JPS592527B2 - Bifuntokunisekitanbifunnogiyoushuuhouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to the production of fine powder (fins) in a slurry or powder state.
esX (especially coal fines) to mineral oil products (m 1neralo
This invention relates to a method for agglomeration using an aqueous dispersion (dispersion liquid) of i1product).

Such a cohesive force method can be applied, for example, to an aqueous slurry of coal discharged from a cleaning process or waste water containing coal fines, and in this case, as a result of fines agglomeration, the subsequent dewatering process is extremely difficult. You will be able to do it with practice.

This cohesive force method can also be used with thick slurries or dry dusts.

In each case, this cohesive force method results in an excellent non-dusty granular product.

Therefore, the present invention provides a method for agglomerating fine powder, particularly powdered coal, in a slurry or powder state using bitumen as a binder, in which 5 to 15% by weight (based on the weight of the fine powder in an anhydrous state) of bitumen emulsion is added to the fine powder. , the bitumen has a penetration of less than 5 at 25° C. and a Conradson value of more than 35, and the bitumen emulsion contains an alkaline metal naphthinate.
The present invention relates to a fine powder cohesive force method characterized in that it contains 1 to 10% by weight (based on the amount of bitumen) of Naphthenate).

The preferred fine powder is coal fine powder, but the method can also be applied to other fine powders, such as coke powder, iron powder, sponge iron powder from steel mills, powdered iron (eg, iron ore powder), etc.

If desired, it is also possible to process the agglomerated granular product into briquette-like products.

It is also possible to carry out heat treatment. Mineral fines are generally preferred.

The recovery and utilization of fines, particularly those produced during the mining and processing of coal, has always been an important technical problem in the mining industry.

With the increasing mechanization of the field of factory operations and transport operations, the amount of fine powder produced becomes increasingly large, and the above-mentioned problem becomes increasingly important.

The effluent from the washing process contains a large amount of coal fines and must be purified in settling basins and/or centrifuges.

Although the resulting slurry may still be subjected to some finishing operations, e.g. dewatering to some extent by centrifuges or vacuum filters, what is recovered has limited applications. It is only dusty low grade coal.

This also applies to somewhat dry coal dust obtained in large quantities.

Several methods have already been proposed for removing moisture from coal slurries.

For example, in the convertol process and the new olifloc process, mineral oil fractions, ie light or heavy fuel oils, are mixed into this slurry.

This mineral oil fraction is subjected to mineralization processing (working-up
It acts as a flotation agent for slurry dewatering and as a flocculation agent for slurry dewatering.
nt) and performs both functions at the same time.

However, special equipment is required for mineral oil contamination, and the addition of mineral oil reduces the consistency of coal powder.
does not have any appreciable impact.

This drawback has been overcome by a method developed by the Edge Research Engineering Company (UK Patent No. 1041).
No. 547 and No. 1123597).

This known process is characterized in that a hydrocarbon with a relatively low boiling point is used simply as a flocculant.

In the above-mentioned known methods, the addition of liquid surfactants such as long-chain alcohols is also suggested.

As is clear from GB 1,351,986, in this known process the mineral oil fraction is used initially in the form of a dispersion.

However, this known method is not a coal fines cohesion method, but a treatment power method for sludge obtained during biological sewage purification operations.

The various known methods described above used fluids that were miscible with water and capable of selectively wetting coal particles.

In contrast, the present inventors have now discovered that similar effects can be obtained even when solid bitumen is used.

By mixing about 5 to 15% by weight (based on the weight of the fine powder in an anhydrous state) of bitumen emulsion into waste water or slurry containing fine coal powder, a sufficient flocculation operation can be carried out reliably.
As a result, subsequent dehydration operations (for example, dehydration operations using a screen-type centrifugal separator) can be carried out very quickly and easily.

Suitable bitumens are those having a ring and ball softening point of at least 100°C.

Although straight-run bitumen can also be used, pyrolysis (th
Preferably, bitumen meeting the above-mentioned specifications is produced by subjecting the residue obtained during the mechanical cracking process to high-vacuum distillation and is used in the cohesive force method of the present invention.

The effects of the present invention will be explained.

According to the invention, the dehydrated fine powder (particularly the coal fine powder) is tightly agglomerated or granulated, so that the product is easier to handle and has a wider range of applications than coal dust obtained according to conventional methods.

Next, an experimental example will be shown.

Flotation concentrate obtained in the hard coal cleaning process
A portion of the cation concentrate was dehydrated using a vacuum filter according to a conventional method (sample A).

Another part of this flotation concentrate was agglomerated by adding 15% by weight (based on the weight of the coal in anhydrous state) of a specific bitumen emulsion before carrying out the dewatering operation (sample B).

This bitumen emulsion contained about 50% by weight of bitumen having a penetration value (at 25 DEG C.) of 1 to 2 and a Conradson value of 40.

Particle size analysis or sieve analysis (5clean
The results of the analysis are shown in the table below.

Furthermore, it has been found that the emulsifier contained in the bituminous emulsion plays a role in this cohesion method due to its chemical nature.

That is, the microscopic structure of the aggregates formed in the aqueous slurry can vary from spongy to coarse particles.

This cohesive force method is highly influenced by emulsifiers.

The formation of agglomerated products with a granular microscopic structure means that the settling of the slurry agglomerates can be carried out well, that is, the dewatering in the centrifuge can be carried out rapidly and completely, in particular: This means that when slurry is dehydrated in a vacuum filter, it can be filtered and dehydrated at a fairly high filtration rate.

In known methods, emulsifiers consisting essentially of alkaline compounds of higher fatty acids are often used as emulsifiers for bitumen emulsions.

However, such emulsifiers are only "slightly suitable" for the process of the present invention.

Very good results were obtained when using certain emulsions prepared with, for example, 3% by weight (based on the weight of bitumen) of alkaline metal naphthinates.

The naphthinate is a salt of a high molecular weight naphthenic acid,
Preferably, the boiling point is approximately the same as that of the lubricating oil fraction.

Generally, during the vacuum distillation of naphthenic mineral oils, the acids mentioned are neutralized in the column with caustic soda or caustic potash and removed as a side fraction.

This crude product, taken off as a side fraction, contains, for example, about 50% non-saponifiable minerals, 25% alkaline naphthinates, 25% water and a surplus of alkali.

It is advantageous to use the naphthinate in its crude form, ie to mix it with a calculated amount of water and a calculated amount of bitumen in a customary manner to form a dispersion.

It is then generally unnecessary to add further additives to the dispersion.

Next, another experimental example will be shown.

Dry matter having the particle size composition described above
A filtration test (Test A) was conducted using a coal slurry (Sample A) containing 20% by weight of

The results of this test are based on the specific bitumen emulsion described above.
The results were compared with the results of an agglomeration test (Test B) conducted using Three (Sample B) having the same composition as Sample A except that it contained 5% by weight (based on the dry matter weight).

The emulsion contained a commercial grade emulsifier consisting essentially of an alkaline compound of higher fatty acids.

Yet another test (Test C) was conducted.

In Test C, an emulsion prepared using about 3% by weight of alkaline naphthinate according to the method previously described was used to carry out a flocculation operation according to the invention.

Trials A and B were control trials.

The results of these tests are shown in the table below. The time values in the table below (
seconds) represents the time required to pass the same amount of P liquid under the same conditions.

The method of the present invention is applicable to coal slurries with various moisture contents.

In each case, it is sufficient to add a predetermined amount of bituminous emulsion to the slurry at room temperature and to briefly stir vigorously.

This stirring is advantageously carried out using a continuous stirrer.

The gravity method is also applicable to dry coal dust.

In this case, the specified bitumen emulsion is added at room temperature; high temperature addition generally yields relatively poor results).
In this case, stirring is only required for a short period of time, and is therefore advantageously carried out using a worm screw kneader designed for continuous operation. In this case, granules are obtained which are completely similar to those produced from the aqueous phase described above.

Even in the case of this dry process, the type and consistency of the bitumen to be emulsified and the chemical properties of the emulsifier have a great influence on the flocculation effect.

Under the same processing conditions, the preferred alkaline naphthinate emulsion described above gives the best results.

That is, it has a relatively uniform particle size distribution, with fine particles (0,2
A very good granulated product is obtained, containing only a small amount of grains (less than 5 mm) and coarse grains (more than 5 mm).

This will be better understood from the following experimental results.

The air-dried coal dust was intimately mixed with a 10% by weight bitumen emulsion using a kneader designed for continuous operation.

This bituminous emulsion contained approximately 50% by weight of bitumen.

The rotational speed of the kneader screw was 105 rpm, so the average residence time of the contents in the trough was 5 minutes.

The bituminous emulsion was sprayed into the mixing zone of the kneader a little after the population (corresponding to 1° of the total length).

The sieve analysis of untreated coal dust (4) is combined with the sieve analysis of dry granules (B) obtained by agglomeration using a bituminous emulsion containing a commercial grade emulsifier, and the sieve analysis of approximately 3 wt. % of alkaline naphthinate was compared with the sieve analysis of the dry granules (C) obtained by carrying out the agglomeration process according to the invention using an emulsion made with alkaline naphthinate.

The results are shown in the table below. As can be seen from the following table, Granule C has a much lower amount of undesired fines and coarse particles than Granule B.

Said particular preferred emulsions containing bitumen with a penetration degree at 25°C of less than 5, a Conradson value of less than 35, and containing alkaline naphthinates as emulsifiers are by no means standard products.
Note that it is not t ), i.e. it does not meet various standards (eg road construction material standards).

In the case of the agglomeration treatment of coal fines according to the invention, the agglomerated product is ready for use in various applications, for example in power station boilers.
It can be used immediately as fuel, etc.

Claims (1)

[Claims] 1 Fine powder in slurry or powder state, especially pulverized coal,
In a method of agglomeration using bitumen as a binder, 5 to 15% by weight (based on the weight of the fine powder in anhydrous state) of bitumen emulsion is added to the fine powder, so that the bitumen has a penetration degree of less than 5 at 25°C. and has a Conradson value above 35, and the bituminous emulsion contains 1-10% by weight (based on the amount of bitumen) of alkaline metal naphthinates. Cohesion method.