JPS586254A - Screening and separating system for rock and stone included in coal - Google Patents

Abstract

PURPOSE:To screen coal and rocks and stones continuously without requiring large scale installations and costs by screening and separating the rocks and stones included in coal by the utilization of differences in magnetism between the coal and the rocks and stones. CONSTITUTION:Lumps are supplied by each piece from an aligning machine 8 on a screening conveyor 9 of a non-magnetic material such as belt conveyor, and are passed through a detector 10 consisting of a transmission part 10a creating high-frequency magnetic fields and a reception part 10b. The magnetism possessed by rocks and stones is detected by this, and a signal is outputted to a distributor 12 which distributes the coal to a coal crusher 13 side and the lumps of the rocks and stones to a foreign matter conveyor 14 side. The coal and the rocks and stones are screened efficiently and economically with such simple device and operations.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for sorting and separating rocks mixed in coal.

In recent years, with the international energy transition, there has been a significant increase in the import of thermal coal domestically as a fuel for thermal power plants, general industrial boilers, kiln heating furnaces, combustion furnaces, civil use, etc. .

Conventionally, domestic coal has been produced in thin layers and is produced through underground mining, so raw coal contains a large amount of foreign substances such as rocks. For this reason, the purified coal was shipped to the market after undergoing coal cleaning treatment mainly using the specific gravity sorting method, and there was no contamination with rocks, etc.

On the other hand, foreign coal imported for fuel is spread over a wide area.
In addition, since coal that is present in thick coal seams is mined in large quantities using open pit mining methods, there is relatively little foreign matter such as rocks mixed into the raw coal, so coal preparation processing that requires a large amount of expense and equipment is not possible. Most of the products are shipped without being processed.

Therefore, imported coal contains a small amount of lumpy rock.

This lumpy rock is unfavorable in terms of coal usage, such as loss of unnecessary crushing energy in the pulverization process, decrease in calories due to increased ash content, and increase in fly ash in the combustion process, efficiency, maintenance, and environmental pollution. , it is desirable to eliminate as much as possible before use.

However, it is economically disadvantageous to adopt wet coal washing methods that utilize differences in specific gravity, such as jigs and heavy liquid coal washing, in order to remove rocks with relatively low contamination rates from large amounts of coal, and In many cases, it is difficult to process due to environmental and locational conditions.

In addition, the adoption of dry coal preparation with a preferential crushing method that takes advantage of the difference in the crushability of coal and rock means that coal that has been naturally subjected to preferential crushing during various transportation processes from the production area can be transported to the place of use. This means that re-crushing and sorting will be carried out in the process, which may lead to forced crushing of the rock and increase the ash content, and depending on the quality of the carbonaceous rock, sorting may not be possible at all.

The present invention focuses on the fact that coal and rock have a difference in magnetism (magnetic permeability), and utilizes this to mix rock into a large amount of coal at a relatively low rate, requiring large-scale equipment and expense. Without,
The purpose is to provide a method for continuous sorting and separation.

In other words, the present invention utilizes this fact to demonstrate that the rock mixed in coal has some magnetism, but that coal has no magnetism at all. The principle is to sort and separate the mixed rocks\.

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

FIG. 1 shows an embodiment of the present invention, in which a coal storage yard 1 is provided with a coal delivery conveyor 2, and this coal delivery conveyor 2 delivers coal from the coal storage yard 1 and supplies it to a sieving machine 3. The sieve separator 3 is a vibrating sieve having sieve meshes set in advance according to the ash composition of the coal particles to be supplied, and separates the coal supplied from the coal discharging conveyor 2 into a relatively small amount of sifted product (4). It is classified into blocky sieve souvenirs with a high rock content (B).

An under-sieve product conveyor 4 is installed below the sieve machine 3 so as to be connected to a predetermined bunker 5, and an under-sieve product (a) of the sieve machine 3 is connected to a predetermined bunker 5.
received and transported to Bunker 5.

On the other hand, a sieve souvenir conveyor 6 for receiving the sieved souvenirs (hulls) of the sieving machine 3 is connected to the cylindrical sieve 7, and the sieved souvenirs (hulls) are supplied to the cylindrical sieve 7.The cylindrical sieve 7 has large sieve openings. This is to remove large foreign matter C such as large blocks of rock and wood chips, and the product after removing the large foreign matter C is supplied to the sorting machine 8 as a sorting target. In some cases, it may not be necessary.

In this embodiment, the sorting machine 8 is composed of a specially shaped gutter and a vibrator, and aligns the supplied lump-like products in a line, and supplies them one by one to the sorting conveyor 9. This alignment machine 8 may be any other type of device as long as it has an alignment function.

The sorting conveyor 9 is provided with a detection device 10 that detects mixed rocks by utilizing the magnetic difference between coal and rocks, and a distribution device 12 that distributes each lump of product into coal and rocks is provided at the subsequent stage.

The sorting conveyor 9 is a conveyor made of a non-magnetic material such as a belt conveyor, and by increasing or decreasing its speed, the interval between the lumps supplied one by one from the aligning machine 8 can be freely set. The detection device 10 includes a transmitter 10a that generates a high frequency magnetic field.
and a receiving section 10b, and when the lumps of rocks mixed in the coal conveyed at regular intervals on the sorting conveyor 9 pass between the transmitting section 10a and the receiving section 10b of the detection device 10, the rocks are The detection output generated by the magnetism of the receiving unit 1
0b, the signal is received and amplified, and a signal for cutting through the distribution device 12 is output according to a preset determination value. The distribution device 12 receives a switching signal sent through a signal port-path 11 connected to the detection device 10, and transfers the coal lumps to the coal crusher 13 side and the rock blocks to the foreign matter conveyor 14. This is a switching damper that switches and distributes the coal block or rock block to the side, and there is a time delay of about 10 seconds to 1 minute from when the coal lump or rock block passes through the detection device 10 until it arrives at the distribution device 12, and the switching signal is sent. It is operated in conjunction with. This time delay is provided by a timer, such as a monostable multivibrator, in the signal circuit 11. Note that other types of distribution device 12, such as a switching tripper, can be used. Coal crusher 1
3 is appropriately selected depending on the size of coal.

The coal sent from the distribution device 12 to the coal crusher 13 is crushed into a predetermined size and then fed into the sieved product conveyor 4, where it joins the sieved product (4) of the sieve separator 3 and is transferred to the sifter 5. Transport to.

The foreign matter conveyor 14 carries large foreign matter C removed by the cylindrical sieve 7.
and the rocks discharged from the distribution device 12 are transported to the foreign matter hopper 15.

Above, an example of single-row group detection/stem using the sorting machine 8 has been described. , detecting the presence of mixed rock, separating the part containing rock lumps, and then feeding this part containing rock lumps to a secondary and tertiary sorting conveyor to repeat the sorting and convergence to separate rocks and coal. You can also do it.

Figure 2 shows an example of the structure of a detection coil for detecting rocks mixed in coal. Coil 21 is an excitation coil. An alternating current l) having an angular frequency) is flowing through the coil 21, and an alternating magnetic field H (e) is generated.

Coil 22. Coil 23 is a receiving coil. coil 2
2 and 23 are mutually connected with opposite polarities to form a set of receiving coils, but each coil is equal in size and located at a three-dimensionally symmetrical position with respect to the excitation coil 21. arranged in a relationship. Therefore, the magnitudes of the voltages induced in the coils 22 and 23 by the magnetic field H (e) are approximately equal.

As a result, when there is no rock between the excitation coil 21 and the coils 22 and 23, the output terminals a-b of the receiving coil have
Each of these induced voltages cancels out and no output voltage is generated.
It maintains a so-called zero equilibrium state. Now, when the above-mentioned mixed rock mass P passes in the direction of the arrow through the space constituted by the excitation coil 21 and the receiving coils 22 and 23 in this state,
Depending on the magnetic permeability or conductivity of the mixed rock mass P, a change occurs in the strength of the magnetic field (H) at a position interlinked with the mixed rock mass P, and the amount of interlinked magnetic flux between the coils 22 and 23 differs. occurs, so a voltage detection signal corresponding to this difference is sent to the output terminals a and b of the receiving coils 22 and 23. It closes and appears.

In a similar situation, if a lump of coal is passed instead of the above-mentioned mixed rock lump P, it has almost no effect on the magnetic field due to its electrical properties, so no change in the strength of the magnetic field occurs. It has been confirmed that, if any changes occur, they are extremely small.

Therefore, by comparing the amplitudes of the output voltages generated at the output terminals a and b of the receiving coils 22 and 23 in both cases and distinguishing this difference, it is possible to selectively detect the rock mass P mixed in the coal. .

Output voltage e of the coils 22 and 23 described above. has phase characteristics determined by the respective magnitudes of magnetic permeability and electrical conductivity of the mixed rock. In the present invention, by utilizing this change in phase characteristics, it is possible to more effectively select and detect mixed rocks in coal.

FIG. 3 is a block diagram showing an example of a detection device 30 (ie, the detection device 10) for implementing the present invention. In FIG. 3, the detection coil 32 is the same as that shown in FIG. The 0 output from the detection coil 32 has a phase characteristic as described above. The phase discrimination section 33 performs phase discrimination according to the phase change of SI0 using the phase reference voltage SI, and also performs amplitude discrimination according to the amplitude change of eQ by removing the normally used amplitude limiter, for example. It also has functions that allow you to do so. The oscillating section 11 supplies an excitation current i to the excitation coil 21 side of the detection coil 32, and supplies reference voltage power e to the phase shift section 34.
creates a phase reference voltage a8 from e and sends it to the phase discriminator 3
Lead to 3. Therefore, a mixed rock mass P to be detected is placed on the detection coil 32, and in this state, the phase shifter 34 is adjusted so that the output Eo becomes maximum, and the phase angle of the phase reference voltage is determined. By setting , it is possible to select and detect mixed rocks with extremely high sensitivity.

As is clear from the above, in the present invention, coal is sieved through a sieve mesh that is preset according to the ash composition by particle size, and a sieve with a relatively small amount and high rock mass content obtained by sieving. Since the process is carried out using a continuous sorting and separation method that uses the magnetic difference between the coal and rocks in the souvenirs to detect mixed rock lumps, there is no need for large-scale equipment such as the conventional gravity sorting method or flotation sorting method. Rocks can be efficiently and economically removed from a large amount of coal. Furthermore, since no water is used, there is no problem with sewage treatment, and there is little noise and dust generation, resulting in no environmental pollution. This prevents energy loss during the pulverization process when using coal and contributes to reducing the amount of ash generated during combustion.

[Brief explanation of drawings]

Fig. 1 is a system diagram showing an embodiment of the present invention, Fig. 2 is a perspective view showing a structural example of a detection coil used in the invention, and Fig. 3 is a block diagram showing a specific example of a detection device used in the invention. It is. 1...Coal storage yard, 2...Coal delivery conveyor, 3.
... Sieving machine, 4... Under-sieve product conveyor, 5... Bunker, 6... Sieve souvenir conveyor, 7... Cylindrical sieve, 8
... Sorting machine, 9... Sorting conveyor, 10... Detection device, 11... Signal circuit, 12... Distribution device, 13
... Coal crusher, 14 ... Foreign matter conveyor, 15 ...
・Foreign object hopper, 21...excitation coil, 22, 23・
...Receiving coil, 31... Shooting section, 32... Detection coil, 33... Phase discrimination section, 34... Phase shifting section. Patent applicant: Furukawa Mining Co., Ltd. Agent: Manabu Inuzuka, Nissin Electronics Co., Ltd.

Claims (1)

[Claims] a sorting conveyor made of a non-magnetic material; and a classifying means for supplying coal mixed with rock lumps that has been sieved using a sieve machine having sieve meshes set according to the ash content composition by particle size to the sorting conveyor; a detection means attached to the sorting conveyor and configured to detect mixed rock from the coal conveyed by the sorting conveyor by utilizing a difference in magnetism between the coal and the mixed rock and output a detection signal; and a sorting and separating means for sorting and separating the mixed rock from the coal by supplying the detection signal to a distributing device that separates the mixed rock from the coal.