RU2699424C1 - Device for vacuum degassing of graphite powder for synthesis of diamonds - Google Patents

Abstract

FIELD: chemical or physical processes.

SUBSTANCE: invention relates to means of processing mineral raw materials for further use in metallurgy and other industries. Device for vacuum degassing of graphite powder for synthesis of diamonds, containing vacuum chamber with means of supply and control of air pressure. Device is equipped with tempering hollow forging for initial powder with volume of 100 cm³ and a receiving hollow forging for collection of finished powder, which are mounted in a vacuum chamber. Axes of hollow forgings are located on one straight line perpendicular to horizon line, at that, sleeves are equipped with remotely controlled vacuum-tight covers, and vacuum chamber volume makes 1 m³.

EFFECT: higher degree of evacuation of powder with simplified design of chamber.

1 cl, 1 dwg

Description

The invention relates to means for processing mineral raw materials for further use in metallurgy and other industries.

A device is known for stabilizing a powder layer using low pressure (Canadian patent CA 2886438, priority dated September 28, 2012). The device comprises an open container, on one side containing a bottom, one side wall and an opening for the container, a filter inside or above the bottom, on one side wall, wherein the area occupied by the filter corresponds to the area of the bottom or the area of the side wall and in which the filter is substantially impermeable for the powder, and the connection on the bottom or on the side wall of the container or on the side of the filter facing away from the opening of the container, the connection coming up to the suction pump, so that the powder layer located in the container is pressed filter and stabilized by means of a vacuum created by the pump. The disadvantage of this device is the insufficient degree of evacuation (degassing) of the powders.

A device is known consisting of a metal capsule comprising a cylindrical body, lower and upper covers connected to the body by welds (USSR patent SU 513603 priority from 12/03/1973). Inside the capsule is a compression powder. In the upper cover there is a nozzle for evacuating the capsule, made in the form of a screw coupling with an opening. A base plate with a flange is also installed on the lid. The assembly connecting the vacuum system to the capsule is attached to the coupling using a nut mounted on the plate. The assembly is connected to the vacuum system through a nozzle and is equipped with a plug for closing the hole after the capsule is evacuated. The device for moving the plug consists of a holder mounted on a piston rod, a cylinder with a piston connected to a source of compressed gas by tubes. The holder is made in the form of a magnet. The disadvantage of this device is the insufficient degree of evacuation of the powders.

A powder coating feed device is known comprising

a pump equipped with two alternating powder chambers between the powder inlet valve and the powder outlet valve, each of these power chambers having a centrally located tubular filter, a unit for connecting to an air duct for alternately applying vacuum or compressed air to one of the two alternating powder chambers controlling a pump to switch one of two alternating powder chambers between suction and pressure modes, in which the powder inlet valve is open and the powder outlet valve and closed, and one of the at least two powder chambers communicates through a unit for connecting air to the vacuum channel, whereby the vacuum is able to aspirate the powder to apply the powder to the powder chamber in the suction mode (US patent US 8231310 priority from 02.02.2007) . The mode in which the powder inlet valve is closed and the powder outlet valve is open, and one of the powder chambers is communicated through a device for connecting air to the compressed air pipeline, so that compressed air is able to displace the dose of powder for the coating stored in the powder chamber in the operating mode under pressure and in which the powder coating supply device includes a pressure sensor communicating with each of the two powder chambers continuously. The disadvantages of the device include the limited volume and range of defects with this technology and, also, the insufficient degree of evacuation of powders.

A known method of preparing granules for pressing, including vacuum thermal degassing of granules and filling granules of a steel capsule (Russian patent RU 2477669 priority from 10.21.2011). The degassing chamber is evacuated to a pressure of not more than 1⋅10 ^-4 mm Hg. Art., carry out a metered supply of granules on an inclined surface heated to 130-150 ° C, conduct thermal degassing of granules in a moving layer with a thickness of 8-15 monolayers when moving on this surface, fill a steel capsule heated to 400 ° C and placed with granules in a vacuum chamber, and carry out its sealing. The disadvantage of this technology is the difficulty of its use for finely dispersed powders.

A known method comprising loading sponge titanium into a retort, evacuating and heating it in a vacuum, removing hydrogenated sponge titanium from a retort and grinding it (Russian patent RU 2628228 priority from 12/22/2015). Sponge titanium is crushed in an argon atmosphere at an overpressure of not more than 10-20 kPa, and dehydrogenation is carried out by sealing the retort, evacuating it to a residual pressure of 0.01 kPa, heating and supplying argon with an overpressure of 10-30 kPa, while releasing during dehydrogenation, hydrogen is combined with argon to ensure a residual pressure of 0.01 kPa and thermal exposure is carried out for 3-5 hours. It provides the production of titanium powder of a given shape - fragmentation, needle type, with a reduced content of gas impurities such as hydrogen, nitrogen, chlorine and oxygen. The disadvantages of this method include the use of sponge samples as raw materials and limited use for powders.

A known method of producing fine monodisperse powders of metal, semiconductor and dielectric materials, including the evaporation of the material, the condensation of its vapor and crystallization (Russian patent RU 2063306 priority from 06/08/1993). Evaporation is carried out in a previously evacuated chamber to obtain supersaturated steam, and the condensation of the supersaturated steam is carried out under the influence of electromagnetic radiation, followed by removal of condensate from the crystallization chamber. The disadvantage of this method is the high cost and low productivity of the process.

A device for producing tantalum powder containing a heated reaction vessel with a lid, a vacuum system, argon inlet and exhaust, a system for controlling and maintaining argon pressure inside the device (Russian patent RU 2349656 priority from 05.10.2005). The device is equipped with a pipeline for moving sodium with a reaction vessel, a second heated vessel with a beveled bottom and having a lid with a device for loading sodium, argon supply and vacuum fittings and a sodium discharge pipe, while the reaction vessel is made with a beveled bottom and has a perforated collector of the recovered product, the lid of the reaction vessel is equipped with a potassium fluorotantalate loading port. The disadvantages of the device include the need to include additional reagents with their subsequent withdrawal from the process.

A known method of producing a finely dispersed spherical titanium-containing powder (Russian patent RU 2631692 priority from 03/26/2017). The method includes hydrogenating the starting material in the form of ingots, rolled products and titanium-based rolled products and titanium alloys, grinding and sieving the hydrogenated material, dehydrogenation, grinding, sieving, classification and subsequent spheroidization of the powder. Dehydrogenation is carried out at a temperature of 580-610 ° C, at the end of dehydrogenation, the reactor is evacuated with a vacuum of 0.67-0.93 Pa. The disadvantage of this method, as in the previous patent, is the need for input and subsequent withdrawal of additional reagents from the process.

Closest to the claimed is a device for the vacuum process of isostatic pressing of powdered material (US patent US 8690561 priority from 07.27.2010). The device comprises a rubber bag configured to load powder in it, a vacuum box configured to accommodate the rubber bag, and creating a vacuum medium from the rubber bag, a cylinder assembly configured to seal the inlet of the rubber bag located in the vacuum box, the assembly the cylinder is located in a vacuum box, a clamp made with the possibility of complete sealing of the inlet of the rubber bag, which was temporarily sealed by the cylinder assembly. The disadvantage of this device is the difficulty of controlling the degree of evacuation of the powder.

The objective of the invention is to develop a device for evacuating powders of any mineral and chemical composition and any dispersion.

The technical result is a device in which powders are evacuated in one stage, while the air content in the initial portion of the powder is reduced by 10,000,000 times. The device has a simple design, the process of evacuation of powders is remotely controlled at all stages.

The technical result is achieved by the fact that the device has a vacuum chamber and two sleeves are mounted in the vacuum chamber, which can be remotely sealed with vacuum caps. The first sleeve is a holiday, which contains the original raw material powder. The second sleeve is designed to receive powder after evacuation of the chamber.

The invention is illustrated by a diagram of a device for evacuating powders. The device is shown at the top of the circuit before evacuating the chamber, where 1 is the chamber body, 2 is the tempering case body, 3 is the powder being processed, 4 is a remotely controlled vacuum cap, 5 is the receiving sleeve body. Lid control units and a chamber pressure control device are not shown in the diagram. In the lower part of the diagram, the device is shown after the end of the technological process of evacuating the powder, where 6 is the vacuum cover controlled remotely, 7 is the powder ready for subsequent use. The axis of the outlet and the receiving sleeves are located on the same line perpendicular to the horizon level.

The device operates as follows. The air is evacuated by a vacuum pump from the space bounded by the sealed housing 1 to a pressure of 10 ^-6 mm. Hg. Art. The lid 4 opens and the powder from the sleeve 2 is gravity poured into the sleeve 5, which is then sealed by the cover 6. This state is shown in the lower part of the circuit. The air content in the powder 7 is many orders of magnitude less than in the initial powder 3.

Consider, as an example, the preparation of graphite powder for subsequent use in the synthesis of diamonds. The best raw material is very pure graphite in the class OS4-7-4. To a dispersion of 0.03-0.05 microns, such a powder can be processed in a collider nano-grinder KNI (Russian patents RU 2450861, RU 2457033 and RU 2473389). The sleeve 2 is manufactured with an internal volume of 100 cm ³ . The bulk density of such graphite powder is 0.8 g / cm ³ , i.e. in a sleeve with a volume of 100 cm ³ will be 80 g of graphite, which will occupy a partial volume of 35.6 cm ³ . Accordingly, in 64.4 cm ^{3 there} will be air - 9.4 10 ²⁰ molecules of N ₂ + O ₂ .

If the volume of the vacuum chamber is 1 m ³ , then with a residual pressure of 10 ^-6 mm Hg. Art., it will contain 3.43 ^{16 16 16} molecules of N ₂ + O ₂ , and in 1 cm ³ will be 3.43 ⋅ ^{10 10} molecules of air. In the receiving ampoule will be 80 g of graphite, which will occupy a volume of 35.6 cm ³ . After opening the cover of the dispensing sleeve, to 3.43⋅10 ¹⁶ air molecules in the vacuum chamber will be added 9.4⋅10 ²⁰ air molecules in the dispensing sleeve and air will spread through the chamber at a concentration of about 9.4⋅10 ¹⁴ molecules N ₂ + O ₂ in 1 cm ^{3 the} volume of the vacuum chamber and the pressure in it will rise to about 2.74 × 10 ^-2 mm. Hg. Art. The receiving sleeve will contain 80 g of graphite (4 и10 ²⁴ atoms) and 6⋅10 ¹⁵ air molecules, i.e. in the receiving ampoule there will be much fewer air molecules than there are carbon atoms on the surface of the powder particles. Vacuum tight sleeve 5 with finished powder 7 can be directly used for the synthesis of diamond with a grain size of 300 carats or more according to O.I. technology Leipunsky (Uspekhi Khimii, 1939, v. 10, No. 8, pp. 40-43) in one of the NRNT devices (High pressure high temperature).

Claims (1)

A device for evacuating graphite powder for diamond synthesis, containing a vacuum chamber with means for supplying and controlling air pressure, characterized in that it is equipped with a dispensing sleeve for the initial powder with a volume of 100 cm ³ and a receiving sleeve for collecting the finished powder, which are mounted in a vacuum chamber, the axis of the sleeves are located on one straight line, perpendicular to the horizon line, while the sleeves are equipped with remotely controlled vacuum tight covers, and the volume of the vacuum chamber is 1 m ³ .

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