JPH0657830B2 - Deashing granulation method for high ash coal - Google Patents

Description

TECHNICAL FIELD The present invention relates to deashing granulation of high ash content coal.

[Conventional technology]

As is well known, for example, as a pretreatment method for coal charged into a coke oven and carbonized to be coke, preheating drying, classification and pulverization, molding and the like can be mentioned.

In recent years, the problem of increased ash content in coal has been highlighted due to an increase in demand and supply of Canadian coal, Australian coal, and the like. In addition, the need for expanding the use of non-caking coal, so-called steam coal, has further increased, and establishment of technology for improving coke quality has become an urgent task.

A large amount of ash in the coal causes various adverse effects such as a decrease in coke yield, a decrease in coke quality such as strength, and an increase in the calorific value in the furnace operation.

As a method of reducing the ash content in coal, generally, a washing method of washing away the adhered ash content, a specific gravity separation method using the difference in specific gravity between ash content and coal, an oil agglomeration method using the difference in affinity between water and oil And so on. As such a technique, for example, as disclosed in Japanese Patent Laid-Open No. 60-35094, there is a method of separating coal and ash in coal in a tower by using a flotation method. Further, as an example of the oil method, as shown in JP-A-56-125491, deashing is carried out by adding, for example, a hydrocarbon oil that is immiscible with water to an aqueous slurry of coal fine powder containing a surfactant to granulate. There is a law.

[Problems to be solved by the invention]

As a conventional deashing method, a deashing granulation method in which an oil such as petroleum is added is used. When the obtained granulated coal is charged into a coke oven, the particle size is at least 2 to 4 mm, so that a large amount of I needed oil. If a large amount of oil is not added, not only the particle size does not grow to a predetermined value, but the deashing efficiency is lowered. Further, even if tar produced as a by-product in a coke oven is used as an alternative to oil, if used in a large amount, it causes a problem in quantitative balance.

The present invention, when deashing granulation using a hydrocarbon oil as a binder, grinds the raw coal under specific conditions to significantly reduce the amount of binder used, improve coke quality, and improve coke oven equipment. It is an object of the present invention to provide a deashing granulation method for economically producing granulated coal having a particle size suitable for coal feeding.

[Means for solving problems]

The gist of the present invention is that when an aqueous slurry prepared by adding an oil component such as tar to pulverized coal is subjected to warm deashing granulation, 5 to 10% by weight of raw coal to be pulverized into the pulverized coal is 0.5 to 1.0 mm.
It is a method for deashing and granulating high ash coal, which is characterized by pulverizing into granulated core particles and finely pulverizing the rest to 0.3 mm or less.

[Action]

Next, the present invention will be described in detail together with its action by taking as an example the deashing treatment of raw coal to be charged into a coke oven.

First, high ash coal is selected in advance from raw coal to be charged into a coke oven and finely ground to 1 mm or less. Since ash is scattered in various forms in coal, it is necessary to pulverize it to 0.3 mm or less to improve the deashing rate. In order to separate the ash from this pulverized coal, it is sufficient to use the affinity of carbon and tar and the affinity of ash and water for producing coal water slurry with pulverized coal and water, adding tar and stirring. When granulated, tar acts as a binder and attracts carbon one after another to form granulated coal having a low ash content. The granulation action is a continuous action in the collision process of particles, and it is important how efficiently the binder and the carbon content are bound to the core of the granulation. For this purpose, it was found through various experiments that adding a small amount of coarse coal, adjusting the coal water slurry concentration, slurry and tar temperature were very effective.

In the present invention, 5 to 10% by weight of raw coal which is pulverized into pulverized coal as described above is blended as granulated core particles with coarse-grained coal pulverized to 0.5 to 1.0 mm. When the particle size of the granulated core particles is less than 0.5 mm, the granulation efficiency decreases. On the other hand, if it exceeds 1.0 mm, cracking occurs due to collision of particles with each other during deashing and granulation, and it becomes easy to be crushed, which is not suitable.

FIG. 2 shows the influence of the blending ratio of the coarse coal on the average grain size and the decarburization rate in the decarburizing granulation of the pulverized coal containing the coarse coal. As can be seen from this figure, when the coarse coal content exceeds 10%, the decarburization rate decreases significantly, and
If it is less than%, the average grain size becomes small.

Although the water slurry concentration of pulverized coal of 0.3 mm or less in which the above coarse grain coal is blended as core particles depends on the particle size distribution of the pulverized coal,
In order to ensure uniform dispersibility, it is known to be in the range of 10-40%. In addition, since the viscosity of oil such as tar added as a binder increases at low temperatures, coal water slurry and tar are heated by using warm waste water, etc.
Keeping the temperature at 0 to 70 ℃ and decalcifying and granulating at warm temperature, tar becomes 1
When it is less than 00 cp, it is finely dispersed, which effectively works to reduce the binder.

FIG. 3 shows the difference in granulation property due to the difference in temperature with the same amount of tar added in the same experiment. When the temperature is 15 ° C., the granulated particle size is small, whereas when heated to 50 ° C., a granulated coal having a large particle size can be obtained even with a low binder amount.

Incidentally, if a surfactant is added to the deashing granulation as needed, uniform dispersion will proceed, which is advantageous for granulation, which is preferable.

In this way, the demineralized granulated raw coal is strongly consolidated by the action of the binder together with the effect of demineralization, so coal with poor caking property is also modified to increase bulk density and improve coke quality. Leads to.

〔Example〕

An example in which the present invention is applied to the pretreatment of coal for producing coke will be described.

FIG. 1 shows a deashing granulation method of the present invention. First, it is classified into a coal yard 1 for deashing with an ash content of 11.5% and a coal yard without deashing for a ash content of 7.3%, which are determined according to the brand. Then, the powder was stored in the blending tank 3 and preliminarily crushed by the coarse crusher 4 into a coal grain size of 3 mm or less, which is the usual size of the coal. The coal to be deashed was crushed to 0.5 to 1.0 mm by the crusher 4a. Part of it was stored in the coarse-grain coal hopper 19, and the rest was finely pulverized by the wet pulverizer 5 to a grain size of 0.1 to 0.3 mm.

Next, the finely pulverized coal was supplied to the slurry tank 7, stirred and kneaded, slurried to have a concentration of 10 to 30%, and supplied to the deashing granulator 8 together with tar. At this time, tar as a binder was supplied while the tar component in the coke gas discharged as a by-product from the coke oven 14 and discharged from the gas rising pipe 13 was separated and collected by the tar decanter in the tar tank 9.

The temperature of the tar and coal water slurry was controlled by a heater 18 using factory steam so as to maintain the temperature at 50 to 70 ° C.

Coarse-grained coal stored in a hopper 19 crushed to 0.5 to 1.0 mm was blended at a ratio of 7% with respect to a pulverized coal slurry, and the mixture was supplied to a deashing granulator 8.

The amount of tar supplied was 150 / T-coa to granulate, and granulated coal having an average particle diameter of 3.0 mm was obtained. At this time, the coal recovery rate was 96% and the deashing rate was 30%.

The deashed and granulated coal is sent to the granulated charcoal hopper 11 after removing surface-attached water containing ash in the dehydrator 10.
The mixture was mixed with another low ash coal, which was sized by another coarse crusher 4 that was not deashed, at a predetermined ratio in the coal blender 12, and then charged into the coke oven 14.

On the other hand, the ash-containing water was removed from the ash by the tail sickener 16 and the filter press 17, and was sent to the slurry tank 7 for recycling.

In this way, 70% coal with ash content of 7.3% that is not deashed and coal with 11.5% ash content are deashed and granulated to 7% ash content.
As a result of 0% blending and dry distillation in a coke oven, the coke cold strength (▲ DI ¹⁵⁰ ₁₅ ▼) was improved by about 3%, and the strength after coke reaction (CSR was improved by about 10%. In addition, the tar used as a binder. Minutes were volatilized again during coke carbonization,
It was reusable with a yield of 5%.

〔The invention's effect〕

As described above, according to the method of the present invention, the amount of the granulating binder necessary for deashing coal can be significantly reduced, and the granulated coal having a particle size suitable for charging the coke oven can be efficiently decalcified and granulated. It is an excellent invention in the pretreatment of coal because it can be done and also helps improve the quality of coke.

[Brief description of drawings]

FIG. 1 is a systematic diagram of demineralization granulation in an example of the present invention, FIGS. 2 and 3 are diagrams showing experimental results, and FIG. 2 is a blending ratio of coarse-grained coal and granulation / decalcification properties. FIG. 3 is a diagram showing the relationship between the coal water slurry / tar temperature and the granulation property. 1 ... coal yard that requires demineralization, 2 ... coal yard that does not require demineralization,
3 ... Blending tank, 4, 4a ... Coarse crusher, 5 ... Wet crusher, 6 ... Stirrer, 7 ... Slurry tank, 8 ... Deashing granulator, 9 ... Tar tank, 10 ... … Dehydrator, 11
...... Granulated coal hopper, 12 …… Combination machine, 13 …… Gas riser, 14 …… Coke oven, 15 …… Tar decanter, 16 …… Tail schener, 17 …… Filter press, 18 …… Heater, 19 ... Coarse-grain charcoal hopper.

Claims (1)

[Claims] 1. When dewatering and granulating an aqueous slurry obtained by adding an oil component such as tar to pulverized coal at a warm temperature, 5 to 10% by weight of raw coal to be pulverized to pulverized coal is adjusted to 0.5 to 1.0 mm. A deashing granulation method for high ash coal, which comprises pulverizing to form granulated core particles and finely pulverizing the rest to 0.3 mm or less.