JPS6084392A - Preparation of concentrated coal/water slurry by wet process - Google Patents

Abstract

PURPOSE:To prepare a low-foaming high-fluidity coal/water slurry in high concn., by adding a specified grinding aid and a defoamer to coal and grinding the mixt. in water. CONSTITUTION:A polyether having an M.W. of about 100,000-600,000 obtained by polymerization of alkylene (or deriv. thereof obtained by adding acid, etc. to terminal hydroxyl groups of the polyether) is used as grinding aid and a silicon compd. of the formula (where A is H, alkyl or phenyl; n is 0-2,500) (e.g. silicone oil) is used as defoamer. Water and coal are ground in a wet mill in the presence of the grinding aid in an amt. of about 0.3-2wt% of total slurry and the defoamer in an amt. of about 0.01-5wt% of the grinding aid.

Description

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

In recent years, due to the depletion of oil resources, the use of coal has been reaffirmed.
Various ways of using it are being considered.

A third step is to pulverize the coal and disperse it in water to create a pumpable water slurry.

In general, when coal is pulverized using a pulverizer, it is possible to use either a dry method or a wet method, but in the case of the dry method, the more pulverized the coal, the more likely there will be an explosion risk due to coal dust and environmental pollution problems. happened.

Also, work efficiency decreases. On the other hand, in the case of the wet method, not only does this problem not occur, but the process of dispersing pulverized coal into water, which is necessary when turning coal into water slurry, is
This can be omitted by wet grinding in water. For the above reasons, it is advantageous to wet-pulverize coal to produce a coal-water slurry.

In addition, since coal-water slurry is used as fuel,
The coal in the water slurry is in high concentration.

In addition, in order to improve the combustibility of coal, it must be finely pulverized. However, in the general wet pulverization method, bubbles are generated during the manufacturing process of the highly concentrated coal-water slurry, and pulverization does not proceed, making it very difficult to obtain the desired slurry.

These bubbles are fine and the highly concentrated coal-water slurry is
Since it has a relatively high viscosity, it is difficult to remove the slurry, and the slurry containing air bubbles becomes soft cream-like and has low fluidity, which prevents pulverization from proceeding, which poses a major problem in production.

Furthermore, even during pump transportation, air bubbles cause cavitation and pressure loss, making it difficult to transport the slurry smoothly and posing a major handling problem.

The present inventors have completed the present invention as a result of extensive research in order to improve these problems. Namely, during the wet mill: (a) coal;

(b) water, (c) a polyether compound with a molecular weight of 10,000 to 60,000 as a grinding aid, and (d) a high-concentration coal characterized by adding a silicone compound as an antifoaming agent to grind the coal. - Wet production method of water slurry.

The coal used in the present invention is anthracite coal, bituminous coal, sub-bituminous coal, etc., and the former two are particularly preferred. Furthermore, it is preferable to use coal that has been dry-crushed in advance.

Next, the polyether compound used as a grinding aid in the present invention is a polyether compound having a molecular weight of 10,000 to 60,000 obtained by reacting a starting material with an alkylene oxide, or a polyether compound obtained by reacting various terminal hydroxyl groups of the polyether compound. derivatives, etc.

Starting materials include (1) compounds having one or more active hydrogens in the molecule, such as aliphatic alcohols, alicyclic alcohols, aromatic alcohols, aliphatic amines, alicyclic amines, aromatic amines,
” The above polyhydric alcohols, the above polyhydric amines, amides, polyalkylene imines, phenols, aliphatic aldehyde condensates of aromatic compounds having phenolic hydroxyl groups, aliphatic carboxylic acids, alicyclic carboxylic acids, aromatic carboxylic acids Acid (2) Compounds having one or more functional groups capable of reacting with alkylene oxide in the molecule, such as water, ammonia, urea, dicyandiamide, halogenated organic substances, cyanate compounds, and the like.

Particularly preferred starting materials include:

(1) Alcohols having 3 or more, preferably 5 or more active hydrogen atoms in the molecule, or derivatives thereof.

(2) Amines having 3 or more active hydrogen atoms, preferably 5 or more active hydrogen atoms in the molecule, or derivatives thereof.

(3) An aliphatic aldehyde condensate of an aromatic compound having a phenolic hydroxyl group.

(4) 7 to 200 nitrogen atoms, preferably 9 to 200 nitrogen atoms in the molecule
A polyalkyleneimine having 100 or a derivative thereof.

Next, as alkylene oxide, ethylene oxide,
Examples include propylene oxide and butylene oxide, which may be used alone or in combination of two or more.
In the case of two or more types, the arrangement may be either block polymerization type or random polymerization type, but block polymerization type is common. In particular, ethylene oxide is included as an alkylene oxide, and its content is 6% of the total alkylene oxide.
A polyether compound having a content of 0 to 100% by weight, preferably 80 to 100% by weight, or a derivative obtained by reacting the terminal hydroxyl group of the polyether compound in various ways exhibits an excellent effect and has high pulverization efficiency under high concentration. Not only can a finely pulverized slurry with good fluidity be obtained, but it also has the effect of being able to withstand the impact of the pulverizing media during pulverization in a wet mill, that is, it exhibits an excellent effect of preventing gelation of the slurry. Especially when the ethylene oxide content is 80-1
A polyether compound or its derivative in a range of 0.00% by weight has an extremely excellent prevention effect, such as preventing slurry from gelling even after long-term grinding.

As mentioned above, polyether compounds obtained by reacting alkylene oxide with starting materials having a molecular weight of 10,000 to 600,000 are effective.

Next, examples of derivatives obtained by subjecting the terminal hydroxyl group of the polyether compound to various reactions include the following.

(1) Esterified products reacted with organic acids or inorganic acids.

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

(3) Aldehydes and carboxylic acids produced by oxidation reactions.

(4) Reaction product of hydroxyl group and monoisocyanate-1.

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

Next, the silicone compound used as an antifoaming agent has the general formula A s sio + sio −)-n siA 3
[A represents hydrogen, an alkyl group, or a phenyl group. n represents a number from θ to 2500. ] In the silicone oil represented by, for example, dimethyl silicone oil, methyl hydrogen silicone oil, diphenyl silicone oil, methylphenyl silicone oil, or the silicone oil represented by the above general formula, a part of A contains an organic group, such as an organic fatty acid or a higher alcohol. , modified silicone oil into which amino groups, epoxy groups, methacrylic groups, etc. have been introduced;
0.65-1 million csj, preferably 100-10
10,000 cst is valid. As for the form during use, it may be added as is, but it is better to add a surfactant, inorganic powder, etc. to form an emulsion in water, which becomes fine powder and has good dispersibility, and is more effective.

Next, regarding the addition rate of the grinding aid and antifoaming agent, the addition rate of the grinding aid is 0.03 to 2 to the final coal-water slurry.
．． It is 0% by weight.

The upper limit was determined solely for economic reasons.

The addition rate of the antifoaming agent is 0.0% relative to the grinding aid. O1 to 5.0% by weight, preferably 0.03 to 2.0% by weight.

The method of the present invention, in which the above-mentioned coal, water, grinding aid, and antifoaming agent are placed in a wet mill and pulverized, involves charging the entire amount of coal to the final slurry composition and pulverizing it all at once in one stage, or pulverizing it in a wet mill. This is a wet method for producing a highly concentrated coal-water slurry in which coal is charged and pulverized in at least two or more stages, and any method may be used. However, it is easier to obtain a highly concentrated and finely pulverized slurry by dividing the slurry into two or more stages.

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 the first step.

In a one-stage production method, the entire amount of the antifoaming agent is added to one stage, but in a multi-stage production method, the entire amount of the antifoaming agent may be added to any stage, or it may be added in portions to the first stage and thereafter.

Next, the wet mill used in the present invention is a known wet mill having a grinding function such as a ball mill or a rod mill, and may be of a vertical type or a horizontal type.

If the above wet grinding method is followed using the specific grinding aid and antifoaming agent of the present invention, the coal concentration in the final slurry will be 60 to 8.
Even at a very high concentration of 5% by weight, there are very few bubbles and good fluidity, preventing coal particles from agglomerating and making pulverization easy.
Finely pulverized, low-foaming with over 70% mesh pass by weight.
A slurry with good fluidity is obtained.

Note that when the grinding aid and antifoaming agent according to the present invention are not used, it is difficult to obtain a slurry of 60 weight or more due to foaming, and it is difficult to obtain an efficiently finely ground slurry because wet grinding cannot be easily performed. can't get it.

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

Example 1 Using Datong coal, which is a type of bituminous coal, and Hongei coal, which is a type of anthracite coal, 17 types of coal-water slurries were manufactured using the following three methods.

The coal used was coarsely ground to a particle size of about 2 mm using a dry mill. The grinding aids used were eight types (ah) of the present invention shown in Table 1. The antifoaming agent is Invention Product 1 shown in Table 2.
There are two types (A-L).

Method A: A grinding aid, an antifoaming agent, coal, and water were put into a ball mill and ground for 70 minutes in a one-stage process.

Method B: t3) Pour the entire amount of crushing aid, the entire amount of antifoaming agent, the predetermined amount of coal, and the entire amount of water into a ball mill, and in the first step
The ball mill was milled for 0 minutes and then an additional amount of coal was charged to the ball mill for a second stage of milling for 30 minutes.

Method C: Put the entire amount of grinding aid, the entire amount of antifoaming agent, the predetermined amount of coal, and the entire amount of water into a rod mill, perform the first stage of pulverization for 40 minutes, then add an additional amount of coal to this rod mill,
A second stage of grinding was carried out for 0 minutes.

Details of each production condition, properties of the final slurry produced, and stability evaluation results are shown in Table 3.

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 adjusted to 110.
The slurry viscosity was measured at 25° C. using a B-type viscometer.

In addition, to evaluate the crushability, the crushed coal-water slurry coal was sieved through a 200-mesh sieve.
It was determined by mesh passing amount (%). A large passing amount (%) indicates good crushability.

The foam content is determined by accurately measuring the final slurry produced into a 100 mQ cylinder, measuring its weight, and calculating the specific gravity (p I
). At the same time, the theoretical specific gravity (P2) of the slurry produced without any bubbles is calculated from the specific gravity of the coal itself. From these, the foam content is shown as follows. Further, the stability of the obtained slurry was evaluated by the following rod penetration test.

That is, the prepared coal-water slurry was placed in a measuring cylinder with an inner diameter of 5.5 cm and a height of 20 cm, and left to stand to a height of 18 cm from the bottom, and after 30 days, the cylinder was covered with a lid with a central guide hole drilled in the top. A stainless steel rod with a diameter of 5 mm and a smooth tip (total weight of 50 g) was dropped vertically from the surface of the coal slurry through the central guide hole.
The time it took for the tip to reach the bottom of the cylinder was measured. The shorter this time, the less sedimentation and consolidation of the pulverized coal and the more stable it is.

As is clear from the above examples, in a wet mill according to the present invention! By adding crushed coal, water, a grinding aid, and an antifoaming agent to produce a coal slurry using a wet manufacturing method, the coal concentration is 68 to 80% and the 200 mesh pass is 75.3 to 95%, regardless of the coal type. .2% finely ground viscosity 5
A slurry with good fluidity of 20 to 2000 cp is obtained,
Grinding was easy even under high concentrations. This is because the foam content of the slurry is extremely small at 2% or less due to the effect of the antifoaming agent.

Further, regarding the slurry production conditions, a finely ground slurry with a higher concentration was obtained in the two-stage wet production method than in the one-stage production method.

Furthermore, by the method of the present invention, the slurry obtained is 30%
Even after standing for a day, the rod penetration time was as short as 3.0 to 9.5 seconds, and the secondary effect of obtaining a homogeneous coal slurry with excellent long-term stability was also observed.

On the other hand, in the case where no grinding aid and antifoaming agent are added, or in the case of a comparative example which does not satisfy the essential conditions of the present invention, sufficient grinding is not possible even with a coal concentration of 60 to 66%, resulting in poor grindability. Further, the slurry did not flow at all, and further pulverization was impossible, and a finely pulverized coal slurry could not be obtained.

Example 2 By the same slurry manufacturing method as in Example 1 above.

Using the grinding aid shown in Table 1 and the antifoaming agent shown in Table 2,
Wet pulverization was performed until the slurry gelled and the fluidity of the slurry disappeared, and the pulverization time (gelation time) was measured by H1.

The longer the gelation time, the better the energy resistance or mjm resistance.

Details of slurry production conditions and test results are shown in Table 4.

As is clear from the above examples, according to the present invention, coal, water and grinding aid 71. When coal slurry was produced by adding + and an antifoaming agent, the gelation time was as long as 120 to 230 minutes. That is, when a crushing aid and an antifoaming agent are used together, the gelation time is long, the impact resistance is strong, and the gelation prevention effect is also excellent.

Moreover, in the case of a comparative example that does not satisfy the essential conditions of the present invention, a slurry was not formed even at a coal concentration of 60 to 66%, and gelation occurred in a short gelation time of 15 to 20 minutes.

Example 3 5 (H1) The rigid balls were charged to a continuous wet ball mill at a filling rate of 30%, and the test Nn (1-1-1-, 5, l -8-1-12,1-1
The slurry was manufactured under the same slurry manufacturing conditions as the coarsely crushed coal, manufacturing method, crushing aid, and coal concentration of 5 to 1-17), and the amount of slurry manufactured was adjusted so that the residence time of the final slurry in the mill was 70 minutes. .

As a result, test No. 1-1-1-5.1-8-1-
In the continuous production method carried out under the same conditions as in No. 12, a finely pulverized slurry with good fluidity was obtained with an amount of 75 to 95% passing through 200 meshes, 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.

Further, similar continuous wet pulverization was carried out under the same conditions as Tests Nα1-1 to 1-5 and 1-8 to 1-12, with the amount of slurry produced being reduced to 50% of that of the previous example.

The residence time of the final slurry in the mill at this time was 140 minutes. As a result, Test No. 1-2 to 1-5, ]-9
~ Only when carried out under the same conditions as in 1-12, a finely pulverized slurry with good fluidity with a 200 mesh passing rate of 85-98% was obtained, but in other cases the slurry gelled and was not discharged from the mill. . That is, according to the wet grinding method of the present invention, it was possible to continuously produce a slurry with good fluidity even when the residence time in the mill was long.

Claims (1)

[Claims] (1) In a wet mill: (a) coal; (b) water. (C) A polyether compound with a molecular weight of 10,000 to 600,000 as a grinding aid, and (d) A wet method for producing a highly concentrated coal-water slurry characterized by adding a silicone compound as an antifoaming agent to grind the coal.