RU2282503C1 - Method of dry coal conversion - Google Patents

Abstract

FIELD: coal industry; conversion of difficultly enriched coals.

SUBSTANCE: proposed method includes preliminary crushing at separation of 0-25 mm class, selective grinding, treatment on pneumatic classifier at separation of 0-1 mm class and sieving remaining class of 1-35 mm on sieve. Size of mesh of previous sieve relative to subsequent one is equal to 1.7-2.0 for obtaining respective classes at ratio of larger particles to smaller ones within 1.7-2.0; then, each class is fed to conveyer with belt made from screen and provided with nozzles having rarefaction of 300-800 mm of water column. First nozzle (in way of motion of conveyer) whose shear is mounted at maximum distance from belt is used for removal of material at density of 1250-1350 kg/m³ at ash content of A^d=8-11% which is just coal-concentrate; second nozzle whose shear in mounted at lesser distance from belt as compared with first nozzle is used for removal of material having density of 1350-1600 kg/m³ (A^d=11-25%) and third nozzle whose shear is mounted at minimum distance from belt is used for removal of material at density of 1600-1800 kg/m³ (A^d=25-45%). Material remaining on belt having density of 1800-2500 kg/m³ at ash content of A^d=70-80% goes to the dump and material of classes of +25 mm remaining after screening is subjected to selective grinding to size of 0-25 mm and classification at separation of class of 0-1 mm followed by separation in sieves and conveyer as described above.

EFFECT: enhanced efficiency of conversion of coals used as solid fuel.

2 dwg, 1 ex

Description

The invention relates to the coal industry and can be used for dry processing of hard-to-concentrate coals.

A known method of coal enrichment using air supplied under pressure (enrichment in a "fluidized bed"). It is characterized by low productivity and process instability, "ineffective compared to other enrichment methods" [1].

The closest by achieved results is the method of dry enrichment of raw coal, in which all technological operations for dry enrichment are carried out in the process of its transportation on a single vehicle with preliminary separation of the raw coal into low-ash and high-ash classes, while low-ash classes (concentrate) are removed from the transport flow into the sublattice product and sent to the consumer, and high-ash classes are subjected to selective crushing with subsequent separation of crushed coal For from the transport stream of raw coal into the under-sieve product, then the remaining rock in the form of an over-sieve product is removed from the enrichment process [2].

The marked method is ineffective and unsuitable for coals of difficult dressability.

The objective of the invention is to achieve the processing of difficult-to-concentrate coal in a dry manner with the release of concentrate and intermediate products suitable for use as solid fuel.

The essence of the invention lies in the fact that in the method of dry processing of coal, including preliminary screening, processing on the classifier, selective crushing and sieving of the processed products on the sieves, according to the invention, the material of the 0-25 mm class isolated on the screen is processed on the classifier, where the class 0- is separated 1 mm, and the remaining product of the class 1-25 mm is screened on sieves with a ratio of the size of the previous sieve to the next equal to 1.7-2.0.

Supersieve material of one class (for example, 1-2 mm) is fed onto a conveyor with a mesh tape, where, with the help of nozzles mounted above the ribbon, material with a density of 1250-1350 kg / m ³ , ash content A ^{d is} sucked out under the first nozzle = 8-11%, under the second nozzle with a density of 1350-1600 kg / m ³ (A ^d = 11-25%) and under the third nozzle with a density of 1600-1800 kg / m ³ (A ^d = 25-45%). The nozzle sections above the tape are installed at distances — the first nozzle is the largest, the second nozzle is the middle, and the third is the smallest. The distance values are determined empirically. The remaining sieve material + 25 mm after preliminary screening is subjected to selective crushing with transfer to the 0–25 mm class, separation from it of the 0–1 mm class on the classifier, and subsequent processing as described above. The magnitude of the vacuum in the nozzles is the same and is 300-800 mm of water. Art.

The material remaining on the conveyor with a density of 1800-2500 kg / m ³ represents the rock that is sent to the dump.

Figure 1 presents a diagram of the processing of coal on a conveyor with a mesh belt. Figure 2 - diagram of the processing of coal sucked out by one of the nozzles (for example, the first along the conveyor)

Designations:

1 - mesh belt conveyor;

2 - loading hopper;

3 - nozzle for suctioning a coal-air mixture (first);

4 - the second nozzle;

5 - the third nozzle;

6 - precipitation chamber;

7 - cyclone;

8 - ventilation installation;

9 - filter;

10 - the remaining processing material (waste);

a, b, c - the distance of the nozzle sections from the tape (a> b> c)

The proposed method of dry processing of coal is as follows: all coal (material) is subjected to preliminary screening with the allocation of a class of 0-25 mm, which is processed using a jet pneumatic classifier (for example, [3]), where a class of 0-1 mm, which is coal concentrate, and the remaining material with a grain size of 1-25 mm is fed to a sieve with a ratio of the cell sizes of the previous sieve to the next equal to 1.7-2.0 and divided into the corresponding classes with the ratio in each class of a larger particle to a smaller one in the range of 1.7-2 , 0 (e.g. cl assy 1-2 mm, 2-4 mm, 4-8 mm, 8-14 mm, 14-25 mm). A ratio of less than 1.7 leads to an unnecessarily large number of classes and unnecessarily complicates the process of dry coal processing, and a ratio of more than 2.0 complicates the further separation of the material into fractions (a fraction with a density of 1350 partially starts to enter the fraction with a density of 1250-1350 kg / m ³ -1600 kg / m ³ ).

Supersieve material of one class is fed to the conveyor with the mesh belt 1 (Fig. 1) from the hopper 2 as a monolayer under the nozzle 3, where the lightest fraction with a density of 1250-1350 kg / m ³ and ash content A ^d = 8-11% is sucked out of the material why the nozzle 3 is adjusted to the desired height relative to the canvas of the mesh belt of the conveyor a and the nozzle is installed using the ventilation unit 8, the required vacuum in the range of 400-800 mm of water. Art. The suctioned material falls out of the air stream in the precipitation chamber 6 (FIG. 2), and the air is dedusted in the cyclone 7 and removed by the ventilation unit 8 through the filter 9 into the atmosphere. The material from the precipitation chamber 6 is mixed with dust settled in small quantities in the cyclone 7 and filter 9 and having an ash content of up to 12%. A class of 0-1 mm obtained on an inkjet pneumatic classifier and having an ash content of about 12% is also added here. The resulting material - coal - concentrate - is shipped to the consumer.

The remaining material on the mesh conveyor is fed under the next nozzle 4, mounted at a lower height 6 relative to the canvas of the mesh tape than nozzle 3 (b <a), and a fraction with a density of 1350-1600 kg / m ³ is sucked out of it. This intermediate product having an ash content of A ^d = 11-25% falls out of the air stream in its precipitation chamber, and the air is dust-free in its cyclone and filter. The products of the precipitation chamber, second nozzle, cyclone and filter are mixed together.

The heavy industrial products remaining on the belt with a density of 1600-1800 kg / m ³ with an ash content of A ^d = 25-45% are sucked off the conveyor belt by a nozzle 5 installed at a lower height relative to the mesh belt web than nozzle 4 (c <b), and removed from their precipitation chamber and cyclone.

The air pressure in the nozzles 3, 4, 5 is set the same.

Middlings sucked out by nozzles 4 and 5 are either mixed together and used as steam coal with an ash content of A ^d ≈20-35%, or used separately.

Material 10 that has passed through the entire conveyor with a density of 1800-2500 kg / m ³ and an ash content of A ^d = 75-85% is a rock that is sent to a dump.

Oversize materials of other classes are processed on their mesh conveyors in a similar way.

Classes of material with a particle size of more than 25 mm are subjected to selective crushing with transfer to a class of 0-25 mm and further processing on the classifier, sieves and mesh conveyor in the described manner.

The proposed method of dry processing of coal makes it possible to isolate coal concentrate and separately steam coal of two grades from difficultly processed coal.

Example: KS grade coal from the Alardinskaya mine of the Kuznetsk coal basin, the ash content of which is 23.5%, is fed to a screen with a cell diameter of 25 mm. The isolated oversize product has an ash content of 29.7%. The under-mesh product with an ash content of 15.9% is transferred to a pneumatic classifier, where a class of 0-1 mm with an ash content of 12% is removed from it. The remaining product of 1-25 mm class is scattered on the sieves with the formation of classes 1 - 2 mm, 2 - 4 mm, 4 - 8 mm, 8 - 14 mm, 14 - 25 mm.

Each formed class (for example, 1-2 mm) is fed to a mesh conveyor, where it is subjected to air suction with three nozzles. After the first nozzle, coal concentrate with an ash content of 9% is obtained, along with dust in the cyclone and filter, dust with an ash content of 12% falls in the cyclone and filter. After the second nozzle, an intermediate product with an ash content of 18% is obtained, and after the third nozzle, 35%. The remainder of the material after processing has an ash content of 77% (rock) and is not intended for further use.

All remaining classes with fineness from 2 to 25 mm are subjected to similar processing.

Processing products are combined in terms of ash content and as a result, coal concentrate with an ash content of A ^d = 10.5%, (intermediate product) steam coal with A ^d = 25% and a rock with an ash content of 77%, which is waste, are obtained.

Thus, the possibility of processing hard coal is shown.

Literature

1. Fomenko T.G., Butovitsky B.C., Pochartseva E.M. Coal Preparation Technology: A Reference Guide. - 2nd ed., Revised. and add. - M .: Nedra, 1985 .-- 367 p.

2. Application 96114936/03, the application. July 23, 1996, publ. 10/20/1998, class 07 V 1/00, BI 29.

3. SU A.c. No. 1238811, B 07 B 4/04.

Claims (1)

Method for dry processing of hard-to-digest coal, including preliminary screening with separation of class 0-25 mm, selective crushing, processing with a pneumatic classifier with separation of class 0-1 mm and sieving of the remaining class 1-25 mm on sieves, characterized in that the mesh size of the previous sieve is subsequently taken equal to 1.7-2.0 to obtain the corresponding classes with the ratio in each class of a larger particle to a smaller one in the range of 1.7-2.0, then each class is fed to a conveyor with a tape from a grid, where using nozzles installed over tapes oh and having a vacuum of air within 300-800 mm of water. century, sucked off sequentially by the first nozzle along the conveyor, installed by its cut at a maximum distance from the belt, providing removal of material with a density of 1250-1350 kg / m ³ , having an ash content of A ^d = 8-11%, which is a coal concentrate, then a second nozzle installed with a cut at a shorter distance from the tape than the first nozzle, a material with a density of 1350-1600 kg / m ³ (A ^d = 11-25%), and finally, a third nozzle installed with its cut above the tape at the smallest distance, providing removal of material with a density of 1600-1800 kg / m ³ (A ^d = 25-45%) moreover, the material remaining on the tape with a density of 1800-2500 kg / m ³ , having an ash content of A ^d = 70-80%, is a rock that is sent to the dump, and material of classes + 25 mm remaining after screening is subjected to selective crushing to size 0-25 mm and classification with the allocation of a class of 0-1 mm, and then separation into screens and conveyor, as described above.

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