JPH05230477A - Coal slurry composition and its preparation - Google Patents

Abstract

PURPOSE:To obtain the title composition excellent in aqueous dispersion stability and fluidity by incorporating a specified amount of cellulose fibers as a dispersion stabilizer into a specified aqueous slurry of coal. CONSTITUTION:An aqueous slurry of coal, consisting of fine coal particles having a mean particle diameter of 200mum or smaller and water, which contains a dispersion stabilizer comprising cellulose fibers (e.g. microbial cellulose) in an amount of 0.005-0.04wt.%, in terms of dried cellulose fibers, based on the slurry.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to improving the dispersion stability of coal aqueous slurries.

[0002]

2. Description of the Related Art Petroleum, which is widely used as an energy source, is expected to run out in the near future as well as rising prices. Nuclear power, solar heat, biomass, etc. are considered as alternative energy sources, but it is considered that a considerable amount of time will be required before they can be put to practical use in terms of safety and price.

On the other hand, coal is being reviewed in recent years as the use of petroleum is expanded. Because of the abundance of coal in the world and the low cost, the world is trying to reconsider the reuse of this coal as an energy resource. In recent years, there were problems such as low transportation efficiency caused by the solid state of coal, poor workability of supplying to the boiler, risk of explosion due to generation of dust during work, etc. It may be possible to solve the problem. For this purpose, a method for producing a coal aqueous slurry having good water dispersion stability and fluidity is desired. Heretofore, as a method for producing an aqueous coal slurry, there has been a method in which water and a water-soluble polysaccharide or a surfactant are added to powder coal (JP-A-58-969693).

It is generally known that the finer the coal particles, the greater the water dispersibility. That is, although a coal aqueous slurry having an aqueous solution concentration of 60% or more can be obtained by using fine coal having an average particle size of 200 μm or less, the coal aqueous slurry has almost no fluidity and therefore cannot be used for pipe transportation and the like.

On the other hand, in an aqueous coal slurry prepared by adjusting the concentration of the aqueous solution to 40 to 50% and imparting fluidity to some extent, coal particles are precipitated in a short time or coal particles are solidified. When such a phenomenon occurs, coal particles settle in the pipe during transportation, which lowers transportation efficiency and causes clogging of the pipe. From these things, the preparation method of the coal aqueous slurry with fluidity is desired.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a coal aqueous slurry composition having excellent dispersion stability of coal fine particles in water and excellent fluidity, and a method for producing the same.

[0007]

[Means for Solving the Problems] In order to solve the above problems, the inventors of the present invention have conducted extensive studies, and as a result, by adding and mixing cellulosic fibers to a coal aqueous slurry, coal having excellent dispersion stability is obtained. It was found that an aqueous slurry composition was obtained, and the present invention was completed. In other words, the present invention is a coal aqueous slurry containing coal fine particles having an average particle size of 200 μm or less and water, in which a cellulosic fiber or an aqueous solution or gel containing the same is converted into a cellulose fiber dried product, and the coal aqueous slurry is obtained. On the other hand, a coal slurry composition containing 0.005 to 0.04% by weight of a dispersion stabilizer as a dispersion stabilizer and a method for producing the same.
The present invention will be described in detail below.

The cellulosic fiber used in the present invention means plant-derived cellulose such as wood pulp, cotton pulp, hemp pulp, MFC (manufactured by Daicel Chemical Industries Ltd.) or microbial cellulose produced by microorganisms.

As the plant-derived cellulose used in the present invention, cellulose obtained from toilet paper, rice straw, wood pulp or the like can be used after being finely divided. For miniaturization, add 5 to 20 times the amount of water to vegetable cellulose and add 10 to 10 at 10,000 rpm with a Waring blender.
It is preferably used after being granulated for 60 minutes. The microbial cellulose is a cellulose produced by using microorganisms, particularly acetic acid bacteria, and a fibrous form having a width of 10 to 100 nm is preferably used. As produced, microbial cellulose has a network-like structure in which very thin (width or diameter of 100 nm or less) ribbon-shaped fibers made of cellulose with extremely high crystallinity and uniaxial orientation are intricately entangled. This structure contains a large amount of liquid in the voids therein, and its appearance is gel-like. The liquid component contained in the voids in the microbial cellulose structure, such as water, exists as free water and is easily squeezed out when an external force is applied. Since it is composed of a large number of ribbon-shaped fibers having extremely high crystallinity, it can withstand external forces such as tension even in a wet state. Microbial cellulose is not different in the primary structure from cellulose of plant-derived cotton, wood pulp, etc., but the so-called higher-order structure such as the network described above is not found in plant-derived cellulose. It is peculiar to cellulose, and therefore has strength despite being gelled.
It exhibits various properties. In addition, the sheet-shaped microbial cellulose is characterized in that it is composed of α-cellulose having high crystallinity and has a very strong surface orientation.

Microbial celluloses include those containing cellulose and heteropolysaccharides having cellulose as the main chain and β,
Including glucan such as α. In the case of a heteropolysaccharide, as constituent components other than cellulose, mannose, fructose, galactose, xylose, arabinose, rhamnose,
It includes hexoses such as uronic acid, pentoses and organic acids. There are celluloses in which these polysaccharides exist as a single substance, and there are celluloses in which two or more types of polysaccharides are mixed. Microorganisms that produce such cellulose are not particularly limited, for example, Acetobacter pasturianus ATCC 10821, aceti (A.
aceti), A. ransens, Sarcina ventriculi, Bacterium xyloides, Pseudomonas bacteria, Agrobacterium bacteria, Rhizobium bacteria and the like.

For the production and accumulation of microbial cellulose,
A general method for culturing ordinary bacteria using the above-mentioned microorganism may be followed. That is, it may be added to a normal nutrient medium containing a carbon source, a nitrogen source, an inorganic salt, and other organic micronutrients such as amino acids and vitamins, if necessary, and controlled at 20 ° C to 40 ° C for culturing. The microbial cellulose produced in this manner can be used without washing, but since it contains bacterial cells or medium components, it can be washed depending on the application. The washing may be performed with a dilute alkali, a dilute acid, an organic solvent, hot water or the like alone or in combination.

The microbial cellulose gel obtained after washing may be used by micronizing it using a Waring blender until the microbial cellulose gel becomes fibrous.
That is, when refining the microbial cellulose to be added to the coal aqueous slurry, 10 kg of a 1 cm square gel of microbial cellulose with a water content of 98% is used with a Waring blender for 10,0
15 to 30 minutes at 00 rpm is preferred.

The method for producing the coal slurry composition of the present invention comprises:
A dry or water-soluble or gelled cellulose fiber is added to the conventional coal aqueous slurry as the dispersed water solution,
It can be preferably prepared by slowly stirring and mixing at 100 to 500 rpm for 20 minutes to 3 hours. A description will be given below based on examples.

[0014]

【Example】

Test Method 1 Water Dispersion Test 100 ml of coal slurry or coal aqueous slurry was placed in a graduated cylinder having a diameter of 28 mm and allowed to stand at room temperature, and it was determined from the interface between pulverized coal and water.

Test Method 2 Viscosity Test Viscometer: Measured with a DVK-B type, Tokyo Keiki Co., Ltd. at 20 degrees Celsius.

Preparation of Coal Aqueous Slurry 140 g of lignite coal (obtained as fine dust coal from G-Ben Chemical Co., Ltd.) having a particle size of 150 μm or less is dispersed and mixed in 60 g of water to 500 r.
It was adjusted by stirring at pm for 30 minutes.

Preparation of Microbial Cellulose Gel Microbial cellulose gel was prepared by using a Waring blender at 10,000 rpm for 15 minutes so as to be 2% in terms of dry matter.

[0019]

Examples 1-4: Warming microbial cellulose gel
The amount shown in Table 1 was added to the coal aqueous slurry in the amount shown in Table 1 after being refined by a blender at 10,000 rpm for 15 minutes, and then mixed with a mixer at 500 rpm for 30 minutes to obtain a coal slurry. The viscosity and the degree of separation when this was allowed to stand at 20 degrees Celsius for a predetermined time were measured and are also shown in Table 1.

[0020]

[Table 1]

[0021]

[Comparative Example 1-4] Coal aqueous slurry or microbial cellulose, polyoxyethylene lauryl ether (LEO), and sodium lignin sulfonate (LAS) were added to each as shown in Table 1 and then added to 20 degrees Celsius. The viscosity and the degree of separation when left to stand for a predetermined time were measured and shown in Table 1.

[0022]

[Example 5-9] MFC (manufactured by Daicel Chemical Industries, Ltd., product number 409051, cellulose 2 was added to an aqueous coal slurry.
%, Moisture 98%) is untreated, wood scrap 31g WO
Put it in 980 g of tap water and use a Waring Blender 1
Toilet paper finely cut at 30,000 rpm for 30 minutes, toilet paper cut into about 1 cm square 2
2 g of tap water was put into 980 g of water and finely divided by a Waring blender at 10,000 rpm for 15 minutes.
After converting the finely divided product with a blender at 10,000 rpm for 15 minutes into a dried product, and adding the cellulose shown in Table 2 in the amount shown in Table 2, 500 rpm3 with a mixer.
The mixture was mixed for 0 minutes to obtain a coal slurry. This was allowed to stand at 20 ° C. for a predetermined time, and the viscosity and the degree of separation in this state were measured and shown in Table 2.

[0023]

[Table 2]

[0024]

[Comparative Example 5-6] Aqueous coal slurry and LAS in the amounts shown in Table 2 were added, and then 500 rpm3 with a mixer.
The mixture was mixed for 0 minutes to obtain a coal aqueous slurry. 20 degrees Celsius
The test piece was allowed to stand for a predetermined time at a temperature, and the viscosity and the degree of separation in this state were measured and are also shown in Table 2.

[0025]

[Effect] The coal slurry composition and the manufacturing method of the present invention are stable in water dispersion by adding a small amount of cellulose as compared with the conventional method.
This is a useful technique with excellent fluidity.

Claims (2)

[Claims] 1. A coal aqueous slurry containing fine coal particles having an average particle size of 200 μm or less and water, in which cellulosic fibers are converted into a dried cellulose fiber product and 0.005 to 0.04 relative to the coal aqueous slurry. A coal slurry composition, characterized by containing as a wt% dispersion stabilizer. 2. A coal aqueous slurry containing coal fine particles having an average particle diameter of 200 μm or less and water, in which cellulosic fibers are converted into a dried cellulose fiber product, and 0.005 to 0.04 weight of the coal aqueous slurry is obtained. % A dispersion stabilizer is added, and the manufacturing method of the coal slurry composition characterized by the above-mentioned.