CN115140732B - Diamond preparation device and diamond preparation method thereof - Google Patents
Diamond preparation device and diamond preparation method thereof Download PDFInfo
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- CN115140732B CN115140732B CN202210526044.2A CN202210526044A CN115140732B CN 115140732 B CN115140732 B CN 115140732B CN 202210526044 A CN202210526044 A CN 202210526044A CN 115140732 B CN115140732 B CN 115140732B
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/25—Diamond
- C01B32/26—Preparation
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
- C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
- C25C3/02—Electrolytic production, recovery or refining of metals by electrolysis of melts of alkali or alkaline earth metals
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/36—Hydrogen production from non-carbon containing sources, e.g. by water electrolysis
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Abstract
The diamond preparing apparatus includes one sealed electrolytic tank with anode chamber and anode chamberA graphite electrode is arranged in the anode chamber, and an exhaust pipe and a drain pipe are arranged in the anode chamber; a cathode rod is arranged in the cathode chamber, and a hanging basket is arranged on the cathode rod; the connecting cathode chamber is provided with a blow-down pipe and an argon inlet pipe; the electrolytic tank is also internally provided with a pipe ring with air holes, and the connecting pipe ring is provided with an air duct which extends out of the electrolytic tank and is provided with a second flow measuring instrument; the air duct is connected with the blow-down pipe through a circulating pipe, and the circulating pipe is sequentially provided with a circulating pump, a first flow measuring instrument and a heat exchanger; the electrolytic tank is provided with a feeding unit and a heating unit; a cooling system is arranged outside the electrolytic tank. The invention can control the reaction speed by controlling the electrolysis current or the concentration of carbon tetrachloride in the circulating gas, and can ensure that the diamond crystal seed surface is orderly connected with sp 3 The hybridized carbon atoms are combined to obtain large-particle and high-quality diamond crystals.
Description
Technical Field
The invention belongs to the technical field of superhard materials, and particularly relates to a diamond preparation device and a diamond preparation method thereof.
Background
Natural diamond, not only an advanced ornament, but also the hardest working tool and wear-resistant material, is unfortunately extremely scarce. For this reason, the theory and practice of synthetic diamond has been greatly developed since the first success of diamond synthesis by humans in 1953. The existing method for producing artificial diamond can be divided into 3 classes, (1) the generation condition of the simulated natural diamond, and graphite is allowed to produce high-temperature and ultrahigh-pressure artificial diamond at high temperature and ultrahigh pressure or by utilizing explosive explosion; (2) alkane or carbon dioxide is used as a carbon source, and carbon separated out by reaction is firstly adsorbed and dissolved in catalytic metal to be regenerated into diamond under the conventional pressure at about 1000 ℃; (3) the diamond is prepared by taking tetrahalocarbon and alkali metal as raw materials and utilizing the Wuz reaction at 700 ℃ under normal pressure.
Both (1) and (2) are industrialized, and large-particle diamond can be obtained, but the problems of harsh reaction conditions, low diamond phase yield and high manufacturing cost exist. The reason for this is that the reaction of graphite to diamond is "non-spontaneous reaction" at normal temperature and pressure, and the Δg and activation energy Δe values of the reaction are large. (3) The reaction Δg is negative and the activation energy Δe is much smaller, so that the reaction speed can occur at 700 ℃ and normal pressure, and an explosion can be caused by carelessness, and the reaction is easy to be carried out, so that the reaction speed is too fast, the diamond yield is only 2%, and only nano-scale diamond grains can be produced. The reason for this is that the halogenated hydrocarbon and the alkali metal are simply mixed and heated, and a problem of 'can effectively control the reaction speed and leave reasonable growth time for the diamond seed crystal' is not designed.
In addition, (1) the so-called "high temperature and high pressure" is not separated from the molten material such as pyrophyllite, and (2) the "molten state of catalytic metal" is required, and can be regarded as providing a "rotating and turning" free space for carbon atoms. While (3), while also having "molten metal", is also a highly "reactive" reactant, it is not possible to provide sufficient "spin, flip" crystallization time for the diamond-forming precursor. Most of the current artificial diamond technologies are operated intermittently, and human resources and energy sources are wasted greatly.
Disclosure of Invention
The invention aims to provide a diamond preparation device and a diamond preparation method thereof, which can prepare diamond by carbon tetrachloride and lithium chloride-potassium chloride fusion electrolysis method, realize effective control of the reaction speed of halogenated hydrocarbon and liquid lithium, and lead precursor molecules forming diamond to be formed
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Can "freely rotate and turn" in the lithium chloride-potassium chloride molten salt, thereby enabling sp 3 Maintaining sp of carbon atoms 3 The hybridized state is orderly assembled into a diamond structure, so that the purposes of safe production and large-particle and high-quality diamond products can be achieved.
The technical scheme adopted by the invention for achieving the purpose is as follows:
The diamond preparation device comprises a closed electrolytic tank, wherein an anode chamber and a cathode chamber are arranged in the electrolytic tank:
a graphite electrode is detachably arranged in the anode chamber, and an exhaust pipe for discharging electrolytic gas and a drain pipe for discharging graphite powder are arranged in the anode chamber;
a cathode rod is detachably arranged in the cathode chamber, and a hanging basket for collecting the prepared diamond is arranged on the cathode rod;
the connecting cathode chamber is provided with a blow-down pipe for exhausting tail gas and an argon inlet pipe for introducing argon into the cathode chamber;
a pipe ring with air holes is also arranged in the electrolytic tank, and a connecting pipe ring is provided with an air duct which extends out of the electrolytic tank and is used for introducing carbon tetrachloride;
the gas guide pipe is connected with the blow-down pipe through a circulating pipe so that gas in the electrolytic tank can circulate along the electrolytic tank, the blow-down pipe, the circulating pipe and the gas guide pipe, a circulating pump, a first flow measuring instrument and a heat exchanger for adjusting the temperature of the gas flowing in the circulating pipe are sequentially arranged on the circulating pipe, and a second flow measuring instrument is arranged on the gas guide pipe;
the electrolytic tank is provided with a feeding unit for adding lithium chloride-potassium chloride mixed materials into the electrolytic tank and a heating unit for heating substances in the electrolytic tank;
The outside of the electrolytic tank is provided with a cooling system which is convenient for stabilizing the reaction temperature in the electrolytic tank.
Further, the electrolytic tank comprises a column casing, a flange plate I arranged at the top of the column casing and used for sealing the column casing, and a cone casing connected with the column casing and arranged below the column casing:
the cylindrical barrel is coaxially provided with a cylindrical barrel I with an open lower end, the anode chamber is formed by the inner periphery of the cylindrical barrel I, the graphite electrode is arranged in the cylindrical barrel I, and the cathode chamber is formed by the outer periphery of the cylindrical barrel I and the cylindrical barrel;
the lower end of the cone cylinder is provided with an outlet pipe, and the outlet pipe is provided with a switch valve.
Further, a cylindrical barrel II communicated with the cathode chamber is arranged on the flange I, a cylindrical barrel III is arranged on the cylindrical barrel II, a knife switch valve capable of blocking the communication between the cylindrical barrel III and the cathode chamber is arranged between the cylindrical barrel II and the cylindrical barrel III, and the cathode rod penetrates through the cylindrical barrel III and the cylindrical barrel II and stretches into the cathode chamber; the argon gas inlet pipe is arranged on the cylinder III.
Further, the cylinder II is provided with a plurality of cylinders, and a plurality of cylinders II are arranged on the flange I at equal intervals around the cylinder I, and correspondingly, the cylinder III and the cathode rod are provided with a plurality of cylinders in one-to-one correspondence with the cylinder II.
Further, the flange I is provided with an auxiliary electrode which is positioned outside the cylinder II and inside the cylinder and used for forming an electrode pair with the cylinder so as to detect the position of the molten salt liquid level in the electrolytic tank.
Further, the device also comprises a pressure tank for providing carbon tetrachloride, wherein the pressure tank is connected with the air guide pipe through an eduction pipe, and a bypass with a peristaltic pump is arranged on the eduction pipe.
Further, a plurality of layers of crystal filtering screens with sequentially reduced apertures from top to bottom are arranged in the hanging basket.
Further, one end of the drain pipe and the exhaust pipe, which are positioned outside the electrolytic tank, are respectively provided with an absorption barrel, a float valve is arranged in the absorption barrel, a charging port and a vacuum pump for vacuumizing the absorption barrel are arranged on the absorption barrel, and a connecting pipe for connecting the exhaust pipe with an air compressor is arranged.
A method of producing diamond comprising the steps of:
(1) Firstly adding a half amount of lithium chloride-potassium chloride mixture into an electrolytic tank, circularly drying air in the electrolytic tank at 200 ℃ by using a heating unit and a circulating pump, heating to 400 ℃, adding the rest half amount of lithium chloride-potassium chloride mixture into the electrolytic tank, cooling the outer wall of the electrolytic tank to form a solidified molten salt layer on the inner wall of the electrolytic tank, and then removing oxygen in the electrolytic tank by vacuumizing and filling argon;
(2) After argon in the electrolytic tank is fully circulated, gradually adding carbon tetrachloride into the gas guide pipe under the condition of vacuumizing the electrolytic tank, starting a graphite electrode and a cathode rod to electrolyze the mixture, and intermittently supplementing anhydrous lithium chloride into the electrolytic tank in the electrolysis process;
(3) And after the electrolysis is finished, taking out the hanging basket, putting the hanging basket into absolute ethyl alcohol, collecting diamond particles generated by the electrolysis, and washing, filtering and drying the diamond particles to obtain diamond crystals.
Further, the process of adding carbon tetrachloride in (2) is as follows: and adding carbon tetrachloride into the gas guide tube by utilizing the peristaltic pump, slowly increasing the rotating speed of the peristaltic pump, and simultaneously maintaining the flow difference between the second flow measuring instrument and the first flow measuring instrument to be less than 0.2-0.5L/h until the carbon tetrachloride is completely reacted.
The invention has the beneficial effects that:
1. the invention takes part in the reaction by controllable newly generated metallic lithium, avoids the blocking effect of 'oxide film' generated on the surface of the metallic lithium on the reaction, omits the removal of the oxide film, and the newly generated metallic lithium and the metallic lithium dissolved in molten salt can take part in the reaction in an atomic state, thereby having good product quality, safe production, less by-product amorphous carbon and relatively approaching to clean production.
2. The invention has certain solubility of tetralithium carbide and carbon tetrachloride in molten salt, and in the reaction for preparing diamond, the process of building block assembly is actually adopted, and the addition of the reactants of lithium metal and carbon tetrachloride is controllable, so that the growth speed and high yield of diamond are effectively ensured, 0.24g of diamond can be produced per hour, and the maximum value of the method is 95.32 times of that of the traditional method.
3. The invention has the operating temperature of 430+/-5 ℃ and relatively loose operating conditions, not only can greatly prolong the service life of equipment, but also can continuously run and stop the reaction at any time according to the requirement, and is stopped for maintenance.
Description of the drawings:
fig. 1 is a schematic view of the overall structure of a diamond preparation apparatus according to an embodiment;
FIG. 2 is an enlarged schematic view of the structure at B in FIG. 1;
FIG. 3 is an enlarged schematic view of FIG. 1 at C;
FIG. 4 is an enlarged schematic view of the structure of FIG. 1 in the E direction at D;
FIG. 5 is a schematic top view of the cross-section A-A' of FIG. 1;
fig. 6 is a schematic structural view of a float valve in the diamond manufacturing apparatus according to the embodiment;
fig. 7 is a schematic structural view of a basket in the diamond manufacturing apparatus according to the embodiment;
fig. 8 is a schematic front view of a cooling jacket in a diamond manufacturing apparatus according to an embodiment.
The marks in the figure: 100. the electrolytic tank, 101, column casing, 102, cone casing, 103, outlet pipe, 104, rotary shaft switching valve, 105, column casing V, 106, filter screen barrel, 107, movable handle, 108, filter screen, 109, molten salt outlet pipe, 110, column casing I, 111, quartz glass cylinder, 112, gas-guide pipe, 113, cooling jacket supporting ear I, 114, graphite electrode, 115, tee I, 120, cathode rod, 121, argon inlet pipe, 122, gas-guide pipe, 123, terminal, 124, glass two-way plug I, 125, absorption barrel, 126, glass two-way plug II, 127, switching valve VI, 128, sodium hydroxide solution, 129, sight glass II, 130, float valve, 131, anode chamber, 132, cathode chamber, 133, drain pipe, 134, glass tee, 135, feed inlet, 136, vacuum pump, 137, interface, 138, sealing interface, 139, water, 140, basket, 141, feed pipe 142, feed inlet, 143, pipe rings, 144, molten salt liquid level, 145, cooling jacket supporting ear II, 150, check valve I, 151, cooling water inlet I, 152, heat exchanger, 153, switch valve II, 154, first flow measuring instrument, 155, circulating pump, 156, switch valve III, 157, tee II, 158, second flow measuring instrument, 159, carbon tetrachloride content measuring instrument, 160, check valve II, 161, peristaltic pump, 162, switch valve IV, 163, reducing tee I, 164, carbon tetrachloride lead-out pipe, 165, vent valve, 166, carbon tetrachloride inlet valve, 167, pressure gauge, 168, level gauge, 169, pressure tank, 170, reducing tee II, 171, tee III, 172, switch valve V, 173, safety valve, 174, tee IV, 175, blow-down pipe, 201, zero line, 202, temperature measuring probe, 203, convection hole, 204, cylinder IV, 205, fire wire, 206, asbestos pad, 207, insulating jacket, 208. washers, 209, nuts iii, 210, arc heaters, 211, thermometer probes, 300, tail gas outlets, 301, flanges i, 302, flanges ii, 303, glass flanges iii, 304, flanges iv, 305, flanges v, 306, flanges vi, 307, flanges vii, 308, glass flanges viii, 310, cylinders ii, 311, knife valves, 312, lug rings, 313, shafts i, 314, springs, 315, cylinders iii, 320, glass flanges ix, 321, long bolts, 322, stainless steel gaskets, 323, second set of nuts, 324, nuts on cathode, 325, glass flanges x, 326, expanded graphite, 327, stainless steel rims, 330, nuts ii, 331, rim protrusions, 332, drain piping rims, 333, flexible washers, 334, nuts i, 335, gaps, 340, auxiliary electrodes, 401, flanges I, 402, worm and gear driving devices, 403, heat insulation couplings, 404, conical cylinders, 405, sight glass I, 406, charging port covers, 407, buckles, 408, end socket covers, 410, airtight balls, 411, swivel balls, 412, rotating shafts III, 413, material pits, 501, cooling water inlets II, 502, cooling water outlets II, 503, water tee I, 504, double-half-cylinder cooling jackets, 505, first fixed edges, 601, limit bolts, 602, gas outlet holes, 603, hollow floats, 604, plugging balls, 605, positioning protrusions, 606, glass tubes, 701, frames, 702, crystal filtering screens, 703, suspension arms, 801, cooling water inlets III, 802, cooling water outlets III, 803, water tee II, 804, double-half-cone cooling jackets, 805, second fixed edges.
Detailed Description
The invention will be further described with reference to the drawings and detailed description, wherein, unless otherwise indicated, the meaning of "a plurality" is two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front," "rear," "head," "tail," and the like are used as an orientation or positional relationship based on that shown in the drawings, merely to facilitate description of the invention and to simplify the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be construed as limiting the invention. Furthermore, the terms "first," "second," "third," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
The invention provides a specific embodiment of a diamond preparation device, which comprises:
as shown in fig. 1 to 8, the diamond manufacturing apparatus of the present embodiment includes a closed electrolytic cell 100, an anode chamber 131 and a cathode chamber 132 are provided in the electrolytic cell 100, a graphite electrode 114 is detachably provided in the anode chamber 131, an exhaust pipe 122 and a drain pipe 133 are provided in communication with the anode chamber 131, the exhaust pipe 122 is used for exhausting electrolytic gas, and the drain pipe 133 is used for exhausting graphite powder.
A cathode rod 120 is provided in the cathode chamber 132, the cathode rod 120 is made of 304 stainless steel, and a basket 140 for collecting the prepared diamond is provided on the cathode rod 120.
The electrolytic cell 100 is composed of a stainless steel column 101 and a conical barrel 102, a flange I301 at the upper end of the column 101 is connected with a flange II 302 through bolts, a round hole K with the diameter of d1 is formed in the center of the flange II 302, a cylindrical barrel I110 is arranged on the outer side of the round hole K, the inner diameter of the cylindrical barrel I110 is larger than d1, the upper end of the cylindrical barrel I110 is welded and connected with the lower surface of the flange II 302, the lower end of the cylindrical barrel I110 is located below the junction of the stainless steel column 101 and the conical barrel 102, and a quartz glass cylinder 111 with the outer diameter slightly smaller than d1 and the outer turned-over upper end is placed in the round hole K (hereinafter, the glass is quartz glass or high-boron glass). The flexible washer 333 is arranged on the upper part, the outer part and the lower part of the flanging of the glass cylinder 111, the flexible washer 333 is made of asbestos, an expanded graphite pad can be adopted when electric insulation is not needed, and the lower end of the glass cylinder 111 is retracted by about 2cm than the cylinder I110 so as to ensure that carbon tetrachloride vapor does not overflow to an anode region.
The flange plate iii 303 is a glass disc, a circular hole KY with a diameter d2 is provided in the center thereof for fixing the terminal 123 of the graphite electrode 114, two sides with a diameter slightly smaller than the inner diameter of the glass cylinder 111 around KY are respectively provided with a circular hole KCL and KCF, the circular hole KCL is used for connecting the discharge tube 122 made of glass, the discharge tube 122 is already sleeved with two opposite outer spinnerets before being turned up at both ends, the diameter of the lower half section of the circular hole KCL is the same as the inner diameter of the discharge tube 122, the diameter of the upper half section is the same as the outer diameter of the discharge tube turned up 332, and the discharge tube 122 is used for discharging chlorine.
The round hole KCF is used for fixing the drain pipe 133, the drain pipe 133 is used for discharging graphite powder in the electrolytic tank, the drain pipe 133 is sleeved with two outer spinning heads with opposite directions, the outer diameter of the drain pipe 133 is slightly smaller than the inner diameter of the lower part of the KCF, the inner diameter of the upper part of the KCF is larger than the outer diameter of the drain pipe 133 by a space of a soft sealing ring, namely the soft sealing ring is arranged between the drain pipe 133 and the upper part of the KCF.
Two impervious pits KD are symmetrically arranged on the upper plane of the flange III 303 and between the two sides of the round hole KY and between the KCL and the KCF, a flange IV 304 is further arranged on the flange III 303, the inner diameter of the flange IV is the same as that of the round hole KY, the pits KD can accommodate a disc protrusion 331 arranged on the lower plane of the flange IV 304, and the disc protrusion 331 is used for preventing the flange IV 304 from rotating.
The terminal 123 of the graphite electrode 114 is a copper metal rod with a wire at one end, the wire section is divided into two parts along the central axis, the gap 335 is used as a thermal expansion gap, one end of the wire is sleeved with a nut I334, then connected with the upper wire port of the graphite electrode 114, the upper plane of the nut I334 is flush with the upper plane of the graphite electrode 114, the wire-free end of the terminal 123 of the graphite electrode 114 sequentially spans the elastic pad, the flange III 303 and the flange IV 304 from bottom to top, the SKL, the KCL and the SKF are aligned with the KCF, the nut II 330 is used for fixing, the flange III 303 and the quartz glass cylinder 111 are connected and fixed with reserved wire holes of the flange II 302 by using a nut-free bolt, an elastic gasket is respectively plugged into the KCL and the KCF, an expanded graphite pad is sleeved in the outer flanging of the discharge pipe 122 and the discharge pipe 133, and then the expanded graphite pad is respectively inserted into the holes through the SKL, the KCL and the SKF, the F, and the KCF, and the discharge pipe 133, after the SKL and the predetermined ends are properly screwed down, the SKL and the flange III are arranged, and the quartz glass cylinder 111 are formed inside the electrolytic chamber 131.
The end of the drain pipe 133 and the exhaust pipe 122 outside the electrolytic tank 100 is respectively provided with an absorption barrel 125, a float valve 130 is arranged in the absorption barrel 125, a charging port 135 and a vacuum pump 136 for vacuumizing the absorption barrel 125 are arranged on the absorption barrel 125, and a connector pipe 137 for connecting with an air compressor is arranged on the connection exhaust pipe 122.
The drain pipe 133 is provided with a glass two-way plug ii 126, and is connected with the absorption barrel 125 through the sealing interface 138, water 139 is provided in the absorption barrel 125, the float valve 130 adopts a polytetrafluoroethylene float valve, the upper end of the float valve is located below the water surface in the absorption barrel 125, as shown in fig. 6, the float valve 130 comprises a glass pipe 606 for connecting with a pipeline, a hollow float 603 extending out of the lower end is provided in the glass pipe 606, a blocking ball 604 is provided on the float 603, a positioning protrusion 605 is provided at the top end of the blocking ball 604, a gas outlet 602 and a limit bolt 601 are provided at the lower end of the float 603, and the float valve is closed by using a "buoyancy force" to make a "closing compression spring" so that the reaction product chlorine can only be discharged, once negative pressure appears, the float valve can be closed immediately, and water can not enter the system in a large amount, even if a small amount of water is mixed into the float valve, and the chlorine after drying can be carried out of the system.
The chlorine discharge pipe 122 is provided with a glass tee 134, a glass two-way plug I124 and an absorption barrel 125 which is connected with the exhaust pipe 122 through a sealing interface 138, the absorption barrel 125 is used for containing sodium hydroxide solution 128, the float valve 130 is still a polytetrafluoroethylene float valve, the upper end of the float valve is positioned below the liquid level of the sodium hydroxide solution in the absorption barrel 125, a branch pipe of the glass tee 134 is connected with an air compressor interface pipe 137, and the interface pipe 137 is provided with a valve.
The side of the absorption barrel 125 is provided with a sight glass II 129, the upper cover of the absorption barrel 125 is connected with the barrel body by a flange, the upper cover of the absorption barrel 125 is also provided with a switch valve VI 127 and a charging port 135 which are connected with a vacuum pump 136, and the corresponding pipeline is fixed on the upper cover of the absorption barrel 125 by a sealing interface 138.
And n uniformly distributed round holes KF are also arranged outside the central round hole of the flange plate II 302. The outer edge vertical lines of n KF holes fall in the stainless steel cylinder 101, the minimum distance between the vertical lines and the inner wall of the stainless steel cylinder 101 is not less than 5cm, a cylinder II 310 with a flange plate 305 at the upper end and the same as the inner diameter of the round KF is welded on the n uniformly distributed round KF, a cylinder III 315 with flanges VI 306 and VII 307 at two ends is arranged on the flange V305 at the upper end of each cylinder II 310, a spring 314 is arranged on a connecting bolt of the flange V305 and the flange VI 306, namely, the distance between the flange rings is allowed to change, two lugs 312 are further arranged between the flange rings 312, the inner diameter of the lug rings 312 is the same as that of the cylinder II 310 and the cylinder III, ears of the lug rings are welded, a knife switch 311 is positioned under the round rings, the upper ring is tilted up and the lower ring, the knife is positioned through a rotating shaft I313, the knife switch 311 is also provided with two asymmetric handles, the two flanges VI 306 and the knife rings are positioned by the rotating shaft I313, and the two flanges are conveniently inserted into the flanges 315, and the flange rings can be conveniently inserted into the flanges 312 when the two flanges are not connected with the flanges 315, and the flange rings are conveniently inserted into the flanges.
The connection cathode chamber 132 is equipped with the argon gas import pipe 121 of letting in argon gas, and argon gas import pipe 121 sets up in the upper portion side of cylinder III 315, is equipped with the ooff valve on the argon gas import pipe 121, and the reducing interface that one and the II export of argon gas steel bottle are matchd is connected to the other end of ooff valve, is convenient for let in argon gas, fills up an elastic washer on the upper end ring flange VII 307 of cylinder III 315, puts in proper order ring flange VIII 308 and ring flange IX 320 of glass material to fix them together with 3 or 4 long bolts 321.
Wherein, an everting stainless steel rim 327 is arranged on the inner aperture of the flange VIII 308, the inner diameter of the stainless steel rim 327 is slightly larger than the outer diameter of the cathode rod 120, the inner diameter of the flange IX 320 is 6 cm to 8cm larger than the outer diameter of the cathode rod 120, expanded graphite 326 is filled in the gap between the flange IX 320 and the cathode 120, the expanded graphite 326 has elasticity, the sealing of the system can be realized, the corrosion of lithium vapor and carbon tetrachloride can be prevented, then a stainless steel gasket 322 with a downward tilted edge is sleeved on the cathode 120, the outer diameter of the stainless steel gasket 322 is slightly smaller than the inner diameter of the flange IX 320, a flange X325 made of glass material is sleeved on the cathode rod 120, and a second set of nuts 323 of long bolts 321 and nuts 324 on the cathode are screwed tightly, thus, the cathode chamber 132 of the electrolytic cell 100 is formed below the flange VII 307, in the cylinder II 310 and III and between the cylinder I110 and the stainless cylinder 101.
After the lower end of the cathode rod 120 is directly inserted to about 2cm below the molten salt liquid level 144 in the electrolytic tank, the two arms 703 of the hanging basket 140 are connected through a horizontal cross rod, a plurality of layers of crystal filtering screens 702 with frames 701 are arranged on the two arms 703 of the hanging basket 140 up and down, the diameters of holes of the crystal filtering screens 702 are sequentially reduced from top to bottom, for example, a plurality of layers of crystal filtering screens 702 are sequentially arranged from top to bottom for 40 meshes, 60 meshes, 100 meshes, 160 meshes and 200 meshes, so that carbon tetrachloride gas can be uniformly distributed.
The side wall of the upper end of the stainless steel column 101 is provided with a carbon tetrachloride-argon tail gas outlet 300, a vent pipe 175 for discharging tail gas is arranged in the connection cathode chamber 132, a tee joint III 171 and a safety valve 173 are sequentially arranged on the vent pipe 175, a branch pipe of the tee joint III 171 is connected with a switch valve V172 and then is turned upwards by 90 degrees, a tee joint IV 174 and the vent pipe 175 are sequentially connected, and a branch pipe of the tee joint IV 174 is communicated with a branch pipe of the safety valve 173 through a pipeline.
The electrolytic tank 100 is also internally provided with a pipe ring 143 with air holes, the connecting pipe ring 143 is provided with an air duct 112 which extends out of the electrolytic tank 100 and is used for introducing carbon tetrachloride, the air outlet holes of the pipe ring 143 are distributed under the pipe ring, molten salt which invades the pipe ring 143 can be discharged at any time, a stainless steel bar is welded on the pipe ring 143 at a position 180 degrees with the air duct 112, and the other end of the stainless steel bar is welded on the inner wall of the stainless steel cylinder 101.
The air duct 112 is connected with a pressure tank 169 for adding carbon tetrachloride through a carbon tetrachloride delivery pipe 164, an inlet of the carbon tetrachloride delivery pipe 164 is directly inserted below the carbon tetrachloride liquid level in the pressure tank 169, two reducing tee joints are arranged on the carbon tetrachloride delivery pipe 164 and are respectively a reducing tee joint I163 and a reducing tee joint II 170, a bypass branch pipe is connected with the two reducing tee joints, a peristaltic pump 161 is connected in series on the bypass, a switch valve IV is arranged between the two reducing tee joints, an exhaust valve 165, a carbon tetrachloride inlet valve 166 and a pressure gauge 167 are further arranged on an upper cover of the pressure tank 169, and a liquid level meter 168 is arranged on the side face of the pressure gauge.
After the carbon tetrachloride delivery pipe 164 is connected with the air duct 112, a second flow measuring instrument 158, a carbon tetrachloride content measuring instrument 159 and a one-way valve II 160 for detecting carbon tetrachloride-argon flow are sequentially arranged on the pipeline, in order to realize gas circulation in the electrolytic tank, the air duct 112 is connected with a tee joint I115 arranged on a blow-down pipe 175 through a circulating pipe, so that gas in the electrolytic tank 100 can circulate along the electrolytic tank 100, the blow-down pipe 175, the circulating pipe and the air duct 112, a circulating pump 155, a first flow measuring instrument 154, a heat exchanger 152 for adjusting the temperature of flowing gas in the circulating pipe and a one-way valve I150 are sequentially arranged on the circulating pipe, a switch valve III 156 and a tee joint II 157 are sequentially arranged between the outlet of the circulating pump 155 and the first flow measuring instrument 154, and the carbon tetrachloride delivery pipe 164 is connected with the tee joint II 157.
The electrolytic cell 100 is provided with a feeding unit for feeding a lithium chloride-potassium chloride mixture into the electrolytic cell 100 and a heating unit for heating the contents of the electrolytic cell 100.
When the electrolytic bath 100 is arranged, as shown in fig. 4, the middle part of the side wall of the stainless steel cylinder 101 forms a 30-degree direction with the bus of the stainless steel cylinder 101, a feeding hole 142 of lithium chloride and potassium chloride is arranged, the feeding hole is connected with the feeding unit through a feeding pipe 141 and a flange I401, the feeding unit adopts an airtight feeding device, a system for strictly preventing trace lithium vapor and carbon tetrachloride from overflowing is adopted, the outer shell of the airtight ball 410 is connected with the upper flange plate of the flange I401, a rotary ball 411 is sleeved in the airtight ball 410, two symmetrical pits 413 are arranged in the vertical direction of the spherical center of the rotary ball 411, a rotary shaft III 412 fixed with the rotary ball is arranged on the horizontal diameter of the rotary ball 411, two ends of the rotary shaft III 412 are fixed on the outer shell of the airtight ball through bearings, one end of the rotary shaft III is connected with a heat insulation coupler 403 through a fixed flange, and the heat insulation coupler 403 is connected with a worm gear driving device 402.
An upper fixed hole 414 and a lower fixed hole 414 which can be in butt joint and communicated with the rotary hole 416 are also arranged on the shell of the airtight ball 410, a conical cylinder 404 for containing lithium chloride is connected on the shell of the airtight ball 410, a sight glass I405 is arranged on the side face of the cylinder of the conical cylinder 404, the top face is connected with a seal head cover 408 which is convenient to detach by a buckle, and a circular charging cover 406 made of glass material is arranged in the center of the seal head cover 408 so as to observe the quantity of lithium chloride and is also connected with the seal head cover 408 by the buckle 407.
When the heating unit is arranged, 2 circular holes KJ for installing an arc heater are symmetrically reserved on the side surface of the conical barrel 102, the inner diameter of each circular hole KJ is matched with an interface of the arc heater and used for starting electrolytic reaction and maintaining the reaction temperature of the invention, the arc heater is shown in figure 2, an insulating porcelain sleeve 207, a gasket 208 and an asbestos pad 206 are arranged between two electrodes of a live wire 205 and a zero wire 201 and an interface end plate thereof, the insulating porcelain sleeve 207 and the gasket 206 are fixed by screws and nuts 209, the zero wire electrode 201 is a hollow pipe, a temperature measuring probe 202 is arranged in the hollow pipe so as to be convenient for monitoring the reaction temperature of each link in electrolysis, the temperature measuring probe 202 is fixed at the outer end of the electrolytic tank 100 of the hollow pipe in a wire opening connection mode, one end of the electrolytic tank 100 of the hollow pipe is closed, an outer wire is arranged on the end of an electrode of a live wire of the electrolytic tank 100 for initiating an arc, a convection hole 203 is arranged on the side wall of the cylindrical barrel IV 204 and is used as a molten electrolyte channel, and the convection hole 203 is sleeved at the end of the hollow pipe at the electrolytic tank at equal interval, so that the large convection area is beneficial to heat conduction and heat transfer.
An auxiliary electrode 340 insulated from the cylinder II 310 and the stainless steel cylinder 101 is arranged on the flange II 302, the lower end of the auxiliary electrode 340 is positioned 1cm above the upper edge of the hanging basket 140, and the auxiliary electrode 340 and the stainless steel cylinder 101 form an electrode pair for detecting the liquid level position of molten salt.
A horn-shaped outlet pipe 103 is connected to the lower end of the conical barrel 102, the outlet pipe 103 is connected with a rotary shaft switch valve 104 through a flange, the rotary shaft switch valve 104 is sequentially connected with a cylindrical barrel V105 and a crystal filtering screen barrel 106 through a flange, the crystal filtering screen barrel 106 is connected with a molten salt outlet pipe 109 through a flange, a crystal filtering screen 108 of the crystal filtering screen barrel 106 is clamped between the flanges, and the crystal filtering screen 108 is used for recovering and discharging fine diamond particles in molten salt.
In order to facilitate the regulation of the reaction temperature in the electrolytic tank 100, a cooling system arranged around the electrolytic tank 100 is arranged outside the electrolytic tank 100, as shown in fig. 5, a cooling jacket supporting lug I113 fixed on the column casing 101 is arranged outside the column casing 101, a double-half-column cooling jacket 504 arranged around the electrolytic tank 100 is connected to the cooling jacket supporting lug I113 through bolts, a layer of cooling layer is arranged outside the electrolytic tank 100, a first fixing edge 505 of the double-half-column cooling jacket 504 is connected to the cooling jacket supporting lug I113 through bolts, a water dividing tee I503 is arranged on the double-half-column cooling jacket 504, a cooling water inlet II 501 is arranged on the water dividing tee I503, the entering cooling water is divided into two paths through the water dividing tee I503, and after the two paths of cooling water are converged through another water dividing tee, the cooling water flows out through a cooling water outlet II 502 on the water dividing tee, so that the cooling of the electrolytic tank 100 is completed.
Referring to fig. 8, a cooling jacket supporting lug ii 145 is disposed on the outer side of the conical cylinder 102, a double half-cone cooling jacket 804 is disposed on the cooling jacket supporting lug ii 145 by bolting, a second fixing edge 805 of the double half-cone cooling jacket 804 is connected with the cooling jacket supporting lug ii 145, a water diversion tee joint ii 803 is disposed on the double half-cone cooling jacket 804, a cooling water inlet iii 801 is divided into two paths by the water diversion tee joint ii 8033, and the cooling water inlet iii 801 and the cooling water outlet iii 802 on the upper portion of the double half-cone cooling jacket 804 are respectively led.
The cooling water channel of the heat exchanger 152 is introduced from a cooling water inlet i 151, the cooling water outlet may be connected to a cooling water inlet ii 501 of a double-half-column cooling jacket 504 installed on the outer side of the column casing 101, the cooling water outlet ii 502 of the double-half-column cooling jacket 504 is connected to a cooling water inlet iii 801 of a double-half-cone cooling jacket 804 installed on the outer side of the conical casing 102, and hot water discharged from the cooling water outlet iii 802 is cooled by a cooling water tower and recycled.
In this embodiment, the diameter of the cylindrical barrel 101 of the electrolytic cell 100 is 20cm, the height of the cylindrical barrel is 18cm, the height of the conical barrel 102 is 8.8cm, the diameter of the anode chamber is 4.2cm, the diameter of the graphite electrode 114 is 2.6cm, the volume of the electrolytic cell 100 is 6576.4 when immersed in about 6cm below the molten salt level 144 cm 3 When in use, the molten salt holding volume is 3970.85cm 3 。
The molten salt contained therein had a mass of about 8017.75g, of which 3567g (purity: 99.75%) and 4450g (purity: 98.5%) of potassium chloride.
The tank voltage is 7.48V, the current is 2.15A, the carbon tetrachloride flow rate is 1.54g/h, the lithium chloride supplement amount is 1.70g/h, the circulating argon flow rate is 16.55L/h, and the gas carbon tetrachloride concentration is 2.65%.
The invention also provides a diamond preparation method, which is carried out by using the diamond preparation device and mainly comprises the following steps:
(1) Firstly adding a half amount of lithium chloride-potassium chloride mixture into the electrolytic tank 100, circularly drying air in the electrolytic tank 100 at the temperature of 200 ℃ by utilizing a heating unit and a circulating pump 155, heating to 400 ℃, adding the rest half amount of lithium chloride-potassium chloride mixture into the electrolytic tank 100, cooling the outer wall of the electrolytic tank 100 to form a solidified molten salt layer on the inner wall of the electrolytic tank 100, and then removing oxygen in the electrolytic tank 100 by vacuumizing-filling argon, wherein firstly adding a half amount of material, and then immersing an 'electrolytic cathode-anode' after the lithium chloride-potassium chloride is melted, and then sequentially adding rest molten salt mixed solids, wherein the melting process absorbs heat, thereby being capable of reducing cooling load, saving 'alternating current energy' and cooling quantity in the later stage of electrolysis.
(2) After argon in the electrolytic tank 100 is fully circulated, carbon tetrachloride is gradually added into the gas guide pipe 112 under the condition of vacuumizing the electrolytic tank 100, a graphite electrode 114 and a cathode rod 120 are started to electrolyze the mixture, specifically, the peristaltic pump 161 is utilized to add carbon tetrachloride into the gas guide pipe 112, the rotating speed of the peristaltic pump 161 is slowly increased firstly, meanwhile, the difference between the flow rates of the first flow meter 154 and the second flow meter 158 is maintained to be less than 0.2-0.5L/h until the carbon tetrachloride is fully reacted, and anhydrous lithium chloride is intermittently added into the electrolytic tank 100 in the electrolytic process.
(3) After the electrolysis is completed, the hanging basket 140 is taken out and put into absolute ethyl alcohol to collect diamond particles generated by the electrolysis, and the diamond crystals are obtained after washing, filtering and drying.
In practice, the preparation comprises the following detailed preparation process:
first, prepare work
1. Checking the air tightness of the device: the switch valve I121, the glass two-way plug I124, the glass two-way plug II 126, the rotating shaft switch valve 104, the carbon tetrachloride inlet valve 166 and the switch valve V172 are closed, and the air compressor interface valve 137, the switch valve IV 162, the switch valve II 153 and the switch valve III 156 are opened. Both the carbon tetrachloride-argon gas flow meter 158 and the tail gas flow meter 154 are set to maximum flow values. The outlet of the air compressor is connected to the air compressor interface pipe 137, the argon steel cylinder I is connected to the exhaust valve 165, the dried air is pumped in from the inlet end of the air compressor interface valve 137, the pressure of the pressure gauge 167 is enabled to be 0.12MPa, the air compressor interface valve 137 is closed, the pressure value of 2min is not reduced, the related switch valve is closed, and the air leakage point is checked and removed in parts until the system is free from air leakage.
2. Adding molten salt electrolyte: the connecting flange I401 of the conical column casing 404 is disassembled, 3567g of lithium chloride and 4450g of potassium chloride are taken, and after being stirred and mixed uniformly, about half of the lithium chloride-potassium chloride mixture is added into the electrolytic tank 100.
3. Dehumidification and drying of the electrolytic cell 100: the circulation pump 155 and the arc heater 210 are started, the control temperature of the temperature controller connected with the thermometer probe 211 is set to be 200 ℃, the temperature rising speed is 15 ℃/h, the heat preservation time at 200 ℃ is 2h, after heat preservation is carried out for 1h, the connecting flange I401 of the feed cylinder 404 is restored, and the outlet of the switch valve I121 is opened. After 1h, the water vapor content of the gas discharged from each outlet is checked in turn, the outlet is closed after no water vapor is detected, the switch valve I121 is closed, the switch valve V172 is opened, the control temperature of the temperature controller connected with the thermometer probe 211 is set to 430 ℃, the heating speed is 20 ℃/h, and meanwhile, the cooling water pump is started to allow cooling water to enter from the cooling water inlet I151 of the heat exchanger 152 and to exit from the cooling water outlet II 502 of the double-half-column cooling sleeve 504.
4. When the temperature rises to 400 ℃, the connecting flange I401 of the conical column casing 404 is disassembled again, the rest half amount of lithium chloride-potassium chloride mixture fully enters the electrolytic tank 100, the connecting flange I401 of the feed cylinder 404 is restored, the cooling water outlet II 502 of the double-half column cooling sleeve 504 is connected with the cooling water inlet III 801 of the double-half cone cooling sleeve 804, so that a solidified molten salt protective layer is formed on the inner wall of the electrolytic tank 100 by molten salt to protect refractory materials from being corroded by the molten salt, the service life of the refractory materials is prolonged, the water vapor content is checked at the outlet of the blow-down pipe 175 until the water vapor cannot be detected, and the next step is carried out.
5. Replacing air with argon gas, and removing oxygen in the electrolytic cell: the circulation pump 155 is closed, the argon steel cylinder II is connected to the argon inlet pipe 121, the switch valve V172 and the air compressor interface pipe 137 are closed, the glass two-way plug I124 is opened, the vacuum pump 136 is started for exhausting, the worm and gear driving device 402 is started, the rotary ball 411 is rotated until the vacuum degree is reduced to no more reduction, the glass two-way plug I124 and the vacuum pump 136 are closed, the exhaust valve 165 is opened, after the outlet valve of the argon steel cylinder I is loosened, the main valve is opened, the outlet valve of the argon steel cylinder I is slowly opened, argon is added into the electrolytic tank 100, the main valve of the argon steel cylinder I is closed after the pressure is 0.01MPa (namely slightly higher than the atmospheric pressure), the vacuumizing-argon filling process is carried out in this way, and after repeated times, the next step is carried out.
6. Checking whether the system 'dead angle' still contains oxygen: starting peristaltic pump 161, opening a feed port cover 406 of a charging barrel 404, opening an argon steel cylinder I total valve, discharging argon from an upper opening of the charging barrel 404, closing the feed port cover 406 after detecting no oxygen by an oxygen content detector, opening a switch valve V172, closing the switch valve V172 after detecting no oxygen by an oxygen content detector in a blow-down pipe 175, checking the oxygen content of discharged gas from an argon inlet pipe 121 in sequence in the same way, closing the argon steel cylinder I total valve after the oxygen content is not detected, and simultaneously closing the argon steel cylinder I total valve.
7. 1200g of anhydrous carbon tetrachloride is filled: the peristaltic pump 161, the switch valve IV 162 and the anhydrous carbon tetrachloride storage bottle are closed, the lower side surface of the anhydrous carbon tetrachloride storage bottle is provided with a lower mouth bottle with a glass three-way plug, the three-way plug is in an outer and side communicated state, a drying pipe (for introducing the atmosphere) is arranged at the upper mouth of the three-way plug, the main valve of the argon steel bottle I and the carbon tetrachloride inlet valve 166 are opened, the inlet of the carbon tetrachloride inlet valve 166 is connected with a connecting hose, and the other end of the hose is connected with the outlet of the glass three-way plug of the anhydrous carbon tetrachloride lower mouth bottle. Slowly opening an outlet valve of the argon steel cylinder I, and discharging argon from the glass three-way plug branch pipe. And closing the main valve and the outlet valve of the argon steel cylinder I. Disconnect argon cylinder i from vent valve 165. The anhydrous carbon tetrachloride storage bottle is arranged above the pressure tank 169, and the glass three-way plug is rotated (the branch pipe is closed) to enable the three-way plug to be communicated, so that the anhydrous carbon tetrachloride can flow into the pressure tank 169. And then the three-way plug is restored, the carbon tetrachloride inlet valve 166 is closed, the argon steel cylinder II is connected with the exhaust valve 165, the total valve of the argon steel cylinder I is opened, the low-pressure gauge is regulated to enable the pressure of the pressure gauge to be 0.2MPa, and the total valves of the exhaust valve 165 and the argon steel cylinder I are closed.
8. The feed ports 135 of the two sets of absorption barrels 125 are opened, 6150g of 20% sodium hydroxide solution and tap water are respectively added into the corresponding absorption barrels 125, and then the feed ports 135 are restored.
(II) preparation operation
1. The electrolysis voltage of the positive electrode and the negative electrode is set to 7.48V (the electrolysis current is 2.15A), the flow of carbon tetrachloride-argon, namely the flow of the second flow measuring and controlling instrument is set to 19.5L/h, the circulating pump 155 is started, and the rotating speed of the peristaltic pump 161 is set to zero.
2. Observing the flow readings of the first flow meter 154 and the flow of the flow meter 158 to be X, Y respectively until the flow readings are stable and unchanged, namely, circulating argon reaches a temperature balance state, starting a glass two-way plug I124, starting a vacuum pump 136 to control the vacuum pressure to be 0.01MPa, switching on a direct-current power supply, starting a peristaltic pump 161, slowly increasing the rotating speed of the peristaltic pump, observing the change of the value of X, Y, maintaining the difference value of the flow of the second flow meter 158 and the flow of the first flow meter 154 to be less than 0.2-0.5L/h, after circulation balance, enabling carbon tetrachloride to quickly react with lithium metal to be consumed after entering a cathode chamber to generate diamond, and not participating in gas circulation any more until the flow is stabilized at Y=X+0.45L/h under the condition that the temperature difference and the argon flow are ignored and the residual carbon tetrachloride flow are far greater, so that the carbon tetrachloride is completely reacted.
In the process of adding, note that the difference between the two is not excessively large, otherwise, the rotation speed of the peristaltic pump 161 is reduced, or the electrolysis current is increased, the upper limit of the rotation speed of the peristaltic pump 161 and the electrolysis current is the growth speed of diamond crystal, and the reaction is not excessively large at the beginning because of no diamond crystal seeds in the cathode chamber 132 of the electrolytic tank 100, so that the rotation speed of the peristaltic pump 161 and the electrolysis current are not excessively large, the current is kept to be 2.15A, the rotation speed of the peristaltic pump is 6 revolutions per minute finally, namely, the flow of liquid carbon tetrachloride is 0.45L/h.
3. The lithium chloride supplementing speed is 1.7g/h, the worm and gear driving device 402 is started every 2 hours, the starting time lasts for 15s, 3.4g of anhydrous lithium chloride is supplemented, and the conditions are maintained, and the continuous operation is carried out for 24h.
4. And opening an argon steel cylinder II main valve and an argon inlet switch valve I121. The circulation pump 155, peristaltic pump 161 and vacuum pump 136 were turned off, and the outlet pressure of the argon cylinder II was adjusted to 0.01MPa by adjusting the pressure reducing valve. The cylindrical tube III 315 of the argon steel bottle II is connected, the power connector of the negative electrode 120 is disconnected, the second set of nuts 323 is removed, the glass flange X325 is removed, the hanging basket 140 is slowly pulled up until the guillotine 311 of the guillotine switch I can be pushed into the space between the circular rings 312 with ears, namely, the connection between the cylindrical tube II 310 and the cylindrical tube III 315 is disconnected, and the molten salt is kept for about 1h, so that the molten salt flows cleanly as much as possible.
5. The glass flange IX 320 was illuminated by a flashlight from one side and the state of the precipitated diamond crystals was observed from the other side, and a small amount of reflective "crystals" were found on the top layer of the basket 140, restoring the apparatus and allowing the manufacturing process to continue.
6. After 72h, repeating the step 4, observing by using the method of the step 5, finding that the top layer of the hanging basket 140 has more reflective crystals, and the particles are obviously enlarged, taking out the long bolts 321, taking out the hanging basket 140, immediately putting the hanging basket into absolute ethyl alcohol, replacing the glass flange VIII 308 with a spare non-porous flange, fixing the glass flange VIII 308, the glass flange IX 320 and the glass flange X325 by using the bolts, fixing the two spare bolts together, closing the argon steel cylinder II main valve and the first argon inlet switch valve I121 connected with the argon steel cylinder II main valve, and disconnecting the argon steel cylinder II main valve and the first argon inlet switch valve I121.
7. And sequentially connecting an argon steel bottle II to the 2 nd to 8 th argon inlet pipes 121, repeating the steps 4, 5 and 6, taking out all the hanging baskets 140, and putting all the hanging baskets into an absolute ethyl alcohol container.
8. When no bubbles emerge from the absolute ethyl alcohol, a small amount of residual lithium replaces hydrogen, one hand holds the combination of the flange VIII 308, the glass flange IX 320 and the glass flange X325, the other hand holds the cathode rod 120, the hanging basket 140 is inclined, and the absolute ethyl alcohol is violently shaken up and down, so that lithium chloride and potassium chloride are dissolved in the absolute ethyl alcohol, diamond particles are dropped into the absolute ethyl alcohol, the hanging basket 140 is sequentially lifted, and the existence of the diamond particles which are not dropped is checked. If the lithium chloride is contained in the molten salt, the molten salt is transferred to absolute ethyl alcohol, the hanging basket is dried in an oven at 115 ℃, the electrolytic tank 100 is restored, production is continued, a stainless steel molten salt sampling rod is used for dipping a little molten salt sample from the electrolytic tank before restoration, the content of the lithium chloride in the molten salt sample is analyzed, and the content of the lithium chloride is 44.43%, so that adjustment is not needed.
9. Standing for more than 24 hours in a container for containing absolute ethyl alcohol, pouring out supernatant liquid by a pouring method, filtering the rest supernatant liquid by quantitative filter paper, washing the supernatant liquid for three times, recovering filtrate, combining the filtrate with the supernatant liquid, washing the filtrate with water for three times, drying to obtain 17.34g of diamond crystals, combining and distilling the supernatant liquid and the filtrate of the absolute ethyl alcohol, recovering the absolute ethyl alcohol, drying the supernatant liquid by a 4A molecular sieve for later use, transferring a distillation tail to an evaporation tray, continuously drying the distillation tail at 105 and 200 ℃, and adding the distillation tail into the electrolytic tank 100 when a hanging basket is taken out.
10. When equipment needs to be overhauled or production is needed to be stopped, repeating the 6 th to 9 th steps, after diamond crystals in the hanging basket 140 are treated, continuously introducing argon gas to the electrolytic tank, wherein the outlet pressure of the argon gas is 0.01MPa, closing the vacuum pump 136, the circulating pump 155, the peristaltic pump 161, the alternating current-direct current power supply and the cooling water pump, taking a large-mouth stainless steel barrel with a cover (% of 30L), placing the large-mouth stainless steel barrel under the molten salt outlet pipe 109 of the crystal filtering screen barrel 106, heating the horn-shaped outlet pipe 103 and the rotating shaft switch valve 104 of the electrolytic tank 100 by using a flame heater, opening the rotating shaft switch valve 104 by using a movable handle 107, immediately closing the rotating shaft switch valve 104 and an argon gas cylinder total valve after molten salt is discharged, allowing the electrolytic tank 100 to be naturally cooled to room temperature, supplementing the argon gas in time, preventing the temperature of the electrolytic tank from reducing and sucking air, if the electrolytic tank 100 does not need to be overhauled, directly under the condition of introducing the argon gas, pouring the discharged molten salt into the electrolytic tank 100, recovering 404, and closing the argon gas cylinder total valve, if the electrolytic tank 100 needs to be overhauled, placing the stainless steel barrel cover to be placed in a 300 ℃ and kept for 10 h.
11. After the screen barrel 106 is cooled to room temperature, it is removed and put into absolute ethyl alcohol, and the subsequent treatment method is the same as the 9 th step, except that the diamond crystal particles obtained in the process have larger particle size and better quality as the production time is longer, they can be placed on the top layer of the basket 140 to be used as seed crystals for continuous culture, and can also be used as products for sale, but in the embodiment, the obtained diamond particles are used as seed crystals only after 72 hours.
12. The electrolysis current density of the present invention is only 50% of that of the latter, so that the pulverization speed of the graphite electrode 114 is also relatively slow, and when thicker graphite powder on the molten salt liquid surface 144 in the anode chamber 131 is observed to affect chlorine gas discharge through the glass flange III 303, namely when the black interface (which shakes up and down) of the quartz glass cylinder 111 buries the lower mouth of the graphite powder drain tube 133, the "powder discharge operation" must be performed as follows:
the glass two-way plug I124 is closed, the argon steel cylinder II is connected to the air compressor interface valve 137, and the glass two-way plug II 126 and the air compressor interface valve 137 are opened. The vacuum pump 136 connected with the absorption barrel 125 containing tap water 139 is started, then the main valve of the argon steel cylinder II is opened, and the outlet valve of the argon steel cylinder II is slowly opened, so that the graphite powder in the anode chamber 131 is discharged. When the dithered black interface in the quartz glass cylinder 111 is not observed, it can be considered that "the powder discharge is completed", and the apparatus is then restored to the state before "the powder discharge".
13. If the electrolytic tank 100 is overhauled, the molten salt in the stainless steel barrel with the cover can be heated to more than 390 ℃, then the connecting flange I401 of the conical column casing 404 is disassembled, and after the molten salt in the stainless steel barrel is directly poured into the electrolytic tank 100, the connecting flange I401 of the charging barrel 404 is restored.
The working principle of the invention is as follows.
The lowest eutectic point of the known molten salt system is 44.49% containing lithium chloride, the melting point is 355 ℃, and the following electrolytic reaction exists:
in molten salt on the carbon tetrachloride gas distribution pipe of the cathode chamber, the following reactions can occur between carbon tetrachloride and metallic lithium on the cathode and in the process of floating up the carbon tetrachloride and metallic lithium:
due to the density of the diamond of 3.47-3.56g/cm 3 A density of more than 2.02g/cm of molten salt 3 As diamond crystal particles grow up, the proportion of absorbed metal lithium atoms and carbon atoms which are the components of the diamond crystal particles is smaller and smaller, so that the density of crystal grains is larger and larger, the buoyancy of molten salt on the crystal grains and the upward movement of liquid metal lithium and carbon tetrachloride gas are oppositeThe supporting force of the diamond particles is insufficient to offset the gravity of the diamond particles, so that the diamond particles grow to a certain degree and must sink, obviously, the surfaces of the diamond particles continue to grow in the sinking process until the diamond particles are separated from a negative electrode zone and carbon tetrachloride airflow, the diamond particles which are dissolved in molten salt only depend on the extremely slow growth of metal lithium and carbon tetrachloride and fall into (or are manually put into) a hanging basket can continue to grow healthily, and carbon tetrachloride gas reacts with the metal lithium dissolved in the molten salt to generate when moving from bottom to top 
Its density is about 0.41g/cm 3 The floating must be continued, which also makes it possible to prepare the dissolved metallic lithium to continue to diffuse toward the anode to some extent, thereby improving the current efficiency. Another reason for the higher current efficiency of the present invention is that a too high current density is not required.
The reaction speed of the reaction is controlled by controlling the concentration of carbon tetrachloride in the electrolysis current or the circulating gas, and enough time is left for the growth of diamond microcrystals (crystal nuclei), thereby leading the surface of the diamond seed crystal to be orderly and sp 3 The hybridized carbon atoms are combined, so that large-particle high-quality diamond crystals are obtained.
It should be noted that the above embodiments are only for illustrating the present invention, but the present invention is not limited to the above embodiments, and any simple modification, equivalent variation and modification of the above embodiments according to the technical substance of the present invention falls within the protection scope of the present invention.
Claims (7)
1. A diamond preparation device, characterized in that: the electrolytic cell comprises an airtight electrolytic cell (100) internally provided with an anode chamber (131) and a cathode chamber (132), wherein a graphite electrode (114) is detachably arranged in the anode chamber (131), an exhaust pipe (122) and a drain pipe (133) for discharging graphite powder are arranged in the anode chamber (131), a cathode rod (120) is detachably arranged in the cathode chamber (132), a hanging basket (140) for collecting prepared diamond is arranged on the cathode rod (120), a vent pipe (175) for discharging tail gas is arranged in connection with the cathode chamber (132), an argon inlet pipe (121) for introducing argon into the cathode chamber (132), and a feeding unit for adding lithium chloride-potassium chloride mixed materials into the electrolytic cell (100) and a heating unit for heating substances in the electrolytic cell (100) are arranged on the electrolytic cell (100);
A pipe ring (143) with air holes is also arranged in the electrolytic tank (100), and the connecting pipe ring (143) is provided with an air duct (112) which extends out of the electrolytic tank (100) and is used for introducing carbon tetrachloride;
the gas guide pipe (112) is connected with the blow-down pipe (175) through a circulating pipe so that gas in the electrolytic tank (100) can circulate along the electrolytic tank (100), the blow-down pipe (175), the circulating pipe and the gas guide pipe (112), a circulating pump (155), a first flow measuring instrument (154) and a heat exchanger (152) for adjusting the temperature of the gas flowing in the circulating pipe are sequentially arranged on the circulating pipe, and a second flow measuring instrument (158) is arranged on the gas guide pipe (112);
the electrolytic tank (100) comprises a column casing (101), a flange plate I (301) arranged at the top of the column casing (100) and used for sealing the column casing (100), and a cone casing (102) connected with the column casing (101) and arranged below the column casing (101);
the cylindrical barrel (101) is internally and coaxially provided with a cylindrical barrel I (110) with an open lower end, the anode chamber (131) is formed by the inner periphery of the cylindrical barrel I (110), the graphite electrode (114) is arranged in the cylindrical barrel I (110), and the cathode chamber (132) is formed by the inner periphery of the cylindrical barrel I (110) and the cylindrical barrel (101);
The lower end of the cone (102) is provided with an outlet pipe (103), and the outlet pipe (103) is provided with a switch valve (104);
a cylindrical barrel II (310) communicated with the cathode chamber (132) is arranged on the flange plate I (301), a cylindrical barrel III (315) is arranged on the cylindrical barrel II (310), a knife gate valve (311) capable of blocking the communication between the cylindrical barrel III (315) and the cathode chamber (132) is arranged between the cylindrical barrel II (310) and the cylindrical barrel III (315), and the cathode rod (120) penetrates through the cylindrical barrel III (315) and the cylindrical barrel II (310) and stretches into the cathode chamber (132); the argon inlet pipe (121) is arranged on the cylindrical barrel III (315);
the device also comprises a pressure tank (169) for providing carbon tetrachloride, the pressure tank (169) is connected with the air duct (112) through an eduction tube (164), and a bypass with a peristaltic pump (161) is arranged on the eduction tube (164).
2. A diamond fabricating apparatus according to claim 1, wherein a plurality of cylinders ii (310) are provided, and the plurality of cylinders ii (310) are disposed on the flange plate i (301) at equal intervals around the cylinder i (110), and correspondingly, the cylinder iii (315) and the cathode rod (120) are provided in one-to-one correspondence with the cylinder ii (310).
3. A diamond fabricating apparatus according to claim 1, wherein the flange plate i (301) is provided with an auxiliary electrode (340) located outside the cylinder ii (310) and inside the cylinder (101) for forming an electrode pair with the cylinder (101) to detect the position of the molten salt level in the electrolytic cell (100).
4. A diamond fabricating apparatus according to claim 1, wherein a plurality of layers of crystal filtering screens (702) with sequentially decreasing apertures from top to bottom are provided in the basket (140).
5. A diamond preparation device as claimed in claim 1, wherein the end of the drain pipe (133) and the exhaust pipe (122) outside the electrolytic cell (100) is provided with an absorption barrel (125), a float valve (130) is arranged in the absorption barrel (125), a feed inlet (135) and a vacuum pump (136) for evacuating the absorption barrel (125) are arranged on the absorption barrel (125), and a connecting pipe (137) for connecting with an air compressor is arranged on the exhaust pipe (122).
6. A diamond preparing method of a diamond preparing apparatus according to any one of claims 1 to 5, comprising the steps of:
(1) Firstly adding a half amount of lithium chloride-potassium chloride mixture into an electrolytic tank (100), circularly drying air in the electrolytic tank (100) at the temperature of 200 ℃ by using a heating unit and a circulating pump (155), heating to 400 ℃, adding the rest half amount of lithium chloride-potassium chloride mixture into the electrolytic tank (100), cooling the outer wall of the electrolytic tank (100) to form a solidified molten salt layer on the inner wall of the electrolytic tank (100), and then removing oxygen in the electrolytic tank (100) by vacuumizing-filling argon;
(2) After argon in the electrolytic tank (100) is fully circulated, gradually adding carbon tetrachloride into the gas guide tube (112) under the condition of vacuumizing the electrolytic tank (100), starting the graphite electrode (114) and the cathode rod (120) to electrolyze the mixture, and intermittently supplementing anhydrous lithium chloride into the electrolytic tank (100) in the electrolysis process;
(3) And after the electrolysis is finished, taking out the hanging basket (140), putting the hanging basket into absolute ethyl alcohol, collecting diamond particles generated by the electrolysis, and washing, filtering and drying to obtain diamond crystals.
7. The method of producing diamond according to claim 6, wherein the process of adding carbon tetrachloride in (2) is: carbon tetrachloride is added to the gas guide (112) by a peristaltic pump (161), the rotation speed of the peristaltic pump (161) is slowly increased, and meanwhile, the difference between the flow rates of the second flow measurer (158) and the first flow measurer (154) is maintained to be less than 0.2-0.5L/h until the carbon tetrachloride is completely reacted.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210526044.2A CN115140732B (en) | 2022-05-16 | 2022-05-16 | Diamond preparation device and diamond preparation method thereof |
Applications Claiming Priority (1)
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| WO2003093173A2 (en) * | 2002-05-01 | 2003-11-13 | Blacklight Power, Inc. | Diamond synthesis |
| CN111719166A (en) * | 2020-07-16 | 2020-09-29 | 赣州有色冶金研究所 | Metal lithium electrolytic bath and preparation method of metal lithium |
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| WO2003093173A2 (en) * | 2002-05-01 | 2003-11-13 | Blacklight Power, Inc. | Diamond synthesis |
| CA2483780A1 (en) * | 2002-05-01 | 2003-11-13 | Blacklight Power, Inc. | Diamond synthesis |
| CN111719166A (en) * | 2020-07-16 | 2020-09-29 | 赣州有色冶金研究所 | Metal lithium electrolytic bath and preparation method of metal lithium |
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