JP2847131B2 - Additive for coal water slurry - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an additive that is added to a coal water slurry to improve the fluidity and stability of the slurry.

2. Description of the Related Art In recent years, attention has been paid to the use of coal from the viewpoint of rising oil prices and diversification of energy resources. Coal is a solid fuel and has difficulties in handling, and it has been proposed to pulverize it into a water slurry. By converting coal into a water slurry, pipe transport becomes possible and can be handled in the same manner as liquid fuel, but it is necessary to increase the concentration to improve transport efficiency. However, it is difficult to obtain a high-concentration slurry of 50% or more simply by dispersing coal as it is in water, and if it is allowed to stand, coal powder will settle and become non-uniform, resulting in poor storage stability. There is a problem.

Therefore, it has been proposed to mix additives in the slurry to increase the concentration and improve the dispersion stability. As such additives, for example, polystyrene sulfonate, formalin condensate of naphthalene sulfonate, and the like are used.

Further, a two-component system comprising a sulfonic acid polymer having an aromatic ring or a triazine ring such as polystyrene sulfonate and an α, β-unsaturated carboxylic acid polymer (Japanese Patent Application Laid-Open No. 60-6019)
No. 1), a two-component system of an α, β-unsaturated carboxylic acid polymer and the like (Japanese Patent Application Laid-Open No. 60-2500).
No. 95), a three-component system comprising a polystyrene sulfonate, an α, β-unsaturated carboxylic acid-based polymer, and a polyether to which an alkylene oxide is added (JP-A-63-35694). I have.

Coal water slurries have been put to practical use using these additives, but as a result of long-term actual operation, soft agglomeration may occur in the coal water slurries, which is a new problem that hinders handling. There has occurred.

Problem to be Solved by the Invention The present invention is to provide an additive for coal water slurry that suppresses soft agglomeration in coal water slurry and facilitates handling in an actual machine.

Configuration of the Invention The additive for coal water slurry of the present invention is characterized by containing the following components (A) and (B).

(A) Hypophosphorous acid or hypophosphite is used as a reducing agent in an amount of 1 to 15 mol% based on a monomer, and a weight average molecular weight of 20,000 or less produced by redox polymerization using a persulfate as an oxidizing agent Water-soluble acrylic polymer.

(B) A water-soluble sulfonic acid polymer having an aromatic ring or a triazine ring and a sulfonic acid group in the molecule.

The water-soluble acrylic polymer as the component (A) preferably has a weight-average molecular weight of 20,000 or less, and is preferably 1,000 or less.
~ 20,000. If the molecular weight exceeds 20,000, the fluidity of the coal water slurry becomes poor, which is not preferable. Also,
The polymer of the component (B) may be an acid type or a salt type, and the degree of neutralization is not particularly limited, and is appropriately selected according to the desired properties of the additive. When used as a salt, lithium,
Suitable are alkali metal salts such as sodium and potassium, alkaline earth metal salts such as magnesium and calcium, ammonium salts and organic amine salts, preferably sodium, potassium or ammonium salts.

As the acrylic polymer of the present invention, those produced by a specific production method are used, and hypophosphorous acid or a salt thereof is used as a reducing agent in an amount of 1 to 15 mol% based on a monomer, and as an oxidizing agent The one produced by redox polymerization using a persulfate is used.

As the hypophosphite, sodium hypophosphite is typical. As the persulfate, potassium persulfate, ammonium persulfate, sodium persulfate and the like are used.

In redox polymerization, the amount of reducing agent used is 1 mol%
If it is smaller, the molecular weight of the obtained acrylic polymer tends to be too high.

On the other hand, if it is used in an amount of more than 15 mol%, there is no remarkable effect on the reduction of the molecular weight, and it is not preferable in terms of economy.

The use amount of the oxidizing agent is preferably 0.3 to 5 mol% based on the monomer.

(A) The oxidizing agent and (B) the reducing agent are (a) /
It is preferable to use (b) in the range of 2/1 to 1/20.
In addition, hydrogen peroxide is further added to this redox catalyst system.
The ratio of (i) persulfate to (filter) hydrogen peroxide can be used in a molar ratio of (ii) / (filter) = 10/1 to 1/2.

As the acrylic monomer used in the polymerization, acrylic acid and methacrylic acid are preferable, and other water-soluble vinyl monomers that can be copolymerized therewith can be copolymerized. Examples of monomers copolymerizable with (meth) acrylic acid include itaconic acid, fumaric acid, maleic acid, hydroxyethyl (meth) acrylate, hydroxymethyl (meth) acrylate, hydroxypropyl (meth) acrylate, and (meth) acrylamide. And 2-acrylamido-2-methylpropane sulfonic acid styrene sulfonic acid. In the above description, for example, (meth) acrylic acid means "acrylic acid or methacrylic acid".

These monomers are preferably subjected to polymerization in the form of an acid, but may be subjected to polymerization in the form of a salt as long as the performance of the obtained polymer is not impaired.

By conducting a polymerization reaction using the above-mentioned acrylic water-soluble monomer, oxidizing agent and reducing agent, (B)
An acrylic water-soluble polymer as a component is obtained, and polyacrylic acid or a salt thereof is particularly preferable.

The polymerization method and conditions are not particularly limited, and for example, a known solution polymerization technique can be used.

The monomer concentration is preferably in the range of 1 to 60% by weight,
~ 45% by weight is preferred.

The polymerization temperature varies depending on the type of the oxidizing agent and the reducing agent, but generally can be carried out within a range of 40 to 100 ° C.,
~ 100 ° C is preferred.

A polymerization time of usually 4 to 10 hours is sufficient. The atmosphere in which the polymerization reaction is performed may be air or an inert gas atmosphere such as nitrogen or carbon dioxide, but a nitrogen atmosphere is preferred.

In the additive of the present invention, the following component (B) is used in combination with the component (A).

(B) A water-soluble sulfonic acid polymer having an aromatic ring or a triazine ring and a sulfonic acid group in the molecule.

As the water-soluble sulfonic acid polymer as the component (B), those having an aromatic ring such as a benzene ring or a naphthalene ring or a triagazine ring and a sulfonic acid group are used. Acid or salt thereof, aromatic sulfonic acid formaldehyde condensate or salt thereof,
Aminotriedine formaldehyde condensate, formic acid or a salt thereof, and the like.

The polyaromatic sulfonic acid or a salt thereof is obtained by polymerizing a polymerizable aromatic sulfonic acid (monomer) or copolymerizing with another monomer, and sulfonating an aromatic polymer (polymer), and And polystyrenesulfonic acid or a salt thereof is preferred. Specific examples of the polymerizable aromatic sulfonic acid include styrene sulfonic acid, α-methylstyrene sulfonic acid, methyl nucleus-substituted styrene sulfonic acid, and vinyl naphthalene sulfonic acid. Sulfonation of aromatic polymers such as polystyrene and poly-α-methylstyrene can be carried out by a conventional method using a suitable sulfonating agent, for example, sulfuric anhydride, chlorosulfonic acid and the like.

The degree of sulfonation of polyaromatic sulfonic acid (salt) is 75 to
100% is preferred, more preferably 80-95%. The weight average molecular weight of the polyaromatic sulfonic acid (salt) is 2,000
The above is suitable, preferably about 5,000 to 80,000.

As the formaldehyde condensate of aromatic sulfonic acid or a salt thereof, those having a weight average molecular weight of 700 or more are suitable, and preferably 800 to 5,000. Examples of the aromatic sulfonic acid include benzenesulfonic acid, short-chain alkylbenzenesulfonic acid, naphthalenesulfonic acid, short-chain alkylnaphthalenesulfonic acid, phenolsulfonic acid, naphtholsulfonic acid, and sulfonated creosote oil.

A sulfonated product of an aminotriazine formaldehyde condensate or a salt thereof is an amino-s-triazine compound,
For example, melamine, hexamethylol melamine, acetoguanamine, benzoguanamine and the like, a polycondensation reaction product of formaldehyde with a sulfonated product obtained by further sulfonation or a salt thereof, having a weight average molecular weight of 700
The above are suitable, and preferably in the range of 800 to 5,000.

The water-soluble sulfonic acid polymer of the component (B) may be an acid type or a salt type, but is preferably a polymer in which half or more of the sulfonic acid groups are neutralized. Suitable salts of such a polymer include alkali metal salts such as lithium, sodium and potassium, alkaline earth metal salts such as magnesium and calcium, ammonium salts and organic amine salts, and preferably sodium, potassium and ammonium salts. Of each salt.

The components (A) and (B) are (A) / (B) = 0.1 / 9.
It is suitable to use them together in the range of 9.9 to 25/75, preferably in the range of 1/99 to 20/80. By using both components in this range, a further surplus effect is exhibited.

(A) The amount of the water-soluble acrylic polymer of the component is 0.1 / 99.9.
If the amount is less than the above range, soft agglomeration of the coal water slurry cannot be suppressed. On the other hand, when the amount of the component (A) is more than 25/75,
Although the fluidity of the coal water slurry is improved, a hard pack is easily formed.

The coal water slurry additive of the present invention comprises (A) and (B)
Depending on whether both components are in acid form or salt form, the pH can be changed over a wide range from acidic to alkaline.However, since the addition effect is greatly exhibited in a highly alkaline region, the pH of the slurry after addition is 9 or more. It is desirable to do.

By adding and mixing the above additives, a high-concentration coal water slurry can be obtained. The amount added to the coal water slurry is preferably 0.1 to 3.0% by weight.

In the coal water slurry of the present invention, the viscosity index of the slurry is
It is advisable to prepare the slurry so as to be 0.5 to 1.0, preferably 0.7 to 0.9. If the viscosity index of the slurry is lower than this, soft agglomeration increases, and if the viscosity index increases, dilatant flow is exhibited, and the tendency of forming a hard pack when the slurry is allowed to stand still increases.

The additive of the present invention can be applied to various coal slurries such as lignite, subbituminous coal, bituminous coal, and anthracite. The particle size of coal in the slurry can be used if there is substantially no coal particle size of 1 mm or more. Generally, the smaller the particle size, the better the dispersion stability of the water slurry. Therefore, the 200 mesh pass (about 74 μm or less) 50 weight % Or more is preferable, especially
Those in the range of 65 to 95% by weight are preferred.

The coal water slurry can be obtained by pulverizing coal by a dry pulverization method or a wet pulverization method to form a water slurry, and the additive can be dispersed in an appropriate step so as to be included in the final water slurry. For example, when coal fine powder is obtained by a dry pulverization method, the additive may be dissolved or dispersed in water, and the coal fine powder may be added thereto to prepare a high-concentration water slurry by an appropriate mixing device. When the wet pulverization method is adopted, the additive may be dispersed in water used for the wet pulverization in advance, or may be dispersed during or after the wet pulverization.

Further, in addition to the components (A) and (B) of the present invention, a sulfonated dicyclopentadiene polymer, an anionic surfactant, a nonionic surfactant, an alkali agent, and the like may be added to the coal water slurry. it can.

Examples of the anionic surfactant include alkylbenzenesulfonic acid and polyoxyethylene alkyl ether sulfate.

Nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene fatty acid amides, alkylene oxide polymers such as polyethylene oxide-polypropylene oxide, and polyethyleneimines obtained by adding propylene oxide and ethylene oxide. Polyether and the like.

As the alkali agent, sodium hydroxide, potassium hydroxide and the like can be suitably used, and these can be added at any stage of slurry production.

Effects of the Invention According to the coal water slurry additive of the present invention, by using (A) a specific water-soluble acrylic polymer and (B) a water-soluble sulfonic acid polymer in combination, a soft water Agglomeration can be suppressed, and handling properties in an actual machine can be improved.

Although the mechanism of action of the additive of the present invention has not been sufficiently elucidated, considering that it is generally said that soft agglomeration is derived from the second minimum of the interparticle potential, the water-soluble acrylic polymer of the present invention It is considered that the interparticle repulsion (steric repulsion and electrical repulsion) was increased and the second minimum became shallower. Further, it is considered that the above-mentioned repulsion between particles is synergistically enhanced by using the water-soluble acrylic polymer of the present invention in combination with the water-soluble sulfonic acid polymer (B).

Example 6l containing stainless steel balls at a filling rate of 50% (inner diameter
A predetermined amount of component (A), component (B), water, and Mount Soray charcoal pulverized to a particle size of 3 mm or less are charged into a stainless steel ball mill of 19 cm), and then rotated at 65 rpm to obtain a laser diffraction type particle size distribution meter. While measuring the particle size of the slurry (the number of particles of 74 μm or less), the slurry was pulverized until the amount of particles of 74 μm or less became 80%.

After the pulverization, the slurry was taken out of the ball mill and stirred with a homomixer at 4000 rpm for 10 minutes, and then the soft cohesion of the slurry was evaluated. The coal concentration of the slurry was adjusted so that the viscosity became about 1000 cp, and the viscosity was measured by a Haake viscometer at 100 sec ^-1 down.

Next, when the viscosity index of the slurry was produced by the following equation, each of the slurries shown in Table 3 below was 0.7 to 0.9.
Was in the range.

Hereinafter, the evaluation method of the soft cohesion, the analysis value of the properties of the coal used (Table 1), the synthesis method and properties of the component (A), and (B)
The properties of the components (Table 2) and the evaluation results of the coal water slurry to which the components (A) and (B) were added are shown in order.

(1) Evaluation method of soft cohesiveness After putting the slurry in a 250 ml wide-mouth bottle and allowing it to stand at 25 ° C for 1 day, the amount on the sieve when opened on a 16-mesh sieve (% by weight based on the total amount of the slurry) Soft agglomeration was determined.

(2) Properties of Mount Soray coal (2) Synthesis of Component (A) The following three components (A), A-1, A-2, and A-3, were synthesized, and the molecular weight was measured.

(I) Synthesis of A-1 97 g of distilled water was placed in a five-neck separable flask equipped with a stirrer, thermometer, reflux ring, nitrogen inlet tube, and Y-dropper.
, And the temperature is raised to 90 ° C. while introducing nitrogen and stirring. A solution obtained by dissolving 4.86 g of potassium persulfate (0.5 mol% with respect to the monomer) in 135 g of distilled water and 15.26 g of sodium hypophosphite monohydrate (4 mol% with respect to the monomer) in 324 g of an 80% aqueous acrylic acid solution Was continuously added dropwise over 3 hours, followed by aging at 90 ° C. for 3 hours. Then, 300 g of a 48% aqueous sodium hydroxide solution was added for neutralization.

The obtained polymer solution had a solid content of 40.1% and a weight average molecular weight of 5,700.

(Ii) Synthesis of A-2 205 g of distilled water was placed in a five-neck separable flask equipped with a stirrer, thermometer, reflux ring, nitrogen inlet tube, and Y-dropper tube.
, And the temperature is raised to 90 ° C. while introducing nitrogen and stirring. A solution prepared by dissolving 4.32 g of potassium persulfate (0.5 mol% based on monomer) in 120 g of distilled water and 40.7 g of sodium hypophosphite monohydrate (12 mol% based on monomer) in 288 g of an 80% aqueous acrylic acid solution Was continuously added dropwise over 3 hours, followed by aging at 90 ° C. for 3 hours. Then, 267 g of a 48% aqueous sodium hydroxide solution was added for neutralization.

The obtained polymer solution had a solid content of 35.4% and a weight average molecular weight of 1800.

(Iii) Synthesis of A-3 239 g of distilled water was placed in a five-neck separable flask equipped with a stirrer, thermometer, reflux ring, nitrogen inlet tube, and Y-dropper.
, And the temperature is raised to 90 ° C. while introducing nitrogen and stirring. A solution prepared by dissolving 4.32 g of potassium persulfate (0.5 mol% based on monomer) in 120 g of distilled water and 6.78 g (2 mol% based on monomer) of sodium hypophosphite monohydrate in 288 g of 80% aqueous acrylic acid solution Was continuously added dropwise over 3 hours, followed by aging at 90 ° C. for 3 hours. Then, 267 g of a 48% aqueous sodium hydroxide solution was added for neutralization.

The obtained polymer solution had a solid content of 33.2% and a weight average molecular weight of 15,000.

(4) Properties of the water-soluble sulfonic acid polymer as the component (B) (5) Evaluation results

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-275696 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C10L 1/32

Claims (3)

(57) [Claims] (1) Redox polymerization using (A) hypophosphorous acid or hypophosphite as a reducing agent in an amount of 1 to 15 mol% based on a monomer and persulfate as an oxidizing agent. A high-concentration coal comprising: a water-soluble acrylic polymer having a weight average molecular weight of 20,000 or less; and (B) a water-soluble sulfonic acid polymer having an aromatic ring or a triazine ring and a sulfonic acid group in the molecule. Additive for water slurry. 2. The additive according to claim 1, wherein the component (B) is polystyrenesulfonic acid or a salt thereof. 3. The additive according to claim 1, wherein the component (A) and the component (B) are contained in a weight ratio of (A) / (B) = 25/75 to 0.1 / 99.9. .