JPS59157186A - Wet process for preparation of coal-water slurry having high concentration - Google Patents

Abstract

PURPOSE:To obtain a homogeneous coal-water slurry having high concentration and fluidity, and excellent long-term stability, by charging a wet mill simultaneously with roughly crushed coal, water and a specific pulverization assistant, and carrying out the pulverization until the particle size is reduced to a specific level. CONSTITUTION:A wet mill is charged simultaneously with (A) roughly crushed coal, (B) water and (C) a pulverization assistant containing, as an essential component, a polyether compound (derivative) having a molecular weight of 16,000- 300,000 and obtained by the addition of an alkylene oxide to an alcohol (derivative) having >=3 (preferably >=5) active hydrogen atoms in the molecule, and the coal is pulverized until the ratio of the coal particles passing through a 200 mesh sieve reaches 70-90wt%. The objective coal-water slurry having a coal concentration of 60-80% can be obtained thereby.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wet method for producing a highly concentrated coal-water slurry.

In recent years8, due to the depletion of petroleum resources, the use of coal has been reaffirmed, and various ways of using it are being considered.

Another method involves pulverizing coal and dispersing it in water to create a water slurry that can be pumped. 1 - Generally, when coal is pulverized using a pulverizer, either the dry method or the wet method is possible, but in the case of the dry method,
The more you try to pulverize the coal, the more there is a risk of explosion due to coal dust.
Problems of environmental pollution occur and work efficiency decreases. On the other hand, the wet method not only does not solve these problems, but also eliminates the step of dispersing pulverized coal in water, which is necessary when turning coal into a water slurry, by wet-pulverizing it in water. can. For the following reasons, it is advantageous to wet-pulverize coal to produce a coal-water slurry.

In addition, since lime-water slurry is used as a fuel,
The coal in the water slurry has a high concentration and needs to be finely pulverized to improve the combustibility of the coal. However, in the wet H)r+1'= method, as a solid is pulverized, a new cross section with high surface energy always appears, causing condensation due to the interparticle condensation force and inhibiting pulverization. It is very difficult to obtain a slurry and also to finely grind it. The higher the concentration is, and the finer the particle size is, the more pronounced this tendency becomes, resulting in a significantly low pulverizing efficiency and an increase in the pulverizing force. Furthermore, the coal-water slurry eventually becomes a gelatinous state with no fluidity, making it impossible to grind it any further and making it impossible to take out the slurry from the mill.

Therefore, there is a need for agents to increase the grinding efficiency, ie, what should be called grinding aids. There is an example of a method similar to this in JP-A No. 56-136665, but in reality, it is one-component crushing at a low concentration, and the crushing aid is not suitable, so the coal concentration must be reduced. The limit was to keep it at around 60%. Even if we attempt to increase the concentration of L from this point forward, the pulverization will proceed and the fluidity will be lost until the amount passing through the 200 mesh reaches 70 weight ㎡, making it impossible to use the combustion efficiently. There were drawbacks.

The inventors of the present invention have completed the present invention as a result of intensive research to improve these drawbacks.

The method of the present invention is a method of wet-pulverizing coal in water, in which coarsely crushed coal, water, and a grinding aid are simultaneously put into a hot-wet mill, 13. At that time: the coal concentration in the final slurry is 60. ~80
Coal was added so that the weight percentage was 200% of the coal particles.
This is a wet preparation method for highly concentrated coal-water slurry, which is characterized by pulverizing until the mesh passing amount is 70 to 90% by weight, and using a C0 specific pulverizing aid. □The coal used in the present invention is anthracite coal, bituminous coal, or sub-bituminous coal, and the first two types of coal used are cattle and porcelain. It is best to use one that has been dry-crushed in advance.

A grinding aid is a unique substance that is suitable for the wet manufacturing method, and it continues to be formed while grinding is progressing in water.The new coal surface strongly adsorbs it and prevents coagulation. Because it requires the ability to withstand mechanical energy and impact force during pulverization, it requires a chemical that has different performance from the chemical used when pulverizing coal using a dry method and simply mixing it with water.

The grinding aid used in the present invention is prepared by adding an alkylene oxide to an alcohol or a derivative thereof having 3 or more active hydrogen atoms in the molecule, preferably 5 or more, and having a molecular weight of 160 Qo to 30 Qo. ．． These include polyether compounds which are polyether compounds, or derivatives obtained by subjecting the terminal hydroxyl groups of the polyether compounds to various reactions.

Examples of starting materials include the following.

Alcohols having 3 active hydrogen atoms, such as glycerin, butane-1-liol, hexane-1-liol, 1-
Alcohols having 4 active hydrogens such as limethylolpropane, 1-liethanolamine, etc., alcohols having 5 or more active hydrogens such as diglycerin, pentaerythryl, tsurupit 1-, etc., such as xylitol,
Sorbitol, glucose, sucrose, partially saponified polyvinyl acetate, partially saponified polyvinyl acetate copolymer>
Hydrogen compounds, cellulose, starch, etc. are useful, and even derivatives such as partial esterification products of alcohols having more than 4 active hydrogens are useful. ti can be used.

As the grinding aid of the present invention, a polyether compound having a molecular weight of 16,000 to 300,000, obtained by adding alkylene oxide to these starting materials, or a derivative obtained by reacting the terminal hydroxyl group of the polyether compound in various ways is effective.

As the alkylene oxide, ethylene oxide, propylene oxide, butylene oxide, etc. are used, and these may be used alone or in combination of two or more types. In the case of two or more types, the arrangement is a block polymerization type or a rung 1 type.
Although either monopolymerization type may be used, block polymerization type is common. In particular, a polyether compound containing ethylene oxide as an alkylene oxide and having a content of 60 to 95% by weight, preferably 8o to 95% by weight of the total alkylene oxide, or a derivative obtained by subjecting the terminal hydroxyl group of the polyether compound to various reactions is used. It not only shows excellent effects and provides a finely pulverized slurry with high pulverization efficiency and good fluidity at high concentration + H, but also has the effect of being able to withstand the impact of the pulverizing media during pulverization in a wet mill, i.e. It exhibits an excellent effect in preventing IF from gelling of slurry. Especially when the ethylene oxide content is 80-9
The polyether compound or derivative thereof according to the present invention in the range of 5% modification has an extremely excellent effect of preventing slurry from turning into paper gel even after long-term pulverization.

Further, derivatives obtained by subjecting the terminal hydroxyl group of the =1-polyether compound to various reactions are also effective. For example, we can cite the one listed in F.

■) Esterified products reacted with organic acids or inorganic acids.

2) Hydroxyl groups are replaced with halogens by reaction with hydrogen halides or phosphorous halides.

3) Aldehydes and carboxylic acids produced by oxidation reactions.

/I) Reaction product of hydroxyl group and monoisocyanate.

However, the present invention is not limited to the above examples.

The reason why the specific grinding aid of the present invention exhibits an excellent effect is that the molecule of Meng is not linear, but has a multi-headed structure with 3-sided, 1-unit branches, and has 16,000 or more [-] It has a high molecular weight and has many alkylene oxide ether bonding groups, so after it is strongly adsorbed on the particle surface, the numerous ether bonds drain the surrounding water and protect the charcoal particles.
Because it is well dispersed, pulverization can easily proceed with high concentration. In addition, because the polymer has a three-dimensional groove structure and the ethylene oxide content is within the preferred range of 1, it can withstand the impact of coal particles during pulverization, prevent particles from agglomerating, and shorten gelation time. Things that can be done directly, similar things, and 15.
Those with small molecular weight! The reason for this can be well understood from the fact that it has no effect at all as an auxiliary agent in the type pulverization method.

The grinding-aiding lyan addition rate is 0 per final coal-water slurry.
．． 03% by weight to 2.0% by weight, and the upper limit was determined simply based on economic considerations. The method of the present invention, in which the above-mentioned coal, water, and grinding aid are simultaneously put into a wet mill and pulverized, can be carried out in at least two stages in a wet mill, even if the entire amount of coal is charged and pulverized in one stage to achieve the final slurry composition. A method may also be used in which a highly concentrated coal-water slurry is wet-manufactured by dumping the coal into the above parts. However, if the slurry is charged in two or more stages, it is easier to obtain a highly concentrated slurry that is pulverized into 4 fine particles.

The grinding aid only needs to be added at the stage when the coal is fed into the ball mill. In the one-stage production method, it is added to the first stage, but in the multi-stage production method, even if the entire amount is added in the first stage, it is added in the first stage and the second stage. Although it may be added in portions thereafter, it is necessary to add at least a portion in step ①.

Next, the wet mill used in the present invention is a known wet mill having a crusher cape, such as a ball mill or a rad mill.
It can be vertical or horizontal. In the present invention, the amount of grinding media such as balls and rods packed into the wet mill is 15 to 55% of the apparent mill content, fIF or 20 to 40%.
%, if it is less than 15%, the pulverization of the coal is poor, and if it exceeds 55%, the amount of pulverizing media becomes too large, and the distance it travels is not 1 minute, and the pulverizing property is still poor. It is not possible to obtain a fluid coal-water slurry.

Also, when pulverizing in one stage, coal is added all at once,
In multi-stage pulverization, the amount of coal in the first stage fed into the wet mill is 65% by weight of the water slurry, preferably 50% by weight.
~60% by weight, but the amount of coal is 40% by weight
If it is less than that, the amount of coal added at a later stage will increase,
Grindability deteriorates, and conversely, if the amount of coal is higher than 65% by weight, the particle size distribution becomes difficult to achieve a high concentration, making it difficult to obtain the desired final slurry.

In any case, it is necessary to add the remaining amount of coal and continue pulverization so that the final high concentration coal-water slurry has a coal concentration of 60.-80% by weight.

If the specific grinding aid of the present invention is used and the wet grinding method is followed, even if the coal concentration in the final slurry is extremely high (60 to 80% by weight), the coal particles will not coalesce among themselves. The average coal particle size is 20.
A preferable finely ground slurry of 0 to 9011% is obtained with a millimeter pass of 70 to 9011%.

If the amount exceeds 90% by weight, the surface area of the coal particles becomes too large and a sufficient effect of the addition of the grinding aid cannot be expected.
: It is not possible to obtain a slurry with ff < i% or more, nor is it possible to obtain an efficiently finely pulverized slurry because wet pulverization cannot be easily carried out.

That is, in the present invention, the coal is divided into one stage, preferably two or more stages, in a mixture of a specific grinding aid and water, and then charged into a wet mill and pulverized under the retention conditions. Coal concentration 60. -8°! 1. It is possible to efficiently obtain a high-concentration, high-performance coal-water slurry with an average coal particle size of 200 mesh pass 7 [1.~90 mass%.

Next, examples of the present invention will be shown. In addition, "r%" in the examples is "
% by weight.

Example 1 Seventeen kinds of coal-water slurries were prepared using Datong coal, which is a type of charcoal, and Hongei charcoal, which is a type of anthracite, using the following three methods.

The coal used was coarsely ground to a grain size of approximately 2 m'y using a dry mill. The grinding aids used were 8 types of the present invention products (Nα1-1 to 1-8) and 2 types of comparative products ('
No! -9""1-10).

Method A: The entire amount of crushed coal and ring water was put into a ball mill □ and crushed for 70 minutes using a one-stage method.゛Method 13: A predetermined amount of coal and a total amount of water, including the total amount of grinding aid, are put into a ball mill and ground for 40 minutes in the first stage.Then, an additional amount of coal is put into this ball mill, and the total amount of water is put into a ball mill for 30 minutes. Two stages of crushing were performed.

(Method J: Pour the entire surface of the grinding aid □, the specified amount of coal, and the entire amount of water into the Rado Mill, perform the first stage of pulverization for 40 minutes, and then add additional amount of coal to the Rado Mill. 30
A second stage of grinding was carried out for minutes.・
゛Details of each production condition, properties of the final slurry produced, and stability evaluation results are shown in Table 2.

The final slurry produced was tested according to the test method shown below.

After production, the slurry was taken out from the mill and its fluidity was observed, and the slurry viscosity was measured at 25° C. using a B-type viscometer. )
In addition, the crushability was evaluated by sifting the crushed coal-water slurry using a 200-mesh sieve.
') Passage amount (%'). A large passing amount (%) indicates good pulverization properties.The pulverization properties of the obtained slurry were evaluated by the following stick-piercing test.

That is, the inner diameter is 5', 5 cm, and the volume is 20 cm.
Pour the coal-water slurry to a height of 18 cm from the bottom into a 3 m measuring cylinder and let it stand for 3 minutes.
After 0 days, cover the cylinder with a lid that has a center guide hole in it, and insert a cylinder with a diameter of 5 ml through the center guide hole.
A stainless steel rod with a smooth tip (total weight 6 g) is added to the coal.
It was dropped vertically from the slurry surface, and two hours were measured until the tip reached the bottom of the cylinder. The shorter the time of step 9, the less precipitation and consolidation of the pulverized coal and the more stable it is.

As is clear from the example of [Yu], according to the present invention, coarsely crushed coal water and grinding aid were added six times at the same time in a wet mill,
By producing coal slurry using a wet production method, the coal concentration is 66-78% and 200%, regardless of the coal type.
A finely pulverized slurry with a viscosity of 450''-2400c] with a mesh pass amount of 72.0 l-86.0 was obtained, and could be easily pulverized even at a high temperature of 1.

In addition, regarding the slurry production conditions, a finely ground slurry with a higher concentration can be obtained in the two-stage wet production method than in the one-stage production method.

Furthermore, by the method of the present invention, the obtained slurry is 3
Even after standing for 0 days, the test time is as short as 3.0 to 9.5 seconds, and the product has excellent long-term stability. We also recognized the side effect of obtaining a coal slurry with a high quality.

It was.

On the other hand, in the case where the grinding aid is not used in the male blade, or in the case of the comparative example which does not satisfy the essential conditions of the present invention, the coal concentration is 60~
Even at 66%, sufficient pulverization is not possible and the pulverization performance is poor. Also,
The slurry did not flow at all, and further pulverization was impossible, and a finely pulverized coal slurry could not be obtained.

Example 2 According to the same slurry production method as in Example 1, using the grinding aid shown in Table 1, wet grinding was carried out until the slurry gelled and the slurry lost its fluidity, and the grinding The time (gelation time) was measured.

The longer the gelation time, the better the energy resistance or impact resistance of the grinding aid.

Details of slurry production conditions and test results are shown in Table 3.

As is clear from the above implementation, when coal, water and a grinding aid are simultaneously put into a wet mill according to the present invention to produce a coal slurry, the content of ethylene oxide in the grinding aid of the present invention based on the total alkylene oxide is 65%. When the ethylene oxide content is ~73%, the gelation time is 80-85 minutes, whereas when the ethylene oxide content is 82-94%, it is 115-15 minutes.
It was 0 minutes long. In other words, this drug had a long gelation time, had strong impact resistance, and had an excellent gelation prevention effect.

On the other hand, when no grinding aid is added.

In the case of 11 ratios that did not meet the essential conditions of the present invention, gelation occurred in a short time of 15 to 20 hours with one force from the slurry even with a coal concentration of 60 to 66%. .

Example 3 5 (Hl) Hard balls were charged into a continuous wet ball mill with an apparent filling rate of 30%, and the test numbers shown in Table 2 of Example 1 were (21~2-52-8~ 2-122-15~2
The slurry was produced under the same slurry production conditions as in -1'7), including the same coarse pulverized coal, production method, grinding aid, and coal concentration, and the slurry production amount was adjusted so that the final slurry residence time in the mill was 70 minutes. As a result, test No. 2-1-2-52-9
-200 in the continuous manufacturing method carried out under the same conditions as in 2-12.
A finely pulverized slurry with good fluidity was obtained with a mesh passing rate of 70 to 85%, but other than that, the slurry gelled and was not discharged from the mill.

That is, according to the wet pulverization method of the present invention, it is possible to produce a pulverized high-concentration slurry even by a continuous pulverization method.

Furthermore, test No. 2-1 to 2-52-8-2]
Continuous wet pulverization was carried out under the same conditions as in Example 2, except that the amount of slurry produced was reduced to 70% of that in the previous example.

The residence time of the final slurry in the mill at this time was ioo minutes. As a result, trial @ No 2-2 ・~2-52-
Only when carried out under the same conditions as 9-2-12, a slurry with good fluidity that passed through 200 meshes and was finely pulverized to M80-90% was obtained, but except for the pillars, the slurry gelled and was discharged from the mill. There wasn't. In other words, when the grinding aid of the present invention with an ethylene oxide content of 80 to 92% is used according to the wet grinding method of the present invention, the gelation prevention effect is even more excellent, so even when the residence time of the powder in the mill is long, the fluidity is good. Continuous production of slurry was possible.

patent applicant Dai-Chengyo Pharmaceutical Co., Ltd.

Claims (1)

[Claims] (1) A method of wet-pulverizing coal in water, comprising: A.
Put coarsely crushed coal, water, and grinding aid into a wet mill at the same time, and then add the coal so that the coal concentration in the final mill is 60% to -80% by weight. So, the amount of coal particles passing through 200 meters per day is 7.
C, t3) Grinding aid starting from an alcohol or derivative thereof having 3 or more, preferably 5 or more, active hydrogen atoms in the molecule. Alkylene oxide is added to this as a substance, and the essential component is a polyether compound having a molecular weight of 16,000 to 30 nm, or a derivative obtained by various reactions of the terminal hydroxyl group of the polyether compound. The wet grinding aid (2) for a highly concentrated coal-water slurry, characterized by the following, contains ethylene oxide as alkylene oxide, the content of which is 60 to 95% by weight, preferably 80 to 9.5% by weight of the total alkylene oxide. % of the wet method for producing a highly concentrated coal-water slurry according to claim 1. (3) The coal is anthracite. , bituminous coal, sub-bituminous coal, preferably anthracite coal, bituminous coal.
Highly concentrated coal-water slurry according to any of paragraphs q) Wet production method.