RU2540162C2 - Method of producing anisotropic carbon powder and device to this end - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: carbonisation product of coal-tar pitch is processed by aromatic solvent. Then, phase separate is executed to obtain the solvent, anisotropic pitch fraction and anisotropic carbon powder by extraction in pendulum -type device including extractor 6 secured at base 1 for continuous pendulum motion. Extractor 6 consists of cylindrical housing with heat-insulation and heating jacket, used solution drain pipe arranged at housing bottom, initial suspension feed pipe arranged at housing cover upper part. Vessel with cylindrical cartridge is arranged inside said housing and secured therein, filter material being secured at perforated bottom, in its circle. Further flushing, filtration and drying are performed in the same device.

EFFECT: higher yield of anisotropic carbon powder.

2 cl, 3 dwg

Description

The invention relates to the field of coke chemistry and metallurgy, in particular to a method for producing high-density carbon materials used for the preparation of structural graphites. Carbon materials are widely used in many industries: in metallurgy - for the manufacture of crucibles, molds, containers for semiconductor materials, nozzles for continuous casting of metals; in mechanical engineering - for the production of bearings, friction rings, precision engineering tools. Such products can be used for the manufacture of antifriction materials used in the friction elements of aircraft engines. In addition, carbon materials are widely used in the electrode industry, as well as for the manufacture of replaceable elements of nuclear reactors, parts of industrial equipment, in organizing the production of silicon, quartz glass, and the need for them is constantly increasing. Therefore, work aimed at obtaining new carbon materials and using new types of raw materials for this are very relevant.

A known method [1] of obtaining a mesophase carbon powder from carbonized coal tar pitch by extracting in a closed loop by circulating an aromatic solvent in countercurrent mode in three continuous stages — extraction, adjustment, washing, followed by hydrocyclone separation and drying. The raw material for extraction may be the product of the carbonization of hydrocarbons: shale resins, oil pitch and coal tar. As a solvent, 40-100% by weight of aromatic hydrocarbons are used, which are one or more selected from the group consisting of one, bi- or tricyclic aromatic hydrocarbons. The suspension is circulated in the apparatus over time at the boiling point of the solvent. Then, using a hydrocyclone, they are divided into the components: solvent + resin and carbon powder. In the hydrocyclone, the powder and part of the solvent goes into the lower hole and amounts to 12-17%. After separation, the extracted and washed powder is heat treated to constant weight in a drying apparatus at the boiling point of the solvent.

The disadvantage of this method (prototype) are:

1. The process of separation of the suspension takes place in a hydrocyclone apparatus with a large percentage of powder losses (from 20 to 30%), which increases the cost of purchased pitch and, as a result, leads to an increase in the cost of production.

2. There is a possibility of unstable operation of the hydrocyclone due to the uneven distribution of the powder in the suspension and the unstable pressure of the suspension at the inlet of the hydrocyclone, which leads to clogging of the lower hole.

The aim of the work was to develop a technology for producing mesophase carbon powder of improved quality for the production of structural graphite materials and products operating under conditions of high temperatures, neutron irradiation, erosion, aggressive environments and regime friction. As a result, new generation graphite will be introduced to the Russian market, which will reduce the import of similar materials.

The problem to which the invention is directed, is to optimize the hardware design of the process and increase the yield of mesophase carbon powder.

The solution to this problem is achieved by the fact that in the method for producing a mesophase powder from carbonized coal tar pitch, extraction is carried out in a closed circuit by circulating the carbonizate with an aromatic solvent, followed by washing, filtering and drying in the proposed pendulum type device (hereinafter MT). This allows to reduce the percentage loss of powder compared with the prototype by 5%.

The raw material for extraction is the product of carbonization of coal tar pitch.

At present coal tar sands are the most promising raw material for the creation of structural graphites.

Organic solvents, which are one or more hydrocarbons with a high content of aromatic substances, were considered as an extractant. These solvents typically include one, two, and three cyclic aromatic hydrocarbons. Specific solvents that can be used in the present invention include one of the solvents selected from the group: tetraline, xylene, toluene, benzene, α-methyl-naphthalene, anthracene fraction, coal oils. The boiling point of this series lies in the range of 80-330 ° C. This series of aromatic compounds is the best for dissolving asphaltene components contained in the β-fraction of coal tar pitch.

The ratio of solid material to liquid, as in the prototype, ranges from (1:20) to (1: 5) mass%. The circulation of the suspension at a boiling point of the solvent and atmospheric pressure for a short time of 5-60 minutes contributes to the deep extraction of high molecular weight hydrocarbons.

The method is carried out in the following sequence. Extraction is carried out in an apparatus with a closed loop, through which the suspension circulates. Next, the suspension is sent to an extractor (MT). A filter is installed in the pendulum extractor, through which only a solution of coal tar passes, the carbonizate powder remains on the filter. The extractor is equipped with a drive that ensures the swing of the MT extractor on special supports. Thus, the carbonizate powder is washed. The washing of the carbonizate continues until the solvent reaches the boiling point inside the pendulum extractor. The resulting extract (solvent + resin), with each washing, is pumped through the drain pipe from the tank by distillation pump. The final stage of the whole process is the drying of the clean washed powder, which takes place in the same apparatus. The whole process continues as long as it takes to obtain a solid phase with a certain amount of volatile substances.

The separation of the resulting three-phase mixture (solvent + resin, carbon powder) in the MT apparatus allows:

- perform three processes in one apparatus: washing, filtering and drying;

- perform the processes closed, which allows you to embed this operation in the production line and ensure human safety.

To implement the proposed method, a pendulum type device is used to produce carbon powder. The proposed device is illustrated by drawings. Figure 1 shows the design of the proposed installation for washing, filtering and drying the mesophase carbon powder; figure 2 - sectional view of the extractor; figure 3 - design of the filter cartridge.

The installation consists of the following main units: base 1, made in the form of two welded structures of channels 2, connected by five couplers 3 with bolts, and four supports 4; an extractor 6, which is mounted on the base 1 using two half shafts 7, based on the bearing units 9; at the end of one axle shaft 7 is fixed with screws 11 a lever 10; a pneumatic cylinder 12 mounted on a special platform 5 of the base by means of a hinge flange 13 and connected by a hinged head 14 with a lever 10.

The extractor 6 consists of a welded housing 15 of a cylindrical shape made of sheet steel containing an inner container 16, a heating jacket 17, a flange 18, a drain pipe 19, pipes 23 and 24, boss 20 and column 21. The wall of the inner container 16 is separated from the wall of the shirt heating 17, forming a cavity into which coolant is supplied through the pipe 23 - oil, preheated and forcedly circulated by the thermostat through the pipe 24. A cassette 25 is inserted into the inner container 16, which is a welded cylindrical structure -cylindrical shape in the form of a skeleton. The frame of the cartridge 25 is made of sheet steel and consists of two sides 36 in the form of rings fixed at a distance by rods 37; the flange 38 and the bottom 39. For immediate removal of dirty solvent from the washed powder, the bottom 39 is perforated concentrically around the circles with holes 40. Filter media 26 is attached to the sides 36 and the bottom 39 of the cartridge 25, holding the powder 27 and passing the dirty solvent 28 to drain through the drain pipe 19 The cover 30 is fastened to the flange 18 of the housing 15 with bolts 29. The gap between the ends of the flange 18 and the cover 30 is sealed with a fluoroplastic gasket 31. The inlet pipe 32 is welded to the cover 30 and there are additional pipes 33 for connecting and with the atmosphere. The casing 34 is bolted 22 to the columns 21. Thermal insulation 35 of the housing 15 is placed in the gap between the housing 15 and the casing 34. To form the swing axis "a", the extractor 6 is fastened by bolts 8 to the axle shafts 7 using bolts 20.

The pneumatic cylinder 12 is driven by compressed air coming from the compressor. The reciprocating movements of the rod of the pneumatic cylinder 12 by means of the lever 10 are converted into pendulum movements of the extractor 6.

The device operates as follows. The extracted slurry enters the MT apparatus through the inlet pipe 32. Using pendulum movements, the powder undergoes dynamic washing. Dynamic flushing promotes better contact of the powder particles with the solvent compared to a static extractor. After washing, the resulting extract, passing through the filter material 26, is pumped through the drain pipe 19. Then the wet powder goes through the drying stage here. Dynamic drying contributes to faster and better drying of the powder. Next, the lid 30 is removed from the apparatus and the filter with the powder is removed.

Information sources

1. RF patent No. 2443624, zak No. 2009139850/05, 10.29.2009.

2. A.G. Kasatkin. Basic processes and apparatuses of chemical technology. M., "Chemistry", 1973.

Claims (2)

1. A method of producing a mesophase carbon powder, comprising treating a hydrocarbon feed with an aromatic solvent, phase separation to form a solvent, a mesophase pitch fraction and a mesophase carbon powder, by extraction in a closed-loop apparatus by circulating carbonizate with an aromatic solvent and drying, characterized in that the phase separation carried out with subsequent washing and filtering in a pendulum-type device with further drying in the same device. 2. The pendulum type device for implementing the method according to claim 1, comprising an extractor fixed on the base so that it is constantly in a pendulum movement, consisting of a cylindrical body, including a casing with thermal insulation, a heating jacket and an inner container with a fixed cylindrical cartridge in the form of a frame in which the filter material is mounted on a perforated hole around the bottom circumference; a drain pipe for discharging the spent solution located in the central lower part of the housing; an inlet pipe for introducing an initial suspension located in the central part of the housing cover.

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