WO2012137893A1

WO2012137893A1 - Coal molded body

Info

Publication number: WO2012137893A1
Application number: PCT/JP2012/059421
Authority: WO
Inventors: 西田　美佳; 鈴木　哲雄
Original assignee: 株式会社神戸製鋼所
Priority date: 2011-04-06
Filing date: 2012-04-05
Publication date: 2012-10-11
Also published as: JP2012219139A

Abstract

This coal molded body contains dehydrogenated low-grade coal bonded to a non-water-soluble organic compound having a viscosity-average molecular weight of 10,000 or higher, the amount of non-water-soluble organic compound being 0.1-10 mass%; and has a sufficiently high initial strength immediately after molding and a minimal drop in strength thereafter despite a history of heating and water absorption or the like during transportation and storage.

Description

Coal molding

The present invention relates to a coal molding using low-grade coal, and particularly to a coal molding in which the initial strength after molding is high and the strength reduction during storage is suppressed.

低 Low-grade coal has abundant reserves, but because it contains a lot of moisture, it generates a small amount of heat during combustion. Such low-grade coal is improved in calorific value by removing moisture by drying such as heating in airflow or dehydration in oil. When drying low-grade coal, it is usually pulverized before drying in order to increase drying efficiency. And low-grade coal after drying is inferior in handling property if it is in powder form and inconvenient for transportation, etc., so it can be converted into briquettes (coal molded products) using a pressure molding machine such as a double roll press. Molded.

Various types of such coal molded products have been proposed. For example, Patent Document 1 discloses a coal molded product containing molasses, a water-soluble polymer compound and the like as a binder (see Example 1). However, those using molasses or a water-soluble polymer as a binder are easily embrittled by expansion due to moisture absorption or submergence, and tend to cause a reduction in briquette strength. Patent Document 2 describes a coal molded body (see Example 1) in which coal, polyvinyl alcohol and calcium oxide are mixed and molded in the presence of water and then cured by reaction. In this coal molding, the initial strength after molding was insufficient.

Patent Documents 3 and 4 describe a coal molded product in which waste plastic is mixed with coal. In these coal moldings, the content of waste plastic is high because it is used as fuel (see Paragraph [0042] Table 2 of Patent Document 3 and Paragraph [0009] of Patent Document 4). The initial strength of is insufficient. Patent Document 5 describes a coal-molded product (see paragraphs [0020] and [0023], Table 3) obtained by heating and kneading a mixture containing coal and a thermoplastic at 170 ° C. to 210 ° C. Yes. However, since coal has low heat conduction, it becomes harder to cool as it becomes larger. Therefore, when the coal molded product is heated and kneaded at a high temperature of 170 ° C. or higher, if the coal molded product after molding is put into the air at a high temperature, there is a risk of spontaneous ignition. Note that spontaneous ignition can be prevented by kneading and cooling in an inert atmosphere (nitrogen, argon, etc.) without oxygen, but the production cost is increased.

Japanese Laid-Open Patent Publication No. 61-271022 Japanese Unexamined Patent Publication No. 59-206493 Japanese Unexamined Patent Publication No. 2000-319674 Japanese Unexamined Patent Publication No. 2001-342475 Japanese Unexamined Patent Publication No. 10-306288

However, briquettes molded using a pressure molding machine are very hard immediately after molding, but brittle brittle progresses during handling such as transportation and storage outdoors, and powder generation occurs. was there. The coal molded body in which the powder is generated has a problem that it can no longer be used because dust becomes a problem during use. In particular, a molded coal using low-grade coal having high hydrophilicity tends to easily become brittle due to expansion due to moisture absorption or submergence, and tend to cause a reduction in briquette strength. However, a binder suitable for a coal molded product using such low-grade coal has not been sufficiently studied.

The present invention is a coal molded body using low-grade coal, which has a sufficiently high initial strength immediately after molding, and has little deterioration in strength even if it receives a history of heating, moisture absorption, etc. during subsequent transportation and storage. The purpose is to provide a body.

The coal molding of the present invention that has been able to solve the above-mentioned problem contains dehydrated low-grade coal, and a water-insoluble organic compound having a viscosity average molecular weight of 10,000 or more to bind the coal, The content of the water-soluble organic compound is 0.1% by mass to 10% by mass. The low-grade coal is preferably dehydrated in oil. The particle size of the low-grade coal is preferably 3 mm or less. The low-grade coal is preferably at least one selected from the group consisting of drought, bituminous coal, and subbituminous coal.

The coal molding of the present invention has a high initial strength immediately after molding, even though low-grade coal having high hydrophilicity is used, and suppresses a decrease in strength even when moisture is absorbed during subsequent storage. .

It is a schematic diagram which shows the installation state of the coal molding in a crushing test.

The coal molding of the present invention uses low-grade coal as coal, and contains a predetermined amount of a water-insoluble organic compound having a viscosity average molecular weight of 10,000 or more as a binder. By adding the specific water-insoluble organic compound, not only the initial strength immediately after molding is increased, but even when low-quality charcoal absorbs moisture during subsequent storage, the binding strength does not decrease, and a history of moisture absorption and the like is received. However, the strength reduction is suppressed.

The water-insoluble organic compound is an organic compound and is not water-soluble. The solubility of the water-insoluble organic compound in water (liquid temperature: 25 ° C., under atmospheric pressure) is 1 g / 100 g or less, preferably 0.5 g / 100 g or less, more preferably 0.1 g / 100 g or less. The lower the solubility, the more the strength reduction due to moisture absorption during storage can be suppressed. Here, the solubility is the mass (g) of an organic compound that can be dissolved in 100 g of water.

Examples of the water-insoluble organic compound include polyolefins such as polyethylene and polypropylene; polystyrene; thermoplastic epoxy resin; thermoplastic phenol resin; Polyvinyl alcohol is water-soluble, but completely saponified polyvinyl alcohol is soluble in hot water, but its solubility in water at 25 ° C. is 1 g / 100 g or less. include. Among these, as the water-insoluble organic compound, polyolefin is preferable, and polyethylene is more preferable.

The viscosity average molecular weight of the water-insoluble organic compound is 10,000 or more, preferably 20,000 or more, more preferably 30,000 or more. When the viscosity average molecular weight is 10,000 or more, embrittlement can be prevented even when the coal molded body absorbs moisture. In addition, although the upper limit of a viscosity average molecular weight is not specifically limited, Usually, it is 1 million. A method for measuring the viscosity average molecular weight will be described later. In addition, what is necessary is just to refer to the catalog value, when using a commercial item as a water-insoluble organic compound.

Content of the said water-insoluble organic compound in the coal molding of this invention is 0.1 mass% or more, Preferably it is 0.3 mass% or more, More preferably, it is 0.5 mass% or more, More preferably, it is 0.7 It is 10% by mass or less, preferably 5% by mass or less, more preferably 3% by mass or less, and particularly preferably 0.8% by mass or less. By setting the content of the water-insoluble organic compound within the above range, it is possible to obtain a coal molded body having high initial strength and suppressed strength reduction during storage.

The low-grade coal used in the present invention means a naturally occurring coal containing 20% by mass or more of water. Examples of the low-grade coal include brown coal such as Victoria coal, North Dakota coal, and Belga coal; sub-bituminous coal such as West Banco coal, Vinungan coal, and Saramangau coal; and bituminous coal. Among these, lignite is highly hydrophilic and absorbs water and expands. For this reason, in the charcoal obtained by molding the lignite particles, each particle expands due to moisture absorption, and the grain boundary is easily peeled off, and is very fragile. When a water-insoluble organic compound is added to a coal molding containing such depleted particles, it not only serves as a binder that binds the particles, but also fills the gaps between the particles to prevent moisture from entering. There is also an effect. Therefore, when drought is used as low-grade coal, the embrittlement suppressing effect of the present invention becomes more prominent.

The particle size of the low-grade coal is preferably 3 mm or less, more preferably 2 mm or less, and even more preferably 1 mm or less. In particular, in the low-grade coal, the proportion of particles having a particle size of 0.5 mm or less is preferably 50% by mass or more, more preferably 70% by mass or more, and further preferably 80% by mass or more. The smaller the particle size of the low-grade coal, the higher the strength of the resulting coal molding. The particle size of the low-grade coal can be adjusted by pulverization and classification using a sieve. The proportion of particles having a particle diameter of 0.5 mm or less can be determined from the total mass of low-grade coal subjected to sieving and sieving with a sieve having a mesh size of 0.5 mm and the mass under the sieve.

The low-grade coal is used after being dehydrated. By using low-grade coal that has been dehydrated, the water content of the resulting coal molding is reduced, and the amount of heat generated during combustion is further improved. Examples of the dehydration method include an in-oil dehydration method in which heat treatment is performed in oil, a heat treatment method in an inert atmosphere, and the like, and the dehydration method in oil is more preferable from the viewpoint of high moisture removal rate.

In the dewatering method in oil, for example, low-grade coal is mixed with petroleum light oil having a boiling point of 150 ° C. to 300 ° C., and the mixture is heated to 100 ° C. or more to evaporate and remove water in the low-grade coal. . The low-grade coal after dehydration in oil is taken out of the petroleum-based light oil and then dried with hot air to remove the petroleum-grade light oil remaining in the low-grade coal. At this time, the content of petroleum light oil in the low-grade coal is preferably 10% by mass or less, more preferably 3% by mass or less, and further preferably 2% by mass or less.

The coal molded body of the present invention can be produced by mixing dehydrated low-grade coal and the water-insoluble organic compound and molding the resulting mixture. Examples of the mixing method of the dehydrated low-grade coal and the water-insoluble organic compound include dry mixing and wet mixing. Among these, dry mixing is preferable because the moisture content of the obtained coal molding can be reduced.

For the dry mixing, a known mixer, ball mill, kneader, V-type mixer or the like may be used. In the case of dry mixing, it is preferable to pulverize the water-insoluble organic compound in advance and adjust the volume average particle diameter to 500 μm or less, more preferably 100 μm or less, and still more preferably 50 μm or less. The volume average particle diameter can be measured with a laser diffraction particle size distribution measuring apparatus.

In wet mixing, an emulsion of a water-insoluble organic compound or an aqueous solution of a water-insoluble organic compound (heated and dissolved) is prepared, and the emulsion or aqueous solution and low-grade coal are mixed. The concentration of the water-insoluble organic substance in the emulsion or aqueous solution is preferably 10% by mass to 80% by mass. When the wet mixing is employed, it is preferable to remove the solvent used for the wet mixing before performing the molding described later.

A method for molding a mixture of low-grade coal and a water-insoluble organic compound is not particularly limited, and a known pressure molding apparatus such as a double roll press may be used. The pressurizing pressure is preferably 98 N / mm ² (1000 kgf / cm ² ) or more, more preferably 147 N / mm ² (1500 kgf / cm ² ) or more, and further preferably 196 N / mm ² (2000 kgf / cm ² ) or more. is preferably not more than ^{588N / mm 2 (6000kgf / cm} 2), more preferably ^{490N / mm 2 (5000kgf / cm} 2) or less, and more preferably not more than ^{392N / mm 2 (4000kgf / cm} 2).

The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to the following examples, and may be appropriately modified and implemented within a range that can meet the purpose described above and below. All of which are within the scope of the present invention.

Preparation of low-grade coal Brown coal dehydrated in oil (water content 35% by mass, residual amount of oil used for dehydration in oil 2% by mass), particle size of 1 mm or less and particle size of 0.5 mm or less A particle having a content of 80% by mass or more was prepared.

Production Examples 1-5, 9-12
A water-insoluble organic compound was added to the low-grade coal whose particle size was adjusted as described above so as to have the content shown in Table 1, and mixed using a pot mill to obtain a mixture.
6.0 g of the obtained mixture was weighed and heated by holding it at 150 ° C. for 60 minutes in a nitrogen stream dryer (nitrogen inflow rate 5 L / min). The heated mixture was taken out of the dryer and immediately subjected to compression molding to produce a coal molded body. For compression molding, a cylindrical mold having an inner diameter of 20 mm and an inner cylinder mold having substantially the same diameter as the cylindrical mold were used, and the pressurizing pressure was 196 N / mm ² (2000 kgf / cm ² ). Moreover, the coal molding after compression molding was demolded immediately. The obtained coal molding had a diameter of 20 mm and a height of 15 to 18 mm.

Production Examples 6 and 7
To the low-grade coal whose particle size is adjusted as described above, an emulsion or an aqueous solution is added so that the content of the water-insoluble organic compound after removal of the solvent becomes the value shown in Table 1, and the stirring connected to the motor Mixing was performed using a wing to obtain a mixture.
6.0 g of the resulting mixture was weighed and held at 150 ° C. for 60 minutes in a nitrogen stream dryer (nitrogen inflow rate 5 L / min) to remove the solvent and heat. Using the mixture after heating, compression molding was performed in the same manner as in Production Example 1 to produce a coal molded body. The obtained coal molding had a diameter of 20 mm and a height of 15 to 18 mm.

Production Example 8
Using the low-grade coal whose particle size was adjusted as described above, compression molding was performed in the same manner as in Production Example 1 to produce a coal molded body. The obtained coal molding had a diameter of 20 mm and a height of 15 to 18 mm.

The physical properties of the water-insoluble organic compounds shown in Table 1 are as follows.
High density polyethylene (viscosity average molecular weight 10,000 or more, solubility 1g / 100g or less)
Carboxyl group-modified polyolefin (viscosity average molecular weight 10,000 or more, solubility 1 g / 100 g or less)
Epoxy resin emulsion (manufactured by Japan Epoxy Resin, "Epiletz (registered trademark) YL7162P", high molecular weight phenol-modified epoxy resin (viscosity average molecular weight 10,000 or more, solubility 1 g / 100 g or less), concentration 60 mass%)
Completely saponified polyvinyl alcohol aqueous solution (concentration 20% by mass, dissolved in hot water) Viscosity average molecular weight 10,000 or more, solubility 1 g / 100 g or less stearic acid (manufactured by Wako Pure Chemical Industries, molecular weight 284)
Oxidized wax (Mitsui Chemicals, "High Wax", molecular weight 2000)
Wax (manufactured by Nippon Seiwa Co., Ltd., “Luvax (registered trademark) 2191”, molecular weight 700)
Calcium lignin sulfonate (manufactured by Nippon Paper Chemicals Co., Ltd., “Sun Extract (registered trademark) P201”, water-soluble)

The viscosity average molecular weight of the organic compound is as follows. Each material is dissolved in a soluble solvent to prepare a polymer diluted solution, and the intrinsic viscosity ([η]) of the polymer diluted solution is measured with a capillary viscometer. The viscosity average molecular weight was determined from the formula. In the formula, M represents a viscosity average molecular weight, and K and a represent constants.
[Η] = KM ^a

About the obtained coal molding, the intensity | strength after an initial strength and a weather resistance test was measured with the following method, and the result was shown in Table 2.
<Initial strength>
The initial strength was determined by a split tensile test. Specifically, as shown in FIG. 1, the coal molded body 1 is tilted and sandwiched between two compression plates 2, and is 1 mm using a universal material testing machine (Instron, “4505 type”). Compressed in the direction of the arrow at a speed of / min, the load at which initial fracture occurred was defined as the maximum load. From the maximum load and the size of the coal molding, the tensile strength (initial strength) was calculated according to Equation 1.

[Σt: Tensile strength (N / mm ² ), P: Maximum load (N), d: Diameter of the coal molding (mm), l: Length of the coal molding (mm)]

<Strength after weather resistance test>
The coal molded body was allowed to stand for 24 hours in a 30 ° C. 100% RH environment to absorb moisture, and then the tensile strength was measured in the same manner as the above initial strength measurement.

From the initial strength and the strength after the weather resistance test, the strength retention was determined from the following formula. The initial strength is 0.78 N / mm ² (8 kgf / cm ² ) or more, and the strength retention after the weather resistance test is 80% or more, “」 ”, the initial strength is 0.78 N / mm ² (8 kgf / cm ² ) or more and strength retention of 60% or more and less than 80% “◯”, initial strength of less than 0.78 N / mm ² (8 kgf / cm ² ), or strength retention of less than 60% Were marked "△".
Strength retention (%) = 100 × strength after weather resistance test / initial strength

Production Examples 1 to 7 are cases where a water-insoluble organic compound having a viscosity average molecular weight of 10,000 or more was added as a binder, and it was found that all of them were excellent in initial strength and strength retention. Among these, when Production Examples 1 to 3 or Production Examples 4 and 5 are compared, it can be seen that the greater the amount added, the better the initial strength.
Production Example 8 is a case where no binder was used, but it was found that although the initial strength was excellent, the strength retention was very poor. Production Examples 9 to 11 are cases where the molecular weight of the binder is less than 10,000, but all have poor initial strength. Production Example 12 is a case where the binder is water-soluble, but although the initial strength is excellent, the strength retention is very poor.

Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.
This application is based on a Japanese patent application filed on Apr. 6, 2011 (Japanese Patent Application No. 2011-084630), the contents of which are incorporated herein by reference.

The coal molding of the present invention is a coal molding using low-grade coal, and the initial strength immediately after molding is sufficiently high, and the strength decreases even if it receives a history of heating, moisture absorption, etc. during subsequent transportation and storage. There are few.

1: Coal molded body, 2: Compression plate

Claims

Containing dehydrated low-grade coal and a water-insoluble organic compound having a viscosity average molecular weight of 10,000 or more for binding the same,
A coal molded body characterized in that the content of the water-insoluble organic compound is 0.1 mass% to 10 mass%.
The coal molded product according to claim 1, wherein the low-grade coal is dehydrated in oil.
The coal molding according to claim 1 or 2, wherein a particle diameter of the low-grade coal is 3 mm or less.
The coal molding according to any one of claims 1 to 3, wherein the low-grade coal is at least one selected from the group consisting of dry coal, bituminous coal, and subbituminous coal.