JP2004141797A - Flotation method of pulverized coal, pulverized coal surface modification apparatus, and flotation system of pulverized coal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a floatation method or the like of pulverized coal capable of imparting floating a property even to pulverized coal whose bonding force to oil drops is weak, that is [H/C×100] value is ≤80, to be impossible to apply the floatation method heretofore thereby applying the floatation method, and reducing the quality of oil to be used in a pulverized coal precipitation. <P>SOLUTION: The floatation method of coal for recovering the pulverized coal (c) from coal slurry S2 containing fine powdery coal having [H/C×100] value of 0-80 and ≤0.5 mm particle diameter is constituted so as to include a oil addition process for adding floatation oil A to the coal slurry S2, a shearing process for rapidly stirring the coal slurry S2 to impart a shearing force to the pulverized coal and the oil drops (a) of the floatation oil A and a floatation process for floating the pulverized coal (c) after the shearing process to clean and recover. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a pulverized coal surface modification method, a pulverized coal flotation method, a pulverized coal surface modification apparatus, and a pulverized coal flotation system.
[0002]
[Prior art]
Pulverized coal used for pulverized coal combustion of coal is separated by specific gravity if it is 0.5 mm or more, while coal that is 0.5 mm or less forms coal slurry and is flotated from this coal slurry. The method (floating coal separation method) produces high quality clean coal with low non-combustible content.
[0003]
In this flotation method, a trapping agent and a foaming agent are added to a coal-water slurry (coal slurry), bubbles are formed mechanically or by air injection, and coal containing fine combustible components (pulverized coal) is added to the bubbles. In the method for producing a deashed high-concentration coal-water slurry, low-ash fine coal particles (pulverized coal) are collected as floating components, and so-called coal ash sludge (ash) with high ash is removed. It is used in a decalcification process in which sedimentation is performed (for example, see Patent Document 1).
[0004]
In the conventional flotation method, conditioning is performed before the flotation step in order to prevent sedimentation of the pulverized raw coal (pulverized coal). In this conditioning, gentle stirring is performed to homogenize the slurry and increase the probability that the pulverized coal and the oil droplets of the flotation oil associate with each other. The association between the pulverized coal and the oil droplets forms a water film on the surface of the pulverized coal. Replaced with oil slick.
[0005]
[Patent Document 1]
JP-A-7-11268 (page 3, left column, lines 33 to 45)
[0006]
[Problems to be solved by the invention]
However, in this conditioning with gentle stirring, the degree of coalification is low and there are many oxygen-containing functional groups, and there are too many hydrophilic groups on the surface of pulverized coal covered with a water film, or the degree of coalification is high and hydrogen content is high. When the amount is small and the surface energy of the pulverized coal surface is originally low, there is a problem that the water film on the pulverized coal surface is not sufficiently replaced with an oil film.
[0007]
In other words, there are various types of carbonaceous materials, and there is also a carbonaceous material having a poor flotation property (flotation flotation property) in which the water film on the surface of the pulverized coal is difficult to replace with an oil film. For example, FIG. 11 shows a carbonaceous diagram. In FIG. 11, a value [H / C × 100] of 100 times the atomic ratio of hydrogen atoms to carbon atoms on the vertical axis is 80 or more, and carbon atoms on the horizontal axis correspond to carbon atoms. Coal having an [O / C × 100] of about 7 or less, which is 100 times the atomic ratio of oxygen atoms, has a very good flotation property and easily replaces a water film on the surface of pulverized coal with an oil film. Not only good coal, but also so-called semi-anthracite with an [H / C × 100] of 60 or less, a coal type with poor flotation properties called anthracite, or a so-called sub-bituminous coal with an [O / C × 100] of 10 or more There are also many types of charcoal called “floatable” that have poor flotation properties.
[0008]
In more detail, in FIG. 11, the increase / decrease of the oxygen-containing functional group is shown in the horizontal axis [O / C × 100] direction, and this [O / C × 100] corresponds to the hydrophilicity such as hydroxyl group and carboxyl group. Since it is related to the functional group ratio, an increase in the value of [O / C × 100] means an increase in hydrophilicity, that is, a decrease in lipophilicity, and a decrease in flotation property.
[0009]
Further, the increase / decrease in the chaininess / aromaticity of the hydrocarbon is shown in the direction of the vertical axis [H / C × 100], and the decrease in [H / C × 100] indicates the saturation (chain-like) of the hydrocarbon. ) Shows the transition from hydrocarbons to unsaturated (aromatic) hydrocarbons, which reduces lipophilicity and reduces flotation.
[0010]
In the case of a high-rank coal having an [H / C × 100] value of about 80 or less, the chaininess characteristic of fats and oils is reduced, and the development of aromatic rings is advanced. Energy is also lower. In particular, in the case of so-called semi-anthracite and anthracite whose [H / C × 100] value is about 60 or less, the surface energy tends to be low. Therefore, even if the slurry is covered with a water film, the bonding force with water molecules is weak. However, at the same time, since the bonding strength with the oil droplets is also weak, the water film cannot be replaced with the oil film even with the oil droplets by gentle stirring, and the flotation property is poor. There is a problem that the law cannot be adopted.
[0011]
In general, when the flotation method is applied to coal whose flotation properties are not very good, the recovery of pulverized coal in the flotation machine is poor, and the flotation flotation speed is slow, so that the flotation Instead, a large amount of pulverized coal and a large amount of flotation oil added excessively flow to the drainage thickener, and the pulverized coal floats in the thickener to form a pulverized coal layer on the surface. As a result, the load exceeds the processing capacity of the thickener, resulting in an overload condition, which may cause contamination of the surrounding environment.
[0012]
The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to select a pulverized coal, which has a weak bonding force with an oil droplet and cannot apply a flotation method. [C × 100] values of about 60 or less, so-called semi-anthracite or anthracite, can also impart flotation properties to pulverized coal, making it possible to apply the flotation method and using a small amount of oil. It is an object of the present invention to provide a pulverized coal flotation method that can be used.
[0013]
A further object of the present invention is to provide a flotation pretreatment device and a pulverized coal flotation system used for carrying out the pulverized coal flotation method.
[0014]
[Means for Solving the Problems]
The pulverized coal flotation method of the present invention for achieving the above object is a pulverized coal flotation method for collecting pulverized coal from a coal slurry containing pulverized coal of 0.5 mm or less, An oil addition step of adding a flotation oil to the oil, and a shearing step of rapidly stirring the coal slurry to impart a shearing force to the particles of the pulverized coal and the oil droplets of the flotation oil after the oil addition step. A flotation step of flotting pulverized coal to recover clean coal after the sharing step, wherein the pulverized coal has a hydrogen atom ratio of 100 to 100% of hydrogen atoms to carbon atoms contained in the coal. The double value [H / C × 100] is 0 to 80.
[0015]
The fine coal of 0.5 mm or less refers to coal passing through a 0.5 mm square mesh.
[0016]
Further, the rapid stirring is for slow stirring by a conventional conditioner, and the stirring energy is 10 kW / m. ³ This means the above, preferably 25 kW / m ³ ~ 100 kW / m ³ It is.
[0017]
In other words, in the conditioner, the stirring is performed to homogenize the slurry for the purpose of preventing the sedimentation of the pulverized coal, and the stirring is performed slowly (for example, the stirring energy is several kW / m). ³ On the other hand, the rapid agitation according to the present invention uses particles of pulverized coal and oil droplets of flotation oil to fix a fixed portion (a cylindrical wall surface of a drum, a partition plate, a fixed blade) in a container (drum). Forcible contact with moving parts (stirring plates, stirring blades), etc., to apply shearing force, to adhere or spread oil droplets on the surface of pulverized coal particles, to improve the flotation of the surface of pulverized coal. In order to improve, a high stirring energy is used.
[0018]
According to the pulverized coal flotation method of the present invention, a shear active surface is formed on the particles of the pulverized coal and the oil droplets of the flotation oil by shearing (imparting a shear force) by rapid stirring. Due to the occurrence, the surface energy is relatively increased although it is transient. This increase in surface energy allows an oil film to form on the surface of the pulverized coal by association of the pulverized coal with the oil droplets.
[0019]
Therefore, the flotation method can be applied to so-called semi-anthracite and anthracite whose [H / C × 100] value is about 60 or less, which was not applicable in the prior art. In addition, the amount of flotation oil for forming the oil film is also small.
[0020]
In particular, a great effect is exhibited when the finely divided coal has a value of 100 times the hydrogen atom ratio [H / C × 100] of 0 to 80, which is the ratio of hydrogen atoms to carbon atoms contained in the coal. . This is because the flotation property of the coal type in this range is not good, and the reforming effect of the shearing step of the present invention is large.
[0021]
In the oil addition step, the amount of the flotation oil is 0.005% to 0.05%, preferably 0.007% to 0.02% by weight based on dry raw coal. In particular, in the case of poorly lipophilic carbonaceous materials such as semi-anthracite and anthracite, the amount of oil that adheres even after reforming is smaller than that of the originally good oleophilicity, so the amount added is very small. Only needs to be done. Thereby, flotation of pulverized coal can be performed efficiently and the load of wastewater treatment can be reduced.
[0022]
The pulverized coal surface reforming apparatus and the pulverized coal flotation system used for performing the pulverized coal surface modification method and the pulverized coal flotation method described above are configured as follows.
[0023]
First, the pulverized coal surface reforming device is a rapid stirring device that performs a shearing process before the pulverized coal flotation process, and is provided with a plurality of partition plates having a flow path at the center inside a cylindrical drum. A rotating shaft having a plurality of agitating plates with agitating blades for rotating the agitating chamber and agitating the coal slurry in the drum while forming a plurality of agitating chambers communicating with each other at the center; It is configured by setting.
[0024]
In this pulverized coal surface reforming apparatus, the stirring blade of the stirring plate is provided so as to protrude from the stirring plate in the axial direction of the rotating shaft, and when viewed from the axial direction of the rotating shaft, the stirring blade rotates. It is formed in a shape in which the front side is convex with respect to the direction.
[0025]
Further, a circulation hole is provided near the rotation shaft of the stirring plate.
[0026]
In the above pulverized coal surface reforming apparatus, at least one of the partition plates is provided with fixed blades protruding in the axial direction of the rotating shaft.
[0027]
The pulverized coal flotation system includes a surface modification unit and a flotation processing unit, and the surface modification unit includes any one of the pulverized coal surface modification device and the flotation oil. A supply system, wherein the flotation processing unit includes at least one flotation machine.
[0028]
In addition, the above-mentioned pulverized coal flotation method, the pretreatment device for flotation and the pulverized coal surface reforming method used in the pulverized coal flotation system are used for combustible coal slurry containing pulverized coal of 0.5 mm or less. A surface modification method for pulverized coal that increases the flotation property of pulverized coal containing a large amount of coal, by rapidly stirring a coal slurry to which flotation oil has been added in a container to remove particles of pulverized coal and flotation oil. This is a method in which an oil droplet is attached to the surface of pulverized coal particles by applying a shearing force to the oil droplet. The application of the shearing force is performed by bringing the particles of the pulverized coal and the oil droplets of the flotation oil into contact with at least one of the fixed part and the moving part in the container by rapid stirring.
[0029]
BEST MODE FOR CARRYING OUT THE INVENTION
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a pulverized coal flotation method, a flotation pretreatment device, and a pulverized coal flotation system according to the present invention will be described with reference to the drawings.
[0030]
First, a pulverized coal flotation method and a pulverized coal flotation system for performing the method will be described, together with a brief description of the flotation pretreatment device according to the present invention.
[0031]
FIG. 1 shows a process flow of a pulverized coal flotation system 1 for carrying out the pulverized coal flotation method of the present invention. FIG. 2 shows the principle of flotation performed by this pulverized coal flotation method.
[0032]
As shown in FIG. 1 and FIG. 2, the pulverized coal flotation system 1 is a system for the purpose of recovering pulverized coal C having a low ash content (clean coal recovery) from a coal slurry S1 of 0.5 mm or less, It comprises a surface modification unit 10 and a flotation processing unit 20.
[0033]
The surface reforming unit 10 includes a slurry adjusting tank (coal slurry receiving tank) 11, a slurry pump 12, a flotation oil tank 13, a flotation oil constant supply pump 14, a pulverized coal surface reforming device 15, a sump tank 16, a slurry It is composed of a pump 17 and the like.
[0034]
Further, the flotation processing unit 20 includes a conditioning tank (condition tank) 21, a foaming agent tank 22, a foaming agent constant supply pump 23, a roughing flotation machine 24, a fine screening flotation machine 25, a vacuum filtration machine 26, and the like. It consists of.
[0035]
In the surface reforming section 10, a coal slurry S1 obtained by mixing pulverized coal, which has been pulverized in advance and has a particle size of 0.5 mm or less (in practice, a mesh having a size of 0.5 mm square) with water, is mixed. Enters the slurry adjustment tank 11 and is supplied to the pulverized coal surface reforming device 15 by the slurry pump 12. Further, the flotation oil A is supplied by the flotation oil supply system including the flotation oil tank 13 and the flotation oil constant supply pump 14, and is added to the coal slurry S1 before being supplied to the pulverized coal surface reforming device 15. The coal slurry S1 is mixed and supplied to the pulverized coal surface reforming device 15 as a mixture S2 with the flotation oil A. This state is the state of (mixing) shown in FIG. 2, in which pulverized coal c, ash d, and oil droplets (flotation oil) a are mixed.
[0036]
As the flotation oil A, mineral oils such as kerosene and light oil can be mainly used. Depending on the carbonaceous quality, semi-anthracite or anthracite with low lipophilicity is 0.005% by weight based on the slurry S1. Pulverized coal floss can be formed in the flotation machines 24 and 25 by adding a very small amount of the flotation oil A of from 0.005% to 0.05%, preferably from 0.007% to 0.02%.
[0037]
Then, the mixture S2 of the coal slurry S1 and the flotation oil A is rapidly stirred in the pulverized coal surface reforming device 15. That is, the stirring energy is 10 kW / m ³ Above, preferably 25 kW / m ³ ~ 100 kW / m ³ Stirring is performed so that
[0038]
By this rapid stirring, the coal slurry S1 and the oil droplet a are mixed to highly disperse the oil droplet a in the coal slurry S1, and the particles c and the oil droplet a of the pulverized coal are shown in FIGS. By bringing the surface of the pulverized coal surface reforming device 15 into contact with the surfaces of the cylindrical wall surface 41a, the partition plate 42, the stirring plate 52, and the like, a strong shearing force is applied to the pulverized coal particles c and the oil droplets a. Then, as shown in FIG. 2 (surface modification), a very thin oil film a is adhered or spread on the surface of the particles c of the pulverized coal. By this oil film spreading, the wettability of the surface of the pulverized coal c is modified to improve flotation.
[0039]
Then, in the pulverized coal surface reforming device 15, the surface of the pulverized coal c is reformed, and the modified coal slurry S3 in a state where the oil film a adheres to the pulverized coal c is, as shown in FIG. It enters the tank 16 and is sent to the conditioning tank 21 of the flotation unit 20 by the slurry pump 17.
[0040]
Then, in the conditioning tank 21, the foaming agent B supplied by the foaming agent system including the foaming agent tank 22 and the foaming agent constant supply pump 23 is added to the modified coal slurry S3. In the conventional flotation process of the prior art, the foaming agent B and the flotation oil A are added in the conditioning tank 21. However, in this flotation system 1, the flotation is already performed before the pulverized coal surface reforming device 15. Since the oil A is added, the conditioning tank 21 does not add the flotation oil A with only the foaming agent B.
[0041]
The foaming agent B is for foaming the modified coal slurry S3, and pine oil, terpineol, polyoxypropylene alkyl ether, higher alcohol, and the like can be used.
[0042]
In the conditioning tank 21, the modified coal slurry S3 is homogenized by gentle stirring, and the pulverized coal c is brought into contact with the foaming agent B and the oil droplets a and combined. By the gentle stirring, the adjusted coal slurry S4 is sequentially sent to the rough-selection flotation machine 24 and the fine-selection flotation machine 25.
[0043]
In the flotation machines 24 and 25, the low-ash pulverized coal c to which the oil film a has adhered has adhered to the bubbles e generated by the foaming agent B, as shown in FIG. Since it floats, it is collected as a floating fraction, and the floated pulverized coal c is separated by a thickener (not shown) or the like, and collected as pulverized clean coal C.
[0044]
The ash d, on the other hand, has higher hydrophilicity than the pulverized coal c, and sinks without floating, and is separated as the coal sludge D. This coking sludge D is sent to the vacuum filter 26 and separated from the water W, and is discarded or reused as a raw material of “low-grade coal-water slurry”. On the other hand, the water W from which the coking sludge D has been separated is reused as water for the coal slurry.
[0045]
Therefore, according to the pulverized coal flotation system 1, the pulverized coal surface reforming apparatus 15 reforms the mixture S3 of the coal slurry S2 and the flotation oil A to thereby improve the flotation clean coal recovery rate and the flotation flotation. Speed can be greatly improved. In addition, since the solid content in the wastewater can be reduced by improving the recovery rate, the wastewater load in the coal preparation plant can be reduced.
[0046]
In addition, the pulverized coal flotation method and the pulverized coal flotation system 1 according to the present invention can support a wide range of slurry concentrations from concentrated flotation to direct flotation, By improving the flotation properties by this surface modification, the flotation method can be applied to coal with poor flotation properties, which was difficult to recover. It can be performed efficiently.
[0047]
Next, the pulverized coal flotation method and the pulverized coal surface modification method which plays an important role in the pulverized coal flotation system 1 of the present invention and the pulverized coal surface modification apparatus 15 for carrying out this method will be described. I do.
[0048]
The pulverized coal surface reforming device 15 is configured as a horizontal multi-stage high-speed mixer, as shown in FIG. The horizontal multi-stage high-speed mixer 15 includes a drum 41 supported on a base by supporting legs 47, a motor 61 and a speed reducer 62, and is provided with a stirring shaft provided on a rotating shaft 51 driven by the motor 61. By rotating the plate 52 at high speed, the pulverized coal particles c and the oil droplets a in the pulverized coal slurry S2 are brought into contact with the cylindrical wall surface 41a, the partition plate 42, the agitating plate 52, etc., and a shear force is applied to remove the pulverized coal. Reform.
[0049]
More specifically, in the pulverized coal surface reforming apparatus 15, a partition plate (baffle) 42 as shown in FIG. They are provided at substantially equal intervals. The partition plate 42 is formed in a disk shape in which two upper and lower semi-circles are arranged facing each other, the outer peripheral side is fixedly supported on the cylindrical wall surface 41a of the drum 41, and the coal slurry S2 and the flotation are provided at the center. A flow passage 43 through which the oil mixture S3 and the air E flow is provided. The reason why the partition plate 42 is composed of two upper and lower semicircles is to facilitate assembly and disassembly.
[0050]
Further, in the partition plates 42a and 42b provided near the inlet 44 of the coal slurry S1, band-shaped or rectangular fixed blades 48 are protruded from the disk in a substantially vertical direction. In FIG. 4, in order to promote agitation of the mixture S3, fixed blades 48 are provided on both surfaces of the partition plate 42a, and a plurality of fixed blades 48 are provided only on one surface of the partition plate 42b on the inlet 44 side (3 in FIG. 5). ) Are provided.
[0051]
A rotating shaft 51 pivotally supported by bearings 46 on both sides of the drum 41 is disposed inside the drum 41. The rotating shaft 51 has a stirring blade 53 as shown in FIGS. And a stirring plate 52 having a flow hole 54 are fitted through a boss 52a. The stirring plates 52 are provided perpendicular to the axial direction of the rotating shaft 51 and are arranged at substantially equal intervals in the axial direction of the rotating shaft 51. Thus, when the stirring plates 52 are disposed in the drum 41, the respective stirring plates 52 are disposed in the respective stirring chambers 50 partitioned by the partition plates 42.
[0052]
In order to increase the stirring efficiency, the stirrer blades 53 are arranged such that the belt-shaped body formed to be convex and radial with respect to the rotation direction R is substantially perpendicular to the stirrer plate 52 on both sides of the stirrer plate 52. , That is, in the axial direction of the rotating shaft 51. The plurality of (four in FIG. 6) stirring blades 53 are provided at substantially equal intervals in the rotation direction of the rotating shaft 51.
[0053]
The surfaces of the drum 41 that come into contact with the mixture S2, that is, the surfaces of the cylindrical wall surface 41a, the partition plate 42, the fixed blade 48, the stirring plate 52, and the stirring blade 53 are in contact with the pulverized coal c and the oil droplet a. A ceramic lining 60 of alumina or the like is applied to efficiently apply a shearing force and to prevent abrasion due to contact with the pulverized coal c. The grid-like hatching in the figure indicates that the ceramic lining 60 is provided, and although the figure is partially grid-like hatched, it is provided on the entire surface.
[0054]
The rotating shaft 51 is connected to the speed reducer 62 by the chain coupling 64, and the speed reducer 62 is connected to the motor 61 by the chain coupling 63.
[0055]
The size and shape of the pulverized coal surface reforming apparatus 10 vary greatly depending on the quality and amount of carbon to be treated, but as an example, the diameter of the drum 41 shown in FIG. 4 is about 1.3 mφ.
[0056]
Next, a shearing process using the pulverized coal surface reforming apparatus 10 will be described.
[0057]
In the pulverized coal surface reforming apparatus 10, the mixture S2 of the coal slurry S1 and the flotation oil A is supplied into the drum 41 from the inlet 44, and the rotating shaft 51 is rotated at a high speed, whereby the coal supplied from the inlet 44 is supplied. The mixture S2 of the slurry S1 and the floating oil A is stirred at high speed. Due to this high-speed stirring, the mixture S2 passes through the flow passage 43, the gap between the stirring plate 52 and the cylindrical wall surface 41a, etc., while being rapidly stirred by the stirring plate 52 that rotates together with the rotation of the rotating shaft 51, and is sequentially downstream. And is converted into a modified coal slurry S3 and discharged from the outlet 45.
[0058]
By the rapid stirring in the drum 41, the pulverized coal c and the oil droplet a are highly dispersed, and the pulverized coal c and the oil droplet a are separated from the cylindrical wall surface 41a, the partition plate 42, the fixed blade 43, the stirring plate 52, and the stirring blade. 53 and the like. By this contact, a strong shearing force is applied to the pulverized coal c and the oil droplet a, and a very thin oil film a is spread on the surface of the pulverized coal c. This oil film a improves and improves the wettability of the surface of the pulverized coal c, increases the lipophilicity of the surface of the pulverized coal c, and dramatically improves flotation.
[0059]
This shearing force (shearing) is rapid stirring unlike conditioning, so that a shearing force is applied to the pulverized coal particles c and the oil droplets a to induce a shear surface. At the moment when the shear surface is generated, the surface energy is instantaneously and transiently high, so that the oil droplets a can easily adhere to the particles c of the pulverized coal. That is, at the moment when the shear surface is generated, it is considered that water and oil are excluded from the shear surface and the shear surface is in a state close to a vacuum.
[0060]
Further, according to the structure of the pulverized coal surface reforming device 15, the partition plates 42 and the stirring plates 52 are alternately arranged. Short path can be prevented, and efficient mixing and application of shear force by contact can be performed. By applying the shearing force by the mixing and the contact, the oil droplet a can be efficiently attached to the surface of the pulverized coal c. Therefore, the surface of the pulverized coal c can be modified with a small amount of the flotation oil A and in a short time.
[0061]
Therefore, the pulverized coal surface reforming device 15 having this configuration is a very compact device, and requires less installation space. Therefore, even in the existing pulverized coal flotation system, it can be easily incorporated in the pre-stage of the flotation process.
[0062]
Next, examples of the present invention will be described.
[0063]
FIG. 8 shows an example of the surface modification effect of applying the pulverized coal flotation method of the present invention to pulverized coal having poor flotation properties. According to FIG. 8, the flotation time related to the yield of the clean coal and the flotation speed in the flotation method is shown by comparing the embodiment of the present flotation method with the comparative example of the conventional flotation method. It can be seen that is greatly improved.
[0064]
FIG. 9 shows the material balance of the example and the comparative example. In the example, while the yield of clean coal is increased as compared to the comparative example, the ash content of the tailing is increased, and the combustible coal and incombustible ash are separated with extremely high efficiency. I understand. As a result, it can be seen that the outflow of coal that should be originally recovered to the tailing is reduced, and consequently the concentration in the downstream thickener, the dewatering of the concentrated tailing, and the use of the circulating water of the overflow water can be performed smoothly.
[0065]
【The invention's effect】
As is clear from the above description, the pulverized coal flotation method, pulverized coal surface reforming apparatus, and pulverized coal flotation system according to the present invention can provide the following effects.
[0066]
In the conventional pulverized coal flotation method of the prior art, the value of the hydrogen atom ratio [H / C × 100], which is the ratio of hydrogen to carbon, which was unrecoverable at zero yield, seems to be 80 or less. Even with a high coal quality, the flotation property of pulverized coal can be greatly improved in the shearing step before the flotation step, so that a high clean coal recovery rate can be realized.
[0067]
In addition, a thin oil film can be efficiently attached to coal by the sharing process, so that the amount of oil used is small compared to the conventional ordinary flotation method.
[0068]
In addition, the flotation flotation speed has been greatly improved, and the residence time in the flotation machine can be reduced, so that the number of flotation machines can be reduced. The operation at is possible.
[0069]
In addition, pulverized coal and flotation oil do not float on the surface of the thickener downstream of the pulverized coal flotation system of the present invention, and the drainage load is reduced. Smooth operation can be performed throughout the downstream wastewater treatment system. That is, the load on the drainage system is reduced by achieving good flotation properties, and smooth factory operation and reduction of environmental load can be achieved.
[0070]
According to the pulverized coal surface reforming apparatus according to the present invention, the mixture of the coal slurry and the flotation oil can be stirred to impart a shearing force to the pulverized coal and the like, thereby improving the flotation property of the pulverized coal, and With the configuration of the plurality of partition plates and the plurality of stirring plates, pulverized coal can be modified very efficiently. As a result, the device becomes very compact, and the installation place is reduced. Therefore, even in the existing pulverized coal flotation system, it can be easily incorporated in the pre-stage of the flotation process.
[0071]
Further, according to the pulverized coal surface reforming apparatus, high flotation properties can be imparted to the pulverized coal, so that the residence time in the flotation machine can be shortened. Therefore, the capacity and number of flotation machines can be reduced or reduced, and the power consumption required for flotation machine operation can be reduced.
[Brief description of the drawings]
FIG. 1 is a diagram showing a process flow of a pulverized coal flotation system for carrying out a pulverized coal flotation method according to the present invention.
FIG. 2 shows the principle of flotation performed by the pulverized coal flotation method according to the present invention.
FIG. 3 is a view schematically showing a pulverized coal surface reforming apparatus according to the present invention.
FIG. 4 is a side view showing a cross section of the pulverized coal surface reforming apparatus of FIG.
FIG. 5 is a view taken in the direction of arrows XX in FIG. 4;
FIG. 6 is a diagram showing a stirring plate and a stirring blade of the pulverized coal surface reforming device.
FIG. 7 is a side sectional view showing the shape of the stirring blade, and the lower half is an end view of the stirring plate showing the shape of the stirring plate.
FIG. 8 is a diagram showing the relationship between the floating time and the yield in the example and the comparative example.
FIG. 9 is a graph showing yields in an example (charcoal A) and a comparative example (charcoal A).
FIG. 10 is a diagram showing the weight ratios of raw coal before flotation and components of modified coal after application of the pulverized coal flotation method of the present invention in Example (A coal).
FIG. 11 is a coal quality diagram showing the relationship between the type of F coal and the atomic ratio of its elemental components.
[Explanation of symbols]
10 Surface modification section
15 Pulverized coal surface reformer
20 Flotation processing section
41 drums
42 Divider
43 Flow passage
48 fixed wing
50 Stirring chamber
51 Rotary axis
52 stir plate
53 stirring blade
A flotation oil
C Clean coal
D Settling sludge
E air
a oil drop
c Pulverized coal
d ash
e bubbles
S1 Coal slurry
S2 Mixture of coal slurry and flotation oil
S3 Reformed coal slurry
S4 Adjusted coal slurry

Claims (7)

A pulverized coal flotation method for recovering pulverized coal from coal slurry containing pulverized coal of 0.5 mm or less, comprising: an oil addition step of adding flotation oil to the coal slurry; and A shearing step of rapidly agitating a coal slurry to apply a shearing force to particles of pulverized coal and oil droplets of flotation oil; and a floating step of recovering clean coal by floating pulverized coal after the shearing step. And a selection step, wherein the finely divided coal has a value of 100 times the hydrogen atom ratio [H / C × 100], which is a ratio of hydrogen atoms to carbon atoms contained in the coal, being 0 to 80. A feature of pulverized coal flotation. 2. The flotation of pulverized coal according to claim 1, wherein in the oil addition step, an amount of the flotation oil is 0.005% to 0.05% by weight based on dry raw coal. 3. Method. A rapid stirring apparatus for performing a shearing step before a pulverized coal flotation step, wherein a plurality of partition plates having a flow path at the center are provided inside a cylindrical drum, and a plurality of stirring chambers communicating with each other at a central portion are provided. And a rotating shaft having a plurality of agitating plates with agitating blades for rotating in the agitating chamber and rapidly agitating the coal slurry in the drum is disposed in the flow passage. Surface modification equipment. The stirring blade of the stirring plate is provided so as to protrude from the stirring plate in the axial direction of the rotating shaft, and when viewed from the axial direction of the rotating shaft, the front side is convex with respect to the rotating direction of the stirring plate. The pulverized coal surface reforming apparatus according to claim 3, wherein the apparatus is formed in a shape. The pulverized coal surface reforming apparatus according to claim 3, wherein a circulation hole is provided near the rotation axis of the stirring plate. The pulverized coal surface reforming apparatus according to any one of claims 3 to 5, wherein a fixed wing protruding in an axial direction of the rotating shaft is provided on at least one of the partition plates. A surface modification unit and a flotation processing unit, wherein the surface modification unit includes a pulverized coal surface modification device and a flotation oil supply system according to any one of claims 3 to 6, A pulverized coal flotation system, wherein the flotation processing unit includes at least one flotation machine.

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