JPS58214329A - Preparation of stable aqueous coal slurry - Google Patents

Abstract

PURPOSE:To stably disperse a coal fine powder and to prevent the formation of a precipitate or a hard cake even during longterm preservation, by a method wherein a polyether compound shown by specific formula is added to the aqueous dispersion of a coarse coal powder and the obtained compound is comminuted and mixed. CONSTITUTION:A polyether compound shown by formula A[(C3H6O)y(C2H4O)z]x (wherein x is an integer of 2 or more, y and z are an integer of 1 or more, A is residue obtained through the removal of active hydrogen from an x valent active hydrogen compound. The wt. ratio of a polyoxypropylene chain and a polyoxyethylene chain is 50/50-5/95 and M.W. is 3,000-100,000) is added to the aqueous dispersion of a coarse coal powder to carry out crushing and mixing or added to and mixed in the aqueous dispersion prepared by communting said aqueous dispersion of the coarse coal powder. As the active hydrogen compound of the above mentioned polyether compound, for example, there is ethylenediamine or glycerine and the addition amount of the polyether compound is 0.01- 7.5wt% relative to the aqueous dispersion of the coal powder.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a stable water slurry process of fine coal powder. More specifically, the present invention relates to a method for producing a stable coal/water slurry that has good dispersibility, does not produce nod cake even when stored for a long time, and has good redispersibility.

Generally, a water dispersion system of coal powder settles because the specific gravity of the coal powder is higher than water, but by adding various compounds called dispersants, it is possible to obtain a slurry in which fine coal powder is stably suspended in water. ing. However, this slurry is also inherently thermodynamically unstable, so if left for a long time, the fine coal particles will settle. In general, the better the dispersibility, the more closely packed the sedimented particles are, resulting in a hard precipitate that is difficult to redisperse, that is, a node cake.

Examples of such dispersants include polymeric dispersants such as sodium polyacrylate and olefin-sodium maleate copolymers, and surfactants such as polyoxyethylene oleyl ether and polyoxyethylene sorbitan monooleate. . However, although the water slurry of coal prepared by adding these dispersants has excellent dispersibility of coal powder during production, when stored for a long time, a cake is formed and redispersibility is poor. The problem arises that it is bad.

Conventional methods have a strong effect of loosening the secondary particles of fine coal powder into primary particles and preventing separated particles from agglomerating again, but they tend to form hard cakes after sedimentation and are insufficient when stored for long periods Unsatisfactory results were obtained and improvements were desired.

The present inventors have conducted intensive research to find a method for obtaining a water slurry of coal powder that stably disperses fine coal powder and prevents the precipitation from forming a hard cake even when stored for a long time. The present invention has been completed by discovering that a stable slurry can be obtained by pulverizing coarse powder in water and adding a specific compound during or after the pulverization.

That is, the present invention provides an aqueous dispersion of coarse coal powder with the following general formula (
After adding the polyether compound represented by 1, pulverization,
This is a method for producing a stable coal/water slurry, which is characterized by: mixing or adding and mixing a polyether compound represented by the following general formula (I) obtained by pulverizing an aqueous dispersion of coarse coal powder. .

A[c, a6o+y(a2H,, o+g, alX(1)
(In 2m, X is an integer of 2 or more, 7.2 is an integer of 1 or more,
A is a residue obtained by removing active hydrogen from an X-valent active hydrogen compound, and has a weight ratio U of polyoxypropylene chains and polyoxyethylene chains of 50150 to 5/95, and a molecular weight of 3.
．． 000 to 100.000. ) The coal used in the present invention may be of various types such as anthracite, bituminous coal, sub-bituminous coal, lignite, etc., and is pulverized in water. In addition, in an aqueous dispersion of coarse coal powder, the concentration of the coarse powder may be any concentration that produces a dispersion system, but generally it is 0.5 to 70% by weight, and 50% by weight.
-70% by weight are particularly useful. Coarse powder of about 200 mesh baths or about 30 pieces is generally used, and this can be ground into fine powder by pulverizing it in water according to the method of the present invention. Excellent effects can be obtained when the powder is pulverized into a fine powder having a particle size with a 200 mesh bath ratio of 70 to 90%.

In carrying out the present invention, the polyether compound may be used in an amount of 0.01 to 7.5% by weight, preferably 0.05 to 2.5% by weight based on the total system (coal powder + water).
It is desirable to add it at a ratio of . If the amount added is small, the effect will be small, and if it is added too much, the effect will be constant, which is economically disadvantageous. The polyether compound may be added to an aqueous dispersion of coarse coal powder before pulverization, or may be added after this pulverized liquid is pulverized into the above-mentioned fine powder.

The polyether compound used in the present invention has the general formula (,1
), and the button can be easily produced by adding propylene oxide and ethylene oxide to a compound having active hydrogen using a conventional method. That is, the starting material, a compound having active hydrogen, is heated in the presence of a catalytic amount of alkali or acid at a temperature of 80 to 200 ml.
After propylene oxide is added at a temperature of 1 to 5 atm, the desired product is obtained by adding ethylene oxide under the same conditions. By adjusting the number of moles of the active hydrogen compound and the number of moles of propylene oxide and ethylene oxide as starting materials, it is possible to easily obtain a compound having a desired structural formula.

The active hydrogen compound in the polyether compound that can be used in the present invention is a hydroxy compound, an amine compound, a mercapto compound, etc. having a hydroxyl group, an amino group, a mercapto group, etc., and particularly preferably an amine having three or more active hydrogens. compound and a hydroxy compound,
Such as ethylenediamine, diethylenetriamine, triethylenetetramine.

Mention may be made of tetraethylenepentamine, glycerin, trimethylolpropane, pentaerythritol hexasorbitol, sucrose, and hydroxyethylcellulose.

Polyoxypropylene*) 1 (PO) in formula (I)
The proportion of polyoxyethylene chains (EO) is P by weight.
O/KO=50150-5/95, preferably 407
It is 60-10/90. When this ratio becomes larger than 50150, the solubility in water decreases [7] performance is also inferior, and even when this ratio becomes smaller than 5/95, the performance decreases, so the effect of introducing oxypropylene chains is considered to be important.

The molecular weight of the polyether compound used in the present invention represented by formula (T) is 3,000 to 1o0. QOO, preferably 7,500 to 50,000. molecular weight is 3
, ODD, the dispersion effect of coal powder is excellent, but the hard cake generation prevention effect is lost. On the other hand,
If the molecular weight is greater than 100.000, the agglomeration effect on the powder becomes significant and the desired effects of the present invention cannot be obtained.

In the present invention, it is essential to grind the coarse coal powder in water, but any grinding means that satisfies this requirement can be used, such as attri p-, f-to mill, three-roll mill, ball mill, etc. A dispersion device may be used, and
The polyether compound may be added before the process of pulverizing coarse coal powder and/or secondary particles of coal powder with these devices, or may be added after pulverizing. In addition to the compounds, various conventionally known dispersants, such as homopolymers of sodium acrylate, copolymers of olefin-sodium maleate, condensed phosphates, and polyoxyethylene oleyl ether.

A more excellent effect is shown when used in combination with polyoxyethylene sorbitan monooleate, etc. By the method of the present invention as described above, a coal/water slurry with excellent dispersion stability can be obtained, and at the same time, the aqueous dispersion stabilizer of the present invention can be obtained. By using this method, it is possible to obtain a water slurry of fine coal powder that does not produce a nod cake even after long-term storage. The examples are not limited.

Example 1 Using Chinese coal as coal, which had been coarsely ground in advance (passed through a 200-mesh sieve), a coal/water slurry was prepared with a vI of 4 nt.

That is, 252 kg of coarse coal powder was added to 20 m/20 m of an aqueous solution containing a predetermined amount of a polyether compound as shown in Table 1, and after stirring lightly with a spatyl, an appropriate amount of the same polyether compound aqueous solution was added to obtain a dispersion of 10% by weight excluding coal. Get the liquid. This dispersion was ground for 5 hours using a sand mill (manufactured by Igarashi Seisakusho) to obtain a water slurry of fine coal powder. The amount of polyether compound added to this slurry was 1 x 1 for the entire system.

Chinese coal analysis value calorific value 7450 Kcat/kf (J Engineering SM 88
141 ash 8.9 section (J engineering EI
M E+811 Moisture 7.0%
(J Engineering SM 88111 fixed carbon 60.0chi
(J Engineering SM 88121) Next, put this water slurry of fine coal powder into a 5ON/graded emulsification test tube and heat it at 25°C.
The state of dispersion after 1 and 24 hours of standing in a constant temperature room, and the hardness and ease of redispersibility of the precipitate after 20 and 90 days, were evaluated by the following methods.

1) Evaluation of dispersion state After 24 hours, a nod cake had not yet been formed in the dispersion system, so evaluation was made by whether solid fine particles were dispersed without settling in an emulsification test tube.

○: No sedimentation.

△: Slight sedimentation.

×: About 50 cm has settled.

XX: Completely settled.

11) Evaluation of redispersibility The dispersion stability after standing still for 20 days and 90 days was qualitatively evaluated based on the hardness of the precipitate settled at the bottom of the emulsification test tube and the ease of redispersibility.

○: Disperses when water is stirred.

△: Soft and easily crumbles with supertiling.

×: Hard.

XX: Very hard.

Claims (1)

[Claims] 1. A polyether compound represented by the following general formula (I) is added to an aqueous dispersion of coarse coal powder, followed by pulverization and warming, or an aqueous dispersion of coarse coal powder is pulverized. A method for producing a stable coal/water slurry, which comprises adding and mixing a polyether compound represented by the following general formula (I). A[(0,H60)y(C2H11O)2H'JX(I
) (In formula (1), X is an integer of 2 or more, 7.Z is an integer of 1 or more, A is a residue obtained by removing active hydrogen from an The weight ratio of the ethylene chains is 5015-b to 5/95, and the molecular weight is 3.000 to 100.000.) 2. The active hydrogen compound in the polyether compound is an amino compound or a hydroxy compound. A method for producing a stable coal/water slurry according to Scope 1. 3. The method for producing a stable coal/water slurry according to claim 2, wherein the active hydrogen compound in the polyether compound is an amino compound or hydroxy compound having three or more active hydrogens. 4 The active hydrogen compounds in the polyether compound are ethylenediamine and diethylenetriamine. triethylenetetramine, tetraethylenepentamine,
Glycerin, trimethylolpropane, pentaerythritol, sorbitol. 4. The method for producing a stable coal-water slurry according to claim 3, wherein the slurry is sucrose or hydroxyethyl cellulose. 5 The amount of polyether compound added is 0. A method for producing a stable coal-water slurry according to any one of claims 1 to 4, wherein the content is 7.5% by weight.