JPS58103592A - Method for deashing coal - Google Patents

Abstract

PURPOSE:To increase the recovery rate of coal, by mixing an emulsion oil with a coal/water slurry and repeating an ultrasonic irradiation stage, a gas-introducing stage and a separation stage in the deashing of coal by an oil addition/ granulation method. CONSTITUTION:Coal is coarsely crushed 1, and finely divided 2. A coal/water slurry is prepd. in a slurry preparation tank 3 and fed to a mixing tank 10. An emulsion oil 8 is prepd. from water 5, oil 6 and a surfactant 7, and introduced into a pipe line before the mixing tank 10, into a pipe line before an ultrasonic irradiation tank 11, into a pipe line before an ultrasonic irradiation tank 11', and into an agitation type granulator 4. Fine powder and oil in a mixture obtd. in the mixing tank 10 are condensed in the ultrasonic irradiation tank 11 and fed to an ash-separating tank 13. A water slurry rich in the decomposed suspended ash is fed to the ultrasonic irradiation tank 11' and introduced together with gas into an ash-separating tank 13', where the slurry is divided into a slurry rich in condensates and a water slurry rich in ash. The latter is fed from the ultrasonic irradiation tank 11' to an ash-separating tank 13''. Then condensates separated in the separating tanks 13, 13', 13'' are granulated in the agitating granulator 4 and dehydrated by a dehydrator 9 to obtain the deashed coal.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for deashing coal by hot oil granulation.

Coal contains ash, which is a major problem in the use of coal because it causes constant trouble. Therefore, various methods for removing the ash content from coal have been studied and proposed, and among these, a deashing process using hot oil granulation has been established as a promising means of deashing pulverized coal.

The present inventors have proposed various improvements to the deashing process using hot oil granulation, and as one of them, we have previously proposed two types of hot oil granulation that incorporate an agglomeration method using ultrasonic waves. .

One of the above proposed methods will be explained below with reference to FIG.

Coal is coarsely crushed by a coarse crusher 1 such as a dry or wet show crusher, and then further finely crushed by a fine crusher 2 such as a dry or wet ball mill. The finely pulverized coal is prepared into a coal-water slurry of an appropriate concentration in a slurry preparation tank 3, and then sent to a mixing tank 10.

On the other hand, water, oil, and surfactant are fed into the emulsion preparation tank 8 from the water tank 5, oil tank 6, and surfactant tank 7 to prepare emulsion oil, and the core emulsion is transferred to the emulsion in front of the mixing tank 1o.ノ・□Injected into Eveline.

In the mixing tank 10, the coal slurry fed from the slurry preparation tank 3 and the emulsion oil fed from the emulsion preparation tank 8 are uniformly mixed. A static mixer in a pipeline or the like may be used as the mixing tank 1o.

This +21- mixture is sent to an ultrasonic aggregation tank 11, and an ultrasonic vibrator installed in the tank 11 irradiates ultrasonic waves to agglomerate the pulverized coal and oil. This point is a feature of the above proposed method.

When irradiated with ultrasonic waves, the particles in the water differ slightly depending on the wetting characteristics of their surfaces, but due to the resonance of the particles and water, the ratio (amplitude ratio) of the amplitude Xp of the particles and the amplitude χg of the medium (water) is expressed by the following formula. When is between 0.2 and 0.8, the particles aggregate, and when outside the incarnation, they are dispersed and do not aggregate.

Here, ρ: Specific gravity of particles μ: Viscosity of medium Dp = Diameter of particles N: Frequency of ultrasonic waves Here, considering the behavior of coal particles and ash content in coal when irradiated with ultrasonic waves, It is thought that coal and oil selectively form aggregates due to differences in particle specific gravity and wettability to water and oil, and the aggregates and ash are dispersed in water.

At this time, if the coal slurry concentration increases, the ultrasonic waves will be attenuated and the efficiency will decrease, so the slurry concentration is preferably 30% or less.

The pulverized coal aggregated at 11 in the figure is fed into the stirring granulation tank 4, where it is stirred and granulated together with the emulsion oil fed from the emulsion preparation tank 8.

In the stirring granulation tank 4, the coal and oil were combined and granulated, and the ash was dispersed in the water! It exists until

Note that the granulated pellets are dehydrated in a dehydrator 9.

The above is one of the methods proposed earlier, but in this proposed method, since there is a large amount of ash suspended in water, a large amount of ash is mixed into the pellet from the suspension during granulation. The drawback was that it was difficult to increase the demineralization rate.

Therefore, the inventors of the present invention reduced the amount of ash mixed into pellets during granulation by reducing the amount of ash suspended in water, thereby increasing the deashing rate.

In other words, the second method is an oil hot granulation method in which coal and ash are separated by utilizing the difference in wettability of coal and coal-containing ash to water and oil. Along with adding a small amount of emulsion oil to the water slurry,
After irradiating ultrasonic waves to form aggregates of coal and oil, gas bubbles are injected to make the aggregates float by adsorbing the air bubbles, and the aggregates and the settled ash suspension are...・・・
-~ -, -J, Toyuki Wakiru Fusibility 4 Reporting Granules 17, The gist of this is a method for deashing coal, which is characterized by removing coal ash.

The second proposed method will be explained below with reference to FIG. Components in FIG. 2 with the same reference numerals as in FIG. 1 have the same functions and effects, so their explanation will be omitted.

Before entering the ash separation tank 13, the slurry in which oil-coal aggregates and ash are dispersed is formed in the ultrasonic agglomeration tank 11.
Gas such as air or nitrogen gas is blown into the line 12. When gas is blown, air bubbles selectively adsorb to the oil-coal aggregates and become suspended. Utilizing this phenomenon, the ash separation tank 13 separates into a portion rich in oil-coal aggregates and a water slurry rich in suspended ash, and the latter is taken out of the system through line 14, and the former is transferred to line 15 as necessary. The slurry is sent to stirring granulation @ 4 together with the slurry preparation water supplied from the emulsion preparation tank 8 , subjected to oil-temperature granulation with an additional amount of oil emulsion sent from the emulsion preparation tank 8 , and dehydrated in the dehydrator 9 .

In addition, when gas is blown into the surface, the adsorption of air bubbles increases by -F and the separation efficiency improves. As this surfactant, a foaming agent such as an alkylbenzene sulfonate is used, and the effective amount thereof added is in the range of several tens of ppm to several tens of ppm to coal.

According to the method described above, the slurry rich in oil-coal aggregates is separated into a concentrated slurry of ash suspension and then granulated with stirring. Although it is possible to reduce entrainment and thus considerably improve the deashing rate, there is still a large amount of fine powder suspended in the water without flocculating, and it is difficult to carry it to the drainage side during separation. Because of this, the recovery rate of coal was not yet sufficient.

The purpose of the present invention is to further increase the recovery rate of coal in the second method described above. Since the coal still contains fine powder, emulsion oil is mixed into the suspension again, and ultrasonic irradiation, gas injection, and separation are repeated to increase the yield of coal.

That is, the present invention is an oil hot granulation method that separates coal and ash by utilizing the difference in wettability of coal and coal-containing ash to water and oil. Add a small amount of emulsion oil to the slurry and irradiate it with ultrasonic waves to form coaleous and oil aggregates.
After injecting gas into bubbles to adsorb the air bubbles and float the aggregates to separate the aggregates, emulsion oil is added to the non-agglomerate slurry again, and ultrasonic waves are irradiated to produce aggregates,
The present invention relates to a method for deashing coal, which comprises repeating the steps of injecting gas and separating the aggregates, and then stirring and granulating the aggregates to remove ash from the coal.

The present invention will be explained below with reference to FIG. In FIG. 3, components with the same reference numerals as those in FIGS. 1 and 2 have the same functions and effects, so a description thereof will be omitted.

The suspended ash-enriched water slurry from the ash separation tank 16 is led to the ultrasound irradiation tank 11' and then enters the ash separation tank 13' along with the gas from line 12 where it is separated from the flocculate-rich slurry and into the ash. The process of separating the water into a rich water slurry and transferring the latter from the ultrasonic irradiation tank 11'' to the ash separation tank 13'' is repeated in sequence.

In the ultrasonic irradiation tanks 11' and 11'', since the slurry concentration is reduced by the previous separation operation, the attenuation of the ultrasonic waves is small and the efficiency is increased.
The particle size of the coal treated in the ultrasonic irradiation tank 11.11 is smaller than that in the previous ultrasonic irradiation tank.
As the frequency progresses to '1.11//, the effect is greater as the frequency is raised.

Thereafter, the aggregates separated in the separation tank are granulated in the stirring granulation tank 4 and dehydrated in the dehydrator 9. According to the present invention described above, the operation of ultrasonic aggregation → separation is repeated. According to
The recovery rate of coal can be greatly increased.

Hereinafter, the present invention will be explained in more detail by giving specific examples.

After coarsely crushing lump coal of 50 to 60 mm using a hammer crusher to less than 0.5 mm, it was further finely crushed using a dry ball mill and a sieve of 74 micron openings to about 70% below the sieve. 500 as 5ch water slurry
Approximately 300 ffll was added to the beer force of fnl, and C heavy oil (water: oil: surfactant = 50:50) was emulsified into this.
:05, 5% surfactant (lauric acid monoester, etc.) was added to the coal, stirred for 1 to 2 minutes, and then irradiated with ultrasonic waves at a frequency of 400Kc for several seconds using an ultrasonic generator.
Next, air was blown in from the gas inlet using an evaporator for about 3 minutes, and the floating oil-coal aggregates were scooped up with a wire mesh with an opening of about 0.5 t+m, and then the drained liquid was irradiated with ultrasonic waves for several seconds again. , the frequency was 600Kc, and the same operations as above were performed.

Further, these aggregates were subjected to agitation granulation using a batch type agitation granulator as shown in FIG. In Figure 4, 40
is a batch type stirring granulator, 41 is an 850x made of acrylic resin
300+nm granulation tank, 42 is an impeller installed in the same granulation tank 41, 43 is an agitator for the same impeller 42, 4
Reference numeral 4 denotes a constant temperature bath arranged to surround the granulation tank 41.

Agitation granulation involves emulsified heavy oil C and surfactant 3.
After adding 0.00 pprn (based on coal), the mixture was stirred for 2 hours, then classified using a sieve with an opening of 0.5 mm, and the amount of coal recovered was calculated from the amount of coal remaining on the sieve. , we investigated the effectiveness of a method of repeated separation.

The analysis results of the coal and C heavy oil used are shown in Tables 1 and 2.

Table 5 shows the case of one stage of ultrasonic irradiation 400Kc (al and
When ultrasonic waves were irradiated at 600 Kc again after 400 Kc (bl), the lime recovery rate was compared.
It is possible to increase it from wt% to 92wt%.

Table 3 The total amount of oil added was 24wt relative to the coal.

Added to Taheret (granulated coal) The oil amount is corrected and displayed at the coal pace.

Zhang Biang

[Brief explanation of the drawing]

1 and 2 show a flow incorporating the ultrasonic irradiation method which is the basis of the present invention, and FIG. 3 shows a flow of the present invention. FIG. 4 is a schematic diagram of an oil temperature stirring granulation device used in a specific method of the present invention. Sub-agents 1) Meifuku agent Hagiwara Hagi -

Claims (1)

[Claims] In the oil-hot granulation method, which uses the difference in wettability of coal and coal-containing ash to water and oil to separate the coal and ash, a small amount of emulsion is added to the water slurry of pulverized coal before oil-hot granulation. Add oil and irradiate ultrasonic waves to form aggregates of coal and oil, then inject gas into bubbles to make the aggregates float by adsorbing air bubbles to separate the aggregates, and then form non-aggregates. Add emulsion oil to the slurry again,
Coal desorption is characterized by repeating the process of irradiating ultrasonic waves to produce aggregates, injecting gas to separate the aggregates, and then stirring and granulating the aggregates to remove ash from the coal. ash method