JPS58214328A - Aqueous coal slurry composition - Google Patents

Abstract

PURPOSE:To make it possible to stably maintain dispersing effect without generating a hard cake for a long period of time, by mixing a coal powder, water and a polyether compound shown by specific formula in a specific ratio. CONSTITUTION:The titled composition is cnstituted from 0.5-80wt% coal powder, 20-99wt% water and 0.1-7.5wt% polyether compound shown by formula A[(C3H6O)y(C2H4O)zH]x (wherein x is an integer of 2 or more, y and z are an integer of 1 or more, A is a residue formed through the removal of active hydrogen from an x valent active hydrogen compound. The wt. ratio of a polyoxypropylene chain and polyoxyethylene chain is 50/50-5/95 and M.W is 3,000- 100,000). The active hydrogen compound of the above mentioned polyether compound is an amino compound or a hydroxy compound and, for example, there is ethylenediamine or glycerine. By using the above mentioned aq. coal slurry composition, dispersing effect is stably maintained without generating a hard cake for a long period of time.

Description

[Detailed description of the invention] The present invention relates to a water slurry of fine coal powder.

More specifically, regarding a water slurry of coal powder that has good dispersibility, does not produce hard cakes even when stored for a long time, and has good redispersibility. However, when a surfactant called a dispersant is added, the fine coal powder becomes a stable suspension in water. However, since this dispersion system is inherently thermodynamically unstable, the fine coal particles will settle if used for a long time. In general, the better the dispersibility, the more closely packed the sedimented particles are, resulting in a hard cake that is harder to redisperse. Therefore, if the dispersion system is used immediately after making it, the dispersant has a very good effect, but if it is stored for a long time, a hard cake is formed and the redispersibility is poor. A problem arises. Conventional dispersants have a strong effect of separating the secondary particles of fine coal powder from the primary particles Kt1 and preventing the separated particles from agglomerating again.
It tends to form a hard cake after sedimentation and is not fully satisfactory when stored for a long time, so improvements have been desired.

The present inventors conducted research on iron content in order to obtain a water slurry of coal powder that has a dispersion effect on fine coal powder and prevents the precipitation from forming a hard cake. They discovered this and completed the present invention.

That is, the present invention is a coal/water slurry composition comprising coal powder, water, and a polyether compound represented by the following general formula (1) in an amount of 0.01 to 7.5% by weight.

A[(0,H601y(02H10)2H]x(I)(
In formula (I), 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 3.000 to 100,000)0 By using the coal/water slurry composition of the present invention,
It has become possible to store it stably for a long period of time without forming a hard cake.

The polyether compound used in the present invention can be easily produced by adding propylene oxide and ethylene oxide to a compound having active hydrogen by a conventional method. 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°C to 80°C.
After propylene oxide is added at 200°C and a pressure 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 hydroxyl group.

Hydroxy compounds having amino groups, mercapto groups, etc.
These include amino compounds, mercapto compounds, etc., and particularly preferred are amino compounds and hydroxy compounds having 5 or more active hydrogen atoms, such as ethylenediamine, diethylenetriamine, and triethylenetetramine.

Tetraethylenepentamine, glycerin, trimethylolpropane, pentaerythritol.

Mention may be made of sorbitol, sucrose and hydroxyethylcellulose.

The ratio of polyoxypropylene chains (PO) to polyoxyethylene chains (UO) in formula (■) is 1iiiI:,
Ratio PO/KO=50150~5/95. Preferably it is 40/60 to 10/90. When this ratio becomes higher than 50150, water solubility decreases and performance deteriorates, and even when this ratio decreases below 5/95, performance decreases, so the effect of introducing oxypropylene chains is considered to be important.

The molecular weight of the polyether compound represented by formula (I) is 3
, 00.0 to 100,000, preferably 7,500
~50.000. When the molecular weight is less than 3.000, the dispersion effect of coal powder is excellent, but the
- The effect of preventing cake formation is lost. On the other hand, if the molecular weight is 1
If it is larger than 00.000, the agglomeration effect on the powder becomes significant and the desired effect of the present invention cannot be obtained.

The coal/water slurry composition of the present invention is preferably composed of 0.5 to 80% by weight of coal powder, 20 to 99% by weight of water, and 0.01 to 7.5% by weight of the polyether compound; The weight ratio of the ether compound is preferably 0.05 to 2.5.If the weight coefficient of the polyether compound is less than 0.01, the effect is small, and even if the weight ratio exceeds 7.5, the effect remains constant. It is disadvantageous.

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. The particle size of this coal powder may be any particle size that allows direct combustion in a boiler, but the general particle size currently used in thermal power plants for this purpose is a particle size with a 200 mesh bath ratio of 70 to 90q6. belongs to.

Coal, polyether compound, and water may be mixed in any order, but the polyether compound may be dissolved or dispersed in water, and then coal may be added thereto and the mixture may be prepared using an appropriate mixing device or crushing device. In preparing the coal-water slurry of the present invention, an attriter, a sand mill, and a three-roll mill are used.

Any dispersion equipment such as a ball mill may be used, and the polyether compound may be added before the step of pulverizing the coal powder and/or secondary particles of the coal powder with these equipments, or the polyether compound may be added to the pulverized powder. You can add it later.

In addition to this, the coal-water slurry composition of the present invention may contain other compounds such as anionic and nonionic surfactants, homopolymers of sodium acrylate, olefin-
Copolymers of sodium maleate, condensed phosphates, polyoxyethylene oleyl ether, polyoxyethylene sorbitan monooleate qti-altoyo-a exhibit excellent effects.

EXAMPLES The present invention will be specifically illustrated below with reference to Examples, but the present invention is not limited to these Examples.

Example 1 Using Chinese coal as coal and various polyether compounds shown in Table 1, a coal/water slurry composition with a coal concentration of 10% by weight and a polyether compound concentration of 1% (relative to the total system) was prepared. A product was prepared as vlI, and its dispersibility and stability were tested.

Aqueous solution 20R/containing a predetermined amount of various polyether compounds
After adding 25 F of coal powder into the mixture and stirring lightly with a spatyl, an appropriate amount of an aqueous solution of a polyether compound was added to obtain a slurry with a coal content of 10% by weight. This slurry was ground in a sand mill (Igarashi Seisakusho Kuma) for 5 hours, then placed in a 50M/graded emulsification test tube and left in a constant temperature room at 25°C for 24 hours.
The state of dispersion after a period of time, the hardness of the precipitate after 20 days and 90 days, and the ease of redispersibility are evaluated.

In addition, the polyether compound was 1% by weight based on the entire system.

*】Chinese charcoal, 200 mesh sieve passed product analysis value calorific value 7450 KcatACs+ (JIS M
8814) Ash content 8.9% (J
IS M 8812) Water 7,0 yen
(JIS M 88111 fixed carbon 60,0
% (JIS M 8812) The dispersion state and dispersion stability of the slurry were evaluated as follows. The results are shown in Table-1.

Since a hard cake had not yet been formed in the slurry after 24 hours, evaluation was made by whether or not solid fine particles were dispersed without settling in an emulsification test tube.

○: No sedimentation.

△: Slight sedimentation.

×: About 50 cm has settled.

XX: Completely settled.

The dispersion stability after standing for 20 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.

×Knees are stiff.

XX: Very hard.

Claims (1)

[Scope of Claims] 1. A coal/water slurry composition comprising coal powder, water, and a polyether compound represented by the following general formula (■) in an amount of 0.01 to 7.5% by weight. A[(0,H60)y(02)1.0+,H]X(I)
(In formula (I), X is an integer of 2 or more, y and z are integers of 1 or more, A is a residue obtained by removing active hydrogen from an The weight ratio of ethane chains is 50,150 to 5/95, and the molecular weight is 3,000 to 100,000)02 The active hydrogen compound in the polyether compound is an amine compound or a hydroxy compound.Claim 1 The coal/water slurry composition described in . 3. The coal/water slurry composition according to claim 2, wherein the active hydrogen compound in the polyether compound is an amine compound or a 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. The coal/water slurry composition according to claim 3, which is sucrose or hydroxyethyl cellulose.