RU2665852C1 - Method of manufacturing powder refractory products shs and the equipment set for its implementation - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: group of inventions relates to the SHS powder refractory products manufacturing. Method comprises the SHS charge preparation, the densified profiled strip from the SHS charge preparation for its passing through the rolling mill, performance of the produced profiled strip SHS in the reactors to obtain the SHS refractory products, grinding of the obtained SHS refractory products. Before the SHS conducting, the resulting profiled strip is broken into pieces in the placed at the rolling mill exit receiving and distribution adapter, and made with sleeves for the pieces alternate feeding through each of them to the reactors. SHS is conducted in reactors with the chemical igniter, the obtained SHS refractory products are cooled in the reactors by their blowing with the cooling gas from the reactor lower end, and the obtained SHS refractory products grinding is conducted in the rolling mill. SHS powder refractory products manufacturing device is also proposed.

EFFECT: enabling the powder refractory products automated production in the continuous process cycle.

6 cl, 2 dwg, 7 ex

Description

The invention relates to the field of powder metallurgy, namely, to the production of refractory compounds by the SHS method.

Most effectively, they can be used to create automated enterprises for the production of powder refractory SHS products.

A known traditional method of manufacturing powder refractory products, including the following operations: mixing the mixture; compacting (pelletizing) of the blanks, loading the blanks into the reactor, initiating the SHS process with an electric spiral; PS cooling; grinding PS to a working (powder) state in a ball mill [1, 2].

The disadvantage of this method is that, despite the short duration of the synthesis process, which lasts only a few seconds, the total production time of powder refractory products can be tens of hours. This is due to the duration of the preparatory, intermediate and terminal operations. In particular, the cooling rate of PS can be 10 ^-4 -10 ^-3 deg / s) [3], as a result of which the cooling time of even a small reactor for the synthesis of 2.5 kg of product is ~ 2 hours and it can be run only two times per shift (with a synthesis time of several seconds) [1]. In addition, the initiation of the SHS process by an electric spiral complicates the technological process, since in case of ignition failure, the reactor must be disassembled to replace it.

Therefore, the main problem in this direction is the lack of technological process development for the automated manufacture of SHS powder products with a continuous production cycle. Despite the fact that this has been a problem for several decades, even the concept of creating such a production was hardly considered. As a possible option, providing an increase in the cyclicality of the operations “charge loading - unloading synthesis products” (without changing the time for cooling and grinding PS), a “rotary” type installation was proposed, consisting of several (twelve) reactors, in which the charge is loaded in the first the reactor, and the unloading of the synthesis products is in the last reactor [2]. Reactors whose work was carried out at intermediate stages (from the second to the eleventh) are idling, since at in practice, they carry out the same operation — cooling the synthesis products. In addition, the reactor cannot be restarted in the event of ignition failure by an electric coil, since it is necessary to disassemble and reassemble the reactor to replace it.

Also known are improved methods and types of equipment that reduce the duration of technological operations (a heat generating reactor, the operation of which is based on cooling the synthesis products with gaseous refrigerant (nitrogen), blown through the through channels into them [4], chemical ignition of the charge by feeding it liquid or gaseous oxidizing fluoride, manufacturing by rolling flat and shaped compacted strips (blanks), manufacturing of thin profiled strips, grinding ucts synthesis (SS) rolling [5].

An analysis of the methods and devices for the implementation of the manufacturing process of refractory powder products by the SHS method with a continuous production cycle has not been identified.

To date, it has been revealed that the problem in creating automated production of powder refractory products by the SHS method is the duration of the process for the synthesis of refractory products.

The technical result from the use of the proposed solution is to combine disparate discrete technological operations into a single technological process (synchronization of operations among themselves), which makes it possible to create an automated production facility for manufacturing powder refractory compounds with a continuous technological cycle.

This is achieved by the fact that

A method of manufacturing powder refractory compounds in a continuous production cycle consists of mixing the SHS mixture, loading it into the hopper of the rolling mill, forming a compacted strip in the rolling mill, feeding it into a rectangular receiving and distributing two-sleeve adapter and subsequent alternating feeding through the adapter sleeves broken into pieces strips from the SHS-charge into each of the two mobile heat-generating reactors (TGR), transporting the TGR after filling it from rolling mill to the site of chemical ignition of pieces of SHS-charge in the reactor, cooling the resulting PS by blowing cooling gas (nitrogen) from the side of the lower end of the TGR and subsequent transfer of the synthesis products to the roll mill for grinding.

as well as the fact that,

a set of equipment for the manufacture of powder refractory compounds in a continuous production cycle, including a hopper for filling the SHS charge, a rolling mill for sealing strips of SHS reagents, a rectangular receiving and distributing adapter located at the exit from the rolls, at least three movable heat-generating reactors ( TGR), two of which are placed under each sleeve of the receiving and distribution adapter, a chemical igniter, while inside the receiving and distribution at the entrance to the adapter, a rotary damper is placed for alternately blocking each of the adapter sleeves, and a perforated partition is placed in the bottom of the TGR separating its internal cavity from the generator with cooling gas (nitrogen) by means of a fitting placed on the TGR case and connected to it the pipeline.

In a significant number of cases, the cooling gas generator (cylinder) in the set of equipment contains a dual-mode device for regulating the mass of cooling nitrogen within 0.01 M <G <1 M, where G is the flow rate of cooling gas (kg / s) M is the mass of SHS products in the TGR . A nitrogen flow rate of 0.01 kg / s is carried out to remove air from the reactor before igniting the charge. Consumption equal to 1M is carried out during cooling of the PS.

In most cases, chlorine trifluoride or bromine trifluoride is used as a chemical flammable substance (BCH);

In cases where it is necessary to place the PS (in the form of pieces with the required dimensions) in the loading hopper before feeding the rolls of the grinding mill, intersecting protrusions are made on one of the rolls of the rolling mill, for example, around the circumference and along the axis of the rolls.

To complete the manufacturing process of SHS powder products in the continuous production mode, in those cases, a roll mill is used as a grinding device.

In those cases when it is necessary to intensify the process of grinding PS, at least one of the rolls of the grinding mill is made with the possibility of changing the speed of its rotation.

The significance of the signs that provide a solution to the problem is due to the following reasons:

- the use of a rolling mill for compaction of the SHS charge is the initial operation, which provides the possibility of creating a technological process for the synthesis of powder refractory compounds in a continuous production cycle;

- placement at the exit from the rolls of a two-sleeve receiving and distribution adapter with a rotary damper provide alternate filling of the reactors with compacted pieces of SHS-mixture and subsequent synthesis of powder refractory compounds in them;

- the use of the chemical method of ignition of the charge provides remote (without contacting the ignition device with the charge) initiation of the SHS process;

- the implementation on one of the rolls of intersecting grooves or protrusions ensures breaking of the strip inside the receiving and distribution adapter and obtaining pieces of the charge with the required dimensions.

- the application of the roll country for grinding synthesis products completes the continuous technological process of manufacturing powder products.

The invention is illustrated by a detailed description of an example of its implementation and the structural diagram of the crushed roll mill with cooled rolls, where:

- in FIG. 1 shows the calculated curves of changes in the temperatures of nitrogen (a-d) and filler (a ₁ -d ₁ ) in the outlet section of a reactor with a set of fuel elements with a mass of 5 kg and a nitrogen flow rate of 5 kg / s [4];

in FIG. 2 is a flow chart of the synthesis of powder refractory compounds with a continuous production cycle and a set of equipment used for this.

In FIG. 1 adopted the following notation:

aa ₁ -r = 1.25 mm; bb ₁ -r = 2.5 mm; in-in ₁ -r = 5.0 mm; g- ₁ -r = 7.5 mm; dd ₁ -r = 10.0 mm

In FIG. 2 adopted the following notation:

1 - a hopper for loading the SHS mixture from a mixture of titanium + boron components; 2 - mixture SHS; 3 - rolls of a rolling mill; 4 - laminated strip of SHS charge; 5 - two-sleeve receiving and distribution adapter; 6 - shutter; 7 - TGR case; 8 - a glass with a perforated bottom; 9 - a cover; 10 - flammable device; 11 - fitting for supplying a cooling gas (nitrogen); 12 - transportation trolley; 13 - output fitting (nozzle); 14 - pipeline for supplying nitrogen; 15 - nitrogen flow regulator; 16 - gas pipeline for supplying water chemistry; 17 - microcontainer with VHR; 18 - gaseous water chemistry dispenser; 19 - dispenser liquid VHR; 20 - a cylinder with nitrogen; 21 - nitrogen dispenser; A - TGR, filled with pieces of SHS-charge and transported to the compartment (box) for synthesis; B - TGR, filled with pieces of SHS-mixture; B - TGR, located under the right sleeve of the adapter after removing TGR A.

Work on the process of FIG. 1 with a continuous production cycle and the use of a set of equipment for its implementation are carried out as follows:

In the initial state, the TGR A is located under the right sleeve of the adapter 5, and the TGR B is under the left sleeve. Damper 6 is turned to the left, which ensured the overlap of the passage section of the left sleeve and its opening on the right sleeve.

The mixed charge 2, placed in the hopper 1, is fed by gravity to the rolls 3 of the mill, compacted into a profiled strip 4, which is fed into the two-sleeve receiving and distribution adapter 5. Then, when it stops against the shutter 6, the strip 4 breaks into pieces and fills the glass 8 s perforated bottom, after filling the glass 8, the shutter 6 is turned to the right, while the passage section of the left sleeve is opened, the strip 4 begins to fill the TGR B, similar to the TGR A. The filled case 7 with the glass 8 is closed with a lid 9 and transported th on the carriage 12 into the compartment (box) for the refractory product of the synthesis process, and TWG in place under the right adapter sleeve 5.

After the TGR A is placed in the box, they are connected by means of a pipe 14 to the fitting 11 and to a cooling gas flow regulator 15 (nitrogen) placed on the cylinder 20. By means of a gas pipe 16, an ignition device 10 is connected to a dispenser 18 when using ClF ₃ as a VCR. When using BrF ₃ as a VCR, the gas pipeline is connected to the dispenser 19. A portion of BrF _{3 is} supplied by means of a pulsed nitrogen supply from the dispenser 21 from the side of the left end of the dispenser 19. Then, the nitrogen cylinder 20 is opened and the internal cavity of TGR A is purged with nitrogen 11 with a flow rate of 0.01 M (to remove air). After removing the air, the dispenser 18 is opened and ClF ₃ is fed (by gravity) through the gas line 16 to the ignition device 10, and then to the charge surface in the TGR A and ignite it. The supply of ClF _{3 is} carried out by gravity, due to the action of the saturated vapor pressure (P _np = 1107 mm Hg). After the end of the synthesis process (several seconds,) switch the regulator 15 to the gas flow equal to G = 1M and cool the PS (also a few seconds). Switching of the controller 15 can also be carried out simultaneously (or with a certain lead) with the supply of ClF ₃ . In this case, the synthesis and cooling operations are combined in time.

After the synthesis and cooling of the PS are completed, the PS is removed and ground for further use and the TGR is prepared for the next synthesis cycle of the refractory product.

The work of TGR B and TGR B is carried out similarly to the work of TGR A.

Test results

Example 1. A thermodynamic calculation of the cooling process of titanium diboride (initial temperature 3190 K) with a mass of 5 kg placed in a reactor with a diameter of 230 mm and a length of 120 mm with a flow rate of cooling gas (nitrogen) of 5 kg / s was carried out [4].

The results of a thermodynamic calculation performed with the representation of titanium diboride substrates in the form of glowing equivalent balls (fuel elements - fuel elements) with a radius r (equal to 3V / S, where V and S are the volume and area of a real fuel element), showed that the total heat transfer from the fuel element to the cooling refrigerant (nitrogen) during its cooling period to ~ 500 K (~ 200 C) is about 80% of the heat contained in the fuel rod before starting to purge. Further purging of nitrogen leads to a slight change in the cooling rate. Therefore, this temperature can be taken as the temperature of the discharge of PS from the reactor. In addition, as the results of the thermodynamic calculation showed, it is advisable to use fuel rods with a calculated radius of up to 3 mm, since with increasing r, the cooling time of the PS significantly increases.

Example 2

We simulated the cooling process of PS of a rolled thick (4-6 mm) strip of a mixture of titanium and boron. During testing, the rolled strip was manually broken into pieces with dimensions of ~ 4 × 4 × 10 mm (the calculated value of r is ~ 3 mm) and placed in a chamber of a model reactor with a diameter of 60 mm. The total mass of the charge (pieces of the rolled strip) was 0.1 kg. After placing the charge in the model chamber, nitrogen was supplied with a flow rate of 0.1 kg / s from the side of the lower end and ignition of the charge from the side of its upper end. Nitrogen was supplied for 6 sec. Visual control of the extracted PS showed that the synthesized pieces weakly sintered among themselves, while the gaps between the pieces through which nitrogen was purged were preserved. After that, chilled, partially sintered, pieces of the synthesis products were separated from each other by pre-pressing, then crushed in a mill mill and transferred to dispersion into fractions. If necessary, the cross-sectional area between the pieces of the compacted charge in the charge can be increased by rolling the profile strip, while the profile configuration can be practically any available to rolling, for example, in the form of "corrugations".

Example 3

We conducted tests to determine the flow rate of gaseous water chemistry, which provides ignition of the pieces of the mixture from mixtures of Ti + 2B, Ti + C. During testing, the pieces of the mixture were placed on a pallet and fed (by gravity, due to the pressure of saturated steam) through the capillary pipe ClF ₃ from the metering device to the surface of the pieces. The test results showed that when the nozzle was in contact with the charge surface, ignition was carried out at a ClF ₃ flow rate of 1-1.3 mg. When removing the nozzle by 10 mm, ignition was carried out at a flow rate of ClF ₃ weighing 10 mg.

Example 4

Tested to evaluate the effectiveness of chemical ignition of the charge titanium + boron, titanium + carbon (according to example 2) using liquid BrF ₃ . The charge was ignited by feeding one drop of BrF ₃ from a pipette weighing ~ 0.1 g 10 mg.

Thus, the proposed scientific and technical solution under the conditions of the described examples provides a solution to the described problems in the synthesis of refractory SHS products in a continuous production cycle and other advantages confirming the possibility of their manufacture in continuous burning.

Example 5

Comparative tests were conducted to grind 2 kg of TiB ₂ to a size of 40 μm in a ball mill and by rolling. Grinding time The time of PS by rolling was 0.2 hours, while the time of grinding in a ball mill was 2.8 hours, that is, the intensity of grinding of PS by rolling increased by 14 times.

Example 6

When re-grinding the composition of TiC + C ₃ C _{2 by} rolling, an increase in the amount of the fine fraction (<40 μm) by 2 times is ensured.

Thus, the results of thermodynamic calculation and tests of the invention under the conditions of the described examples provided a solution to the problem of developing a technological process for the production of powder PS in the continuous production cycle.

Example 7

Comparative tests were carried out to grind 2 kg of AlN to 3 μm in a ball mill without preliminary rolling and with preliminary rolling. The grinding time was 8 hours and 1 hour, respectively, that is, the grinding time was reduced by 8 times. The grinding time of the AlN composition to 3 μm in a ball mill with preliminary rolling was 1 hour.

Literature

1. V.K. Prokudina, V.I. Ratnikov, V.M. Maslov, I.P. Borovinskaya, A.G. Merzhanov, F.I. Dubovitsky. Titanium carbide technology. In: Combustion processes in chemical technology and metallurgy. Ed. A.G. Merzhanova. Chernogolovka, 1975, p. 136-141.

2. Kukushkin B.I. et al. Technological line for the production of titanium carbide by the SHS method. Report of the Institute of Chemical Physics, Academy of Sciences of the USSR, 1995. In the book. A.G. Merzhanov. Combustion processes and synthesis of materials. Chernogolovka, ISMAN publishing house, p. 361.

3. A.G. Merzhanov. Self-propagating high-temperature synthesis and powder metallurgy: unity of purpose and competition of principles. In the book. Combustion processes and synthesis of materials. Ed. V.T. Teleps, A.V. Khachoyan. Chernogolovka, publishing house ISMAN, 1998, p. 70-121.

4. S.M. Gaidar, V.D. Zhigarev, I / N / Kravchenko, V.A. Ovchinnikov. Thermodynamic Calculations of the Cooling of the Product of Self - Propagating High-Temperature Synthesis in a Heat - Generating Reactor. POWDER METALLURGY TECHNOLOGIES.

5. Gaidar, M.Yu. Karelina, V.D. Zhigarev. The method of grinding powder refractory compounds. Bulletin of the Moscow Automobile and Highway State Technical University (MADI) No. 2 (45), 2016. p. 53-56.

Claims (6)

1. A method of manufacturing powder refractory SHS products, including preparing a charge for SHS, obtaining a compacted shaped strip from a charge for SHS by passing it through a rolling mill, conducting SHS of the obtained shaped strip in reactors to produce refractory SHS products, grinding the obtained refractory SHS products, characterized in that before the SHS, the obtained profiled strip is broken into pieces in a receiving and distribution adapter located at the exit of the swath of the rolling mill and made with sleeves for alternating feeding of the pieces through each of them to the reactors, the SHS being conducted in reactors with a chemical igniter, the obtained refractory products of the SHS are cooled in the reactors by blowing them with cooling gas from the side of the lower end of the reactor, and grinding the obtained refractory products SHS lead in a roll mill. 2. A device for the manufacture of powder refractory products of SHS, containing a hopper for filling the charge for SHS, a rolling mill for manufacturing a profiled strip by compaction of a charge for SHS, reactors for conducting SHS and a device for grinding obtained in reactors of refractory SHS products, characterized in that it contains a two-arm receiving and distributing adapter located at the exit of the rolling mill with a rotary damper in front of the entrance to the sleeves for alternately overlapping each of sleeves made with the possibility of breaking the strip from the charge for SHS with an emphasis on it, while as reactors for SHS it contains at least three movable reactors made with the possibility of installing a receiving and distribution adapter under the sleeves and equipped with a chemical igniter, and from the side of the lower end - a perforated baffle for blowing cooling gas from a cooling gas generator, and the device for grinding the obtained refractory products of SHS ying in the form of a roller grinding mill. 3. The device according to p. 2, characterized in that the cooling gas generator is configured to control the mass of the supplied gas. 4. The device according to p. 2, characterized in that the chemical igniter contains chlorine trifluoride or bromine trifluoride as a flammable substance. 5. The device according to p. 2, characterized in that on the surface of one of the rolls of the rolling mill rolling intersecting conical protrusions are made, made around the circumference and along the axis of the rolls. 6. The device according to p. 2, characterized in that at least one of the rolls of the rolling mill is made with the possibility of changing the speed of rotation.

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