JPS6148985B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for wet pulverizing coal. More specifically, the present invention relates to an auxiliary agent that improves pulverization properties and significantly reduces pulverization power in the process of pulverizing coal in water. In recent years, petroleum has been the most commonly used energy source, but due to its limited reserves and the accompanying price hikes, it has become important to diversify energy sources and ensure a stable supply. It is becoming. For this reason, there are large reserves and
The effective use of coal, which exists all over the world and is not unevenly distributed, is
It is being reviewed. However, unlike petroleum, coal is a solid, so it cannot be transported by pipeline, which is extremely disadvantageous in terms of handling. Furthermore, coal generally contains a larger amount of ash than petroleum, which causes problems such as lower calorific value and fly ash disposal. For this reason, in order to improve the handling disadvantages, various methods have been studied in which coal is pulverized and dispersed in water to form a slurry. Therefore, a technology for efficiently turning coal into fine powder is required. In general, when coal is pulverized using a pulverizer, it is possible to use either a dry method or a wet method, but in the case of the dry method, the more pulverized the coal, the more the danger of explosion due to coal dust and the problem of environmental pollution. This will cause a decrease in work efficiency. On the other hand, in the case of a wet method, not only does this problem not occur, but the step of dispersing pulverized coal in water, which is necessary when turning coal into a water slurry, can be omitted by wet-pulverizing it in water. For the above reasons, it is advantageous to wet-pulverize coal to produce a coal-water slurry. In the wet grinding process, it is desired that particles can be ground to a fine particle size with as little power consumption as possible. However, as a solid is pulverized, new cross-sections with high surface energy always appear, causing agglomeration and aggregation due to interparticle cohesive force, which rapidly reduces fluidity in the pulverizer. It gets worse. The finer the particle size, the more remarkable this tendency becomes, leading to a significant decrease in pulverization efficiency and an increase in pulverization power. In such cases, agents are needed to increase the grinding efficiency without adversely affecting the properties of the grinding product, ie what should be called grinding aids. Although the field is different from the technical field of the present invention, it is known to add an aliphatic alcohol such as ethylene glycol or an amino compound such as triethanolamine as a grinding aid to dry grinding of cement. However, the above-mentioned grinding aid has no effect even when used in the wet grinding of coal, which is the object of the present invention. Therefore, the present inventors conducted intensive research to find a compound that has excellent performance as a wet-grinding aid for coal, and as a result, they discovered a compound that dramatically increases the pulverization efficiency and completed the present invention. That is, in the present invention, a sulfonated polycyclic aromatic compound or a salt thereof, which may have a hydrocarbon group as a substituent, or a formalin condensate thereof is added as a grinding aid, and coal is ground in water. The present invention provides a method for wet pulverizing coal, which is characterized by the following. Sulfonated polycyclic aromatic compounds, salts thereof, or formalin condensates thereof used in the present invention include petroleum sulfonic acid derivatives, ligninsulfonic acid derivatives, naphthalenesulfonic acid derivatives, and formalin condensates thereof. It will be done. The above-mentioned compounds according to the present invention can be obtained by sulfonating, for example, naphthalene, alkyl-substituted naphthalene, anthracene, alkyl-substituted anthracene, lignin, aromatic ring-containing compounds in petroleum residue, etc., by a general method, and if necessary, subsequently It can be obtained by salt formation reaction and further formalin condensation. Furthermore, when the amount of grinding aid added is 0.1% by weight or less (based on the weight of coal), formalin condensation is particularly effective. In this case, the degree of condensation is
Preferably 1.2-30, more preferably 1.2-10
It is. Here, when the condensation time is 1.2 or less, the effect of condensation is small, and when it exceeds 30, it becomes polymerized, which causes practical problems in terms of solubility and the like. Various types of polycyclic aromatic compounds can be used, but preferably lignin, aromatic naphthalene from petroleum residue, or polycyclic aromatic compound having 1 carbon number.
An alkylnaphthalene having 6 to 6 alkyl groups may be used, and of course, a mixture of these alkyl substituents may be used. Examples of salts that can be used include alkali metals such as sodium and potassium, alkaline earth metals such as calcium, and amine and ammonium salts. Furthermore, in addition to these anionic surfactants, nonionic surfactants can be added and used in combination within a range that does not impair the effects of the present invention. The wet pulverization aid of the present invention is added in an amount of 0.001 to 5.0% by weight, preferably 0.005 to 1.0% by weight, based on the coal to be pulverized, thereby increasing the pulverization efficiency and making it possible to sufficiently produce pulverized coal with less power. Coal, auxiliary agent, and water may be mixed in any order; the auxiliary agent may be dissolved or dispersed in water and the coal may be added thereto, or it may be added to the grinding mill together with the coal during crushing. You can also do that. In general, the charging ratio for wet pulverization varies depending on the type of coal and particle size, but coal is about 30% of the total charging amount.
Preferably, it is carried out at ~80% by weight. If the amount of coal is too small, the efficiency of the device will be poor, and if it is too large, the pulverization efficiency will be reduced due to adhesion to the wall surface, etc. Coal referred to in the present invention includes anthracite coal, bituminous coal,
Contains subbituminous coal and lignite. By adding the grinding aid of the present invention, it goes without saying that the grindability is improved, but the fluidity of the coal-water slurry is improved, and the coal concentration can be increased accordingly, resulting in a dramatic increase in transportation efficiency. There is also the benefit of improving your health. Recently, coal particles have been granulated by adding and mixing a small amount of hydrocarbon oil (crude oil, heavy oil, light oil, etc.) to a coal-water slurry system as a method for removing ash from coal and dehydrating coal-water slurry.・The pelletizing method (Japanese Patent Application Laid-open No. 52-37901) is attracting attention, and it is becoming possible to transport coal in a granulated form, unlike the conventional form of coal-water slurry. However, the grinding aid of the present invention shows excellent improvement in grindability without losing the grinding effect even in systems where such hydrocarbon oil coexists. EXAMPLES The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to these Examples. Example (1) Test method 200 magnetic balls with a diameter of 30 mm and 100 balls with a diameter of 20 mm were charged into a pot-shaped ball mill with a diameter of 30 cm, and Belmont charcoal was made to have a particle size of 5 to 6 mm in diameter.*5
Add Kg and 10Kg of water. Then, add the auxiliary agents shown in Table 1 in the amounts shown in Table 1, and turn the pot at a rotation speed of 200 rpm.
Grinding was carried out by rotating for hours. (2) Evaluation of crushability Evaluation of crushability was performed using coal crushed using the above method.
After the water slurry was dehydrated and dried, it was sieved through a 200-mesh sieve, and the wt% passing through the 200-mesh sieve was determined. A large pass rate (wt%) indicates good crushability. The results are shown in Table 1. *Belmont coal (Australian coal): Higher calorific value 6550Kcal/Kg (JIS M8814), ash content 15.95 (JIS M8812), moisture 3.25 (JIS
M8811), fixed carbon 49.35% (JIS M8812),
Elemental analysis (JIS M8813), C: 69.20%, H:
4.71%, N: 1.23%, O: 8.44%, S: 0.50
%, Cl: 0.03%, Na: 0.04%

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Claims (1)

[Scope of Claims] 1. A sulfonated polycyclic aromatic compound or a salt thereof, which may have a hydrocarbon group as a substituent;
Alternatively, a method for wet pulverizing coal, which comprises adding these formalin condensates as a pulverizing aid and pulverizing coal in water. 2. Claim 1, wherein the sulfonated product of a polycyclic aromatic compound, a salt thereof, or a formalin condensate thereof is a petroleum sulfonic acid derivative, a ligninsulfonic acid derivative, a naphthalenesulfonic acid derivative, or a formalin condensate thereof. The method of wet milling of coal described. 3. Claim 1 or 2, wherein the formalin condensate of a sulfonated polycyclic aromatic compound or a salt thereof is a formalin condensate of naphthalene sulfonic acid, which may have an alkyl group as a substituent. method for wet grinding of coal. 4. The method for wet pulverizing coal according to claim 1 or 2, wherein the sulfonate is an alkali metal or alkaline earth metal salt.