JP6141740B2 - Demineralization method and deashing apparatus for brown coal - Google Patents

Description

  The present invention relates to a method for deashing coal removal from lignite and a deashing coal preparation apparatus. That is, it is related with the deashing coal selection method and the deashing coal selection apparatus which select and isolate | separate the coal organic substance and coal inorganic substance (ash content) of brown coal powder using the difference in wettability.

《Technical background》
Brown coal, which is a low-grade coal with a low degree of coalification, has a high degree of oxidation and is brittle, so it has to be a powder-based coal selection.
That is, industrially targeted lignite is either powdered or pulverized to form powder, and is composed of coal organic matter and coal inorganic matter. Coal organic matter has an organic polymer structure with carbon, hydrogen, and oxygen as main constituent elements, and coal inorganic matter mainly consists of clay and minerals.
And as for the coal selection method that separates and sorts coal organic matter (sub-bituminous coal, which is refined coal) from coal inorganic matter (ash), there is a specific gravity selection method, but flotation is typical. It is. An example of a coal selection method that can be industrially established is flotation.

<Conventional technology>
In flotation, bubbles are generated by adding a foaming agent and blowing air into brown coal powder that has been slurried by adding water. The coal organic matter then adheres to the foaming agent around the bubbles and floats, whereas the hydrophilic coal inorganic matter sinks.
In flotation, demineralization of lignite powder is performed in this way. Separation and selection of coal organic matter from coal inorganic matter is performed using the difference in wettability of the particle surface.

Such flotation of lignite is shown, for example, in the following Patent Document 1 (paragraph number 0013 column).
JP-A-10-130669

By the way, the following subject was pointed out about such a prior art.
A problem has been pointed out that even if flotation is performed on brown coal powder, deashing coal selection is not performed as expected. Separation and sorting of coal organic matter from coal inorganic matter has not been performed smoothly, and it has been considered industrially difficult to recover and effectively use lignite coal organic matter by flotation (for example, described later) See test method 0 in the examples).
The cause is as follows. In other words, in the flotation of brown coal powder, coal selection is performed by utilizing a certain difference in wettability of the particle surface between coal organic matter and coal inorganic matter. However, a certain difference in wettability that is indispensable, that is, hydrophobicity and hydrophilicity have not been ensured.
Coal organic matter of brown coal powder has many oxygen-containing functional groups as organic matter terminal groups / surface functional groups on the particle surface. In particular, the extremely strong hydrophilic carboxyl groups and carbonyl groups make the lignite and coal organic matter hydrophilic, and there is a certain difference in wettability necessary for flotation compared to hydrophilic coal minerals. The fact that it was not secured is considered to be the reason why flotation was considered difficult.

<< About the present invention >>
In view of such circumstances, the ash coal deashing method and apparatus for demineralization of lignite according to the present invention are made to solve the above-described problems of the prior art.
And, the present invention firstly ensures the difference in wettability between the lignite coal organic matter and the coal inorganic matter, and secondly, the coal organic matter (refined coal) is surely separated from the coal inorganic matter (ash) by flotation. The purpose of the present invention is to propose a method and a deashing apparatus for demineralizing lignite separated and sorted.

<About each claim>
The technical means of the present invention for solving such a problem is as follows, as described in the claims.
About Claim 1, it is as follows.
The demineralization method of lignite according to claim 1 selects and separates the coal organic matter and the coal inorganic matter of the lignite powder using the difference in wettability of the particle surface.
And it has the following hot water modification | reformation process, slurrying process, a collection agent addition process, a shear force provision process, a surface modification process, a foaming agent addition process, a flotation process, etc.
That is, a high-temperature and high-pressure heat-resistant pressure furnace equipped with a heat source is used, and the reforming treatment is performed in a hot water atmosphere with stirring under a pressure of 250 to 450 ° C. and a pressure of 15 to 20 MPa. And a hydrothermal reforming step that improves hydrophobicity with regard to the wettability of the coal organic matter of the brown coal powder.
A slurrying step in which water is added to the brown coal powder to form a slurry. A collecting agent adding step of adding an oily collecting agent to the slurry. A stirring shear force is applied to the slurry to which the scavenger is added, and the attached water film is peeled off from the coal organic matter, coal inorganic matter, and scavenger oil droplets to increase the surface energy of the particle surface. Shear force application step.
Based on the improvement of the surface energy, first, the hydrophobicity and lipophilicity of the particles of the coal organic matter and the oil droplets are further enhanced, so that the scavenger oil droplets are replaced with the oil film on the surface of the coal organic matter particles instead of the water film. As a result, the surface energy is reduced. The coal mineral is a surface modification step in which the hydrophilicity and oleophobicity of the particle surface are further enhanced, and the surface energy is lowered by being more wet and adaptable to water.
A foaming agent addition step of adding a foaming agent to the slurry after the surface modification. The foaming agent generates bubbles by blowing or sucking air into the added slurry, and thus the coal organic matter floats along with the oil film adhering to the foaming agent around the bubbles. On the other hand, a flotation step in which the coal organic matter and the coal inorganic matter are sorted and separated by the sinking of the coal inorganic matter that has become familiar with water. The demineralization method of lignite according to claim 1 includes these steps.

About Claim 2, it is as follows.
In the lignite deashing coal selection method according to claim 2, in claim 1, the lignite powder is composed of the coal organic matter and coal inorganic matter in powder form. The coal organic matter has an organic polymer structure having carbon, hydrogen and oxygen as main constituent elements. The coal mineral is mainly composed of clay and mineral.
About Claim 3, it is as follows.
In the demineralization method for brown coal according to claim 3, in claim 2, whether the hydrothermal reforming step and the slurrying step are carried out one after the other or simultaneously as the same common step. , Or any of the above.
About Claim 4, it is as follows.
In the demineralization method for brown coal according to claim 4, in claim 3, in the hydrothermal reforming step, an oxygen-containing functional group having particularly strong hydrophilicity is decomposed, extinguished and removed in the surface functional group of the coal organic matter. It is characterized by that.

About Claim 5, it is as follows.
In the demineralization method of lignite according to claim 5, in claim 4, in the hydrothermal reforming step, carboxyl groups and carbonyl groups are decomposed into carbon dioxide and water by reforming treatment in a hot water atmosphere. It disappears and is removed.
At the same time, the iron content contained in the coal mineral becomes a trivalent iron ion in a hot water atmosphere and functions as a catalyst, so that the covalent bond between carbon atoms is deepened in the coal organic matter. Is also characterized by improved hydrophobicity.
About Claim 6, it is as follows.
In the lignite deashing coal selection method according to claim 6, in claim 4, in the slurrying step, slurrying is performed to a lignite concentration of 10 wt% to 30 wt%. In the foaming agent adding step, higher alcohol is added as the foaming agent.

About Claim 7, it is as follows.
The demineralization apparatus for lignite according to claim 7 selects and separates the coal organic matter and the coal inorganic matter of the lignite powder using the difference in wettability of the particle surface. And it has the following hot water reformer, slurry tank, oil addition means, surface reforming machine, foaming agent addition means, flotation machine, etc. That is, a high-temperature and high-pressure heat-resistant pressure-resistant furnace equipped with a heat source The coal in the brown coal powder supplied by heating under a temperature of 250 ° C. to 450 ° C. and under a pressure of 15 MPa to 20 MPa under a hot water atmosphere while stirring. A hydrothermal reformer that improves the hydrophobicity of organic substances.
A slurry tank in which the lignite powder is stirred with water, mixed and suspended to form a slurry. Oil adding means for adding an oil-based scavenger to the slurry supplied from the slurry tank to the surface reforming machine.
The slurry supplied to the stirring chamber in the drum is given a stirring shear force sufficient to transiently increase the surface energy of the particles, thereby further improving the hydrophobicity and lipophilicity of the coal organic matter and the scavenger oil droplets. The surface modification machine that further enhances the hydrophilicity and oleophobicity of the coal mineral as well as enhancing.
A foaming agent adding means for adding a foaming agent to the slurry supplied from the surface reformer to the flotation machine and stirring the slurry. The slurry is supplied and air is supplied, so that the coal organic matter floats with the scavenger oil film adhering to the foaming agent around the generated bubbles, whereas the coal organic matter floats and becomes familiar with the water. The flotation machine in which the mineral minerals sink. The demineralization apparatus for lignite according to claim 7 is characterized by comprising these.

<About the action>
Since the present invention comprises such means, the following is achieved.
(1) Brown coal powder consists of coal organic matter and coal inorganic matter.
(2) The coal organic matter is selected and separated from the coal inorganic matter by flotation. In the present invention, hydrothermal reforming and surface reforming are performed as pretreatment.
(3) First, the hydrophobicity of the coal organic matter is improved by the hot water reformer. The carbonyl group and carbonyl group, which are powerful hydrophilic surface functional groups and oxygen-containing functional groups, are decomposed, eliminated, and removed as carbon dioxide and water molecules. At the same time, the iron content in the coal mineral becomes trivalent iron ions in a hot water atmosphere, and the catalytic function deepens the covalent bond between carbon atoms of the coal organic matter.
(4) The alkali metal bonded to the coal organic matter is also removed and removed by the hot water reforming.
(5) The coal organic matter and the coal inorganic matter are then slurried and a scavenger is added.
(6) By the way, an ether group, a phenol group, an alcohol group and the like exist as surface functional groups and oxygen-containing functional groups in the coal organic matter of the slurry even after hydrothermal reforming. Therefore, the degree is low but hydrophilic, and a water film is attached.
(7) Therefore, the slurry is supplied to a surface reforming machine, to which a high-speed and strong stirring shear force is applied, and the water film is peeled off for each of the coal organic matter and coal inorganic particles, so that the surface energy becomes transient. Enhanced. Coal organic matter is improved in hydrophobicity and lipophilicity, and coal inorganic matter is improved in hydrophilicity and oleophobicity.
(8) The coal organic matter in the slurry is attached as an oil film instead of a water film, and the surface energy is lowered. Coal minerals become more wet and accustomed to water, which reduces the surface energy.

(9) Thereafter, a foaming agent is added to the slurry.
(10) Then, air is blown in or sucked in, and flotation is performed, so that the foaming agent, the oil film, and the coal organic matter float, and the coal inorganic matter sinks.
(11) In the present invention, as a pretreatment for flotation, a combination of hot water reforming and surface modification is adopted, so that there is an industrially necessary and sufficient wettability difference between coal organic matter and coal inorganic matter. It is secured. Therefore, flotation is performed accurately and reliably.
(12) The floated coal organic matter is recovered as flotation floss, solid-liquid separated, dehydrated and dried, and then effectively used as fuel. Coal minerals are also collected as a flotation tail.
(13) Therefore, the deashing method and deashing apparatus for lignite of the present invention exhibit the following effects.

<First effect>
1stly, the difference in wettability is ensured about the coal organic substance and coal inorganic substance of lignite. The demineralization method and the demineralization device for lignite of the present invention are characterized by adopting a combination of hot water reforming and surface modification as pretreatment for flotation.
First, by hydrothermal reforming of lignite, the hydrophobicity of the coal organic matter is improved. That is, on the surface of coal organic matter, strong hydrophilic carboxyl groups and carbonyl groups are decomposed, extinguished and removed as carbon dioxide and water, so that lignite is sub-bituminized. At the same time, based on the catalytic function of iron in the coal mineral, the covalent bond between the carbon atoms of the coal organic matter is deepened, and also from this aspect, the lignite is sub-bituminized.
Next, by applying a stirring shear force that transiently increases the particle surface energy by surface modification, the hydrophobicity and lipophilicity of the coal organic matter are further enhanced, and the hydrophilicity and oleophobicity of the coal inorganic matter are further enhanced. For coal organics, water films based on oxygen-containing functional groups of organic end groups and surface functional groups are excluded.
Thus, by adopting a combination of hot water reforming and surface modification, the difference in wettability between the coal organic matter and the coal inorganic matter is reliably ensured.

<< Second effect >>
Second, coal organic matter (refined coal) is reliably separated and selected from coal inorganic matter (ash) by flotation.
That is, in the ash coal deashing method and the deashing device of the present invention, as described above, the difference in wettability between lignite coal organic matter and coal inorganic matter is ensured. Therefore, when flotation is performed, separation and sorting of coal organic matter from coal inorganic matter is industrially smoothly realized. Coal organic matter floats up and coal minerals sink. In the present invention, demineralization of lignite, which has been difficult with the above-described conventional technology, is possible.
The separated, sorted, and recovered coal organic matter (sub-bituminous coal, which is a refined coal) is effectively used as a fuel with a small amount of ash, for example, as a fuel for a diesel engine or the like.
In addition, the alkali metal combined with the coal organic matter is also removed during the hot water reforming, and from this aspect, it becomes an excellent fuel with less ash content.
As described above, the effects exerted by the present invention are remarkably large, such as all the problems existing in this type of prior art are solved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of the first half of a process for explaining a mode for carrying out the invention of a demineralizing method and a demineralizing device for brown coal according to the present invention. It is used for description of the form for implementing this invention, and is a block diagram of the latter half of a process. It uses for description of the form for implementing this invention, and is explanatory drawing of the process principal part. And (1) figure is a hydrothermal reforming process, (2) figure is a slurrying process, a collecting agent addition process, (3) figure is a shearing force provision process, a surface modification process, (4) figure. Shows a foaming agent addition process and a flotation process. A surface modification machine is shown for explanation of an embodiment for carrying out the invention. And (1) figure is side explanatory drawing which saw through partially, (2) figure is an arrow sectional view which followed the XX line of (1) figure, (3) figure is (1) figure It is arrow sectional drawing along the YY line.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.
<< Outline of the Invention >>
First, the demineralization method of lignite of the present invention selects and separates the coal organic material 8 and the coal inorganic material 9 of the lignite powder using the difference in wettability of the particle surface. And for lignite powder 1, it has a hydrothermal reforming process, a slurrying process, a collecting agent adding process, a shearing force applying process, a surface modifying process, a foaming agent adding process, a flotation process, etc. in order. It becomes.
Moreover, the demineralization apparatus A for lignite according to the present invention sorts and separates the coal organic matter 8 and the coal inorganic matter 9 of the lignite powder 1 using the difference in wettability of the particle surface. And it has in order the hot water reformer 2, slurry tank 3, oil addition means 4, surface reforming machine 5, foaming agent addition means 6, flotation machine 7, and the like.
The target lignite powder 1 is in the form of a powder having a particle size of about 3 mm or less. It is originally powdered or pulverized to form powder, and consists of coal organic matter 8 and coal inorganic matter 9.
The coal organic matter 8 has an organic polymer structure of oxygen-containing hydrocarbons having three elements, carbon (C), hydrogen (H), and oxygen (O) as main constituent elements. In the case of lignite, the [O] value of the [H]-[O] coal band, that is, the number of oxygen atoms (atomic ratio display) per 100 carbon atoms serving as the skeleton of the organic structure is about 15 or more. .
The coal mineral 9 is mainly made of a mineral containing viscosity and iron, and ashes when combusted afterwards.
The outline of the present invention is as described above. Hereinafter, the present invention will be described in detail.

<< Hot water reforming process (1) >>
First, the hot water reforming step will be described with reference to FIGS. In the hydrothermal reforming process (steam reforming process), the hydrothermal reformer 2 is used to improve the hydrophobicity with respect to the wettability of the particle surface of the coal organic matter 8 of the brown coal powder 1.
That is, in the hydrothermal reforming step, the oxygen-containing functional group having particularly strong hydrophilicity is decomposed and removed in the organic matter terminal group / surface functional group of the coal organic matter 8. The carboxyl group and the carbonyl group on the surface of the coal organic matter 8 are decomposed, eliminated, and removed into carbon dioxide and water by the reforming treatment in a hot water atmosphere. Thus, the lignite powder 1 is sub-bituminized.

Such a hot water reforming step will be further described in detail. As the hot water reformer 2, a high-temperature and high-pressure heat-resistant pressure furnace equipped with a heat source such as an evaporator or an autoclave is used. And while the brown coal powder 1 is supplied from the preparation container 10, the water 12 is supplied from water supply facilities, such as the water tank 11. FIG.
Then, with such a hot water reformer 2, hot water reforming of the carboxyl group or carbonyl group on the particle surface is performed on the coal organic matter 8 of the brown coal powder 1.
This hot water reforming is performed with stirring at a temperature of 250 ° C. to 450 ° C., typically about 350 ° C. and under a pressure of 15 MPa to 20 MPa. If it is less than 250 ° C. or less than 15 MPa, hot water reforming becomes difficult. When the temperature exceeds 450 ° C., the handleability deteriorates due to the generated tar content, and when it exceeds 20 MPa, the cost is excessive and the cost is high.

It is no exaggeration to say that the hydrophilicity of the coal organic matter 8 of the brown coal powder 1 is derived from the carboxyl group of the surface functional group on the particle surface. The hydrophilicity which is the characteristic of the brown coal powder 1 is derived from the [O] value derived from the carboxyl group in terms of the [O] value. And this carboxyl group (-COOH) (-C (= O) (-OH) in the characteristic formula display) is partially ionized in the water environment as shown in the chemical formula of the following chemical formula 1, Especially in a hydrothermal environment, the balance of the equation proceeds to the right and the diffusion of protons (H ⁺ ) proceeds.

Then, the proton diffusion, residues of discrete STR1 right side, -O ^- is double bond of the carbon atoms (C) by moving the pair of electrons anion. Thus, the valence 4 of the carbon atom is satisfied and liberated as carbon dioxide (CO ₂ ).
On the other hand, the left side of Chemical Formula ¹ shows the π molecular orbital of the double bond of the carbonyl group (C═O) due to the hydrolytic power of hot water (H ₂ O⇔H ⁺ + OH ⁻ ) that proceeds with ionization in the presence of protons. Eliminate the occupied orbit, π orbit and empty orbit, π ^* ).
That is, the hydroxide ion (OH ⁻ ) in the water region is added and combined with the carbon atom (C) side of the vacant orbit, and the counter electron on the occupied orbit moves to the oxygen atom (O) end, which is converted into an anion. The protons (H ⁺ ) are attracted and added from the water area.
As a result, the left side liberates water molecules (H ₂ O) to become a new carbonyl group (C═O), and the right side is regenerated. By repeating such a reaction, the carboxyl group is decomposed, eliminated, or removed.
The decomposition, disappearance, and removal of the carbonyl group (—CO—) of the surface functional group are as follows. First, in the same manner as described above for the left side of the carboxyl group, a hydroxide ion (OH ⁻ ) and a proton (H ⁺ ) in the water area are added. Thereafter, a carboxyl group is generated based on the diffusion of protons into the hot water, and thereafter, the process follows the above-described decomposition, disappearance, and removal of the carboxyl group.
The hot water reforming step (1) is as described above.

<< Hot water reforming process (2) >>
In the hydrothermal reforming step (part 1), the carboxyl groups and carbonyl groups on the particle surface are thus decomposed, eliminated, and removed, so that the hydrophobicity of the coal organic matter 8 is improved, and the sub-bituminous carbonization of the brown coal powder 1 Progresses.
At the same time, in the hot water reforming step, the iron content contained in the coal mineral 9 becomes trivalent iron ions in the hot water atmosphere and functions as a catalyst.
Therefore, the covalent bond between carbon atoms is deepened about the coal organic matter 8, and hydrophobicity improves also from this surface, and the subbituminous coal powderization of the brown coal powder 1 advances. Such a catalytic function of iron will be described as a hydrothermal reforming step (part 2).

In the above-described hydrothermal reforming step (Part 1), the coal organic matter 8 is converted into a surface functional group carboxyl group (—COOH) or carbonyl group (—CO—), carbon dioxide (CO ₂ ) or water molecule (H ₂ ). When it is decomposed, extinguished and removed as O), a paired electron is transiently left on the organic end side of the coal organic matter 8.
In other words, a counter electron is attached to the carbon atom side of the organic end (schematic expression is C :) (note that: indicates a counter electron), and one electron in the counter electron is not given to others. Reduceability occurs.
On the other hand, the coal mineral 9 contains iron (Fe). This iron content becomes a trivalent iron ion (Fe ³⁺ ) in an acidic hot water atmosphere with excessive protons, and functions as a catalyst as follows.
Therefore, as shown in the chemical formula of the following chemical formula 2, the organic end from which the carboxyl group or carbonyl group has been removed (the carbon atom of which is) temporarily transfers one electron in the counter electron to this trivalent iron ion. To give divalent iron ions (Fe ²⁺ ). Then, it becomes transiently an unpaired electron end having a non-paired electron which is one remaining electron in the paired electron, a radical (-C.) (Where... Represents an unpaired electron). The organic edge becomes a transient unpaired electron edge.

And the unpaired electron end, that is, the radical (-C.) Generated in this way interacts with another radical (-C.) To deepen the carbon-carbon bond (-C: C-). go. That is, the organic ends of the unpaired electron ends are covalently bonded with the counter electrons based on both unpaired electrons, thereby deepening the carbon-carbon bond.
In this way, hydrocarbons (HC) are hydrophobized as a whole of the coal organic matter 8, and the brown coal powder 1 is sub-bituminous carbonized.
The generated divalent iron ion (Fe ²⁺ ) is oxidized in a natural manner in an acidic hot water atmosphere containing a large amount of protons (H ⁺ ) to form the original trivalent iron ion (Fe ³⁺ ). Return. And the catalyst function mentioned above is repeated and a carbon-carbon bond (-C: C-) and a carbon-hydrogen bond are deepened.
The hot water reforming step (part 2) is as described above.

<< Hydrothermal reforming process (part 3) >>
In the hydrothermal reforming step, the alkali metal bonded to the coal organic matter 8 is further removed. Such removal of the alkali metal will be described as a hydrothermal reforming step (part 3).
Alkaline metals such as sodium (Na) and potassium (K) are not limited to lignite (lignite coal powder 1), and in general coal, the amount contained in the coal mineral 9 side is very small, most of which is the coal organic matter 8 side. Included. In most cases, the coal organic matter 8 is connected to the carboxyl group and contained as a salt of a carboxylic acid (organic acid) (for example, —COONa).
Of course, such an alkali metal is also a kind of ash, and after that, when the coal organic matter 8 is burned as a fuel or the like, it is ashed and remains (for example, Na ₂ O, K ₂ O), and is removed beforehand. There is a need.
In the hydrothermal reforming step, the alkali metal is released and separated from the system together with the above-described carboxyl group based on hydrothermal reforming, that is, hydrolysis reaction imparted with thermal energy. For example, in the case of sodium, it becomes sodium hydrogen carbonate (Na ⁺ + HCO ₃ ⇔NaHCO ₃ ) and is removed from and removed from the coal organic matter 8.
In addition, although the bond pair electrons remain transiently on the organic end side of the coal organic matter 8 after leaving and removing, the covalent bond between the carbon atoms is achieved by the catalytic function of the trivalent iron ion as described above. Is deepened.
The hydrothermal reforming step (part 3) is as described above.

<Influence of other oxygen-containing functional groups>
Here, the oxygen-containing functional group of the coal organic matter 8 of the brown coal powder 1 will be described. As described in the hydrothermal reforming step (part 1), it is no exaggeration to say that the hydrophilicity of the brown coal powder 1 and the coal organic matter 8 is derived from the carboxyl group of the oxygen-containing functional group on the particle surface.
The strong hydrophilic carboxyl group and further the carbonyl group can be decomposed, extinguished and removed by hot water reforming. Accordingly, the hydrophobicity of the coal organic matter 8 is improved in terms of wettability, and the difference in wettability from the hydrophilic coal inorganic matter 9 is clarified for the time being.
However, the coal organic matter 8 still has many other oxygen-containing functional groups. The effects on hydrophilicity, hydrophobicity and wettability are as follows.

First, the ether group (—O—), which is the largest oxygen-containing functional group, is relatively inert and does not contribute to hydrophilicity.
The phenol group (aromatic ring —OH) is a hydrophilic group in which protons (H ⁺ ) are partially ionized, but the hydrophobicity of the aromatic ring and the methylene (—CH ₂ —) chain connected thereto is overwhelmingly dominant. is there. Thus, the hydrophilicity of the phenol group is latent.
In the alcohol group (—OH), the hydrophobicity of the continuous methylene (—CH ₂ —) chain is overwhelmingly dominant. The methoxy group (—O—CH ₃ ) also conforms to these.
Since the other oxygen-containing functional groups are bonded to the hydrophobic polymer hydrocarbon as described above, the hydrophilicity is latent and the hydrophobicity is manifested.

However, although such other oxygen-containing functional groups are temporarily latent as described above, the hydrophilicity is maintained to some extent, and the content in the coal organic matter 8 is large. Therefore, even in the above-described hydrothermal reforming step (Part 1), even if a carboxyl group or a carbonyl group having a particularly strong hydrophilic property is removed, it still becomes an inhibiting factor in flotation.
That is, other oxygen-containing functional groups are attached to a water film at the interface with water based on their hydrophilicity. By attaching a water film to the surface functional groups, the coal organic matter 8 is also in a state where the water film is attached and attached. (Incidentally, the coal mineral 9 also has a water film due to its hydrophilicity.)
The presence of such a water film becomes an impediment to flotation for separating and sorting the coal organic matter 8 and the coal inorganic matter 9 based on the difference in wettability. At least industrially, a necessary and sufficient difference in wettability cannot be ensured, which becomes an impediment to flotation and the coal selection effect is reduced.
Therefore, in the present invention, as a pretreatment for the flotation process after the hot water reforming process, a shearing force application process for peeling off such a water film is performed as described later. Therefore, necessary and sufficient wettability is ensured industrially, and flotation can be carried out satisfactorily.
The effects of other oxygen-containing functional groups are as described above.

<< Slurry process >>
Next, the slurrying step will be described with reference to FIGS. In the slurrying step, water 12 is added from the water supply equipment such as the water tank 13 to the supplied brown coal powder 1 in the slurry tank 3, and stirred, mixed and suspended to form a slurry 14. A slurry 14 having a brown coal concentration of 10% by weight to 30% by weight is used.
That is, the brown coal powder 1 is supplied so that the concentration in the slurry 14 is 10 wt% to 30 wt%.
When the lignite concentration exceeds 30% by weight, in the shearing force application step using the surface modification machine 5 described later, the tendency of clogging and solidification due to the slurry 14 becomes remarkable, the fluidity is lost, and it is difficult to apply the stirring shearing force. Turn into. The rotation of the agitating blade and the motor is also hindered. On the other hand, when the lignite concentration is less than 10% by weight, there is a problem in profitability, cost, and economy when industrialized, such as a significant decrease in mechanical efficiency and increased running costs.
Therefore, from the viewpoint of securing fluidity and economy, the lignite concentration is typically set to about 15 wt% to 20 wt%.

By the way, the hydrothermal reforming step and the slurrying step are either carried out one after the other or carried out simultaneously as the same common step. In the illustrated example, brown coal powder 1 that has been hot water reformed by a hot water reformer 2 is supplied to a slurry tank 3. However, the present invention is not limited to such illustrated examples.
For example, when the lignite powder 1 supplied from the preparatory container 10 contains a large amount of water, it is not necessary to supply the water 12 in the slurry tank 3 after the fact, and the slurrying process is a hot water reforming process. Has already been implemented before.
Moreover, it is also possible to place the slurry tank 3 and perform the slurrying step before the hot water reforming step. Furthermore, when water 12 is supplied from the water tank 11 in the hot water reforming process, an amount of water 12 that allows for the formation of a slurry 14 is supplied, so that the hot water reforming process and the slurrying process are used as a common process. It is also possible to do.
The slurrying process is as described above.

《Capturing agent addition process》
Next, the trapping agent adding step will be described with reference to FIGS. In the collecting agent adding step, the oily collecting agent 15 is added to the slurry 14. In the illustrated example, an oil-based scavenger 15 is added from the oil tank 18 of the oil adding means 4 to the slurry 14 supplied from the slurry tank 3 to the surface reforming machine 5.

As the collecting agent 15, kerosene, light oil, heavy oil or the like is typically used. The collector 15 is added to the slurry 14 as collector oil, and is supplied to the surface reforming machine 5 as oil droplets 16 due to interfacial tension. The oil droplets 16 adhere to the coal organic matter 8 afterwards. The oil film 17 is formed.
The addition amount of the collection agent 15 is very small, and is, for example, about 0.5 wt% to 10 wt% with respect to the coal organic matter 8 in the slurry 14.
When the concentration is less than 0.5% by weight, the amount of the oil film 17 to be adhered to the coal organic matter 8 is insufficient in the flotation process using the flotation machine 7 to be described later, and flotation is hindered. When the concentration exceeds 10% by weight, a liquid surface layer is formed by the excessively added oil droplets 16 and the like, which hinders the flotation of the coal organic matter 8 and hinders the flotation. Furthermore, it is uneconomical and causes problems in terms of cost. In the figure, 19 is a pipe and 20 is a pump.
The collecting agent addition process is as described above.

<< Shearing force application process >>
Next, the shearing force application step will be described with reference to FIG. 1, FIG. 2, FIG. 3, FIG. In the shearing force step, a stirring shearing force is applied to the slurry 14 to which the collecting agent 15 is added, and the attached water film is peeled off from the coal organic matter 8, the coal inorganic matter 9, and the collecting agent 15 oil droplets 16. And increase the surface energy of the particle surface.
That is, in the surface modification machine 5, a stirring shear force and a contact friction force sufficient to transiently increase the surface energy of the particle surface are applied to the slurry 14 supplied to the stirring chamber 22 in the cylindrical drum 21.
The slurry 14 to which the collecting agent 15 is added as oil droplets 16 is supplied to the stirring chamber 22 divided by the partition plate 23 in the cylindrical drum 15 of the surface modification machine 5. Thus, the oil droplets 16 of the collecting agent 15 are highly dispersed and mixed in the slurry 14 by stirring, and the surface of the particles of the coal organic matter 8 and the coal inorganic matter 9 in the slurry 14 by applying stirring shearing force to the slurry 14. The surface energy of is transiently increased.

Such a shearing force application step will be further described in detail. First, the surface modification machine 5 will be described. In the surface reforming machine 5, a disc-shaped stirring plate 24 that can rotate at high speed is provided in a stirring chamber 22 formed in a cylindrical drum 21, and stirring blades 25 are provided on the plate surface of the stirring plate 24. Has been. Then, the slurry 14 flows from the inlet 26 to the outlet 27 of the surface modification machine 5.
That is, a plurality of rows of circular annular baffle partition plates 23 are provided at equal intervals in the horizontal axis direction in a cylindrical drum 21 provided with an inlet 26 and an outlet 27 of the surface modification machine 5. It is installed. And the space | interval dividedly formed by each partition plate 23 becomes the stirring chamber 22, respectively.
A shaft 29 is provided in the axial direction through the central communication hole 28 of each partition plate 23. A disc-ring shaped stirring plate 24 with a shaft hole is fitted on and attached to the shaft 29 for each stirring chamber 22, and substantially arc-shaped and strip-shaped stirring blades 25 are provided on both front and rear surfaces of each stirring plate 24. Are convex. The shaft 29 is connected to the speed reducer 30 and the motor 31.
Therefore, the slurry 14 flowing from the upstream stirring chamber 22 to the downstream stirring chamber 22 is subjected to high-speed and powerful stirring shearing force by rotating the stirring plates 24 and the stirring blades 25 at high speed. .
In the illustrated surface modification machine 5, a plurality of stirring chambers 22 are separately formed in the cylindrical drum 21, but the stirring plate with the stirring chamber 22 and the stirring blades 25 is not limited to this. Of course, a batch-type surface modification machine 5 in which only one set 24 is provided is also possible.

In the surface reforming machine 5, by stirring and rotating the stirring plate 24 and the stirring blade 25, the coal organic matter 8, the coal inorganic material 9 of the slurry 14, the oil droplets 16 of the collecting agent 15, and the like are mixed into the stirring plate 24, the stirring blade 25 and the like. Forcibly contact and collide with the rotating part, the inner part of the cylindrical drum 21 and the fixed part such as the partition plate 23.
Accordingly, the coal organic matter 8, the coal inorganic matter 9, the oil droplets 16 of the scavenger 15 and the like are shared and given a high-speed and strong stirring shear force. Then, based on the dilatancy of the slurry 14, the local packing density and surface energy are transiently increased for each of these particles (including generation of surface energy).
That is, each particle of the slurry 14 that is the dilatant fluid, that is, each particle of the coal organic matter 8, the coal inorganic matter 9, the oil droplet 16, etc., is generated in a high-speed powerful stirring shear force field that is instantaneously generated in the surface reforming machine 5. The packing density is increased and the concentration and concentration are increased. As a result, the water 12 between them is eliminated, and the surface of the particles is activated by forming the shearing surface and the active surface by grinding with the surface contact friction between each other. Increased transiently.
The water film attached to and attached to the coal organic matter 8 and the coal inorganic matter 9 is peeled off, and the surface energy level is transiently increased. The coal organic matter 8 of the slurry 14 is further improved in hydrophobicity and lipophilicity on the particle surface, and the coal inorganic material 9 is further improved in hydrophilicity and oleophobicity on the original particle surface.
The shearing force application step is as described above.

<< Surface modification process >>
Next, the surface modification step will be described with reference to FIG. As described above, based on the improvement of the surface energy in the shearing force application step, the coal organic matter 8 and the oil droplets 16 are further improved in the hydrophobicity and lipophilicity of the particle surface. Accordingly, the surface energy of the coal organic matter 8 is lowered by the oil droplets 16 of the scavenger 15 being attached as the oil film 17 instead of the stripped water film.
On the other hand, the mineral mineral 9 is further improved in the hydrophilicity and oleophobicity of the particle surface, so that it becomes more wet and adaptable to water and the surface energy decreases.

Such a surface modification step will be further described in detail. In the surface modification step, based on the application of the stirring shear force to the slurry 14 in the high-speed and strong stirring shear force field, the coal organic matter 8 and the oil droplets 16 are first activated as described above, and the surface energy is increased. The level is increased transiently, and the hydrophobicity and lipophilicity of the particle surface are further increased.
The coal organic matter 8 is peeled off in the surface reforming machine 5 in the strong shear force field and the weak shear force field generated alternately and instantaneously by peeling off the water film adhering to the particle surface. At the same time, the oil droplets 16 are captured and become wet, and the oil droplets 16 become an extremely thin oil film 17 that adheres to and covers the particle surface of the coal organic matter 8.
Thereby, the coal organic matter 8 and the oil film 17 are stabilized by lowering the level of the surface energy once transiently increased.
On the other hand, the coal mineral 9 is further improved in hydrophilicity and oleophobicity due to the activation of the particle surface and the transient increase in surface energy, so that it becomes more familiar with the water 12 and forms a stronger water film. Is done. As a result, the coal mineral 9 is stabilized by lowering the level of the surface energy once transiently increased.
In the surface reforming machine 5, the oil droplets 16 are captured by the coal organic matter 8 whose surface energy has been increased based on the application of the stirring shear force to the slurry 14, thereby forming a thin oil film 17. Displaces the film and adheres. The coal organic matter 8 is entirely covered and coated with an oil film 17 or the oil film 17 is partially attached.
The surface modification process is as described above.

<< Foaming agent addition process >>
Next, the foaming agent adding step will be described with reference to FIGS. In the foaming agent addition step, the foaming agent 32 is added to the slurry 14 after the surface modification. The slurry 14 is supplied from the surface modification machine 5 to the flotation machine 7 after the surface energy of the particle surface of the coal organic matter 8 or the coal inorganic matter 9 is lowered. Then, the foaming agent 32 is added.
As the foaming agent 32, MIBC (methyl isobutyl carbinol) and other higher alcohols are used, which are supplied from the foaming agent tank 33 of the foaming agent adding means 6 to the adjusting tank 34 and into the slurry 14. A small amount is added and stirred to uniformly disperse in the slurry 14.
About the foaming agent addition process, it is as above.

《Flotation process》
Next, the flotation process will be described with reference to FIGS. In the flotation process, the slurry 14 is supplied to the flotation machine 7 and the air 33 is supplied.
Accordingly, bubbles 36 are generated by blowing or sucking air 35 into the slurry 14 to which the foaming agent 32 is added.
Then, the coal organic matter 8 floats together with the oil film 17 adhering to the foaming agent 32 around the generated bubbles 36, whereas the coal inorganic matter 9 that has become wet with water and sinks sinks. Thus, the coal organic matter 8 and the coal inorganic matter 9 are sorted and separated.

Such a flotation process will be further described in detail. The slurry 14 is supplied from the adjustment tank 34 to the flotation machine 7 and air 35 is supplied by blowing or sucking. The air 35 is forcibly blown into the flotation machine 7 or by a mechanical agitation type air supply apparatus that is sucked as the stirring plate 24 in the flotation machine 7 rotates. , Introduced into the flotation machine 7.
With the introduction of the air 35, a thin film is formed at the gas-liquid interface by the foaming agent 32 with respect to the generated particles of the air 35, so that bubbles 36 of the air 35 are generated.
Based on the fact that the foaming agent 32 that forms a thin film around the surface of the bubble 36 is oleophilic, the oil film 17 adheres to the thin film of the foaming agent 32, and the coal organic matter 8 adheres to the oil film 17 as described above. doing. That is, the coal organic matter 8 adheres to the foaming agent 32 around the bubbles 36 using the oil film 17 as a binder.
Therefore, as the bubbles 36 rise and the liquid level floats, the adhering foaming agent 32, the oil film 17, and the coal organic matter 8 also rise and rise to the liquid level.
On the other hand, the coal mineral 9 that has improved hydrophilicity and oleophobicity and has become familiar with the water 12 remains and sinks in the slurry 14 without adhering to the bubbles 36 and rising.
The flotation process is as described above.

《Action etc.》
The demineralizing method and the deashing apparatus A for lignite 1 of the present invention are configured as described above. Therefore, it becomes as follows.
(1) Brown coal powder 1 is composed of coal organic matter 8 having an organic polymer structure mainly composed of carbon, hydrogen, and oxygen, and coal inorganic matter (ash content) mainly composed of clay and mineral (( 1) See figure).

(2) Then, the coal organic matter 8 of the brown coal powder 1 is selected and separated from the coal inorganic matter 9 by flotation as described later, utilizing the difference in wettability of the particle surface.
In the present invention, as a pretreatment for such flotation, hot water reforming and surface modification are performed by the following steps.

(3) First, the brown coal powder 1 is supplied from the preparation vessel 10 to the hot water reformer 2, and the hydrophobicity is improved with respect to the wettability of the particle surface of the coal organic matter 8 by the hot water reforming (FIG. 1, FIG. 1). (See FIG. 3 (1)).
That is, in addition to the organic terminal group, surface functional group, and oxygen-containing functional group of the coal organic matter 8, a particularly strong hydrophilic carboxyl group (—COOH) or carbonyl group (—CO—) is carbon dioxide (CO ₂ ). Or as water molecules (H ₂ O), which can be decomposed, extinguished, or detached. Thus, the brown coal powder 1 is converted into subbituminous coal powder.
At the same time, the iron content in the coal mineral 9 becomes trivalent iron ions (Fe ³⁺ ) in a hot water atmosphere, and the covalent bond between the carbon atoms of the coal organic matter 8 is deepened based on the catalytic function. Also from this aspect, the brown coal powder 1 is converted into subbituminous coal powder.

  (4) The alkali metal bonded to the coal organic matter 8 is also removed by the hot water reforming. That is, sodium (Na), potassium (K), and the like, which are incinerated when the coal organic matter 8 is combusted as fuel or the like later, are also released from the system together with the decomposition, disappearance, and removal of the carboxyl group.

  (5) After such hydrothermal reforming, the coal organic matter 8 and the coal inorganic matter 9 are converted into a slurry 14 in the slurry tank 3 and a small amount of an oil-based scavenger 15 is added to form oil droplets 16. (Refer to FIGS. 1 and 3 (2)).

(6) By the way, in such a slurry 14, the coal organic matter 8 of the brown coal powder 1 has a particularly strong hydrophilic carboxyl group or carbonyl group in the organic matter terminal group / surface functional group / oxygen-containing functional group. As described above, the reforming decomposes, disappears, and is removed.
However, many oxygen-containing functional groups such as an ether group, a phenol group, and an alcohol group remain and have a low degree of hydrophilicity. Therefore, a water film sticks to such an oxygen-containing functional group, and the coal organic matter 8 is in a state where a water film is attached to the particle surface. In this situation, it is difficult to carry out smooth flotation.

(7) Therefore, the slurry 14 is supplied to the surface reforming machine 5, so that a strong stirring shear force is applied at a high speed.
The coal organic matter 8 and the coal inorganic matter 9 in the slurry 14 are increased in the local packing density of individual particles, and the surface energy of the individual particle surfaces is transiently increased by surface contact friction between the particles (FIG. 1, FIG. 1). (See FIGS. 2 and 3, (3), FIG. 4, etc.). The coal organic matter 8 sticks to the particle surface, the attached water film is peeled off, and the surface energy is transiently increased.

  (8) Then, the coal organic matter 8 of the slurry 14 is replaced by the oil film 16 of the scavenger 15 as an oil film 17 instead of the stripped water film, and the surface energy is lowered. The coal mineral 9 with improved hydrophilicity and oleophobicity becomes more wet and accustomed to the water 12, and its surface energy decreases.

  (9) After the surface energy of the slurry 14 is lowered and stabilized as described above, the foaming agent 32 is added in the adjustment tank 34 (see FIGS. 2 and 3 (3)).

(10) Then, the slurry 14 is supplied to the flotation machine 7, and the air 35 is blown in or sucked in, so that the flotation process is performed (see FIGS. 2 and 3 (4)).
That is, along with the generated bubbles 36, the hydrophobic and lipophilic foaming agent 32, the oil film 17, the coal organic matter 8, and the like float. On the other hand, the hydrophilic and oleophobic coal mineral 9 wet and familiar with the water 12 sinks.

(11) And this flotation is performed with high accuracy and certainty. The difference in wettability between the organic coal 8 and the inorganic coal 9 is ensured to an industrially necessary and sufficient level, and both are separated and selected with high accuracy and reliability.
That is, as described above, by adopting a combination of hot water reforming and surface modification, the coal organic matter 8 is improved in hydrophobicity and lipophilicity, and the attached water film is peeled off and eliminated. In addition, the mineral mineral 9 has improved hydrophilicity and oleophobicity and has become familiar with being wet with water.

(12) Note that the floated coal organic matter 8 is recovered as a floatation product of the flotation floss, and the settled coal inorganic matter 9 is recovered as a sedimentation product of the flotation tail.
The recovered coal organic matter 8 is solid-liquid separated from the water 12 by a filter, a concentrator, a filter press or the like, dehydrated and dried, and then effectively used as fuel.
The operation of the present invention is as described above.

Examples of the present invention will be described below.
That is, about the deashing coal selection method of lignite, the test result obtained in the Example of this invention and the test result obtained in the comparative reference example which does not belong to this invention are demonstrated.

"Test method"
First, the test method is as follows. That is, the deashing coal selection test of brown coal powder 1 was carried out by the following four types of test methods (test methods No. 0, 1, 2, and 3). A deashing confirmation test was conducted to remove ash (coal mineral 9) in the sample.
○ Test method 0 (comparative reference example):
The raw material lignite powder 1 was used as a target, and only flotation was performed. In other words, brown coal powder 1 → flotation.
○ Test Method 1 (Comparative Reference Example):
The raw material brown coal powder 1 was used as a target, and flotation was performed after the surface modification. In other words, brown coal powder 1 → surface modification → flotation.
○ Test Method 2 (Comparative Reference Example):
The lignite powder 1 that had been modified with hot water was used as a target, and only flotation was performed. In other words, brown coal powder 1 → hot water reforming → flotation.
○ Test method 3 (Example of the present invention):
Using hot brown-modified lignite powder 1 as a target, flotation was performed after surface modification. In other words, brown coal powder 1 → hot water modification + surface modification → flotation.

《Test sample》

Next, the test samples are as follows. That is, about the brown coal powder 1 used as a test object, it is as the test sample of the said Table 1.
O As shown in the industrial analysis column in Table 1, the ash content (coal mineral 9) of the raw lignite powder 1 is 4.7% by weight. The ash content (coal mineral 9) of the brown coal powder 1 after hot water reforming is 5.0% by weight.
In addition, in the industrial analysis column in Table 1, the moisture (air-dried base) is the weight percent of moisture vaporized in the atmosphere where the surface of the lignite powder 1 is dry. The ash content (dry base) is the weight% of ash content in a state where moisture is 0 for the brown coal powder 1.
○ In the elemental analysis column in Table 1, the problem oxygen is as follows. In the raw material brown coal powder 1, the weight% of oxygen is 22.1% by weight. In the brown coal powder 1 after the hot water reforming, it is 18.8% by weight. When this is converted by the [O] value of the [H]-[C] coal band, that is, the number of oxygen atoms per 100 carbon atoms (atomic ratio display), the [O] value in the raw brown coal powder 1 is 23. There will be four. In the brown coal powder 1 after the hot water reforming, the [O] value is 19.0.
As described above, the [O value] of the brown coal powder 1 after the hot water reforming is reduced by 4.4 from the [O value] of the raw brown coal powder 1 (before the hot water reforming). ing. This difference corresponds to the amount of decomposition, separation, and disappearance of the carboxyl group and the like as described above.

"Test conditions"
The test conditions are as follows. First, surface modification is as follows.
・ Surface reforming machine 5: Batch type, effective volume 2.0L
-Brown coal concentration in slurry 14 (concentration of brown coal powder 1): 15% by weight
Collection agent 15: Kerosene, 0.1% by weight
・ Reforming time: 3 minutes ・ Agitating speed: 873 rpm
Next, regarding flotation:
・ Flotation machine 7: Batch type, effective volume 1.8L
-Brown coal concentration in slurry 14 (concentration of brown coal powder 1): 10% by weight
-Foaming agent 32: Methyl isobutyl alcohol (MIBC), 100 ppm
-Flotation time: 5 minutes-In addition, when only flotation was implemented, the collection agent 15 (kerosene, 0.1 weight%) was added.

"Test results"

The test results are as follows. That is, the test results shown in Table 2 above were obtained when a deashing coal preparation test of brown coal powder 1 was performed based on the test method, test sample, test conditions, and the like described above.
First, the following results were obtained for test method 3 (Example of the present invention: brown coal powder 1 → hot water reforming → surface modification → flotation).
That is, after the lignite powder 1 was subjected to hydrothermal modification and surface modification, flotation was performed. As shown in Table 2, the recovery rate was 32% by weight and the recovered ash content was 2.6% by weight. Data was obtained.
That is, in the examples of the present invention, the floss ratio as the froth recovery rate, that is, the ratio of the collected flotation floss (floating product) to the flotation tail (sedimentation product) was as high as 32% by weight.
In the embodiment of the present invention, the thus-collected flotation floss (floating product) is mostly composed of sub-bituminous coal (coal organic matter 8), which is refined coal, and the ratio of ash (coal inorganic matter 9), that is, floss ash, It was reduced to only 2.6% by weight.

On the other hand, the test method 1 of the comparative reference example (brown coal powder 1 → surface modification → flotation) and the test method 2 of the comparative reference example (brown coal powder 1 → hydrothermal reforming → flotation) are as follows: As a result.
That is, the ratio of the collected flotation floss, that is, the floss recovery rate and the floss ratio, was 12 to 15% by weight, which was low data. And the ratio of ash (coal mineral 9), ie, floss ash, was still as high as 3.7 to 4.0 weight%.
In addition, in the test method 0 (brown coal powder 1 → flotation) of the comparative reference example, flotation floss (floating product) was not obtained. That is, the coal organic matter 8 did not rise at all, and selection and separation from the coal inorganic matter 9 (ash content) could not be achieved. The coal organic matter 8 was contained in the flotation tail (sedimentation product) without being separated and separated from the coal inorganic matter 9.

As described above, the operational effects of the examples of the present invention were confirmed by data in tests.
Only by the present invention adopting a combination of hot water treatment and surface modification as pretreatment, the difference in wettability necessary for flotation is ensured. Thus, sub-bituminous coal (coal organic matter 8) and ash (coal inorganic matter 9), which are refined coals, are separated and selected more reliably and with higher accuracy than each comparative reference example.
As described above, according to the present invention, the flotation froth is recovered at a high recovery rate, and the flotation floss is mostly composed of sub-bituminous coal (coal organic matter 8), which is refined coal, and the ash (coal inorganic matter 9) is There was very little. Thus, the effect of the present invention was supported by the test data.
About an Example, it is as above.

DESCRIPTION OF SYMBOLS 1 Brown coal powder 2 Hydrothermal reformer 3 Slurry tank 4 Oil addition means 5 Surface reforming machine 6 Foaming agent addition means 7 Flotation machine 8 Coal organic matter 9 Coal inorganic matter 10 Preparation container 11 Water tank 12 Water 13 Water tank 14 Slurry 15 Capture Collecting agent 16 Oil droplet 17 Oil film 18 Oil tank 19 Piping 20 Pump 21 Cylindrical drum 22 Stirring chamber 23 Partition plate 24 Stirring plate 25 Stirring blade 26 Inlet 27 Outlet 28 Central communication hole 29 Shaft 30 Reducer 31 Motor 32 Foaming agent 33 Foaming Agent tank 34 Adjustment tank 35 Air 36 Air bubbles A Deashing coal preparation equipment

Claims (7)

A method for deashing and selecting lignite that separates and separates lignite coal organic matter and coal inorganic matter using the difference in particle surface wettability,
A high-temperature and high-pressure heat-resistant pressure furnace equipped with a heat source is used, and the heat treatment is performed at a temperature of 250 ° C. to 450 ° C. and under a pressure of 15 MPa to 20 MPa in a hot water atmosphere while being stirred. A hydrothermal reforming step for improving hydrophobicity with respect to the wettability of the coal organic matter of the brown coal powder;
A slurrying step of adding water to the lignite powder to form a slurry; a collecting agent adding step of adding an oily collecting agent to the slurry;
A shearing force that imparts a stirring shear force to the slurry to which the scavenger has been added, peels off the attached water film of the coal organic matter, coal inorganic matter, and scavenger oil droplets, and increases the surface energy of the particles. Force application process;
Based on the improvement in surface energy, first, the coal organic matter and oil droplets are further improved in the hydrophobicity and lipophilicity of the particle surface, so that the scavenger oil droplets replace the water film on the particle surface of the coal organic matter. The surface of the coal mineral is reduced, and the hydrophilicity and oleophobicity of the particle surface are further enhanced, so that the surface energy is reduced by being more wet and familiar with water.
A foaming agent addition step of adding a foaming agent to the slurry after surface modification;
The foaming agent generates bubbles by blowing or sucking air into the added slurry, and the coal organic matter floats along with the oil film adhering to the foaming agent around the bubbles. And a flotation step in which the coal organic matter and the coal inorganic matter are sorted and separated when the coal inorganic matter that has become wet and familiar with the water sinks. .   The lignite coal powder according to claim 1, comprising the coal organic material and coal inorganic material in powder form, the coal organic material having an organic polymer structure having carbon, hydrogen and oxygen as main constituent elements, Is a method for deashing coal from lignite, which is mainly composed of clay and minerals.   3. The lignite according to claim 2, wherein the hydrothermal reforming step and the slurrying step are carried out one after the other or at the same time as the same common step. Of deashing coal.   4. The demineralized coal preparation method for lignite according to claim 3, wherein oxygen-containing functional groups having particularly strong hydrophilicity are decomposed, extinguished and removed from the surface functional groups of the coal organic matter. In claim 4, in the hydrothermal reforming step, the carboxyl group and the carbonyl group are decomposed, extinguished and removed into carbon dioxide and water by the reforming treatment in a hot water atmosphere.
The iron contained in the coal mineral becomes a trivalent iron ion in a hot water atmosphere and functions as a catalyst. As a result, a covalent bond between carbon atoms is deepened in the coal organic matter. Improved demineralization method of lignite.   In claim 4, in the slurrying step, the lignite concentration is slurried to 10 wt% to 30 wt%, and in the foaming agent addition step, higher alcohol is added as the foaming agent, A demineralization method for lignite, characterized by A demineralization apparatus for lignite that separates and separates lignite coal organic matter and coal mineral using the difference in wettability of the particle surface,
A high-temperature and high-pressure heat-resistant pressure furnace equipped with a heat source is used, and under a heating treatment of 250 ° C. or more and 450 ° C. or less and under a pressure of 15 MPa or more and 20 MPa or less by a reforming treatment in a hot water atmosphere while stirring, A hydrothermal reformer that improves the hydrophobicity of the coal organic matter in the supplied brown coal powder;
A slurry tank in which the brown coal powder is agitated, mixed and suspended with water to form a slurry;
Oil addition means for adding an oil-based scavenger to the slurry supplied from the slurry tank to the surface reforming machine;
The slurry supplied to the stirring chamber in the drum is given a stirring shear force sufficient to transiently increase the surface energy of the particles, thereby further improving the hydrophobicity and lipophilicity of the coal organic matter and the scavenger oil droplets. The surface modification machine, which further enhances the hydrophilicity and oleophobicity of the coal mineral,
A foaming agent adding means for adding and stirring a foaming agent to the slurry supplied from the surface reformer to the flotation machine,
The slurry is supplied and air is supplied, so that the coal organic matter floats with the scavenger oil film adhering to the foaming agent around the generated bubbles, whereas the coal organic matter floats and becomes familiar with the water. A demineralization apparatus for lignite, comprising: a flotation machine in which coal minerals sink.

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