A process for preparing electronic grade monosilane by magnesium silicide method

Abstract

The invention discloses a process for preparing electronic-grade monosilane by a magnesium silicide method. The process comprises the following steps: crushing a prepared silicon-magnesium alloy into a suitable particle size, fully mixing the mixture with dried magnesium chloride, adding liquid ammonia and reacting the mixture in a reactor to obtain products such as monosilane, disilane, ammonia, hydrogen, phosphine and arsine. The products are then passed into an ammonia recovery tank to cool ammonia components in the process gas, and then passing through a purification device to remove residual ammonia and impurities such as phosphine and arsine in the process gas. Magnesium chloride hexaammine, a byproduct obtained at the bottom of the reactor, is discharged through a bottom valve of the reactor to a rake dryer for heating to remove free ammonia in the magnesium chloride hexaammine. The recovered ammonia is then pressurized, cooled and separated to obtain liquid ammonia, which can be used for adding liquid ammonia to the reactor, thereby achieving effective resource utilization, reducing production costs, ensuring efficient utilization of ammonia and reducing waste.

Description

Technical Field

[0001] The invention relates to the technical field of monosilane production, and in particular to a process for preparing electronic-grade monosilane by a magnesium silicide method. Background Art

[0002] When preparing electronic-grade monosilane, silicon powder and magnesium powder are generally mixed and placed in a fixed-bed heating furnace to prepare a silicon-magnesium alloy. The prepared silicon-magnesium alloy is mixed with dried magnesium chloride and reacted in a liquid ammonia environment to obtain the main product monosilane and by-products disilane and trisilane, as well as impurities such as H2, PH3, and AsH3.

[0003] The main overall reaction is as follows:

[0004]

[0005] For a long time, people believed that the by-product produced by the silicon magnesium method was anhydrous magnesium chloride, which led to most people not treating the by-product separately. However, the actual by-product is magnesium chloride hexaammine, which is a complex formed by anhydrous magnesium chloride and ammonia. It has excellent reversible ammonia absorption and release properties and is a good ammonia-fixing material.

[0006] However, during the reaction, the by-product magnesium chloride hexammine has a low solubility in liquid ammonia, which makes it difficult to continuously discharge the solid phase magnesium chloride hexammine during the reaction. At the same time, during the preparation process, the by-product ammonia is generated. For every part of monosilane produced, four parts of ammonia are produced. This characteristic not only increases the difficulty of ammonia treatment, but also affects the cost and efficiency of the production line. Summary of the Invention

[0007] The purpose of the present invention is to provide a process for preparing electronic grade monosilane by magnesium silicide method, so as to solve the above-mentioned shortcomings in the prior art.

[0008] In order to achieve the above object, the present invention provides the following technical solutions:

[0009] A process for preparing electronic-grade monosilane by a magnesium silicide method, the process for preparing electronic-grade monosilane by a magnesium silicide method comprising the following steps:

[0010] S1: Silicon powder and magnesium powder are added to an alloy in a mass ratio of 1:1 to prepare a furnace, and the preparation is carried out at 500-600°C. The prepared silicon-magnesium alloy is then added to an alloy crusher and crushed to 50-80 mesh, and mixed with dried ammonium chloride to generate a reaction raw material;

[0011] S2: The reaction raw materials are put into the reactor and reacted in the liquid ammonia system to obtain reaction products such as monosilane, disilane, ammonia and hydrogen. The stirring speed of the reactor is 30-50r / min.

[0012] S3: The process gas obtained by the reaction is introduced into an ammonia recovery tank, and the ammonia component in the process gas is recovered through a condenser device at the top of the ammonia recovery tank.

[0013] S4: After the crude process gas of the ammonia component is recovered, it is purified by a purification device to adsorb the residual ammonia and impurities such as phosphine and arsine to obtain crude silane gas.

[0014] S5: The crude silane gas passes through the top condenser of the first distillation tower, intercepting heavy components such as disilane, phosphine and arsine in the silane gas, allowing monosilane and light components such as hydrogen and nitrogen to enter the second distillation tower. Then, by adjusting the temperature of the second tower condenser, light components such as hydrogen and nitrogen are discharged from the top of the tower in the form of non-condensable steam.

[0015] S6: After the receiving is completed, the kettle of the first distillation tower is heated, and the monosilane of the first distillation tower is distilled out at the top of the tower to the second distillation tower for the first distillation.

[0016] S7: Transfer the monosilane enriched in the kettle of the second distillation tower to the third distillation tower. When the pressure of the second distillation tower drops rapidly, the material transfer stage is considered to be completed.

[0017] S8: Establish reflux in the three distillation towers and start discharging light components to obtain electronic grade monosilane.

[0018] S9: After the reaction is completed, the by-product, magnesium chloride hexaamine, is transferred to a rake dryer for heating and deammoniation. The obtained gas phase is pressurized by a compressor and passed into a condenser for cooling and recovery of ammonia components. The rake dryer includes a spreading component, which is used to spread the magnesium chloride hexaamine while stirring it to increase its heating area.

[0019] Preferably, in step S3, the condenser is set at a temperature of -50 to -60° C. This can reduce liquid ammonia consumption and extend the purification time.

[0020] Preferably, in step S4, the air inlet speed of the purification device is 10-30 kg / h.

[0021] Preferably, in the step S5, after the S5 reaction stops, the monosilane receiving stage ends, the pressures of the first and second towers are maintained at atmospheric pressure, the condenser temperature of the first tower is -90±10°C, and the condenser temperature of the second tower is -130±10°C.

[0022] Preferably, in step S6, the kettle temperature of the first distillation tower is evaporated to -60°C, the first distillation is completed, the pressure of the first distillation tower is atmospheric pressure, and the condenser temperature is set to -110±10°C.

[0023] Preferably, in step S7, the monosilane enriched in the kettle of the second distillation tower is transferred to the third distillation tower through a bottom pipe, so as to remove heavy components such as disilane carried over during the first distillation or receiving stage.

[0024] Preferably, in step S8, the three distillation towers are set up for full reflux for two hours.

[0025] Preferably, it comprises a bracket, a bin body is fixedly provided on the bracket, a rotating shaft is rotatably provided on the bin body, a reciprocating tube is slidably provided on the rotating shaft, a rake rod is fixedly provided on the reciprocating tube, and a rake head is rotatably provided on the rake rod;

[0026] A storage rod and an ejection rod are slidably provided on the rake rod, a second spring is provided between the storage rod and the ejection rod, two ends of the second spring are fixedly connected to the storage rod and the ejection rod respectively, a second protrusion is fixedly provided on the ejection rod, a spiral groove is provided on the rake head, and the second protrusion is arranged in the spiral groove;

[0027] It also includes a force storage assembly, which is used to make the force storage rod slide and the second spring compress during the rotation of the shaft to store force on the ejection rod;

[0028] The release assembly is used to release the ejection rod of the second spring after the second spring completes compression.

[0029] Preferably, the force storage assembly includes a fixed ring fixedly arranged on the rotating shaft, a telescopic block is slidably arranged on the fixed ring, a cross bar is fixedly arranged on the telescopic block, and the rake rod and the force storage rod are both slidably connected to the cross bar;

[0030] A first spring is provided between the telescopic block and the fixed ring, and two ends of the first spring are fixedly connected to the telescopic block and the fixed ring respectively;

[0031] An arc-shaped rod is fixedly provided on the warehouse body, and the cross bar abuts against the outer side surface of the arc-shaped rod.

[0032] Preferably, the release assembly includes a block slidably arranged on the rake rod, the pop-up rod is provided with a slot, and the block is engaged with the slot;

[0033] A push rod is slidably provided on the rake rod, a round rod is fixedly provided on the push rod, an inclined groove is provided on the clamping block, and the round rod is slidably provided in the inclined groove;

[0034] A third spring is provided between the push rod and the rake rod, two ends of the third spring are fixedly connected to the push rod and the rake rod respectively, and the push rod is in contact with the cross bar.

[0035] In the above technical solution, the process for preparing electronic-grade monosilane by magnesium silicide provided by the present invention has the following beneficial effects:

[0036] 1. The prepared silicon-magnesium alloy is crushed into a suitable particle size, fully mixed with dried magnesium chloride, and liquid ammonia is added to react in a reactor to obtain products such as monosilane, disilane, ammonia, hydrogen, phosphine and arsine. The products are then passed into an ammonia recovery tank to cool the ammonia component in the process gas, and then the residual ammonia and impurities such as phosphine and arsine in the process gas are removed through a purification device. The by-product, magnesium chloride hexaammine, obtained at the bottom of the reactor tower, is discharged to a rake dryer through the bottom valve of the reactor, heated to remove free ammonia in the magnesium chloride hexaammine, and the recovered ammonia is pressurized, cooled and separated to obtain liquid ammonia, which can be used for liquid ammonia feeding in the reactor, thereby achieving effective resource utilization and reducing production costs, ensuring efficient utilization of ammonia and reducing waste.

[0037] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.

[0038] This application document provides an overview of various implementations or examples of the technology described in this disclosure, and is not a comprehensive disclosure of the full scope or all features of the disclosed technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments described in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0040] Figure 1 A process flow chart for preparing electronic-grade monosilane using the magnesium silicide method provided in an embodiment of the present invention;

[0041] Figure 2 A schematic diagram of the overall structure of the warehouse provided in an embodiment of the present invention;

[0042] Figure 3 A schematic diagram of the internal structure of a warehouse provided in an embodiment of the present invention;

[0043] Figure 4 A schematic diagram of the reciprocating tube and rake structure provided in an embodiment of the present invention;

[0044] Figure 5 A schematic diagram of the structure of the rotating shaft and reciprocating rod provided in an embodiment of the present invention;

[0045] Figure 6 A schematic diagram of the deployment structure of a fixed tube provided in an embodiment of the present invention;

[0046] Figure 7 A cross-sectional view of a rake rod provided in an embodiment of the present invention;

[0047] Figure 8A schematic diagram of the structure of a drag head and a release assembly provided in an embodiment of the present invention;

[0048] Figure 9 A side sectional view of a bin body provided in an embodiment of the present invention.

[0049] Description of reference numerals:

[0050] 1. Bracket; 11. Warehouse body; 2. Rotating shaft; 21. Fixed ring; 22. Telescopic block; 23. Cross bar; 24. First spring; 3. Reciprocating tube; 31. First protrusion; 4. Rake rod; 41. Block; 42. Inclined groove; 5. Rake head; 51. Spiral groove; 6. Power storage rod; 61. Pop-up rod; 62. Second spring; 63. Slot; 64. Second protrusion; 7. Push rod; 71. Round rod; 72. Third spring; 8. Fixed tube; 81. Reciprocating groove; 9. Arc rod. DETAILED DESCRIPTION

[0051] To make the purpose, technical solutions, and advantages of the embodiments of the present disclosure more clear, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0052] Please refer to 1-9, a process for preparing electronic-grade monosilane by the magnesium silicide method, which comprises the following steps:

[0053] S1: Silicon powder and magnesium powder are added to an alloy in a mass ratio of 1:1 to prepare a furnace, and the preparation is carried out at 500-600°C. The prepared silicon-magnesium alloy is then added to an alloy crusher and crushed to 50-80 mesh, and mixed with dried ammonium chloride to generate a reaction raw material;

[0054] S2: The reaction raw materials are put into the reactor and reacted in the liquid ammonia system to obtain reaction products such as monosilane, disilane, ammonia and hydrogen. The stirring speed of the reactor is 30-50r / min.

[0055] S3: The process gas obtained by the reaction is introduced into an ammonia recovery tank, and the ammonia component in the process gas is recovered through a condenser device at the top of the ammonia recovery tank.

[0056] S4: After the crude process gas of the ammonia component is recovered, it is purified by a purification device to adsorb the residual ammonia and impurities such as phosphine and arsine to obtain crude silane gas.

[0057] S5: The crude silane gas passes through the top condenser of the first distillation tower, intercepting heavy components such as disilane, phosphine and arsine in the silane gas, allowing monosilane and light components such as hydrogen and nitrogen to enter the second distillation tower. Then, by adjusting the temperature of the second tower condenser, light components such as hydrogen and nitrogen are discharged from the top of the tower in the form of non-condensable steam.

[0058] S6: After the receiving is completed, the kettle of the first distillation tower is heated, and the monosilane of the first distillation tower is distilled out at the top of the tower to the second distillation tower for the first distillation.

[0059] S7: Transfer the monosilane enriched in the kettle of the second distillation tower to the third distillation tower. When the pressure of the second distillation tower drops rapidly, the material transfer stage is considered to be completed.

[0060] S8: Establish reflux in the three distillation towers and start discharging light components to obtain electronic grade monosilane.

[0061] S9: After the reaction is completed, the by-product, magnesium chloride hexaamine, is transferred to a rake dryer for heating and deammoniation. The resulting gas phase is pressurized by a compressor and passed through a condenser for cooling and recovery of the ammonia component. The rake dryer includes a spreading component for spreading the magnesium chloride hexaamine while stirring it to increase its heating area.

[0062] The invention comprises the following steps: crushing a prepared silicon-magnesium alloy into a suitable particle size, fully mixing the mixture with dried magnesium chloride, adding liquid ammonia to react in a reactor, obtaining products such as monosilane, disilane, ammonia, hydrogen, phosphine and arsine, and then introducing the products into an ammonia recovery tank to cool ammonia components in the process gas. The products are then passed through a purification device to remove residual ammonia and impurities such as phosphine and arsine in the process gas. The by-product magnesium chloride hexaammine obtained at the bottom of the reactor is discharged to a rake dryer through a bottom valve of the reactor, heated to remove free ammonia in the magnesium chloride hexaammine, and the recovered ammonia is pressurized, cooled and separated to obtain liquid ammonia, which can be used for adding liquid ammonia to the reactor.

[0063] The purified process gas is received by Silane Columns 1 and 2. During this process, some monosilane, disilane, trisilane, phosphine, and other heavy impurities are retained in the kettle of Column 1. The temperature of the condenser in Column 2 is adjusted to cool the crude monosilane received to a liquid phase, which is retained at the bottom of the kettle. Light impurities such as H2 and N2 are removed as non-condensable gases. After receiving, Column 1 undergoes heated distillation, distilling the residual monosilane at the bottom of Column 1 to Column 2. The monosilane from Column 2 is then transferred to Column 3 to remove heavy components carried over during the reception and distillation process. Finally, distillation continues in Column 3 to produce electronic-grade monosilane.

[0064] In an embodiment further provided by the present invention, in step S3, the condenser is set at a temperature of -50 to -60° C. This can reduce liquid ammonia consumption and extend the time of the purification device.

[0065] In an embodiment further provided by the present invention, in step S4, the air inlet speed of the purification device is 10-30 kg / h.

[0066] In an embodiment further provided by the present invention, in step S5, after the S5 reaction stops, the monosilane receiving stage ends, the pressure of the first tower and the second tower is maintained at atmospheric pressure, the condenser temperature of the first tower is -90±10°C, and the condenser temperature of the second tower is -130±10°C.

[0067] In an embodiment further provided by the present invention, in step S6, the kettle temperature of the first distillation tower is evaporated to -60°C, the first distillation is completed, the pressure of the first distillation tower is atmospheric pressure, and the condenser temperature is set to -110±10°C.

[0068] In an embodiment further provided by the present invention, in step S7, the monosilane enriched in the kettle of the second distillation tower is transferred to the third distillation tower through a bottom pipe, so that heavy components such as disilane entrained during the first distillation or receiving stage can be removed.

[0069] In an embodiment further provided by the present invention, in step S8, the three distillation towers are set up to establish total reflux for two hours.

[0070] Furthermore, it includes a bracket 1, a bin body 11 is fixedly provided on the bracket 1, a rotating shaft 2 is rotatably provided on the bin body 11, a reciprocating tube 3 is slidably provided on the rotating shaft 2, a rake rod 4 is fixedly provided on the reciprocating tube 3, a rake head 5 is rotatably provided on the rake rod 4; a storage rod 6 and a pop-up rod 61 are slidably provided on the rake rod 4, a second spring 62 is provided between the storage rod 6 and the pop-up rod 61, and the two ends of the second spring 62 are fixedly connected to the storage rod 6 and the pop-up rod 61 respectively, and a second spring 62 is fixedly provided on the pop-up rod 61. The second protrusion 64 is provided on the rake head 5 with a spiral groove 51, and the second protrusion 64 is provided in the spiral groove 51; it also includes a power storage component, which is used to make the power storage rod 6 slide during the rotation of the shaft 2, compress the second spring 62, and store power on the pop-up rod 61; a release component, which is used to release the pop-up rod 61 after the second spring 62 is compressed. When the shaft 2 rotates, the reciprocating rod drives the rake rod 4 and the rake head 5 to rotate, so that the rake head 5 can remove the hexachlorobenzene located at the bottom of the bin body 11. The magnesium chloride is picked up. After the magnesium chloride hexammine is picked up, the rake rod 4 rotates, and the storage rod 6 slides and compresses the second spring 62. After the storage rod 6 completes the compression and storage of the second spring 62, the release assembly releases the fixation of the ejection rod 61. Under the action of the second spring 62, the ejection rod 61 slides and pops out. The second protrusion 64 cooperates with the spiral groove 51 to make the ejection rod 61 pop out. When the ejection rod 61 is ejected, the rake head 5 rotates to scatter the magnesium chloride hexammine on the rake head 5, so that the magnesium chloride hexammine is released. Magnesium fully absorbs the heat in the warehouse body 11, accelerating the deamination efficiency of the magnesium chloride hexammine. Furthermore, the spiral grooves 51 provided on the rake heads 5 on the reciprocating tubes 3 on both sides are in opposite directions. When the pop-up rod 61 slides and the rake heads 5 rotate, the rake heads 5 provided on the reciprocating tubes 3 on both sides scatter the magnesium chloride hexammine picked up by the rake heads 5 to the other side, thereby avoiding the accumulation of magnesium chloride hexammine on one side of the bottom of the warehouse body 11 after the rake heads 5 scatter the magnesium chloride hexammine, thereby improving the heating deamination efficiency of the magnesium chloride hexammine.

[0071] The force storage assembly includes a fixed ring 21 fixedly arranged on the rotating shaft 2, a telescopic block 22 is slidably arranged on the fixed ring 21, a cross bar 23 is fixedly arranged on the telescopic block 22, and the rake rod 4 and the force storage rod 6 are both slidably connected with the cross bar 23; a first spring 24 is provided between the telescopic block 22 and the fixed ring 21, and the two ends of the first spring 24 are fixedly connected to the telescopic block 22 and the fixed ring 21 respectively; an arc rod 9 is fixedly arranged on the warehouse body 11, and the cross bar 23 abuts against the outer side of the arc rod 9. After the rake head 5 picks up the magnesium chloride hexammine, the cross bar 23 passes through the position of the arc rod 9 and abuts against the arc rod 9. In the process of rotation of the rake rod 4 and the rake head 5, under the action of the arc rod 9, the cross bar 23 slides relative to the rake rod 4, pushing the force storage rod 6 to slide and The second spring 62 is compressed, and after the cross bar 23 slides to complete the compression of the second spring 62, the fixation of the pop-up rod 61 is released by the release assembly, thereby completing the effect of scattering the magnesium chloride hexaamine on the rake head 5; and after the second spring 62 is compressed and stored, the initial velocity of the pop-up rod 61 when it pops out is large, which can scatter the magnesium chloride hexaamine on the rake head 5 more dispersedly, increase the contact area between the magnesium chloride hexaamine and the hot air in the warehouse body 11, and make the heating and deamination of the magnesium chloride hexaamine more efficient; when the cross bar 23 pushes the storage rod 6 to slide, the first spring 24 is stretched, and after the cross bar 23 is separated from the arc rod 9, under the resetting action of the first spring 24, the cross bar 23 slides and resets, and at the same time drives the storage rod 6, the pop-up rod 61 and the rake head 5 to reset.

[0072] The release assembly includes a block 41 slidably arranged on the rake rod 4, a slot 63 is provided on the pop-up rod 61, and the block 41 is engaged with the slot 63; a push rod 7 is slidably arranged on the rake rod 4, a round rod 71 is fixedly provided on the push rod 7, an oblique groove 42 is provided on the block 41, and the round rod 71 is slidably arranged in the oblique groove 42; a third spring 72 is provided between the push rod 7 and the rake rod 4, and the two ends of the third spring 72 are respectively fixedly connected to the push rod 7 and the rake rod 4, and the push rod 7 is fixedly connected to the cross The rod 23 is in contact with the card block 41, and the ejection rod 61 is fixed under the card action of the card block 41 and the card slot 63. The storage rod 6 slides to compress the second spring 62 and store force. During the sliding process of the storage rod 6, it abuts against the push rod 7 and pushes the push rod 7 to slide. The push rod 7 cooperates with the round rod 71 and the inclined groove 42 to make the card block 41 slide. After the storage rod 6 slides to store force on the second spring 62, the card block 41 slides to disengage from the card slot 63, completing the release of the ejection rod 61. When the block 41 slides, the push rod 7 will still slide through the cooperation of the inclined groove 42 and the round rod 71, and the third spring 72 will be compressed. When the block 41 is engaged with the groove 63, the third spring 72 pushes the push rod 7 to reset.

[0073] A first protrusion 31 is fixedly provided on the reciprocating tube 3, a fixed tube 8 is fixedly provided on the warehouse body 11, a reciprocating groove 81 is provided on the fixed tube 8, and the first protrusion 31 is slidably provided in the reciprocating groove 81. When the reciprocating tube 3 rotates with the rotating shaft 2, under the cooperation of the first protrusion 31 and the reciprocating groove 81, the reciprocating tube 3 slides back and forth at the same time as it rotates, so as to spread the magnesium chloride hexaamine at the bottom of the warehouse body 11, prevent the magnesium chloride hexaamine from accumulating at one place at the bottom of the warehouse body 11, which affects the heating effect of the magnesium chloride hexaamine, and when the magnesium chloride hexaamine is just added to the warehouse body 11, it is convenient to spread the magnesium chloride hexaamine faster, thereby improving the heating efficiency of the magnesium chloride hexaamine.

[0074] Working principle: When adding and deamminating magnesium chloride hexammine, the magnesium chloride hexammine is placed in the bin body 11, and then the rotating shaft 2 rotates, driving the reciprocating tube 3 to rotate. During the rotation process, the reciprocating tube 3 slides back and forth at the same time under the action of the reciprocating groove 81 and the first protrusion 31, and at the same time drives the rake rod 4 and the rake head 5 to slide. During this process, the magnesium chloride hexammine in the bin body 11 can be spread out to prevent the magnesium chloride hexammine from being concentrated below the feed port of the bin body 11, which affects the addition effect of the magnesium chloride hexammine.

[0075] As the reciprocating tube 3 rotates with the rotating shaft 2, multiple cross bars 23 periodically pass through the arc rod 9 and slide relative to the rake rod 4 under the abutment of the arc rod 9. During the sliding process of the cross bar 23, the storage rod 6 is pushed to slide on the rake rod 4 and the second spring 62 is compressed. In this process, the cross bar 23 abuts against the push rod 7 and pushes the push rod 7 to slide, compressing the third spring 72. After the storage rod 6 completes the compression of the second spring 62, the round rod 71 fixedly connected to the push rod 7 cooperates with the inclined groove 42, and the block 4 is 1 slides and disengages from the card slot 63. At this time, the pop-up rod 61 loses the restriction of the card block 41, and the second spring 62 is released to push the pop-up rod 61 to slide. When the spring rod slides, the second protrusion 64 cooperates with the spiral groove 51 to make the rake head 5 rotate half a circle, spilling the magnesium chloride hexaamine picked up by the rake head 5, so that the magnesium chloride hexaamine and the heat in the bin body 11 are further exposed, thereby improving the deammonification efficiency of the magnesium chloride hexaamine. After the cross bar 23 is separated from the arc rod 9, the restoring force of the first spring 24 drives the storage rod 6 and the pop-up rod 61 to slide and reset, and the rake head 5 to rotate and reset.

[0076] The above description is merely illustrative of certain exemplary embodiments of the present invention. It goes without saying that those skilled in the art will be able to modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and description are illustrative in nature and should not be construed as limiting the scope of protection of the claims.

Claims

1. A process for preparing electronic grade monosilane by magnesium silicide method, characterized in that: The process for preparing electronic grade monosilane by magnesium silicide method comprises the following steps: S1: Silicon powder and magnesium powder are added to an alloy in a mass ratio of 1:1 to prepare a furnace, and the preparation is carried out at 500-600°C. The prepared silicon-magnesium alloy is then added to an alloy crusher and crushed to 50-80 mesh, and mixed with dried ammonium chloride to generate a reaction raw material; S2: The reaction raw materials are put into the reactor and reacted in the liquid ammonia system to obtain reaction products such as monosilane, disilane, ammonia and hydrogen. The stirring speed of the reactor is 30-50r / min; S3: The process gas obtained by the reaction is introduced into an ammonia recovery tank, and the ammonia component in the process gas is recovered through a condenser device at the top of the ammonia recovery tank; S4: After the crude process gas of the ammonia component is recovered, it is passed through a purification device to adsorb the residual ammonia and impurities such as phosphine and arsine to obtain crude silane gas; S5: The crude silane gas passes through the top condenser of the first distillation tower, intercepting heavy components such as disilane, phosphine and arsine in the silane gas, allowing monosilane and light components such as hydrogen and nitrogen to enter the second distillation tower. Then, by adjusting the temperature of the second tower condenser, light components such as hydrogen and nitrogen are discharged from the top of the tower in the form of non-condensable steam; S6: After the receiving is completed, the reactor of the first distillation tower is heated, and the monosilane in the first distillation tower is distilled out at the top of the tower to the second distillation tower for the first distillation; S7: transferring the monosilane enriched in the reactor of the second distillation tower to the third distillation tower. When the pressure of the second distillation tower drops rapidly, the transfer stage is considered to be completed; S8: Establish reflux in the three distillation towers and start discharging light components to obtain electronic grade monosilane; S9: After the reaction is completed, the by-product, magnesium chloride hexaamine, is transferred to a rake dryer for heating and deammoniation. The resulting gas phase is pressurized by a compressor and passed into a condenser for cooling and recovery of ammonia components. The rake dryer includes a spreading assembly for spreading the magnesium chloride hexaamine while stirring it to increase its heating area. The rake dryer further comprises a bracket (1), a bin body (11) is fixedly provided on the bracket (1), a rotating shaft (2) is rotatably provided on the bin body (11), a reciprocating tube (3) is slidably provided on the rotating shaft (2), a rake rod (4) is fixedly provided on the reciprocating tube (3), and a rake head (5) is rotatably provided on the rake rod (4); The spreading assembly comprises a power storage rod (6) and an ejection rod (61) slidably arranged on the rake rod (4); a second spring (62) is arranged between the power storage rod (6) and the ejection rod (61); two ends of the second spring (62) are fixedly connected to the power storage rod (6) and the ejection rod (61), respectively; a second protrusion (64) is fixedly arranged on the ejection rod (61); a spiral groove (51) is provided on the rake head (5); and the second protrusion (64) is arranged in the spiral groove (51); It also includes a force storage component, which is used to make the force storage rod (6) slide and the second spring (62) compress during the rotation of the rotating shaft (2) to store force on the ejection rod (61); A release assembly, which is used to release the ejection rod (61) after the second spring (62) is compressed; The power storage assembly comprises a fixed ring (21) fixedly arranged on the rotating shaft (2), a telescopic block (22) is slidably arranged on the fixed ring (21), a crossbar (23) is fixedly arranged on the telescopic block (22), and the rake rod (4) and the power storage rod (6) are both slidably connected to the crossbar (23); A first spring (24) is provided between the telescopic block (22) and the fixed ring (21), and two ends of the first spring (24) are fixedly connected to the telescopic block (22) and the fixed ring (21), respectively; An arc-shaped rod (9) is fixedly provided on the bin body (11), and the cross bar (23) abuts against the outer side surface of the arc-shaped rod (9); The release assembly comprises a clamping block (41) slidably arranged on the rake rod (4); a clamping slot (63) is provided on the ejection rod (61); the clamping block (41) is engaged with the clamping slot (63); A push rod (7) is slidably provided on the rake rod (4), a round rod (71) is fixedly provided on the push rod (7), an inclined groove (42) is provided on the clamping block (41), and the round rod (71) is slidably provided in the inclined groove (42); A third spring (72) is provided between the push rod (7) and the rake rod (4), and both ends of the third spring (72) are fixedly connected to the push rod (7) and the rake rod (4), respectively, and the push rod (7) abuts against the cross bar (23).

2. The process for preparing electronic grade monosilane by magnesium silicide method according to claim 1, characterized in that: In step S3, the condenser is set at a temperature of -50 to -60°C, which can reduce liquid ammonia consumption and extend the time of the purification device.

3. The process for preparing electronic grade monosilane by magnesium silicide method according to claim 1, characterized in that: In step S4, the air inlet speed of the purification device is 10-30 kg / h.

4. The process for preparing electronic grade monosilane by magnesium silicide method according to claim 1, characterized in that: In the step S5, after the S5 reaction stops, the monosilane receiving stage ends, the pressure of the first tower and the second tower is maintained at atmospheric pressure, the temperature of the condenser of the first tower is -90±10°C, and the temperature of the condenser of the second tower is -130±10°C.

5. The process for preparing electronic grade monosilane by magnesium silicide method according to claim 1, characterized in that: In the step S6, the temperature of the kettle in the first distillation tower is evaporated to -60°C, and the first distillation is completed. The pressure of the first distillation tower is atmospheric pressure, and the condenser temperature is set to -110±10°C.

6. The process for preparing electronic grade monosilane by magnesium silicide method according to claim 1, characterized in that: In step S7, the monosilane enriched in the kettle of the second distillation tower is transferred to the third distillation tower through a bottom pipe, so as to remove heavy components such as disilane carried over during the first distillation or receiving stage.

7. The process for preparing electronic grade monosilane by magnesium silicide method according to claim 1, characterized in that: In step S8, the three distillation towers are set up for full reflux for two hours.

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