JP2003003180A - Dispersant for coal slurry - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a dispersant for a coal slurry, with which dispersibility and fluidity of the coal slurry can be stabilized to change in temperature even in the case of a high coal concentration. SOLUTION: A copolymer mixture obtained by copolymerizing a specific monomer (A1) such as a polyoxyalkylene group-containing ethylenically unsaturated carboxylic acid derivative, etc., with a specific monomer (A2) such as (meth)acrylic acid, etc., with changing the molar ratio of (A1)/(A2) in the middle of the reaction at least one time is used as the dispersant for a coal slurry.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a dispersant for coal slurries. More specifically, the present invention relates to a dispersant for coal slurries in which coal powder is stably dispersed in water to facilitate pipeline transportation.

[0002]

2. Description of the Related Art In recent years, due to the exhaustion of petroleum resources, the use of coal resources, which have a large reserve and are not unevenly distributed all over the world, has been re-recognized. However, in the case of coal, unlike oil, since it is a solid, it cannot be transported by pipeline, which is a significant disadvantage in handling. From this, coal is pulverized to improve handling defects,
Various methods of dispersing in water and making it into a slurry state have been studied.

However, also in this case, when the coal concentration is increased, the viscosity is remarkably increased and the fluidity is lost. This is because coal particles in an aqueous slurry of coal powder are aggregated in water to increase viscosity and decrease fluidity.

As a countermeasure against this, it is conceivable to lower the coal concentration, but this is not practical because the transport efficiency is lowered and the dehydration step also costs. Therefore, it has been attempted to add various dispersants. This is because the dispersant is adsorbed on the coal particles by adding a dispersant, which is a surfactant, to loosen the coal particles into pieces and prevent the coal particles from re-aggregating.

For example, conventionally, sodium naphthalene sulfonate formaldehyde condensate, sodium polystyrene sulfonate and the like have been used as dispersants. Further, in order to improve the dispersion stability and fluidity thereof even at a high coal concentration, a polycarboxylic acid type dispersant having a specific structure (JP-A-8-12984) has been developed.

However, even with a polycarboxylic acid type dispersant, there is a problem in that the dispersion stability and fluidity vary depending on the temperature of the coal slurry, and a stable state may not be obtained throughout the year. This tendency is particularly noticeable when the coal concentration is high.

[0007]

An object of the present invention is to provide a dispersant for coal slurry which can stabilize the dispersion stability and fluidity of coal slurry against temperature changes even when the coal concentration is high. is there.

[0008]

The present invention has the following general formula:
(a1) is obtained by copolymerizing at least one monomer (A1) represented by the following general formula (a2) and at least one monomer (A2) represented by the following general formula (a2), and Monomer (A1) and (A2) molar ratio
It relates to a dispersant for coal slurries containing a copolymer mixture in which (A1) / (A2) is changed at least once during the reaction.

[0009]

[Chemical 3]

(In the formula, R ¹ and R ² : hydrogen atom or methyl group R ³ : hydrogen atom or --COO (AO) _{m 1} X m: number of 0-2 p: 0 or number of 1 n: 2-300 AO: an oxyalkylene group having 2 to 4 carbon atoms or an oxystyrene group X: represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms.)

[0011]

[Chemical 4]

(In the formula, R ^{4 to} R ^{6 are a} hydrogen atom, a methyl group or (CH ₂ ) _{m 1} COOM ² ,
(CH _{²⁾ m1} COOM ₂ may form a COOM ¹ or another (CH _{²⁾ m1} COOM ₂ and anhydride, in which case, M ^1, M ² in these groups are not present. M ¹ , M ² : hydrogen atom, alkali metal, alkaline earth metal,
An ammonium group, an alkylammonium group, or a substituted alkylammonium group m1: represents the number of 0 to 2. ).

The present invention also relates to a coal slurry containing the above-mentioned dispersant for coal slurry of the present invention, coal and water.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION In order for a polycarboxylic acid copolymer having an alkylene oxide added thereto to exhibit stable properties with respect to changes in temperature of a coal slurry, a large number of monomers (A2) having different weight ratios should be used. It is necessary that the copolymer is mixed.

However, when copolymers having different weight ratios of the monomer (A2) are produced and mixed, the production efficiency is low for mass production and the production cost increases, so that the types that can be mixed are different. Limited

On the other hand, the copolymer mixture (a) used in the present invention has a molar ratio (A1) / (A2) of the monomers (A1) and (A2).
Is considered to be a copolymer mixture in which the weight ratio of the monomer (A2) is continuously distributed, since it has been changed at least once during the reaction, giving stable properties to the temperature change of the coal slurry. A large amount of dispersant that can be obtained can be obtained at low cost.

[Monomer (A1)] In order to impart good fluidity to the coal slurry, the number of moles n of alkylene oxide added in the monomer (A1) is preferably 50 <n, 70 ≦ n is more preferable, 80 ≦ n is further preferable, 90
≦ n is more preferable, 100 ≦ n is more preferable, 110 ≦ n
Is most preferred.

Further, if n is too large, the viscosity of the coal slurry becomes excessive and the fluidity rather deteriorates.
It is necessary to be 300, and n ≦ 200 is preferable, and n ≦ 150
Is most preferred.

In order to further suppress the fluctuation of the fluidity of the coal slurry with respect to temperature change, the number of moles n of alkylene oxide added in the monomer (A1) is preferably 2 ≦ n ≦ 50, and 5 ≦ n ≦ 40 is more preferable, 5 ≦ n ≦ 30
Is more preferable, and 5 ≦ n ≦ 20 is most preferable.

Further, in order to impart high fluidity to the coal slurry, it is preferable that the monomer (A1) contains different n monomers. In this case, at least 2 ≦ n1 ≦ 50
It is preferable to contain n1 and n2 monomers satisfying <n2 ≦ 300. When the fluidity is more important, 70 ≦ n2 is more preferable, 80 ≦ n2 is further preferable, 90 ≦ n2 is further preferable, 100 ≦ n2 is further preferable, and 110 ≦ n2 is most preferable.
When more emphasis is placed on stability against temperature changes, 5 ≤ n1
≦ 40 is preferable, 5 ≦ n1 ≦ 30 is more preferable, 5 ≦ n1 ≦ 20
Is most preferred.

[Monomer (A2)] Examples of the monomer (A2) represented by the general formula (a2) used for producing the copolymer mixture (a) include (meth) acrylic acid and crotonic acid. Monocarboxylic acid type monomers, maleic acid, itaconic acid, dicarboxylic acid type monomers such as fumaric acid, or their anhydrides or salts,
For example, an alkali metal salt, an alkaline earth metal salt, an ammonium salt, and a mono-, di-, or trialkyl (having 2 to 8 carbon atoms) ammonium salt in which a hydroxyl group may be substituted are preferable,
(Meth) acrylic acid, maleic acid, maleic anhydride are more preferable, and (meth) acrylic acid or an alkali metal salt thereof is more preferable.

[Copolymer Mixture (a)] The copolymer mixture (a) contains the monomers (A1) and (A2), preferably (A1) / (A
2) contains a copolymer mixture (A) obtained by reacting at a molar ratio in the range of 0.02 to 4, and these molar ratios (A1) / (A
2) is changed at least once during the reaction.
And, in the present invention, the average weight ratio (X _I ) of the monomer (A2) to all the monomers for producing the copolymer mixture (a) and the average weight ratio (X _II ) different from that were obtained. It is preferable to use the copolymer mixture (a ′) together. That is, the copolymer mixture (a ′) is obtained by reacting the above monomers (A1) and (A2) with each other, preferably in a molar ratio of (A1) / (A2) = 0.02 to 4. A copolymer mixture having a molar ratio (A
1) / (A2) is changed at least once during the reaction, and the average weight ratio (X _II of the monomers (A2) to all the monomers for producing the copolymer mixture (a ′) is ) Is different from the average weight ratio (X _I ) of the copolymer mixture (A).
The average weight ratio is [total amount of monomers (A2) / total amount of monomers] x
It is represented by 100 (% by weight), and each preferably ranges from 1 to 30 (% by weight). Hereinafter, this average weight ratio may be referred to as “(A2) average weight ratio”. Further, the average weight ratios (X _I ) and (X _II ) are preferably different from each other by at least 1.0 (wt%), more preferably at least 2.0 (wt%), and particularly at least 3.0 (wt%). Incidentally, the copolymer mixture (a) and (a '), the monomers (A1), (A2) used in the production
In the present invention, the average weight ratio (X _I ),
It suffices that (X _II ) be different, but it is preferable to use the same type of monomers (A1) and (A2).

In the present invention, the average weight ratio (X _I ) of the copolymer mixture (A) is 1 to 30% by weight, more preferably 7 to 20% by weight, especially 8%.
It is preferably about 16% by weight. Then, when a blending system is assembled using this copolymer mixture (a) as a main component,
It is possible to obtain a dispersant for coal slurry having a good balance of performances.

In the present invention, as the copolymer mixture (a ′), a plurality of copolymers (A2) obtained from a plurality of monomer mixtures having different average weight ratios can be used. From a practical point of view, it is preferable to use 1 to 3 copolymer mixtures obtained from 1 to 3 monomer mixtures having different (A2) average weight ratios. When one copolymer mixture is used as the copolymer (a ′), that is, when two copolymer mixtures in total are used, they are conveniently added to the copolymer mixture (A _i ), (A _ii ). And the average weight ratio of these (A2) is (X _i ), (X _ii ), it is preferable that 5 ≦ (X _i ) <8 (wt%) 8 ≦ (X _ii ) ≦ 16. Also, a copolymer mixture (a ')
When using two copolymer mixtures as, i.e., when using a total of three copolymer mixtures, they are conveniently copolymer mixtures (A _i ), (A _ii ), (A _iii ), If these (A2) average weight ratios are (X _i ), (X _ii ), and (X _iii ), then 5 ≦ (X _i ) <8 (wt%) 8 ≦ (X _ii ) ≦ 16 (wt%) ) 16 <(X _iii ) ≦ 30 (wt%) is preferable.

(A2) Due to the presence of a large number of copolymer mixtures having different average weight ratios, good dispersibility and dispersion retention are exhibited in a wide range of coal slurry W / C and a wide range of slurry temperatures. In particular, the dispersion holding property becomes stable for a long time.
As a result, the dispersant for coal slurry can sufficiently cope with the fluctuation of the water / coal ratio and the fluctuation of the temperature.

As described above, the dispersant for coal slurry of the present invention comprises the above monomers (A1) and (A2), preferably (A1) / (A
2) = 0.02 to 4 containing a copolymer mixture (a) obtained by reacting in a molar ratio of, preferably further (a '), in any of these molar ratio (A1) / (A2) is changed at least once during the reaction. The change in the molar ratio may be increased, decreased, or a combination thereof. When the molar ratio is changed stepwise or intermittently, the number of changes is preferably 1 to 10 times, particularly preferably 1 to 5 times. When the molar ratio is continuously changed, it may be linear change, exponential change, or other change, but the degree of change is 0.0001 to 0.2 per minute,
0.0005 to 0.1, particularly 0.001 to 0.05 is preferable. Also,
The molar ratio is preferably such that at least one of the molar ratios (A1) / (A2) before and after the change is in the range of 0.02 to 4, and particularly, the molar ratios (A1) / (A2) before and after the change are both 0.02 to It is preferably in the range of 4. Further, as described above, the change in the molar ratio has various modes, but in any case, the difference between the maximum value and the minimum value of the molar ratio (A1) / (A2) in the entire copolymerization reaction is at least 0.05. , Particularly preferably in the range of 0.05 to 2.5.

Such a copolymer mixture can be obtained by a production method having a step of polymerizing by changing the (A1) / (A2) molar ratio at least once. Simultaneously with the start of dropping the aqueous solution, start dropping the monomer (A2),
A method of changing the dropping flow rate (parts by weight / minute) so that the respective molar ratios fall within a predetermined range and dropping for a predetermined time may be mentioned. In this method, the amount of change in the monomer (A1) / (A2) molar ratio (difference between the maximum value and the minimum value) is preferably 0.05 to 2.5, and more preferably 0.1 to 2. The copolymer mixture obtained by changing the molar ratio even once in the reaction as in this method has a higher (A1) / (A2) molar ratio than the copolymer obtained by the reaction. ) / (A2) molar ratio distribution is presumed to be a mixture of a large number of copolymers.

Incidentally, 30% or more of the total weight of the monomers, especially
It is preferable to manufacture 50 to 100% by changing the dropping flow rate as described above.

The polymerization reaction may be carried out in the presence of a solvent.
As the solvent, water, lower alcohols such as methanol, ethanol, isopropanol, butanol; benzene,
Examples thereof include aromatic hydrocarbons such as toluene and xylene; alicyclic hydrocarbons such as cyclohexane; aliphatic hydrocarbons such as n-hexane; esters such as ethyl acetate; ketones such as acetone and methyl ethyl ketone. Among these, water and lower alcohols are preferable from the viewpoints of easy handling and solubility of the monomer and polymer.

In the copolymerization reaction, a polymerization initiator can be added. As the polymerization initiator, organic peroxides, inorganic peroxides, nitrile compounds, azo compounds,
Examples thereof include diazo compounds and sulfinic acid compounds. The amount of the polymerization initiator added is monomer (A1), monomer
It is preferably 0.05 to 50 mol% based on the total of (A2) and other monomers.

In the copolymerization reaction, a chain transfer agent can be added. Examples of the chain transfer agent include lower alkyl mercaptan, lower mercapto fatty acid, thioglycerin, thiomalic acid and 2-mercaptoethanol. The reaction temperature of the copolymerization reaction is preferably 0 to 120 ° C.

The obtained polycarboxylic acid type polymer can be deodorized if necessary. In particular, when a thiol such as mercaptoethanol is used as a chain transfer agent, an unpleasant odor tends to remain in the polymer, and therefore deodorizing treatment is desirable.

The polycarboxylic acid type polymer obtained by the above-mentioned production method can be applied as a dispersant for coal slurry even in the acid form, but from the viewpoint of suppressing the hydrolysis of the ester due to acidity, it can be used with an alkali. It is preferred that the salt form is obtained by neutralization. Examples of the alkali include hydroxides of alkali metals or alkaline earth metals, ammonia, mono-, di-, tri-alkyl (C 2-8) amines, mono-, di-, trialkanols (C 2-8) amines and the like. Can be mentioned. When the (meth) acrylic acid polymer is used as a dispersant for coal slurry, it is preferably partially or completely neutralized. Further, from the viewpoint of protecting the material of the container when the dispersant of the present invention is stored, the obtained polycarboxylic acid-based polymer has a 5% by weight aqueous solution having a pH (20 ° C.) of 4 to 9, particularly pH 5 It is preferable to adjust to ~ 8.

The weight average molecular weight of the polycarboxylic acid polymer obtained by the above-mentioned production method [gel permeation chromatography method, polyethylene glycol conversion, column: G4000PWXL + G2500PWXL (Tosoh Corporation)
Manufactured), eluent: 0.2M phosphate buffer / acetonitrile = 7
/ 3 (volume ratio)] is preferably 10,000 to 200,000 in order to obtain sufficient dispersibility as a dispersant for coal slurries.
Particularly preferred is 0000 to 100,000.

Furthermore, acrylonitrile, (meth)
A copolymerizable monomer such as acrylamide, styrene, an alkyl (meth) acrylate (having 1 to 12 carbon atoms which may have a hydroxyl group) ester, or styrene sulfonic acid may be used in combination. These can be used in a proportion of 50% by weight or less, more preferably 30% by weight or less, based on the total monomers, but 0% by weight is preferable.

The amount of the dispersant for coal slurry of the present invention added is preferably 0.05 to 3.0% by weight, more preferably 0.5 to 1.0% by weight, based on the solid content of coal. The content of water in the coal slurry is preferably 25 to 40% by weight, although it depends on the required viscosity conditions.

A coal slurry is obtained by mixing the coal slurry dispersant of the present invention with coal and water. At this time, coal is crushed by a ball mill or the like, if necessary.

In the present invention, known additives may be optionally used in combination within the range that does not impair the performance of the coal slurry dispersant of the present invention.

[0039]

EXAMPLES [Copolymer Mixture (a)] The copolymer mixture (a) produced by using the monomers of Table 1 as shown in Table 2 was used in the following Examples and Comparative Examples. The production examples of the copolymer mixtures Nos. 1 and 8 in Table 2 are shown below.

<Production Example 1: Production of copolymer mixture No. 1> 423 parts by weight of water was charged into a glass reaction vessel equipped with a thermometer, a stirrer, a dropping funnel, a nitrogen introduction tube, and a reflux condenser. Substitution was made. Then, after raising the temperature to 70 ° C. under a nitrogen atmosphere, 44.9 parts by weight of the monomer E-1 (EOp = 9) in Table 1 and 18.2 parts by weight of methacrylic acid were mixed in the dropping monomer liquid (1).
And 14.2 parts by weight of a 5% -2-mercaptoethanolic acid aqueous solution and 13.8 parts by weight of a 5% ammonium persulfate aqueous solution were simultaneously added dropwise over 15 minutes, and then the monomer E-1 (EOp = EOp =
9) 250.5 parts by weight of methacrylic acid and 65.2 parts by weight of methacrylic acid were added to the monomer liquid for dropping (2), 5% -2-mercaptoethanolic acid aqueous solution 59.2 parts by weight and 5% ammonium persulfate aqueous solution.
57.6 parts by weight of 3 liquids were added dropwise in 75 minutes, and the addition was completed in 90 minutes in total. After completion of the dropping, the mixture was aged at the same temperature for 1 hour, 21.4 parts by weight of 5% ammonium persulfate aqueous solution was added dropwise over 10 minutes, and then aged at 70 ° C. for 2 hours to complete the polymerization reaction. Further, 57 parts by weight of a 48% aqueous sodium hydroxide solution was added for neutralization to obtain a copolymer mixture No. 1 shown in Table 2. The pH of a 5% by weight aqueous solution of this copolymer mixture No. 1 was 6.0 (20 ° C).

Among the copolymer mixtures shown in Table 2, (A1)
The one obtained by changing the molar ratio of / (A2) once is the same as in Production Example 1
It was manufactured according to.

<Production Example 2: Production of copolymer mixture No. 8> A glass reaction vessel was charged with 329.9 parts by weight of water, and after nitrogen substitution, the temperature was raised to 78 ° C. in a nitrogen atmosphere. Next, 216.4 parts by weight of a 60% aqueous solution of the monomer E-2 shown in Table 1, 75.5 parts by weight of a 90% aqueous solution of the monomer E-1 shown in Table 1, and a mixed solution of 38.3 parts by weight of methacrylic acid and a 5% excess. 27.7 parts by weight of an ammonium sulfate aqueous solution and 30.8 parts by weight of a 5% -2-mercaptoethanol aqueous solution were dropped in 55 minutes, and then 78.7 parts by weight of a 60% aqueous solution of the monomer E-2 shown in Table 1 and a unit amount shown in Table 1. 90% aqueous solution of body E-1 32.
A mixed solution of 1 part by weight and 9.7 parts by weight of methacrylic acid, 8.2 parts by weight of a 5% ammonium persulfate aqueous solution and 9.2 parts by weight of a 5% -2-mercaptoethanol aqueous solution were added dropwise over 20 minutes, and the monomer E shown in Table 1 was further added. 59.0 parts by weight of 60% aqueous solution of -2, 26.0 parts by weight of 90% aqueous solution of monomer E-1 shown in Table 1, 5.6% of methacrylic acid
A mixed solution of 5 parts by weight, 5.4 parts by weight of a 5% ammonium persulfate aqueous solution and 6.0 parts by weight of a 5% -2-mercaptoethanol aqueous solution were added dropwise over 15 minutes. Molar ratio (A1) / (A
2) is shown in Table 2. After the dropping was completed, the mixture was aged for 60 minutes at 78 ° C., and then 20.7 parts by weight of a 5% ammonium persulfate aqueous solution was added in 5 minutes. The mixture was further aged for 120 minutes at 78 ° C., and 20.8 parts by weight of 48% aqueous sodium hydroxide solution was added to obtain a copolymer mixture No. 8 shown in Table 2. The pH (20 ° C.) of a 5 wt% aqueous solution of this copolymer mixture No. 8 was 5.9.

[0043]

[Table 1]

[0044]

[Table 2]

Examples 1 to 6 and Comparative Examples 1 to 35 A magnetic ball mill (inner diameter 20 cm) of 30 liters was filled with 30% by volume of stainless steel balls, and 760 g of coal and water (containing the copolymer mixture (a)). 340 g was put and crushed at 50 rpm until the content of 200 mesh (74 μm) or less became 80 to 81%. After crushing, the slurry was extracted from the ball mill and stirred at 4,000 rpm for 10 minutes using TK Auto Homo Kimisa (made by Tokushu Kika Kogyo). The copolymer mixture (a) was used so that the solid content addition rate with respect to coal was the value shown in Table 3.

The coal slurry obtained above is heated to a predetermined temperature.
Hake Rheometer (Measuring head: MK-500, rotor
MV2P) maximum shear rate 15 sec^-1Measure the shear stress up to 10
0 sec ^-1The apparent viscosity is calculated from the shear stress at
-It is the viscosity. Viscosity depends on the slurry temperature of 20 ℃ and 60 ℃.
Calculated. The results are shown in Table 3.

[0047]

[Table 3]

(Note) The addition amount in Table 3 is the solid content weight% relative to coal. Moreover,% of the copolymer mixture (a) in Examples 4-6 is weight% in the total of the copolymer mixture (a).

In each of the examples, the viscosity is 500 mPa · s or less even when the slurry temperature is 60 ° C., the fluidity is high, and the stability of the fluidity with respect to the temperature change is excellent. Both are 580 mPa ・ s or more, low fluidity,
Poor stability of fluidity against temperature change.

[0050]

INDUSTRIAL APPLICABILITY The dispersant for coal slurry of the present invention has good stability of slurry viscosity against temperature change even in a coal slurry system having a very high concentration, and enables high concentration transport of the slurry.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C08F 290/06 C08F 290/06 F term (reference) 4D077 AA07 AB09 AC05 BA02 DC28Y DD28Y DD32Y 4H013 DB06 DB07 DB09 4J027 AC03 AC06 BA04 BA06 CA12 CA20 CD00 4J100 AJ01P AJ02P AJ08P AJ09P AK07P AK08P AK20P AL08Q BA03Q BA04Q BA05Q BA06Q BA08Q BA15Q BC43Q JA28

Claims (2)

[Claims] 1. At least one monomer (A1) represented by the following general formula (a1) and at least one monomer (A2) represented by the following general formula (a2): Coal slurry containing a copolymer mixture obtained by copolymerization and in which the molar ratio (A1) / (A2) of the monomers (A1) and (A2) is changed at least once during the reaction Dispersant. [Chemical 1] (In the formula, R ¹ and R ² : hydrogen atom or methyl group R ³ : hydrogen atom or -COO (AO) _m1 X m: number of 0-2 p: number of 0 or 1 n: number of 2-300 AO : C2-4 oxyalkylene group or oxystyrene group X: represents a hydrogen atom or a C1-18 alkyl group.) (In the formula, R ^{4 to} R ^{6 are a} hydrogen atom, a methyl group or (CH ₂ ) _{m 1} COOM ² ,
(CH _{²⁾ m1} COOM ₂ may form a COOM ¹ or another (CH _{²⁾ m1} COOM ₂ and anhydride, in which case, M ^1, M ² in these groups are not present. M ¹ , M ² : hydrogen atom, alkali metal, alkaline earth metal,
An ammonium group, an alkylammonium group, or a substituted alkylammonium group m1: represents the number of 0 to 2. ) 2. A coal slurry containing the dispersant for coal slurry according to claim 1, coal, and water.