JPS63289096A - Additive for long-life, high-concn. coal-water slurry - Google Patents

Abstract

PURPOSE:To provide the title additive which exhibits an excellent effect on the stable dispersion of coal in water and helps to produce a long-life, high- concn. coal-water slurry of low viscosity and which comprises a mixture of two types of partially sulfonated polystyrenes having different MWs. CONSTITUTION:An additive comprising a partially sulfonated polystyrene or a salt thereof obtd. by partially sulfonating a mixture of a PS having an MW (wt.-average MW) of 400-10,000 (A) and a PS having an MW (wt.-average MW) of 40,000-500,000 (B), pref. 50,000-150,000, is used in the manufacture of a high-concn. coal-water slurry comprising pulverizing coals in the presence of water. This additive exhibits an excellent effect on the stable dispersion of coals in water. When this additive is added to a coal-water slurry, the slurry does not suffer any changes for a prolonged period of time. Even if the slurry is allowed to stand still over a month, neither coagulation nor deposition is observed. Thus, a long-life, self-fluid, high-concn. coal-water slurry having such a low viscosity as the permit pumping is obtd. by the use of this additive.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to long-life, high-concentration coal-water slurry additive milling.

(Prior Art) In recent years, due to the depletion of petroleum resources and the high price of coal, the use of coal has been reaffirmed, and various methods of its use are being studied.

However, since coal is solid and cannot be transported by pump, a water slurry of pulverized coal is attracting attention because it can be transported by pump and can be directly burned as boiler fuel in power plants and the like.

However, if a slurry of coal and water is produced without using chemicals, the viscosity of the slurry becomes high, making it impossible to produce a water slurry with a high coal concentration.

Lower coal concentrations reduce transportation efficiency and require a dehydration step before combustion, which increases costs.

Therefore, research is being conducted on thinning agents that reduce the viscosity of highly concentrated coal-water slurries.

For example, JP-A No. 57-145187 and Ei2-5
No. 90 describes polystyrene sulfonates with a molecule i of 3000 to 200,000 as being useful for this purpose.

However, although the polystyrene sulfonic acid Ill described in these prior art exhibits a considerable dispersion effect, there are problems with stability, that is, viscosity increases over time and sedimentation consolidation occurs.

Furthermore, JP-A No. 80-250094 discloses a heptad copolymer of styrene monomer and Na styrene sulfonate as a highly concentrated and excellent vA machining agent. molar ratio 1
: l) Copolymer (MW 5000) and polyacrylic acid Na are used together in a ratio of 50:50, and JP-A-176897 discloses a copolymer of α-methylstyrenesulfonic acid monomer and styrene monomer. are listed respectively.

However, in the copolymers described in these prior art, a homopolymer of styrene alone or styrene sulfonic acid alone is produced during normalization, making it difficult to obtain the desired copolymer and reducing the amount of the target active ingredient. do. Furthermore, the molecular weight of the obtained polymer is wide ranging from several hundred to several million, and a very high molecular weight substance unsuitable for long-life, high-concentration coal-water slurry is produced as a by-product, resulting in a poor dispersion effect. It becomes inferior.

Furthermore, the slurry evaluation method is simply a rod penetration test, which is extremely inappropriate when assuming a realistic scale. In other words, even if the rod penetrates smoothly after one month of standing, the slurry may have increased viscosity or formed a soft pack, causing problems in discharging from the storage tank or static tank, and combustion. There were problems such as the spray nozzle becoming clogged.

In fact, these additives had no effect at all, and after one month the viscosity of the slurry increased to nearly 1 oooocps.

It was not possible to create a slurry with self-flowing properties, and it was not possible to obtain a slurry that maintained fluidity immediately after production for a long period of time and was free from sedimentation.

As a result of intensive research aimed at improving these problems, the present inventors discovered that partially sulfated polystyrene was suitable as an additive for coal-water slurry, and filed a patent application.

However, even when these additives are used, because the coal particle size in the coal-water slurry has a wide distribution, it has been observed that the fine particles in particular cause partial aggregation, which affects stability. .

(Problems to be Solved by the Invention) The present invention solves the above-mentioned problems and provides a highly concentrated coal-water solution with low viscosity and long-life self-flowing property when the slurry is Jf-rated by the pot method. An object of the present invention is to provide an additive for slurry.

(Means for Solving the Problems) An additive that is added when producing a highly concentrated coal-water slurry by pulverizing coal in the presence of water.

The additives include (1) polystyrene with a molecule rL (weight average molecular weight 1) of 400 to 10,000; and (2) molecule ricmQ (average molecular weight) of 40,000 to 500,000.

This is a long-life, high-concentration coal-water slurry additive characterized by being a polystyrene partially sulfated product or a salt thereof obtained by partially sulfating a mixture with polystyrene of 50,000 to 150,000 tlf, or a polystyrene of 50,000 to 150,000.

The additive used in the present invention is polystyrene (with a molecular weight of 400 to 10,000) obtained by polymerizing styrene monomer.
(hereinafter referred to as component) and a molecular weight of 40,000 to 500,000, preferably 5
A mixture of 10,000 to 150,000 polystyrene (hereinafter referred to as component ①) is partially sulfated so that the degree of sulfation per styrene unit is 65 to 97%, preferably 70 to 95%, or a salt thereof is mentioned. It will be done.

Mixing of component (2) and component (2);'; In 1 case, component (2)/component [b] = 9515 to 10/90, preferably 90/10 to 50150 at ff1ffi.

If the amount of 113 in component (1) is greater than the above range, the resulting coal-water slurry will gel and no effect will be obtained.

Partial sulfation of a polystyrene mixture can be carried out by, for example, using a sulfuric anhydride-dioxane complex as the sulfating agent, and dropping a mixture of polystyrene and 1,2-dichloroethane into the sulfating agent to react. However, the present invention is not limited to this method, and any sulfation method can be applied.

The degree of sulfation of the polystyrene moiety M oxide is 65 to 97% of styrene unit dust, preferably 70 to 95%; within this range, appropriate lipophilicity increases, and the additives are well adsorbed to coal particles, making them more adsorbable. Thickening the layer prevents coal particles from coagulating and settling together, improving stability.

When the degree of sulfation exceeds 97%, the dispersion effect is slightly inferior,
In particular, stability is a problem.

Furthermore, if the degree of sulfation is less than 65%, the dispersion effect is poor and coal particles coagulate and settle together.

Examples of salts of partially sulfated polystyrene include alkali metals such as sodium and potassium, alkaline earth metals such as magnesium and calcium, ammonia, amines, etc., but some of them may remain in the acid form,
Mixed salts of these may also be used.

The amount of additive used is 0, O1 for coal-water slurry.
-5.0% by weight, preferably 0.03-2.0% by weight, and excellent effects are exhibited at this amount.

Generally, if no additive is used, a coal-water slurry loses fluidity when the coal concentration is around 50% by weight, but if the additive of the present invention is used, the viscosity is significantly reduced, so that the coal-water slurry has a coal concentration of 60% by weight! It has fluidity even at lI content of % or more, especially 64% by weight or more, no change in the slurry over time is observed, and even if it is left standing for one month, no agglomeration or sedimentation of coal occurs. It can be easily pumped out from inside the tank.

Furthermore, in the case of a coal-water slurry using cleaner coal, the coal concentration increases by several points.

Coal-water slurry produced using additives is produced by a wet process, and specifically, coal, water, and additives are added to a pulverizer and the slurry is pulverized.

The additives at this time may be added all at once at the beginning, or may be added in multiple stages in the middle.

Alternatively, a method may be used in which coal and water are once put into a pulverizer at a low concentration to produce a low concentration slurry, and then the slurry is dehydrated and additives are added thereto and mixed.

However, the present invention is not limited to these specific manufacturing methods, but is intended for all manufacturing methods that include the step of pulverizing one piece of coal in water.

Coal used in the production of coal-wood slurry can be anthracite,
Any coal may be used, such as bituminous coal, sub-bituminous coal, brown coal, or cleaned coal thereof.

Cleaned coal is coal from which inorganic substances such as ash and sulfur have been removed.

Examples of methods for cleaning stone include the M liquid separation method, the Oil Agglo+5eration method (hereinafter referred to as the OA method), and the floating M coal washing method. However, methods other than these may be used and are not particularly limited.

If such lean coal is used, the effect of the additive of the present invention is significantly superior to coal that has not been cleaned, and a coal-wood slurry with several points higher concentration can be obtained.

Furthermore, when using clean coal, boiler corrosion during combustion is suppressed, and ash removal equipment,
It has great benefits such as reducing the burden on desulfurization equipment.

Further, the particle size of the coal used may be any particle size, but since the fineness currently burned in thermal power plants is 200 mesh pass 70% or more, this particle size is a standard.

However, the additive of the present invention does not depend on the particle size, and exhibits excellent effects regardless of the particle size.

(Effects of the Invention) The additives obtained according to the present invention have an excellent effect of stably dispersing coal in water, and when added to a coal-water slurry, the slurry changes over time and after 1 month of static dispersion. A self-flowing, highly concentrated coal-water slurry with a low viscosity and a long life can be obtained, with no coal aggregation, sedimentation, etc. observed at all, and which can be easily pumped out from the tank.

Considering the reason why the additive obtained according to the present invention has excellent performance, the coal particle size in the highly concentrated coal-water slurry is as shown in Figure 1 - Coal particle size distribution. There are large numbers of coarse particles, and they have a wide distribution (11).As shown in Figure 2 - Molecular weight distribution of additives, the additive itself should also adapt to its particle size distribution, especially as a countermeasure against fine particles. By adding relatively low molecular weight polystyrene to high molecular weight polystyrene, the molecular weight of the additive (111) is reduced to 1.
11 It is necessary to make it wider.

In other words, high-molecular-weight polystyrene is adsorbed to the large coarse particles of coal particles in the slurry, while low-molecular-weight polystyrene is adsorbed to the fine particles of small coal particles, and the thickness of the adsorption layer causes three-dimensional coverage. It is surmised that a self-flowing (low viscosity) and highly concentrated coal-water slurry with a long life can be obtained by preventing agglomeration of coal particles and improving dispersion power.

However, conventional additives, e.g.
00,000 polystyrene sulfonate, styrene monomer/
Styrene sulfone 11Na monomer (molar ratio 1:1
) A combination of a copolymer (MW, 5000) and Na polyacrylate, or a copolymer of α-methylstyrenesulfonic acid monomer and styrene monomer, etc., has problems with the stability of the slurry, resulting in increased viscosity and aggregation over time. It is not possible to obtain a highly concentrated coal-water slurry that maintains fluidity for a long period of time immediately after production.

(Example) Example 1 Coal-water slurry was manufactured by the following two methods using bituminous coal and the additives shown in the ft51 table.

The coal used was pulverized to a particle size of 2 m2 using a dry mill.

(A) 71: Coarsely crushed coal (approximately 3 layers or less), water, and additives were placed in a ball mill in predetermined amounts and pulverized until the coal particle size reached 80% of the 200-mesh passing rate.

Method (B): A predetermined amount of coarsely crushed coal (approximately 3 mm or less) and water were put into a ball mill to produce a slurry with a coal concentration of 40% and a coal particle size of 80% passing through 200 meshes.

Thereafter, the mixture was dehydrated to a predetermined concentration, additives were added thereto, and the mixture was stirred with a laboratory spar to obtain a slurry.

The produced slurry was evaluated by the test method shown below.

l) Slurry viscosity: Haake rotational viscometer at 25°C, Measurement was made at a shear speed of 100 sec-'.

2) Slurry life: It was measured in a pot.

That is, the produced slurry was placed in a 250 x 11M wide-mouth bottle and allowed to stand for one month, after which the slurry was discharged from the poly bottle by natural filtering and passed through a 5-inch sieve.

At this time, the amount remaining in the polyethylene bottle and the amount of slurry on the 5a+m sieve were measured as the amount of aggregation, and the aggregation rate (%) with respect to the total slurry was determined.

The viscosity of the slurry was also measured after it was left standing for one month.

Slurry with a smaller amount of agglomeration and a viscosity that is unchanged from immediately after production is a better slurry with a longer lifespan.

The evaluation results are shown in Table 2.

According to the invention as evident from Table 2.

By wet producing coal-water slurry using method (A) or method (B), the viscosity is 1000 cp at a coal concentration of 77%.
A coal-water slurry with good fluidity was obtained.

Further, even after the slurry was allowed to stand for one month, there were almost no aggregates and the viscosity of the slurry hardly increased, making it possible to obtain a highly concentrated coal-wood slurry with a long life.

On the other hand, in the case of a comparative example that does not meet the essential requirements of the present invention, the viscosity is 800 to 2000 cp at a coal concentration of 73%, and the aggregation rate after standing for one month reaches 20 to 100%, indicating extremely stable It was bad.

Example 2 The same coal as in Example 1 was used, and the additives shown in Table 1 were used.

The method for producing coal-water slurry uses deashed coal,
It was carried out using the following two methods.

Method (C): Coal cleaned by the OA method, water, and additives were put into a ball mill in a predetermined amount and pulverized until the particle size of one coal reached 80% of the amount passing through 200 meshes.

Method (D): A predetermined amount of coarsely crushed coal (approximately 3 mm or less) and water were put into a ball mill to produce a slurry with a coal concentration of 15% and a coal particle size of 80% passing through 200 meshes.

This slurry is deashed by flotation method and Dehydrated to a constant concentration.

Add additives to it and create a lab body spar. At ls2#T! L slurry was obtained.

The final slurry produced was evaluated by the same test procedure as in Example 1.

The evaluation results are shown in Table 3.

fjr, according to the present invention as shown in Table 3 to 11.

By wet producing coal-water slurry using method (C) or method (D), the viscosity is 1000 cp at a coal concentration of 80%.
A coal-water slurry with good fluidity was obtained.

Furthermore, even after the slurry was allowed to stand for one month, there were almost no aggregates, and the viscosity of the slurry was almost not increased, making it possible to obtain a highly concentrated coal-wood slurry with a long life.

On the other hand, in the case of a comparative example that does not meet the essential requirements of the present invention, the value was about 800 to 2 ooocp at 1 jt of stone and 75% at 0 degrees, and the aggregation rate reached 25 to 100% after standing for one month. It was inappropriate for the payment of

[Brief explanation of drawings]

Figure 1 shows the coal particle size distribution. Figure 2 shows the molecular weight distribution of the additive.

Claims (5)

[Claims] (1) An additive added when producing a highly concentrated coal-water slurry by pulverizing coal in the presence of water, the additive having a [a] molecular weight (weight average molecular weight) of 400 to 10,000 A mixture of polystyrene (hereinafter referred to as component [a]) and polystyrene (hereinafter referred to as component [b]) having a molecular weight (weight average molecular weight) of 40,000 to 500,000, preferably 50,000 to 150,000, An additive for a long-life, high-concentration coal-water slurry, characterized in that it is a polystyrene partially sulfated product obtained by partially sulfating or a salt thereof. (2) The degree of sulfation of the partially sulfated polystyrene or its salt is 65 to 97% per styrene unit, preferably 70 to 9
The long-life, high-concentration coal-water slurry additive as claimed in claim (1), which is polystyrene partially sulfated or a salt thereof at a concentration of 5%. (3) The mixing ratio of component [a] and component [b] in the mixture is component [a]/component [b] = 95/5 to 10/90,
The long-life, high-concentration coal-water slurry additive according to claim 1 or 2, which preferably has a ratio of 90/10 to 50/50. (4) Highly concentrated coal-water slurry has a coal concentration of 60% by weight
The additive for long-life, high-concentration coal-water slurry according to claim 1, (2) or (3), wherein the content is preferably 64% by weight or more. (5) The additive for long-life, high-concentration coal-water slurry according to claim 1, (2), (3), or (4), wherein the coal is cleaned coal.