JPH0334793B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Field of Application) The present invention relates to a dispersant for coal-water slurry.
More specifically, the present invention relates to a dispersant that disperses coal powder in water and provides a fluidized coal-water slurry even with a high concentration of coal. (Problems to be Solved by the Prior Art and the Invention) Petroleum, which has been widely used as an energy source, has seen a significant rise in its price and there are concerns that it will run out. Therefore, the challenge is to develop other energy sources that can provide a stable supply, and coal is once again becoming widely available. However, the biggest problem in using coal is transportation problems due to the fact that coal is solid. BACKGROUND ART Conventionally, mined coal is pulverized into powder, which is made into a coal-water slurry to be fluidized and transported by pipeline. On the other hand, COM (Coal−
Oil-Mixture) has reached the practical stage, but
Since oil is used, there are problems in terms of stable supply and price, and high concentration coal-water slurry is seen as a promising coal utilization technology in the future. This slurry technology of coal in water is about to be used in an extremely wide range of coal uses, such as direct coal combustion and gasification, in addition to the above-mentioned coal pipeline transportation, and is becoming an important issue in coal use. ing. It is preferable for this coal-water slurry to be a highly concentrated slurry with little moisture from economical and pollution prevention viewpoints. In particular, in the case of direct combustion of coal-water slurry, which can eliminate wastewater treatment and pollution problems, the coal-water slurry is passed through a cyclone or turbulent burner without dehydration, drying, etc. Since it is charged and burned directly in the furnace, it is necessary to reduce the moisture content as much as possible. However, when attempting to increase the concentration of coal powder using known techniques, the slurry becomes significantly thickened and loses fluidity. On the other hand, if the concentration of coal powder in the slurry is lowered, transportation efficiency, combustion efficiency, etc. will decrease, and if the coal-water slurry is used after being dehydrated, the dehydration and drying processes will also be costly. There are other problems, such as pollution problems. Conventionally, various dispersants for coal-water slurries have been proposed to solve such problems. For example, surfactants such as sodium oleate, sodium dodecylbenzenesulfonate, alkylaryl sulfonate, polyoxyethylene alkyl phenyl ether, stearylamine hydrochloride, polyethylene glycol, polyacrylamide, celluloses, sodium polyacrylate, and lignin sulfone. Examples include water-soluble polymers such as acid soda and sodium naphthalene sulfonate/formalin condensate. However, both have insufficient fluidity and lack practicality. The present inventors continued intensive research to solve the above-mentioned problems in dispersants for coal-water slurries, and found that a certain water-soluble copolymer has excellent effects as a dispersant for coal-water slurries. The present invention was completed based on the discovery that the present invention has the following properties. That is, the present invention provides a dispersant for easily producing a coal-water slurry that has fluidity even at high concentrations. (Means and effects for solving the problems) The present invention is based on the general formula _CH2 =C( _CH3 )COO-XO-) _o Y (wherein, X is an alkylene group having 2 to 4 carbon atoms, n is a number from 1 to 100 on average, Y is hydrogen,
An alkyl group having 1 to 30 carbon atoms, an alkenyl group, an aryl group, an alkyl group having an aryl group as a substituent, a cyclic alkyl group, a cyclic alkenyl group, and a monovalent organic group derived from a heterocyclic compound. ) and one or more polyalkylene glycol monomethacrylate monomers () represented by the general formula CH ₂ =C(CH ₃ )COOZSO ₃ M (wherein Z has 1 to 1 carbon atoms) 4, M represents hydrogen, an alkali metal, an alkaline earth metal, an ammonium group, or an amine base. as a component, the monomer () and the monomer ()
The molar ratio with is in the range of 1:5 to 1:500,
and relates to a dispersant for coal-water slurry comprising a water-soluble copolymer obtained from a raw material monomer in which the sum of the monomer () and the monomer () is 50 mol% or more based on the total monomers. It is something. The coal used in the coal-water slurry is, for example,
Any type of coal, such as anthracite, bituminous coal, sub-bituminous coal, lignite, etc., can be used regardless of its type and origin, as well as its moisture content and chemical composition. Such coal can be milled by wet or dry grinding using conventional methods to produce 200 mesh passes of 50
The standard for use is 70 to 80% by weight or more, preferably 70 to 80% by weight. Further, the slurry concentration is 60 to 90% by weight on a dry basis of pulverized coal, and if it is less than 60% by weight, it is not practical from the viewpoints of economic efficiency, transportation efficiency, combustion efficiency, etc. The water-soluble copolymer that is effective as a dispersant for coal-water slurry of the present invention has monomer () and monomer () as essential components, and has a molar ratio of monomer () and monomer (). The ratio is in the range of 1:5 to 1:500, more preferably 1:20 to 1:200, and the total of monomer () and monomer () is 50 mol% or more of the total monomers. Obtained from a certain raw material monomer. The monomer () is represented by the above general formula and can be obtained by a known method. Examples of monomers () include polyethylene glycol monomethacrylate, polypropylene glycol monomethacrylate, polybutylene glycol monomethacrylate, methoxypolyethylene glycol monomethacrylate, methoxypolypropylene glycol monomethacrylate, methoxypolybutylene glycol monomethacrylate, ethoxypolyethylene glycol monomethacrylate , Ethoxypolypropylene glycol monomethacrylate, Ethoxypolybutylene glycol monomethacrylate, Methoxypolyethylene glycol
In addition to polypropylene glycol monomethacrylate, alkoxypolyethylene glycol monomethacrylates alkoxylated with an alkyl group having up to 30 carbon atoms; alkenoxypolyethylene glycol monomethacrylates alkenoxylated with an alkenyl group having up to 30 carbon atoms; Cypolyethylene glycol monomethacrylate, nonyl phenoxy polyethylene glycol monomethacrylate, naphthoxy polyethylene glycol monomethacrylate, phenoxy polypropylene glycol monomethacrylate, naphthoxy polyethylene glycol/polypropylene glycol monomethacrylate, p-methylphenoxy polyethylene glycol monomethacrylate etc.
Roxypolyalkylene glycol monomethacrylates; alkyloxypolyalkylene glycol monomethacrylates such as benzyloxypolyethylene glycol monomethacrylate; cyclic alkoxypolyalkylene glycol monomethacrylates such as cyclohexoxypolyethylene glycol monomethacrylate; cyclopentenoxypolyethylene glycol monomethacrylate Examples include cyclic alkenoxypolyalkylene glycol monomethacrylates such as methacrylate; heterocyclic ethers of polyalkylene glycol monomethacrylates such as pyridyloxypolyethylene glycol monomethacrylate and thienyloxypolyethylene glycol monomethacrylate; One type or two or more types can be used. Further, the monomer () is similarly represented by the above general formula, and can also be obtained by a known method. Examples of the monomer () include 2-sulfoethyl methacrylate, 3-sulfopropyl methacrylate, 2-sulfopropyl methacrylate, 1-sulfopropan-2-yl methacrylate, 4-sulfobutyl methacrylate, and their sodium and potassium. alkali metal salts of
Examples include alkaline earth metal salts such as magnesium and calcium, ammonium salts, and organic amine salts, and one or more of these may be used. The molar ratio of monomer () to monomer () is in the range of 1:5 to 1:500, and if the ratio is outside this range, the copolymer with excellent dispersion performance will result. Can't get union. In addition to these monomers () and monomers (), monomers () copolymerizable with these monomers can be used within a range of less than 50 mol% of the total monomers. . Examples include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, monovalent metal salts, divalent metal salts, ammonium salts, organic amine salts of these acids, and alcohols with these acids. Resulting esters such as methyl (meth)acrylate, 2-hydroxyethyl acrylate; vinylsulfonic acid, styrenesulfonic acid, allylsulfonic acid, methallylsulfonic acid, 2-acrylamide 2-methylpropanesulfonic acid, 2-sulfonate Various sulfonic acids other than monomers () such as ethyl acrylate, and their monovalent metal salts, divalent metal salts, ammonium salts, and organic amine salts; various (meth)acrylamide, N-methylol (meth)acrylamide, etc. Examples include meth)acrylamide; aromatic vinyl compounds such as styrene and p-methylstyrene; vinyl acetate, propenyl acetate, and vinyl chloride; one or more of these may be used. The amount of these monomers () and monomers () that can be copolymerized with monomers () is within the range of less than 50 mol% of the total monomers, and if used in large amounts exceeding this range, The dispersion performance of the resulting copolymer deteriorates. In the present invention, in order to produce a water-soluble copolymer, the monomer components may be copolymerized using a polymerization initiator. Copolymerization can be carried out by methods such as polymerization in a solvent or bulk polymerization. Polymerization in a solvent can be carried out either batchwise or continuously, and the solvent used in this case is water;
Lower alcohols such as methyl alcohol, ethyl alcohol, and isopropyl alcohol; benzene,
Examples include aromatic or aliphatic hydrocarbons such as toluene, xylene, cyclohexane, and n-hexane; ethyl acetate; and ketone compounds such as acetone and methyl ethyl ketone. In view of the solubility of the raw material monomer and the resulting copolymer, and the convenience of using the copolymer, at least one selected from the group consisting of water and lower alcohols having 1 to 4 carbon atoms should be used. is preferred. Among the lower alcohols having 1 to 4 carbon atoms, methyl alcohol, ethyl alcohol, and isopropyl alcohol are effective. When polymerization is carried out in an aqueous medium, a water-soluble polymerization initiator such as ammonium or alkali metal persulfate or hydrogen peroxide is used as the polymerization initiator. At this time, an accelerator such as sodium hydrogen sulfite can also be used in combination. Also, lower alcohols,
For polymerization using aromatic hydrocarbons, aliphatic hydrocarbons, ethyl acetate or ketone compounds as solvents, peroxides such as benzoyl peroxide and lauroyl peroxide; hydroperoxides such as cumene hydroperoxide; azobisisobutyronitrile Aliphatic azo compounds such as, etc. are used as polymerization initiators. At this time, a promoter such as an amine compound can also be used in combination. Furthermore, when a water-lower alcohol mixed solvent is used, it can be appropriately selected from among the various polymerization initiators or combinations of polymerization initiators and accelerators mentioned above. The polymerization temperature is appropriately determined depending on the solvent and polymerization initiator used, but it is usually carried out within the range of 0 to 120°C. Bulk polymerization uses peroxides such as benzoyl peroxide and lauroyl peroxide; hydroperoxides such as cumene hydroperoxide; and aliphatic azo compounds such as azobisisobutyronitrile as polymerization initiators at a temperature of 50 to 150°C. done within the range. In addition, the molecular weight of the copolymer can be used in a wide range, but considering its performance as a dispersant for coal-water slurry, it is in the range of 1,000 to 500,000, especially 5,000,000 to 500,000.
A range of ~300,000 is preferred. The dispersant for coal-water slurries of the present invention is used in pulverized coal-water slurries, but the amount added is not particularly limited and is effective over a wide range of amounts. 0.05-2% by weight (dry basis), preferably 0.1-1
It is used in a proportion of % by weight. In order to use the dispersant for coal-water slurry of the present invention, the dispersant may be mixed with coal in advance to form a slurry, or the dispersant may be dissolved in water in advance. May be used. Of course, a predetermined amount of the dispersant may be mixed all at once, or may be used batchwise. Furthermore, due to the nature of the dispersant, any device for slurrying coal in water may be used as the slurry device. By these addition methods and slurry making methods,
The scope of the present invention is not limited. Moreover, a rust preventive agent, a corrosion preventive agent, an antioxidant, an antifoaming agent, an antistatic agent, a solubilizer, and the like can be added to the dispersant for coal-water slurry of the present invention as required. (Effects of the Invention) The dispersant for coal-water slurry of the present invention has excellent dispersibility of coal in water, and provides highly fluid and highly concentrated coal-water slurry with the addition of a small amount of dispersant. It is possible. By applying the highly concentrated coal-water slurry obtained using the dispersant for coal-water slurry of the present invention, it becomes possible to economically transport coal by pipeline, and it is possible to transport solid coal by combustion. The above problems can be solved. Therefore, the dispersant for coal-water slurry of the present invention can greatly contribute to the spread of coal utilization technologies such as direct combustion of coal and coal gasification. (Example) Next, the dispersant for coal-water slurry of the present invention will be described in more detail by giving comparative examples and examples, but of course the present invention is not limited thereto. In the examples, unless otherwise specified, parts are by weight. Example 1 200 parts of water was charged into a polymerization container equipped with a thermometer, a stirrer, two dropping funnels, a gas introduction pipe, and a reflux condenser, and while stirring, the inside of the polymerization container was replaced with nitrogen, and the temperature was 95% in a nitrogen atmosphere. heated to ℃. Thereafter, 25 parts of methoxypolyethylene glycol monomethacrylate (containing an average of 80 ethylene oxide units per molecule) as a monomer (), 75 parts of sodium salt of 2-sulfoethyl methacrylate as a monomer (), and water. 150 parts of the solution was added dropwise over 120 minutes, and a solution of 0.4 parts of ammonium persulfate and 50 parts of water was added dropwise over 140 minutes from the other dropping funnel. After the dropwise addition was completed, polymerization was continued at the same temperature for 1 hour and then cooled to produce a copolymer (1) with an average molecular weight of 100,000.
An aqueous solution of was obtained. Examples 2 to 12 Monomers () and monomers () shown in Table 1
And if necessary, monomer () was used in the monomer composition (mol%) shown in Table 1, and polymerization was carried out by a conventional method to obtain an aqueous solution of copolymers (2) to (12). . Comparative Examples 1 and 2 Comparative (co)polymers (1) and (2) were obtained by polymerizing in a conventional manner using the monomer compositions shown in Table 1.

【table】

[Table] Example 13 Copolymers (1) to (12) obtained in Examples 1 to 8,
Coal (bituminous coal) pulverized to pass 74% through a 200-mesh sieve was added little by little at room temperature to an aqueous solution prepared in the amount shown in Table 2 with stirring. After adding the entire amount to achieve the coal concentration shown in Table 2, the coal was stirred for 3 minutes at 5000 RPM using a homo mixer (manufactured by Tokushu Kikako).
A water slurry was prepared. The viscosity of the obtained coal-water slurry was measured at 25°C to evaluate the fluidity. The results are shown in Table 2. Low viscosity indicates good fluidity. For comparison, comparative (co)polymers (1) to (2) obtained in Comparative Examples 1 to 2, sodium polyacrylate (average molecular weight 60,000) or polyethylene glycol (average molecular weight 21,500) were dispersed. Table 2 also shows the results of comparative examples when the dispersant was used as a dispersant and when no dispersant was used at all.

[Table] ×: Defective

Claims (1)

[Claims] 1 General formula CH ₂ =C(CH ₃ )COO(-XO) -- _o Y (wherein, X is an alkylene group having 2 to 4 carbon atoms, and n is an is a number, Y is hydrogen,
An alkyl group having 1 to 30 carbon atoms, an alkenyl group, an aryl group, an alkyl group having an aryl group as a substituent, a cyclic alkyl group, a cyclic alkenyl group, and a monovalent organic group derived from a heterocyclic compound. ) and one or more polyalkylene glycol monomethacrylate monomers () represented by the general formula CH ₂ =C(CH ₃ )COOZSO ₃ M (wherein Z has 1 to 1 carbon atoms) 4, M represents hydrogen, an alkali metal, an alkaline earth metal, an ammonium group, or an amine base. as a component, the monomer () and the monomer ()
The molar ratio with is in the range of 1:5 to 1:500,
A dispersant for coal-water slurry comprising a water-soluble copolymer obtained from a raw material monomer in which the total of the monomer () and the monomer () is 50 mol% or more based on the total monomers.