JPS5896693A - Coal slurry composition - Google Patents

Abstract

PURPOSE:To obtain a coal slurry composition having high concentration and excellent fluidity and dispersion stability, by compounding a specific water- soluble polysaccharide, a nonionic or anionic surface active agent, coal particles having specific particle size, and water. CONSTITUTION:The objective coal slurry composition is composed of (A) about 0.001-3 (wt)% water-soluble polysaccharide having a molecular weight of >=1.5 X10<4> and containing uronic acid as at least one of the constituent saccharides, (B) 0.1-10% nonionic surface active agent and/or anionic surface active agent, (C) 50-85% coal powder wherein the content of the particles of finer than 150mu is >=60%, and (D) the rest part of water.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an aqueous coal slurry composition (hereinafter referred to as coal slurry) that has excellent fluidity and dispersion stability even at high concentrations.

Currently, the price of petroleum, which is widely used as an energy source, has skyrocketed due to the first and second oil siltation, and has not only continued to rise since then, but also that petroleum resources will be depleted in the near future. It is expected that. Especially in a country like Japan, where the absolute amount of oil resources is small and we must rely on imports from overseas for more than 95% of our consumption, there is an urgent need to develop energy alternatives to oil and put them to practical use. . Alternative energy sources include wind, wave,
Tidal power, nuclear power, solar heat, biomass, etc. are being considered, but it is thought that it will take a considerable amount of time in terms of safety, facilities, research, etc., before they are widely put into practical use as an alternative to petroleum energy. There is.

For this reason, coal, which had almost disappeared with the advent of oil, is now being reconsidered. Coal exists in abundance both in Japan and around the world, and reusing coal as an energy resource will greatly contribute to solving current and future energy issues, and is a quick path.

However, the reason why the use of coal drastically decreased with the advent of oil is that
This is due to the low transportation efficiency caused by coal being a solid, the poor efficiency of feeding it to boilers and combustion furnaces, and the generation of dust during handling operations.If these points are not solved, the use of coal will not be possible. Unable to promote.

One possible solution to this problem is to disperse pulverized coal produced and recovered in coal mines, or fine powder found by dividing coal into fine particles, in water to form a slurry, which is then made into a fluid similar to petroleum. By slurrying it like that,
Like oil, it can be easily transported and supplied through pipes, and it also prevents the generation of dust, improving work efficiency in various ways. As a result, the value of using coal q increases, and the conversion to coal energy can be promoted.

The conditions required for coal slurry that can replace petroleum are:
(1) The coal particles are uniformly dispersed and highly concentrated; (2) the coal particles have good fluidity; and (5)
) It must not aggregate or settle during transportation or storage. It is generally known that the finer the coal particles, the greater their water dispersibility. If coal is mechanically divided into extremely fine pieces (approximately 150p) and then poured into water and mixed with appropriate mechanical shearing force, it will be reduced to approximately 60% (approximately 60%).
Coal slurry with a concentration of up to 1% by weight (the same applies hereinafter) can be obtained. However, a slurry with a high concentration of 60 or more cannot be obtained by conventional methods. When using coal particles with a particle size of 200 microns or less, a slurry with a concentration of 60 or more can be obtained, but this slurry has almost no fluidity and therefore cannot be used for pipe transportation, etc., and is therefore unsuitable.

On the other hand, in order to give fluidity, the concentration of the slurry was set to 40~
After 50 **, coal particles settle in a very short time, and in some cases, caking occurs, making redispersion difficult. When such sedimentation occurs, it is deposited in the pipes being transported, reducing transport efficiency and causing clogging of the pipes. Furthermore, when storing in a tank or the like for pipe transportation, it will precipitate and separate if it is not constantly stirred. In addition, when coal slurries of various concentrations are transported through pipes, the inner walls of the pipes are severely damaged due to friction with the coal particles, so it is difficult to maintain the stock. Depending on the selection of particle size distribution, slurry concentration, dispersion/mixing equipment, etc., no coal slurry has been found to have workability comparable to that of petroleum.

Addition of surfactants has been considered in order to improve the dispersibility stability of coal in water.

Suitable such surfactants are nonionic surfactants and/or anionic surfactants.
Thionic surfactants and amphoteric surfactants are not preferred because they often cause aggregation and separation depending on the type of coal.

55-60 when no surfactant is added as mentioned above.
It was extremely difficult to obtain a coal slurry with a concentration of up to 65% by mechanical stirring by adding nonionic and/or anionic surfactants. Even in coal souffle with a concentration of about 60 arcs, fair fluidity is observed. However, even if the types, combinations, and amounts of surfactants to be added are selected, it is not possible to achieve a concentration of 65 arcs or higher, and the coal particles in the slurry begin to settle even after standing for a short period of time (less than 1 hour). It ends up. In particular, when the particle size distribution of the coal particles used is inappropriate, a cake is formed that is even harder than when no surfactant is added, making redispersion extremely difficult.

Moreover, if the concentration exceeds 66, sufficient fluidity cannot be obtained for pipe transportation, and either no fluid is left in pipe transportation, or even if it can be transported, high pump pressure is required. Even if the coal can be transported under high pressure, if sedimentation occurs in the middle of the pipe, it will be completely impossible to transport the coal sewage. Incidentally, the wear of the inner wall of the pipe due to coal particles is hardly improved even by the addition of a surfactant.

Thus, even by adding rheonic and (t) anionic surfactants, a fluid equivalent to petroleum cannot be obtained.

As a result of intensive research, the present inventors found that in addition to at least one nonionic and/or anionic surfactant, the molecular weight is L5 x 10' or more and at least one of the constituent sugars is a uronic acid. 1 m of a certain water bath polysaccharide (hereinafter,
By adding at least one type of uron-containing polysaccharide), the chewiness can be increased to 85%.This discovery has been made, and the present invention has been completed.

Tsudanic acid-containing polysaccharides not only have the effect of increasing the dispersibility of coal particles in water, but also improve the separation and separation of coal particles during electrostatic
It contributes to improving dispersion properties to suppress sedimentation, provides good fluidity even at high concentrations, and has the effect of suppressing wear on the inner wall of pipes caused by coal particles.

Such effects can only be obtained when the molecular weight is high, S x 10' or more, at least one of the constituent sugars is uronic acid, and the composition is water-soluble. Molecular weight is 1.5 x 10
For those less than '', some effects are recognized on the dispersibility of coal particles in water, but they are almost ineffective in suppressing separation and sedimentation during standing. In addition, in the case of water-soluble polysaccharides that do not contain powder, the coal slurry concentration cannot be increased to 65% or more, and it is hardly effective in suppressing separation and sedimentation during standing.

Examples of the acid-containing polysaccharides include arabinogalactan, gum arabic, betatin, carrageenan, alginate, Erwinia Tahitian polysaccharide, gum tragacanth, mallow II, gum karaya, gum seed seed, and derivatives thereof. It will be done.

Such uronic acid-containing polysaccharides can only exhibit the above effects when used in combination with nonionic surfactants and/or anionic surfactants.

The effects of surfactants are as described above, and examples of nonionic surfactants include alkyl polyether alcohols, alkylaryl polyether alcohols,
Polyoxyethylene fatty acid ester, melioxyethylene sorbicun fatty acid ester, melialkylene I? There are side block copolymers, etc., which are blended with ethylene oxide, jetanolamine, antoda sorbicil, glucoside, gluconamide,
Commercially available products such as glycerin-based and glycidol threads can be used as dispersants or ** agents for coal particles. Examples of anionic surfactants include dodecylbenzenesulfonate, oleate, alkylbenzenesulfone I1m, dialkylsulfonate, ligninsulfonate, alcohol ethoxy! There are carboxylic acids, sulfuric esters, sulfonic acids, phosphoric esters, etc. that contain sulfate, secondary alkanesulfate, olefin sulfonic acid, tamol, etc.
Commercially available products such as alkylaryl sulfone threads can be used as dispersants or oil agents for coal particles.

Only one type of surfactant may be used, or a combination of 211 or more of the same type or two or more of different types in any ratio may be used.

The smaller the particle size, the better the dispersibility of the coal particles, so the finer the particle is, the more preferable it is, but coal particles that usually contain 60% or more of fine particles of 150P or less, preferably 200P.
A material containing 80% or more of the following fine particles is used.

The blending ratio is uronic acid-containing polysaccharide from 0.001 to Sumihata, preferably 0.005 to 1, and surfactant from 0.1 to 10.
attack, preferably 0.5-65G, coal particles 50-85
%, preferably 60-80% and the balance is water.

If the content of the uronic acid-containing polysaccharide is less than 0.001%, the desired effect cannot be achieved, and if it exceeds 6%, the viscosity increases and fluidity, which is one of the objectives of the present invention, is severely reduced. If the amount of surfactant is less than 0.1%, the desired dispersibility cannot be obtained.
When the number of additions exceeds 10, no improvement in dispersibility is observed depending on the amount added.O Coal particles can be converted into a slurry with good fluidity up to 85%, but when it exceeds 85%, the fluidity deteriorates.

Uronic acid-containing polysaccharides are anionic, and if the ash content of the coal used is high, the polyvalent metal ions liberated from the ash and uronic acid will react with the uronic acid during storage of the resulting stone layer slurry, resulting in It increases the viscosity and sometimes makes it gel-like. This period can be prevented by using coal with a low ash content, by performing pretreatment such as flotation to reduce the ash content, and by selecting an appropriate leprosy polysaccharide to be used. However, a simpler method is to add a cleaning agent. Chelating agents have the effect of suppressing the reaction between polyvalent metal ions in ash and polysaccharides containing polysaccharides, such as POM,
Examples include sodium tripolyphosphate, tetotsuboriphosphorus II, sodium citrate, sodium glufate, sodium glucoheptonate, low molecular weight sodium polyacrylate, l-lycarboxylic acid, etc. Chelating agents are less than 10% of coal slurry. For trowel-containing polysaccharides, 50 cycles or less may be used. Furthermore, according to the research conducted by the present inventors, when coal having an ash content of 5 s or less is used, no cracking occurs even if no chelating agent is added.

Some surfactants used may foam, and when foaming occurs, coal particles in the slurry stick to the foam and are forced up to the surface, sometimes spilling out of the mixing tank. Moreover, this foaming makes it extremely difficult to increase the concentration of coal particles in the slurry. Addition of an antifoaming agent is effective in suppressing such foaming. As the antifoaming agent, a conventional antifoaming agent such as silicone emulsion may be used, and an amount of 6% or less of the coal slurry is sufficient.

When coal slurry is prepared, stored, and used in a cold region, fluidity may be lost due to freezing, but it is effective to add a freezing point depressant as a countermeasure against this. Some surfactants have a coagulation point lowering effect, but they have no anti-freezing effect if the temperature is below 00A for a very long time, or if the temperature is extremely low even for a short time, so in such cases It is necessary to add freezing point depressants. As the freezing point depressant, for example, lower alkylene glycols such as ethylene glycol and propylene glycol, isoprivyl alcohol, or polyhydric alcohols are effective, and the amount thereof may be 10% or less of the coal slurry.

Furthermore, since many uronic acid-containing polysaccharides are derived from natural products, they are susceptible to decomposition by microorganisms, that is, to decay. Even if a coal slurry containing V and alcohol is not added, mold may form depending on the conditions if the coal slurry is stored for a long period of time. Phenomena caused by such microorganisms can be prevented by adding preservatives or locking doors. Suitable preservatives include formalin,
Penzylpmoacetate, Ha5 Oxyamzoic acid, 2
-Hytonoxymethylamino-2-methylpropatool and the like.

The amount added may be 5≦ or less of the right leg slurry.

Note that when using a substance with a preservative effect such as ethylene glycol as an antifreeze agent in a range of S% or more, it is not necessary to add a new preservative. Anticoagulants such as silica powder are added to prevent agglomeration/sedimentation and caking of cloudy particles, but the molecular weight is 1.
When formulating uronic acid-containing polysaccharides of 5 x 10' or more, anticoagulants should be used, since even if they settle and form a cake during storage, they can be redispersed very easily by mechanical stirring. It is not particularly necessary.

As described above, by blending a nonionic and/or anionic surfactant with a uronic acid-containing polysaccharide, a highly concentrated coal slurry with excellent fluidity and dispersion stability can be obtained.

However, as mentioned above, long-term storage can cause settling and separation (although it can be easily redispersed), and high pump pressures may be required during pipe delivery.

As a result of further research by the present inventors in order to solve this problem, we found that 0, 5 at 6K and 600R using a rotational viscosity needle (coaxial 231 cylindrical soliny rheometer) at 25°0. The ratio of the measured value of the viscosity of the aqueous solution (hereinafter referred to as RI) is 8 or more, and the ratio of the measured value of the viscosity of the 1.0-width aqueous solution (hereinafter referred to as RI) is 15 or more. It has been found that the above problems can be overcome by further incorporating at least one type of certain water bathing heteropolysaccharide.

Examples of water-soluble hetele polysaccharides include guar/mu,
Lee cast bean gum, alginate, xanthan gum, Shiraga canth gum, tate gum, gum arabic, galati gum, karaya gum, tamarind, etc. can be used. However, not all of these polysaccharide pulps can be used, and the fluidity coefficient ( 1) is 6 or more and the flow coefficient (
Must have 15 or more buttons. Flow section & (1
) and fluidity coefficient (button) are the criteria for determining the dispersion stability of coal slurry when it is standing still or stored, and the fluidity when flowing through a pipe.

When the fluidity coefficient (1) is 8 or more and the fluidity coefficient (phantom) is 15 or more, the viscosity is high under conditions of low external force indicated by Br1m, and under the condition of external force indicated by 300rP!+. It exhibits a phenomenon of low viscosity.In other words, when no external force acts, such as under electrostatic conditions such as during storage, the viscosity is high, and this suppresses the settling of coal particles.On the contrary, When an external force is applied, such as during injection, the viscosity decreases, making it easier to transport coal slurry through pipes. 0 low, and this repetition is required to be permanent.

The flow coefficient Wl(1) is less than 8, or the flow coefficient (])
is less than 15, indicating that the viscosity is low or high even under static conditions such as storage, and that the viscosity is low or high under conditions such as injection. If the viscosity is high during storage, sedimentation of coal particles will be suppressed and storage problems will be eliminated, but if the viscosity does not decrease even during injection, the coal slurry will have almost no fluidity. , it becomes impossible to subject the coal slurry to pipe transportation as a pseudofluid that meets the objectives of the present invention.

If the viscosity is low, it is effective for fluid transport during injection, etc., but if the viscosity is similarly low during storage, coal particles will settle, so unless constant mechanical stirring is performed, storage → fluid transport will not be possible. You will not be able to take the process at all. Furthermore, if the pump is stopped for some reason during pipe transportation, coal particles will accumulate in the pipe, clogging the pipe and making it impossible to achieve the object of the present invention.

Examples of water-soluble hedipolysaccharides satisfying the above conditions include guar gum, castor bean gum, xanthan gum, and derivatives thereof. The flow coefficients (1) and (1) of guar gum, recast bean gum and xanthan gum are 8 and 15.9 and old, and 19 and 28, respectively.

For reference, the fluidity coefficients <I) and (1) of alginates are 2 or less and 3 or less, respectively, and a 1% aqueous solution of polysaccharide produced by Erwinia atahitica has a viscosity of 25 qO, which is almost the same as guar gum and xanthan gum, but 7 The fluidity coefficients (1) and (■) are below and below 10, which are inappropriate. In addition, for homopolysaccharides, even if the flow coefficient (
Even if I) and (1) are 8 or more and 15 or more, respectively, the desired effect cannot be obtained.

The amount of the water-bathable heteropolysaccharide that meets the above conditions is 0.01 to 1% of the coal slurry. If the number of hits exceeds one, the viscosity of the slurry becomes too high, which is not preferable.

The preparation of the coal slurry of the present invention is carried out in the following order: uric acid-containing polysaccharide;
After mixing and stirring the surfactant, water and coal particles in the above composition, the water-soluble heteropolyaxes are added and the mixture is stirred at high speed.

Next, the coal slurry of the present invention will be explained with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

Example 1 Coal used was Auscilaria (name: Shishan) having a particle size distribution and physical properties of 1.

Particle size distribution (A (weight) ~ 26.
6 2~56.9 5~10 12.310~20
27.020-1110
14.660～44 16
．． 544~74 15.974~1
49 5.51i 1Q, 0
．． 0 Average particle size: 28-2/A Ash content + 31.9% True specific gravity: 1.47 As a surfactant, anionic surfactant tamol (naphthalene, lumaldehyde V condensed sodium sulfate lump, US p- (Muando Yahesu Shakan) was used. The amounts of uric acid-containing polysaccharides were: 1.0% Tamol, 1.0% Zan 70-0.01%, 6 Coal particles
5, and water at 35.99%, and slooorp using a homomixer (manufactured by Tokushu Kika Kogyo).
A coal slurry having a concentration of 65 ml was prepared by stirring at m for 60 minutes.

Coal slurry is first prepared at 5+00O in a homomixer.
The entire amount of Yugaru was added to a predetermined amount of water while stirring at rpH, and half of the predetermined amount of coal particles was gradually added and mixed for 5 minutes. Next, gradually add a predetermined amount of Zanflow,
After mixing for 5 minutes, the remaining amount of coal particles was added little by little and mixed thoroughly.

In addition, if two types of surfactants are used, 5+00
1ml while stirring using a homomixer at 0ri*
After adding the entire amount of surfactant I, 1/6 of the predetermined amount of coal particles was gradually added and mixed for 5 minutes. Subsequently, the entire amount of the other surfactant was added, and 1/3 amount of coal particles were gradually added and mixed for 5 minutes. Next, the entire amount of a dispersion aid/stabilizer such as Xanfree was gradually added and mixed for 5 minutes, and then the remaining amount of coal particles was added little by little and thoroughly mixed. The total mixing time in the homomixer was 60 minutes.

The following tests were conducted regarding the fluidity, dispersion stability, and caking of the coal slurry.

(Fluidity) The observed slurry was placed in a beaker, and the flow from the beaker was observed with the naked eye. The results are shown in Table 1. [1 was conducted based on the following criteria.

◎: Extremely fluid O: Fluid Δ: Difficult to flow X: No fluidity at all in a solidified state (dispersion stability) The obtained pilgrim slurry 100100O was placed in a 10100O glass beaker marked with 100 scales. 1.
After 0 minutes, 20 minutes, 50 minutes, and 60 minutes, the scale of the surface water syneresis or diluted portion was observed.

The results are shown in Table 1.

(Caking) Using a homomixer, the coal slurry that had been allowed to stand for 60 minutes was stirred and redispersibility was observed. The results are shown in Table 1. Evaluation was performed based on the following criteria.

◎: ON that can be redispersed within 1 minute Δ: Can be redispersed in 1 to 6 minutes X: Redispersion takes more than 6 minutes A coal slurry was prepared in the same manner as in Example 1, except that those shown in Table 1 were used as the slurry, and its fluidity, dispersion stability, and caking were examined in the same manner as in Example 1. The results are shown in Table 1.

Comparative Examples 1 to 14 Coal slurry was prepared in the same manner as in Example 1 using the composition and conditions shown in Table 1, and its fluidity, dispersion stability and caking were evaluated in the same manner as in Example 1. Examined.

The results are shown in Table 1.

Examples 13 to 25 Coal slurries were prepared in the same manner as in Example 1 except that the compositions and conditions shown in Table 2 were used.

If one type of surfactant is used, 5+000
After adding the entire amount of surfactant while stirring with a homomixer at rpm, half of the predetermined amount of coal particles was gradually added and mixed for 5 minutes. Subsequently, the entire amount of the uronic acid-containing polysaccharide was gradually added, and then the remaining amount of coal particles was added little by little and mixed for S minutes. After mixing, hetep polysaccharide was gradually added and mixed thoroughly. The total mixing time using the homomixer was 30 minutes.

When using 2-type surfactants, use s, ooorp.
After adding the entire amount of one type of surfactant while stirring with a homomixer at m, 1/6 of the predetermined amount of coal particles was gradually added and mixed for 5 minutes. Subsequently, the entire amount of the other surfactant was added, and 176 amount of coal particles were gradually added and mixed for 5 minutes. Next, gradually add the entire amount of uronic acid-containing polysaccharide, and then add the remaining amount of coal particles little by little.
Mixed for a minute. After mixing, Heteta polysaccharide was gradually added, and a preservative (for!rin) was added and thoroughly mixed. The total mixing time using the homomixer was 60 minutes.

Their fluidity, dispersion stability and caking were investigated in the same manner as in Example 1. The results are shown in Table 2.

Comparative Examples 15-16 Example 1 using the composition and conditions shown in Table 2!
A coal slurry was prepared in the same manner as in Example 1, and its fluidity, dispersion stability, and caking were examined in the same manner as in Example 1. The results are shown in Table 2.

Claims (1)

[Scope of Claims] 1 (at least one water-soluble polysaccharide having a (trans)molecular weight of 1.5 x 10' or more and at least one constituent sugar being uronic acid, (B> nonionic surfactant) - and (or) at least one kind of anionic surfactant, (0) coal particles containing at least 60% or more of the particle size category of t50P or less, and (high concentration consisting of primary ice and excellent fluidity and dispersion stability) Coal slurry composition. 2 (A) component is 0.001 to B weight percent, (B) component is 0.1 to 10 weight percent, (0) component is 50 to 85 weight percent, and the balance by weight is (to) component. The first claim is
Compositions as described in Section. 3. The composition according to claim 2, wherein the chelating agent is contained in an amount of not more than 10% by weight. 4. The composition according to claim 2 or 6, wherein the freezing point depressant is 10% by weight or less. 5. The composition according to claim 8#I2 and 33J*Tak4, which contains an antifoaming agent in an amount of 5 or less by weight. 6. The composition according to claim 2, 6, 4, or 5, which contains a preservative in an amount of 5 weight or less. 7(A) At least 1 ml of a water-soluble polysaccharide having a molecular weight of S x 10' or more and at least one of the constituent sugars being uronic acid. (1) Coal particles containing at least 1 m of nonionic surfactant and/or anionic surfactant, (0) at least 60% of the particle size category below 160p, (early ice, and (to) at 25°O A water-bathable hete 1 in which the ratio of the measured viscosity of a 0.5% by weight aqueous solution is 8 or more and the measured viscosity of 1.0% by weight is 15 or more at 5 rpm and 300 ryr using a rotational viscometer. at least one polysaccharide
A highly concentrated coal slurry composition consisting of seeds with excellent fluidity and dispersion stability. 8 (A) component is 0.001-3% by weight, (B) component is 0.
．． 1 to 10 weight range, (0) component is 50 to 85 weight ≦, (
The composition according to claim 7, wherein the component I) is 0.01 to 1% by weight, and the remainder is a component. 9. The composition according to claim 82, wherein the chelating agent is 10% by weight or less 10. The composition according to claim 8 or 9, which contains not more than 10% by weight of a freezing point depressant. 11. The composition according to claim 8, which contains not more than 5% by weight of an antifoaming agent. The composition according to item 8, 9 or 10. The composition according to item 1.