripheral equipment and systems due to this increase in size.

For these reasons, it is desirable to make the electromagnet, which is the main part of the magnetic separator, as small as possible to make the whole magnetic separator smaller. 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 of suppressing the temperature rise while maintaining the suction ability, cooling the excitation coil,
Alternatively, it is conceivable to reduce the load factor by energizing only when magnetic pieces are mixed, and furthermore, it is conceivable to use both of these together to further enhance the effect.

The method of exciting the electromagnet only when magnetic pieces are mixed together has the following problems when it is actually applied.

In other words, the electromagnets used in magnetic separators with a large attraction capacity have extremely large inductances, which causes a significant time delay in the rise of the excitation current, and as a result, it is difficult to receive a detection signal containing magnetic pieces. There is a problem in that even if excitation is started immediately, the desired magnetic attraction force cannot be exerted immediately.

To solve this problem, it is necessary to take into account the time delay and the conveyor belt speed and make the distance between the magnetic piece detection means and the magnetic separator sufficiently large. (conveyor, etc.) must also be sufficiently long. This is because the time from when the presence of magnetic pieces is detected until the magnetic pieces reach the magnetic separator needs to be longer than the excitation current rise time.

However, the interior of the unloader is structurally dense, and there is no room to secure this kind of space or to support a long interior conveyor with sufficient strength, making it virtually impossible to implement. Ta.

The present invention was made in order to solve the problems of the conventional technology, and it is possible to make the magnetic separation device smaller and lighter, thereby making it possible to install it even in a narrow place such as the above-mentioned unloader. An object of the present invention is to provide a method of operating a magnetic separation device and an apparatus thereof.

A feature of the present invention is that when a magnetic piece detection signal is emitted from the magnetic piece detection means, an excessive excitation voltage that is larger than the normal excitation voltage that can attract the magnetic piece is applied to the excitation coil to promote the rise of the excitation current. When the voltage reaches a value that can attract a magnetic piece, it is detected or converted to a normal excitation voltage using a preset timer device, thereby reducing the delay in the rise of the excitation current, making it possible to make the device smaller and lighter. It is in the point of doing.

That is, according to the present invention, the magnetic piece detection means detects the presence of magnetic pieces in the raw material, and the detection signal excites the excitation coil of the magnetic separator to attract and separate the magnetic pieces. In the method, when a detection signal of mixed magnetic pieces is issued from the magnetic piece detection means, excitation of the excitation coil is started with an excessive excitation voltage that is larger than a normal excitation voltage that is capable of attracting a magnetic piece, and the rise of the excitation current is promoted. , a method for operating a magnetic separation device, characterized in that the excessive excitation voltage is converted into the normal excitation voltage by detecting this after a preset predetermined period has elapsed or when the excitation current reaches a value capable of attracting a magnetic piece. is provided.

According to another aspect of the present invention, there is provided an apparatus for carrying out the above-mentioned operating method, in which the magnetic piece detection means detects the presence of magnetic pieces in the raw material, and the excitation coil of the magnetic separator is activated by this detection signal. In an operating device for a magnetic separation device that attracts and separates the magnetic pieces by excitation, an excitation circuit connected to a supply source of a normal excitation voltage capable of attracting the magnetic pieces and a source of an excessive excitation voltage larger than the normal excitation voltage; a first switching means for switching the excitation circuit to apply the excessive excitation voltage to the excitation coil in response to a detection signal from the magnetic piece detection means; and when the excitation current reaches a value capable of attracting the magnetic piece; A second switching means for switching the excitation circuit so as to apply the normal excitation voltage to the excitation coil after a set predetermined period has elapsed.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram illustrating a schematic structure of an unloader suitable for applying the present invention, and a man trolley type unloader is illustrated.

The unloader consists of pedestals 3, 3 that can run via rolling wheels 2, 2 on rails 1, 1 laid on land along a quay, and a crossbeam supported by these pedestals and extending to the sea. 4, and a man trolley type crane hoisting device (hereinafter referred to as hoisting device) that can run via a trolley 17 is attached to the crossbeam 4.
6 are deployed. A pedestal 7 is provided at a height that does not interfere with the traveling of the hoisting device 6 of the fuselage 5, and a receiving hopper 8 is disposed near the sea-side end of the pedestal. Delivery hoppers 9 (two in the illustrated example) are arranged.
Also, within the pedestal 7 is an in-machine conveyor 10 that connects the receiving hopper 8 and the sending hopper 9.
is installed. The receiving hopper 8, the sending hopper 9, and the in-machine conveyor 10 constitute a raw material feeding device 11 within the unloader.

A magnetic separator 12 is installed in the middle of the in-machine conveyor 10, and the magnetic separator is equipped with an oil-filled electromagnet 13 (see FIGS. 2 and 3) that forms a magnetic field on its lower surface. The magnetic separator 12 is supported by the frame 7 or the body of the in-machine conveyor 10 via a suitable support member, and is suspended above the in-machine conveyor 10.

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 connected to the lower end of the receiving hopper 8, and the raw materials fed into the receiving hopper are supplied onto the in-machine conveyor 10 through the feeder 15. The raw materials conveyed by the in-machine conveyor 10 and put into the delivery hoppers 9, 9 are supplied from these delivery hoppers onto the above-ground transport conveyors 16, 16, and are sent to the yard by the transport conveyors.

The hoisting device 6 is supported by a trolley 17 so as to be able to travel along the crossbeam 4, and can reciprocate between the sea side position indicated by the solid line in FIG. 1 and the land side position indicated by the two-dot chain line. It's becoming like that. Hoisting device 6
A raw material loading/unloading machine such as a grab bucket 18 is connected to the end of the rope. Therefore, the raw materials on the docked ship are scooped up in fixed amounts by the hoisting device 6, moved to the receiving hopper 8 by running the trolley 17, and then thrown into the receiving hopper, passed through the feeder 15, and placed in a predetermined amount. It is supplied to the in-machine conveyor 10 at the delivery speed. The raw material from the in-machine conveyor 10 is fed through the delivery hoppers 9, 9 to the conveyor conveyors 16, 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 those in FIG. 1 described above are designated by the same reference numerals.

In FIGS. 2 and 3, the magnetic separator 12
has a magnetically active surface 2 on its lower surface in order to apply a magnetic field toward the conveyor belt 19 of the in-machine conveyor 10.
0 and forming the magnetically active surface
The excitation coil No. 3 is immersed in an oil bath of insulating oil. The electromagnet 13 is surrounded by a conveyor belt 1 along the magnetically active surface 20 in the direction marked A in the center of FIG.
Endless belt 21 rotating in a direction crossing 9
is installed. This endless belt is stretched along a driving pulley 22 and a driven pulley 23. The magnetic separator 12 having such a structure is suspended at an appropriate position in the middle of the in-machine conveyor 10.

A magnetic piece detection means 24 such as a metal detector is installed at an intermediate position between the magnetic separator 12 and the feeder 15 of the in-machine conveyor 10 to detect the passage of magnetic pieces such as iron pieces on the conveyor belt 19. There is.

The insulating oil circulation device 14 installed on the pedestal 7 consists of a radiator 25, an oil pump 26, and other fluid control elements (not shown), and is connected to the electromagnet 13 of the magnetic separator 12 via pipes 27, 27. It is configured to forcibly circulate cooling insulating oil to the oil tank of the electromagnet.

At a position of the endless belt 21 of the magnetic separator 12 after passing the conveyor belt 19, a magnetically active surface 2 is provided.
A chute 28 is provided for removing magnetic pieces attracted to the surface of the endless belt while passing through zero. Further, on this chute 28, a second magnetic piece detection means 29 such as a metal detector is disposed for confirming the separation of magnetic pieces by the magnetic separator 12.

Magnetic piece detection means (hereinafter referred to as first magnetic piece detection means) 24 for detecting magnetic pieces on the conveyor belt 19 and a second magnetic piece detection means provided on the magnetic piece sending path from the magnetic separator 12 Means 29
is connected to a control device 30, which is connected to the electromagnet 13 of the magnetic separator 12. Also,
Two types of excitation voltages are supplied to the control device from the DC power supply device 31.

The control device 30 is for controlling the excitation voltage of the electromagnet 13, and receives a magnetic piece detection signal from the first magnetic piece detection means 24 (in FIG.
S ₁ ), excitation is started, and the magnetic piece passing signal from the second magnetic piece detection means 29 (shown in FIG.
S ₂ ), it operates to end excitation.

FIG. 4 is a diagram showing a control circuit within the control device 30.

In FIG. 4, the control circuit includes a supply source P ₁ (connected to one output of the DC power supply 31) of a normal excitation voltage V _s that can attract a magnetic piece, and an excessive excitation voltage V that is higher than the normal excitation voltage. Source of _H P ₂
(connected to the other output of the DC power supply 31), and a current detector 33 inserted into the excitation circuit to detect the excitation current value.
and first switching means MC1-1, MC1- which receives the detection signal S1 from the first magnetic piece detection means 24 and switches the excitation circuit 32 to apply the excessive excitation voltage V _H to the excitation coil. 2, MC1
-3, and when the excitation current reaches a value (I _S in FIG. 5C) that allows the magnetic piece to be attracted, the excessive excitation voltage V _H is changed to the normal excitation voltage V by the detection signal from the current detector 33. It is provided with second switching means MC2 and MC2-1 for switching the excitation circuit 32 so as to change the current to _S and apply it to the excitation coil.

Furthermore, the second magnetic piece detection means 29 described with reference to FIGS. 2 and 3 is electrically connected to the excitation circuit, and detects whether the magnetic piece that has been attracted and separated from the raw material has passed through the delivery path. The second magnetic piece detection means detects the magnetic piece, and the excitation current of the excitation circuit 32 is cut off in response to the detection signal S2 to restore the normal state. By this detection signal S2, the first and second switching means 24 and 29 (usually composed of switching magnetic contactors) are completely returned to their original states (OFF state), and the next magnetic piece is detected. will be in a state of waiting.

The current detector 33 includes a current sensor CS inserted in series with the excitation current of the excitation circuit 32, a current value signal voltage E from the current sensor, and a reference voltage E _S
a comparator 34 that performs a comparison with
It is composed of a driver 36 that drives 5,
Current value signal E from current sensor CS is the reference voltage
When Es is exceeded, the contact point of the second switching means MC2
It operates to switch MC2-1. That is, it operates to open the normally closed contact of contact MC2-1 and close the normally open contact.

Note that if very high precision is not required for controlling the excitation voltage, the above switching operation may be performed only by a switching means such as a current relay directly incorporated into the excitation circuit 32. It is possible.

Next, the operation of the magnetic separation device will be explained with reference to FIG.

When the raw materials move on the conveyor belt 19,
When the mixed magnetic piece passes through the first magnetic piece detection means 24, the detection means outputs a detection signal S1 shown in FIG. 5A.
emits. When the signal S1 is applied to the control device 30, the contacts MC1-1, MC1-2, MC1-3 of the first switching means are closed from the normal state shown in FIG. 4, and the excessive excitation voltage V _H of the terminal _P2 is closed. is supplied to the electromagnet 13.

An excitation current as shown by the dotted line in FIG. 5C flows through the electromagnet 13 and rapidly increases toward the excessive steady-state current I _H corresponding to the excessive excitation voltage V _H (FIG. 5B). That is, it shows a rapid rise that reaches the lower limit value I _L of the excitation current that can attract the magnetic piece in a very short time t ₁ .

Current value at which the excitation current normally corresponds to the excitation voltage Vs
Is, and when the output signal E of the current sensor CS exceeds the reference voltage Es set corresponding to the current value Is, the output of the comparator 34 changes to the driver 3.
6, the relay 35 is activated, and the contact MC2-1 of the second switching means is switched. That is, the fourth
The normally closed contact of MC2-1 in the figure opens, the normally open contact closes, and the voltage supplied to the electromagnet 13 is cut from the excessive excitation voltage V _H from terminal P ₂ to the normal excitation voltage V _s from terminal P ₁ . Change.

Such excessive excitation voltage V _H at the initial stage of excitation
The purpose of this provision is to speed up the initial rise of the excitation current and shorten the time t ₁ required to reach the current value I _L that can attract the magnetic piece.

That is, without using the initial excessive excitation voltage V _H ,
If only the normal excitation voltage V _s is applied, the excitation current will rise toward the normal steady current I _s corresponding to the voltage V _s as shown by the dotted line in FIG. Possible lower limit I _L
The time it takes to reach t becomes longer as shown by t ₂ .

To give a concrete numerical example, a conveyor with a belt width of 1.8 m is used, and the conveyance speed is 70 m/min for ore.
The electromagnet specifications when operating at 140 m/min for coal were as follows.

The excessive excitation voltage V _H was 620V DC, the excitation time t ₁ was 1 second, and the normal excitation voltage V _S was 350V DC.
Further, the values of the steady excitation current corresponding to these excitation voltages were I _H =129A and I _S =1001A, and the electric power was 80KW and 35.5KW, respectively.

Rise time t ₂ when no excessive excitation voltage is applied
is 7 seconds, and according to this specific example, this is expressed as t ₁ =
I was able to shorten it to 1 second.

According to the present invention, since the excessive excitation voltage V _H is initially applied, the rise time until the current value reaches the attractable current value is greatly shortened. It is possible to reduce the spacing between the magnetic separators and the magnetic separator, thereby making it possible to reduce the size and weight of the magnetic separation device. Since the application of the excessive excitation voltage V _H is performed only for the minimum necessary initial time, power is not wasted and the energy saving effect is excellent.

In this way, the electromagnet 13 is energized to attract and remove the magnetic pieces in the raw material, and the magnetic pieces are removed onto the chute 28.

When the removed magnetic piece passes through the second magnetic piece detection means 29 on the chute 28, its detection signal S
2, each contact MC1- of the first switching means
1, MC1-2, MC1-3 are opened, electromagnet 1
3 excitation is completed. At this time, the extinction of the excitation voltage and excitation current has characteristics as illustrated in FIGS. 5A, B, and C. After the excitation is completed, the next magnetic piece must arrive.

In the above embodiment, the application period of excessive excitation current at the initial stage of excitation is the period from when the current value on the way to rise is detected until it reaches the steady current I _S corresponding to the normal excitation voltage, and at this point the normal excitation voltage is applied. Although the configuration is configured to switch, this may be a method of setting the excessive excitation voltage application period to a predetermined period using a timer or the like in accordance with the rise characteristics of the excitation coil.

Further, in the above embodiment, the excitation is terminated by the detection signal S2 from the second magnetic piece detection means 29, but this is also possible by setting the application time of the excessive excitation voltage using a timer or the like. Similarly, it is also possible to set it using a timer or the like.

Further, the magnetic separator 12 is equipped with a suspended electromagnet having an evacuation mechanism using an endless belt 21, but it is possible to use other types of electromagnets depending on the structure of the unloader, the unloading capacity, or the mounting location. It is also possible to create a magnetic separator with an electromagnet. For example, 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 in-machine conveyor 10 can be adopted.

As is clear from the above description, according to the present invention, by applying an excitation voltage higher than the normal excitation voltage at the start of excitation to accelerate the rise of the excitation current, the mixed magnetic piece detection means and the magnetic separator can It is possible to obtain a method and apparatus for operating a magnetic separation apparatus, which can reduce the distance between the magnetic separators, reduce the size and weight of the apparatus, and easily mount it in a narrow space such as an unloader.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram illustrating the overall structure of an unloader equipped with a magnetic separation device suitable for applying the present invention, FIG. 2 is a schematic explanatory diagram showing an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing a cross section along the line - in FIG. 4, FIG. 4 is a circuit diagram illustrating the electric circuit configuration of a magnetic separation device control device according to an embodiment of the present invention, and FIG. 5 is an operating method of the present invention. This is a graph illustrating. 5... Unloader body, 7... Mount, 8...
...Accepting hopper, 9... Sending hopper, 10
...In-flight conveyor, 12...Magnetic separator, 13...
... Electromagnet, 19 ... Conveyor belt, 20 ... Magnetic action surface, 21 ... Endless belt, 24 ...
First magnetic piece detection means, 28... Shoot, 29
... second magnetic piece detection means, 30 ... control device,
31... DC power supply device, 32... Excitation circuit, 33
...Current detection circuit, MC1...First switching means,
MC2...second switching means, S1, S2...magnetic piece detection signal, _VH ...excessive excitation voltage, _VS ...pass excitation voltage, _IH ...excessive steady excitation current, _IS ...normal steady state Excitation current, t ₁ , t ₂ ...rise time.

Claims (1)

[Claims] 1. A method of operating a magnetic separator, in which a magnetic piece detection means detects the presence of magnetic pieces in raw materials, and the detection signal excites an excitation coil of a magnetic separator to attract and separate the magnetic pieces. In this method, when a detection signal of mixed magnetic pieces is issued from the magnetic piece detection means, an excessive excitation voltage higher than a normal excitation voltage capable of attracting a magnetic piece is applied to the excitation coil for a predetermined period to promote the rise of the excitation current. . A method of operating a magnetic separation apparatus, characterized in that the excessive excitation voltage is switched to the normal excitation voltage after the excitation current reaches a value that allows the magnetic piece to be attracted. 2. A second magnetic piece detection means is provided in the sending path of the magnetic pieces separated by attraction from the raw material, and excitation of the excitation coil of the magnetic separator is terminated by a magnetic piece passing signal from the detection means. A method of operating a magnetic separation device according to claim 1. 3. In the operation device of the magnetic separator, which detects the presence of magnetic pieces in the raw materials by means of a magnetic piece detection means, and uses this detection signal to excite the excitation coil of the magnetic separator to attract and separate the magnetic pieces, the magnetic pieces can be attracted. an excitation circuit connected to a source of a normal excitation voltage and an excessive excitation voltage greater than the normal excitation voltage;
a first switching means for switching the excitation circuit to apply the excessive excitation voltage to the excitation coil in response to a detection signal from the magnetic piece detection means; and a first switching means for switching the excitation circuit to apply the excessive excitation voltage to the excitation coil; a second switching means actuated by a timer to switch to a voltage. 4. A second magnetic piece detection means provided in the sending path of the magnetic piece separated by attraction from the raw material and electrically connected to the excitation circuit, and a magnetic piece passing signal is emitted from the second magnetic piece detection means. 4. The operating device for a magnetic separation device according to claim 3, further comprising means for switching said excitation circuit so as to terminate said excitation when said excitation occurs. 5. In the operation device of the magnetic separator, which detects the presence of magnetic pieces in the raw material by the magnetic piece detection means, and uses this detection signal to excite the excitation coil of the magnetic separator to attract and separate the magnetic pieces, the magnetic piece can be attracted. an excitation circuit connected to a supply source of a normal excitation voltage and a supply source of an excessive excitation voltage larger than the normal excitation voltage; a current detector inserted into the excitation circuit to detect an excitation current value; and the magnetic piece detection means. a first circuit that switches the excitation circuit to apply the excessive excitation voltage to the excitation coil in response to a detection signal from the excitation coil;
and a second switching means for switching the excitation circuit to apply the normal excitation voltage to the excitation coil in response to a signal from the current detector when the excitation current reaches a value that allows the magnetic piece to be attracted. , an operating device for a magnetic separation device. 6. A second magnetic piece detection means electrically connected to the excitation circuit provided in the sending path of the magnetic piece separated by attraction from the raw material, and a magnetic piece passing signal is emitted from the second magnetic piece detection means. a third switch that switches the excitation circuit to cut off the excitation when the
An operating device for a magnetic separation device according to claim 5, comprising a switching means.