JPS6345759B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to granules used as granulation nuclei in the production of deashed coal by underwater granulation.

Conventional technology Naturally produced coal contains a relatively large amount of ash, but this ash contains silica (SiO ₂ ),
It is mainly composed of iron sulfide (FeS) and alumina (Al ₂ O ₃ ), and is usually contained in coal at a ratio of about 7 to 25%. As a method for producing deashed coal by removing such ash from coal, the present applicant previously proposed a method using lipophilic synthetic resin granules as granulation nuclei (Japanese Patent Application No. 141504/1986). No. 62-199).

Problems to be Solved by the Invention The method proposed hereafter involves pulverizing coal containing ash to create pulverized coal, mixing this pulverized coal with water to create a pulverized coal slurry, and turning the pulverized coal slurry containing ash into pulverized coal slurry. , oil and granules made of lipophilic synthetic resin that serve as granulation nuclei are mixed and granulated, the granules are separated from the slurry and washed with water to remove ash, and the washed granules are produced. is dried, and the dried granules are decomposed and separated into pellet-like oil-impregnated deashed coal and lipophilic granules to obtain oil-impregnated deashed coal, and the lipophilic granules are recovered to produce the above-mentioned granules. It has been desired to develop lipophilic granules that can be returned to the granulation process and used as granulation nuclei that can further granulate pulverized coal in a very short time.

The object of the present invention is to provide a granular material used as granulation nuclei in the production of deashed coal by underwater granulation as described above, which has extremely good adhesion to pulverized coal.
Pulverized coal can be granulated in a very short time,
The object of the present invention is to provide a structure of granules used as granulation nuclei that can efficiently produce deashed coal with a low ash content.

Means for Solving the Problems The granules used as granulation nuclei in the production of deashed coal by underwater granulation of the present invention are made of a lipophilic synthetic resin, and have a large number of concave or convex portions on the surface. It is characterized by the presence of

Here, as the material for the granules used as granulation nuclei, a lipophilic synthetic resin is used, preferably one having a specific gravity close to that of coal. Specifically, for example, hard polyvinyl chloride (specific gravity 1.4), polyethylene and polypropylene (specific gravity 1.0), polycarbonate (specific gravity 1.2), and nylon (specific gravity 1.09 to 1.14) are used. The seed particles have a diameter of about 1 mm to several mm, and have a shape such as a short columnar shape or a spherical shape. The large number of concave portions and convex portions provided on the surface of the granular material used as granulation nuclei may have various shapes.

Example Next, embodiments of the invention will be described.

1 to 5 show specific examples of granules used as granulation nuclei in the production of deashed coal by underwater granulation according to the present invention.

In Figure 1, the granules used as granulation nuclei consist of short cylindrical granules 1 with a diameter of 3 mm and a height of 1.5 mm, with a height difference of approximately 0.5 mm on both upper and lower surfaces.
It has a large number of convex portions 2. The granules are made from extruded hard polyvinyl chloride resin, have a specific gravity of 1.4, and are lipophilic. Note that the side surfaces of the short cylindrical granules 1 are smooth.

The lipophilic granules shown in FIG. 2 are also made up of short cylindrical granules 3, on the sides of which are provided with a large number of groove-shaped recesses 4 having a square cross section.

The lipophilic granules in FIG. 3 are short cylindrical granules 5 with numerous groove-shaped recesses 6 each having a V-shaped cross section on the side surface.

In addition, the lipophilic particles in Fig. 4 have a diameter of 3 mm.
It is made up of spherical granules 7, and a large number of conical convex portions 8 are provided on the surface thereof.

The lipophilic granules shown in FIG. 5 are also made of spherical granules 9, and the surface thereof is provided with a large number of bowl-shaped recesses 10 having rounded bottom surfaces.

Note that the recesses or projections provided on the lipophilic granules may of course have shapes other than those described above.

Next, a method for producing oil-impregnated demineralized coal using the lipophilic granules according to the present invention as granulation nuclei,
This will be explained with reference to FIG.

This method consists of the following five steps.

First step: Natural coal containing ash is pulverized using, for example, a wet ball mill to produce pulverized coal with a particle size of several hundred μm to several tens of μm. Raw coal usually contains 7 to 25% by weight of ash, but the ash is also finely ground by pulverization. Next, this pulverized coal containing ash is mixed with water to create a pulverized coal slurry. In some cases, coal may be pulverized into so-called ultrafine powder with a particle size of several μm. The coal is preferably pulverized in water, and after pulverization, a required amount of water is added to adjust the concentration of the slurry.

Second step: Next, this pulverized coal slurry is mixed with oil and granules made of lipophilic synthetic resin that will serve as granulation nuclei, and granulated. Here, as the oil, kerosene, light oil, heavy oil, distillation residue oil, vegetable oil, etc. are used. For example, the amount of oil used is approximately 10% for pulverized coal.
~30% by weight. A small amount of surfactant may also be added to facilitate oil dispersion. The lipophilic granules that serve as granulation nuclei are preferably mixed with pulverized coal at a ratio of 1:1 (weight ratio), but the total amount of lipophilic granules and pulverized coal is 30% by weight in the slurry. It is of course possible to increase or decrease the ratio of the lipophilic granules to the pulverized coal within a range that does not exceed this value.

There are the following three methods for mixing pulverized coal slurry, oil, and lipophilic granules that serve as granulation nuclei.

(i) Mixing lipophilic granules with pulverized coal slurry,
Oil is then mixed into this slurry.

(ii) Oil is added to the lipophilic granules in advance so that the oil adheres to the surface of the granules, and then the oil-adhered lipophilic granules are mixed into the pulverized coal slurry.

(iii) Mixing oil into a pulverized coal slurry and then mixing lipophilic granules into this slurry.

In order to stir and granulate the above mixture, a granulating device equipped with a wire mesh stirring blade or other known granulating device is used. In this granulation process, oil is attached to the surface of lipophilic granules that have concave or convex portions on the surface, and pulverized coal is sequentially attached to the oil on the surface of this oil-adhered lipophilic granule as a core. However, since the surface of the lipophilic granules has concave or convex portions,
As the surface area increases, the pulverized coal easily enters the recesses or hits the convex parts at the initial stage of granulation, which improves the adhesion of the pulverized coal. Therefore, the granulation time is very short. Furthermore, since such lipophilic granules are used as granulation nuclei, the amount of oil used can be extremely small. On the other hand, ash that has been crushed to the same size as pulverized coal remains in the water.

Note that if the ash content in the raw coal is very high, for example, about 20% by weight, a primary deashing treatment may be performed before granulation. That is, when pulverized coal slurry is mixed with lipophilic granules and oil, it separates into a liquid phase containing pulverized coal, oleophilic granules, and oil, and a slurry consisting of water containing ash. This slurry containing ash is separated from the liquid phase containing pulverized coal, and then the liquid phase containing pulverized coal is washed with fresh water. This removes a significant amount of ash.

Third step: Next, the granulated material consisting of pulverized coal, oil, and lipophilic granules is separated from the slurry and washed to remove ash. This operation is carried out by, for example, pouring the slurry containing the granules onto a filter and spraying washing water onto the filter. In some cases, the separated granules may be centrifuged to further remove moisture. The slurry containing ash is then introduced into a water treatment device equipped with a thickener, a filter, etc., and treated, thereby separating it into ash and water.

Fourth step: Next, the washed granules made of pulverized coal, oil, and lipophilic granules are dried to completely remove moisture.

Fifth step: By decomposing the dried granules, for example by applying vibration, and separating them into pellet-like oil-impregnated demineralized coal and lipophilic granules, oil-impregnated deashed coal is obtained, and lipophilic granules are obtained. The materials are collected and returned to the second granulation step, where they are reused as granulation nuclei.

In this case, a small amount of oil is attached to the lipophilic granules, but it is also possible to add oil to the lipophilic granules and then return them to the granulation process, or without adding oil. You may send it back as is.

The oil-impregnated deashed coal produced in this manner has the ash content sufficiently removed and can be effectively used as is as a fuel.

Note that in the case of producing deashed coal that does not contain oil, this oil-containing deashed coal may be further subjected to an oil removal treatment. This treatment is carried out, for example, by heating to volatilize the oil when a volatile oil such as kerosene or gasoline is used as the oil for granulation, and when heavy oil or the like is used as the oil. This is done by extracting the oil with a solvent.

Next, an experimental example of producing deashed coal using the lipophilic granules according to the present invention as a granulation nucleus will be explained together with a comparative experimental example.

Experimental example Breasol coal (produced in Australia) with an ash content of 7.02% by weight is crushed to produce less than 200 mesh.
That is, pulverized coal with a particle size of 74 μm or less is produced, and water is mixed with this to create pulverized coal slurry. Next, the lipophilic granules shown in FIG. 1 were mixed into this pulverized coal slurry. That is, the lipophilic granules are made of hard polyvinyl chloride and have a diameter of approximately 3 mm and a height of approximately 1.5 mm.
It is made up of short cylindrical granules 1 having many protrusions 2 with a height of about 0.5 mm on both the upper and lower sides, and its specific gravity is 1.4, which is similar to that of coal. The blending amounts in the slurry were 5% by weight of pulverized coal and 5% by weight of lipophilic granules. Next, kerosene was mixed in this slurry in an amount of 20% by weight relative to pulverized coal, and 1600 g of this kerosene mixed slurry was poured into a tube with an inner diameter of 115 mm and a height of
A container of 180 mm and a diameter of
The mixture was introduced into a granulator equipped with a circular wire mesh stirring blade with an opening of 5 mm made by knitting 0.5 mm stainless steel wire and a diameter of 75 mm.
It was rotated and stirred at a speed of 2000 rpm.

As a result, 20.7% by weight of the pulverized coal in the slurry adhered to the surface of the lipophilic granules in 8 minutes, resulting in granulation. At this time, it was observed that pulverized coal adhered to both upper and lower surfaces having the convex portions 2 of the lipophilic granules, and granulation proceeded.

After granulation, the granules are separated from the slurry and washed with water to remove ash, the washed granules are dried, the dried granules are decomposed by vibration, and pellets are formed. Oil-impregnated demineralized coal was obtained. On the other hand, the separated lipophilic granules were collected, returned to the granulation process, and reused as granulation cores. In order to measure the ash content in the oil-impregnated deashed coal produced in this way, the oil was extracted with a solvent, and the ash content of the obtained deashed pulverized coal was measured. It contained only 1.74% by weight of ash.

Next, pulverized coal slurry was granulated in the same manner as in the experimental example above using the four types of lipophilic granules shown in Figures 2 to 5 above as granulation nuclei to produce oil-impregnated deashed coal. However, almost the same results as in the above experimental example were obtained.

Next, for comparison, a cylindrical lipophilic granule with a diameter of 3 mm and a height of 1.5 mm that has no convex portions and a smooth surface, and a spherical lipophilic granule with a diameter of 3 mm that also has a smooth surface. A pulverized coal slurry was granulated in the same manner as in the above example, using each of the above as granulation nuclei.

The material for these lipophilic granules was also hard polyvinyl chloride (specific gravity 1.4).

As a result, when the former cylindrical lipophilic granules with smooth surfaces were used, granulation did not occur even after 30 minutes had passed after the start of stirring, but granulation started after 40 minutes. . Furthermore, when the latter spherical lipophilic granules with smooth surfaces were used, it was confirmed that granulation started 25 minutes after the start. Incidentally, the ash content of the pulverized coal granulated in these comparative experimental examples was almost the same as in the above experimental examples.

Furthermore, for comparison, decalcified coal was produced by repeating the above experimental example using coarse charcoal having an average particle diameter of 3 to 4 mm as a granulation core as a lipophilic granule. The ash content of the obtained deashed coal was measured three times, and the first measurement was 2.1% by weight, the second
The second time was 2.2% by weight and the third time was 3.4% by weight.

If coarse charcoal is used as the lipophilic granules serving as granulation nuclei in this way, it is not preferable because not only the ash content of the deashed charcoal is high but also the quality varies. This is because if coarse coal is used as the lipophilic granule, the coarse coal will break during granulation or when the granules are crushed after granulation, and the ash in the coarse coal will mix into the deashed coal. This is to do so.

Effects of the Invention As mentioned above, the granules used as granulation nuclei in the production of deashed coal by underwater granulation of this invention are
It is made of a synthetic resin with lipophilic properties and has many concave or convex parts on its surface, so it is necessary to mix oil and lipophilic granules, which will become granulation nuclei, with pulverized coal slurry containing ash. When performing granulation, the adhesion of pulverized coal to lipophilic granules is extremely good, and pulverized coal can be granulated in a very short time, producing high-quality demineralized coal with a low ash content. It can be manufactured efficiently. Moreover, since the lipophilic granules are made of synthetic resin, they are extremely strong and do not break during granulation or when the granules are crushed after granulation, and therefore require almost no replenishment. It can be used repeatedly and has excellent durability. Therefore, the amount of materials used in the production of deashed coal can be reduced overall, resulting in the effect that the production cost of deashed coal can be significantly reduced.

[Brief explanation of the drawing]

Figures 1 to 5 are enlarged perspective views of various lipophilic granules used as granulation nuclei of the present invention, and Figure 6 is production of oil-impregnated demineralized coal using the lipophilic granules of this invention as granulation nuclei. FIG. 3 is a block diagram showing the process. 1, 3, 5, 7, 9... Lipophilic synthetic resin granules used as granulation nuclei, 2, 8... Convex portions, 4, 5, 1
0...Concavity.

Claims (1)

[Claims] 1. A granular material used as a granulation core in the production of deashed coal by underwater granulation, which is made of a lipophilic synthetic resin and has a large number of concave or convex portions on its surface.