JP2747522B2 - Additive for coal-water slurry - Google Patents

Description

The present invention relates to an additive for a coal-water slurry, and more particularly, to a coal-water slurry for dispersing coal powder in water at a high concentration and with good fluidity and stability. The present invention relates to additives for slurries, and particularly to additives for coal-water slurries that reduce wear of transport pipes and burner chips.

[Prior Art] In recent years, there has been a concern that petroleum resources will be depleted, and coal has attracted attention again as a substitute. However, since coal is a solid, handling is complicated, there are problems such as environmental pollution due to scattering of coal dust at the time of unloading at a port and spontaneous ignition at the time of coal storage.

As a result, coal-water slurry (hereinafter referred to as “CWM”) made by dispersing pulverized coal in water at a high concentration and making it fluidized enables bundling similar to petroleum, enables pipeline transportation, and It has good stability and can be used for direct combustion.

CWM is required to have a high concentration of dispersed pulverized coal and to be excellent in fluidity and stability, and various additives have been developed to impart such properties. At the same time, problems that had not been conceived at the test stage in a small pilot plant became apparent.

For example, as an additive for CWM, naphthalene sulfonate and its formalin condensate (JP-A-56-21636),
Polydicyclopentadiene sulfonate (JP-A-60-96)
No. 689) and polystyrene sulfonate (JP-A-57-1)
CWM using anionic additives such as 45187
Is a problem at the practical stage due to severe wear of pipelines and burner tips.

CWM using an alkylene oxide adduct of polyalkyleneimine (JP-A-58-49795) and a polyether polyol type nonionic additive (JP-A-57-56034) have relatively little wear. However, there is a drawback that if the temperature is maintained at a high temperature, the viscosity increases and the pipeline cannot be transported. Furthermore, the stability of CWM using said additives is insufficient. For example, if left for one month, pulverized coal sediments to form aggregates that have lost their self-fluidity, making it impossible to discharge them from the storage tank.

The half ester saponified styrene-maleic acid copolymer (Japanese Patent Application Laid-Open No. 61-225284) has only a carboxylate as a hydrophilic group. Therefore, CWM using the additive has poor dispersibility and high dispersibility. Cannot be concentrated.

Further, CWM using a salt of a sulfonated styrene-maleic anhydride copolymer (JP-A-58-42694 and JP-A-61-221296) has poor stability.

[Problems to be Solved by the Invention] An object of the present invention is to provide an additive which is excellent in high concentration property, fluidity and dispersion stability and enables the production of CWM with less wear of a transport pipe. I do.

[Means for Solving the Problems] The present invention provides a coal-water containing a partially esterified styrene-maleic acid copolymer obtained by reacting the following components (A), (B) and (C). It relates to an additive for slurry.

The component (A) is a styrene-maleic anhydride copolymer represented by the following general formula (1).

(In the formula, 1 represents an integer of 1 to 5, m represents an integer of 1 to 3, and n represents an integer of 4 to 10.) The copolymer may be a random copolymer or a block copolymer. The number average molecular weight of the copolymer is between 1000 and 9000, preferably between 1500 and 3000. In the above general formula (1), 1 represents the number of styrene units,
M is an integer of 5 and m represents the number of maleic anhydride units;
And is preferably an integer of 1 to 3, preferably 1 / m = 3/1 to 1/1. n is an integer of 4 to 10, preferably 6 to 8.

The component (B) is a polyether derivative having a polyalkylene glycol chain represented by the following general formula (2).

X (R) p (C ₂ H ₄ O) qH (2) (wherein, X is a residue of a compound having one active hydrogen having 1 to 4 carbon atoms, and R is an alkylene having 3 to 8 carbon atoms) (The oxide group, p represents an integer of 0 to 10 and q represents an integer of 10 to 200.) The polyether derivative imparts hydrophilicity to a partially esterified styrene-maleic acid copolymer.

Examples of the compound having one active hydrogen having 1 to 4 carbon atoms include alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, allyl alcohol and tert-butyl alcohol, carboxylic acids such as formic acid, acetic acid and propionic acid, and methane. And mercaptans such as thiol and ethanethiol. The above general formula (2)
In the formula, p represents the average addition mole number of the alkylene oxide, and q represents the average addition mole number of the ethylene oxide.
p is an integer from 0 to 10, preferably 0 to 5, while q is
It is an integer of 10 to 200, preferably 20 to 150. When q is less than 10, it is difficult to obtain a water-soluble styrene-maleic acid copolymer partially esterified product, and when q exceeds 200, the fluidity of CWM is deteriorated.

The component (C) is a primary amine having 6 or more carbon atoms. The primary amine is one which mainly gives an imide bond to the styrene-maleic anhydride copolymer to give a hydrophobic group. The primary amines of the component (C) include amines having 6 or more, preferably 8 or more, carbon atoms, for example, those having an unsaturated bond such as an aliphatic amine such as octylamine, laurylamine and stearylamine and an oleylamine. And amines such as aromatic amines such as benzylamine and aniline.

The reaction molar ratio of the components (A), (B) and (C) is as follows: (A) :( B) :( C) = 1: (1-10) :( 1-3)
It is.

The content of the component (B) in the partially esterified styrene-maleic acid copolymer of the present invention is 50 to 95% by weight,
Component (C) is preferably 2 to 20% by weight.
If the component (B) is less than 50% by weight, it is difficult to dissolve in the water of the partially esterified styrene-maleic acid copolymer, while if it is more than 95% by weight, the dispersing performance of CWM is inferior. Poor dispersibility, if more than 20% by weight, it is difficult to dissolve in water.

The reaction of the component (A), the component (B) and / or the component (C) is performed by methyl ethyl ketone, methyl isobutyl ketone,
The reaction may be carried out under reflux in a solvent such as dioxane, or the reaction may be carried out at 120 to 180 ° C. in a nitrogen stream without using a solvent. The esterification reaction between the component (A) and the component (B) can be performed without a catalyst, but a catalyst such as paratoluenesulfonic acid may be used. The same applies to the imidation reaction or the amidation reaction of the component (A) and the component (C). Further, the components (A), (B) and (C) can be reacted simultaneously. Since the partially esterified styrene-maleic acid copolymer thus obtained leaves some carboxyl groups, it can be made into a salt of sodium, potassium, ammonium and the like.

The number average molecular weight of the partially esterified styrene-maleic acid copolymer produced in this manner is 5,000 to 5,000.
0, preferably 8000 to 30,000. Number average molecular weight 5000
If the amount is smaller, the dispersion stability of the pulverized coal is poor, and it is easy to settle,
On the other hand, if it is larger than 50,000, it will agglomerate and lose self-flowability.

The additive for CWM of the present invention may be used together with other dispersants. Other dispersants that can be used in combination include salts of formalin condensates of naphthalenesulfonic acid, polymers of dicyclopentadiene sulfonate, anionic dispersants such as polystyrene sulfonate, alkylphenol ethylene oxide adducts, and alkylphenol formalin condensates And various non-ionic dispersants such as ethylene oxide adducts.

The amount of the additive for CWM of the present invention varies depending on the particle size of the coal. When the particle size of the coal is 200 mesh and 80% by weight, the amount of the additive is usually 0.1 to 2.0% by weight, preferably 0.1 to 2.0% by weight based on the coal powder.
0.3-1.0% by weight.

The additive for CWM of the present invention may be dissolved in water in advance and then pulverized coal may be added thereto, or may be added later to a mixture of water with pulverized coal. Also, as in the case of hybrid pulverization, coal may be pulverized and added together with water.

As the coal powder to be slurried using the additive of the present invention, one having a particle size of 1 mm or less is suitable, but not limited thereto. Examples of the type of coal include various types of coal such as bituminous coal, subbituminous coal, and lignite, and those of the locality of production.
The additive of the present invention can also be applied to coal decalcified by an oil agglomeration method or a flotation method.

[Action] The reason why the additive for CWM of the present invention exhibits excellent effects is considered as follows. First, some additive dissolved in water adsorbs on the coal surface. Since the adsorbed additive is a polymer with several relatively long polyoxyethylene chains,
It is considered that the volume restriction effect and the osmotic pressure effect of the polymer act to cause a repulsion effect due to steric stabilization, or the pulverized coal is dispersed and stabilized by the compression repulsion effect of the polymer dissolved in water between the particles.

The additive also has some carboxyl groups and therefore exhibits some anionic properties, and is also stabilized by repulsive interaction between the electric double layer at the pulverized coal particle-water interface.

Furthermore, it is considered that the pulverized coal forms a weak aggregate network structure by the adsorbed polymer, and can maintain stability for a long period of time.

Further, regarding the lubricity, it is considered that when the polymer molecules existing in the water are compressed as the particles approach each other, a repulsive force is generated, and the sliding between the particles is smoothed, and the wear of the pipe or the burner tip is reduced.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples.
The present invention is not limited to these examples.

Examples 1 to 9 and Comparative Examples 1 and 2 Various additives were produced according to the formulation shown in Table 1.

A predetermined amount (Table 2) of an additive and water were put into a 500 ml container and dissolved therein, and then, Warkworth coal (Australian bituminous coal) pulverized and prepared to 80% by weight in a 200 mesh pass was gradually charged with stirring. After mixing for 10 minutes after charging, the mixture was mixed at 4000 rpm for 10 minutes with a homomixer (“Auto Homomixer” manufactured by Tokushu Kika Co., Ltd.) to prepare a coal-water slurry.

Table 2 shows the results of measuring the coal concentration, the representative viscosity, and the amount of sedimentation and coagulation of the obtained coal-water slurry, and Table 3 shows the abrasion loss of the disk.

 Each measurement was based on the following method.

(1) Coal concentration (% by weight): Determined from the amount of water loss on drying.

(2) Representative viscosity (mPa · s): The rheogram was measured with a “Rheometer” manufactured by Haake, and the viscosity at a shear rate of 100 sec ⁻¹ was determined.

(3) Settling and coagulation amount (% by weight): 300 g of coal-water slurry
The pot was placed in a 250 ml pot and left as it was. After 2 weeks, the pot was turned upside down and the amount remaining at the pot bottom without self-flow was measured.

(4) Disc wear loss (mg): Coal-water slurry 50
0 g was placed in a container, and a copper plate disk of 50 mmφ × 2 mm was immersed and rotated at 2000 rpm × 20 hours to determine the weight loss due to wear of the disk.

Comparative Examples 3 to 6 Coal-water slurries were prepared in the same manner as in Examples 1 to 9 and Comparative Examples 1 and 2 using the additives shown in Table 1, and the coal concentration, the representative viscosity, the amount of sedimented flocculation and the disk were prepared. Was measured for loss on wear. The results are shown in Tables 2 and 3.

As is clear from the table, the coal-water slurry using the additive of the present invention has a high coal concentration, low viscosity, excellent fluidity, excellent slurryability, and low sedimentation and coagulation stability. It can be seen that the disc is excellent in lubrication and that the wear loss of the disc is small.

[Effect of the Invention] The additive for CWM of the present invention mainly contributes to the water reducing effect, and by using the additive, the pulverized coal concentration in CWM can be increased by 10 to 20% by weight as compared with the conventional case. . In addition, the fluidity of CWM is improved, and sedimentation and coagulation of pulverized coal are suppressed, and long-term stability can be maintained.
Increases the lubricity of CWM and reduces wear on transport pipes and burner tips.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08F 222/08 C08F 222/08

Claims (3)

(57) [Claims] An additive for a coal-water slurry containing a partially esterified styrene-maleic acid copolymer obtained by reacting the following components (A), (B) and (C): (A) Styrene-maleic anhydride copolymer represented by general formula (1) (In the formula, 1 represents an integer of 1 to 5, m represents an integer of 1 to 3, and n represents an integer of 4 to 10.) (B) Polyether derivative having a polyalkylene glycol chain represented by the general formula (2) X (R ) P (C ₂ H ₄ O) qH (2) (wherein, X is a residue of a compound having one active hydrogen having 1 to 4 carbon atoms, R is an alkylene oxide group having 3 to 8 carbon atoms, p represents an integer of 0 to 10, and q represents an integer of 10 to 200), (C) primary amines having 6 or more carbon atoms. 2. The reaction molar ratio of each of the components (A), (B) and (C) is (A) :( B) :( C) = 1: (1-10):
The additive for a coal-water slurry according to claim 1, which is (1-3). 3. The styrene-maleic acid copolymer having a partial amide / imide and a partially esterified product having a number average molecular weight of
The coal-water slurry additive according to claim 1, wherein the amount is from 5,000 to 50,000.