CN112320793A - Preparation process of high-purity graphite powder for synthesizing semiconductor-grade SiC powder - Google Patents
Preparation process of high-purity graphite powder for synthesizing semiconductor-grade SiC powder Download PDFInfo
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- CN112320793A CN112320793A CN202011135783.6A CN202011135783A CN112320793A CN 112320793 A CN112320793 A CN 112320793A CN 202011135783 A CN202011135783 A CN 202011135783A CN 112320793 A CN112320793 A CN 112320793A
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- C01B32/215—Purification; Recovery or purification of graphite formed in iron making, e.g. kish graphite
Abstract
The invention relates to the technical field of high-purity graphite preparation, in particular to a preparation process of high-purity graphite powder for synthesizing semiconductor-grade SiC powder, which comprises the following steps: charging → pressurized drying → evacuation → heating → rotary reaction → gas circulation → repeated reaction → cooling → exhaust emission → discharging, through rotary reaction step and gas circulation step, cooperate the purification jar that hourglass shape set up for graphite powder is in the purification jar like the slow dropping of sand and the purification chemical gas of input carry out the homogeneous reaction, can guarantee that the graphite powder that enters into the purification jar can be complete carry out the mixing reaction with purification chemical gas, get rid of the metallic impurity in the graphite powder, realize the even continuous purification processing of graphite powder, solve traditional graphite powder purification difficult, technical problem with high costs.
Description
Technical Field
The invention relates to the technical field of preparation of high-purity graphite, in particular to a preparation process of high-purity graphite powder for synthesizing semiconductor-grade SiC powder.
Background
The purity requirement of the semiconductor industry on graphite powder is high, and the requirement on the purity is more than 99.999%. In recent years, with the rapid growth of the semiconductor industry, the demand for high purity graphite powder has increased. At present, the production capacity of high-purity graphite powder is not formed at home, the domestic graphite powder production is in a low-level state, and the current mainstream purity level is only 99.9 percent. Internationally, only the sagrid company is supplying over 99.999% high purity graphite powder.
The technical level in China is always at a lower level, only 99.9 percent, and the requirements of the semiconductor industry can not be met. Meanwhile, the semiconductor industry has a further requirement for controlling various impurity elements.
At present, the graphite powder is extracted and stored in two ways, one is to remove impurities in the graphite powder by adopting a mechanical physical way, and the other is to remove the impurities in the graphite powder by adopting a chemical reaction way to react with the impurities in the graphite powder.
In chinese patent with patent application No. CN201711415244.6, a method for purifying graphite is disclosed, which comprises the following steps: s1, preparing graphite powder, uniformly mixing, screening and removing impurities from the graphite powder to obtain a graphite powder raw material to be purified; s2, paving the graphite powder raw material to be purified on a heating platform to form a graphite powder layer; s3, arranging a laser above the heating platform, continuously traversing and scanning the graphite powder layer through the laser, and carrying out irradiation heating to gasify impurities in the graphite powder raw material; s4, cooling to obtain graphite with the fixed carbon content of 99.9-99.99%; by adopting a laser irradiation heating method, impurities in the graphite powder raw material are volatilized in a gas form on the premise that the graphite is not influenced, and the high-purity graphite is obtained.
Although the technical scheme disclosed in the above patent utilizes a laser to heat graphite powder to achieve the purpose of purifying graphite powder, the requirement on equipment is high, so that the investment and production cost are high, and continuous production for a long time is difficult.
Disclosure of Invention
Aiming at the problems, the invention provides a preparation process of high-purity graphite powder for synthesizing semiconductor-grade SiC powder, which is characterized in that through a rotary reaction step and a gas circulation step and matching with a purification tank arranged in a hourglass shape, the graphite powder slowly falls down in the purification tank like sand to uniformly react with input purified chemical gas, the graphite powder entering the purification tank can be ensured to be completely mixed and reacted with the purified chemical gas, metal impurities in the graphite powder are removed, uniform and continuous purification processing of the graphite powder is realized, and the technical problems of difficult purification and high cost of the traditional graphite powder are solved.
In order to achieve the purpose, the invention provides the following technical scheme:
a preparation process of high-purity graphite powder for synthesizing semiconductor-grade SiC powder comprises the following steps:
step one, charging, wherein a feeding pipe at the top of a reaction furnace is driven by a corresponding pushing cylinder to be in butt joint with a feeding pipe at the top of a purification tank, synchronously, a rack arranged on the pushing cylinder is matched with a rotating gear of the feeding pipe, a valve is rotated to open the feeding pipe, graphite powder to be purified is input into the purification tank through the feeding pipe via the feeding pipe, and after the feeding is finished, the pushing cylinder drives the feeding pipe to reset, and the feeding pipe is synchronously closed;
step two, pressurizing and drying, namely driving an air feeding pipe at the top of the reaction furnace to be in butt joint with an air feeding pipe at the top of a purification tank through a corresponding pushing air cylinder, synchronously, matching a rack arranged on the pushing air cylinder with a rotating gear of the air feeding pipe, rotating a valve to open the air feeding pipe, introducing argon into the purification tank through the air feeding pipe and the air feeding pipe by an external air source, after the gas transmission is finished, driving the air feeding pipe to reset by the pushing air cylinder, synchronously closing the air feeding pipe, starting an electric heater arranged in the reaction kettle, heating the purification tank, and drying the graphite powder;
step three, vacuumizing, after drying is completed, driving the exhaust pipe at the top of the purification tank to be in butt joint with the exhaust pipe at the top of the purification tank through a corresponding push cylinder through an exhaust pipe at the top of the reaction furnace, synchronously, matching a rack arranged on the push cylinder with a rotating gear of the exhaust pipe, rotating a valve to open the exhaust pipe, vacuumizing equipment arranged outside the reaction furnace to vacuumize the purification tank through the exhaust pipe, and after vacuumizing is completed, driving the exhaust pipe to reset through the push cylinder, and synchronously closing the exhaust pipe;
heating, and after vacuumizing is completed, heating the purification tank by an electric heater arranged on the reaction kettle to raise the temperature in the purification tank to 2200-2600 ℃;
rotating for reaction, wherein a power mechanism arranged on the reaction furnace drives the purification tank to rotate 180 degrees around a horizontal axis, graphite powder in a material storage area of the purification tank is uniformly conveyed to a material receiving area below the purification tank, synchronously, along with the rotation of the purification tank, a gas supply gear in the gas supply mechanism is matched with a gas supply rack, and a gas supply switch is rotated to open a branch pipe in the gas supply mechanism, which is communicated with the material receiving area, close the branch pipe communicated with the material storage area and an external purified chemical gas source, and the purified chemical gas source is input into the graphite powder falling from the material receiving area through an opened main gas pipe through the branch pipe for reaction, so that impurities in the graphite powder are removed;
step six, gas circulation, synchronous with the step five, along with the rotation of the purification tank, a circulation gear in the gas circulation mechanism is matched with a circulation rack, and a first circulation branch pipe communicated with the material storage area and a second circulation branch pipe communicated with the material receiving area in the gas circulation mechanism are opened through a rotary circulation switch, so that the material storage area and the material receiving area form gas circulation;
step seven, repeating the reaction, and repeating the step five and the step six for 2-3 times after all the graphite powder in the material storage area is conveyed into the material receiving area until the graphite powder completely reacts with the purified chemical gas;
step seven, cooling, after the reaction is completed, closing the electric heater in the reaction kettle, and cooling the purification tank to room temperature;
step eight, discharging waste gas, after cooling, driving the waste gas to be butted with an exhaust pipe at the top of a purification tank through an exhaust pipe at the top of the reaction furnace by a corresponding push cylinder, synchronously, matching a rack arranged on the push cylinder with a rotating gear of the exhaust pipe, rotating a valve, opening the exhaust pipe, performing air extraction treatment on the purification tank through the exhaust pipe by a vacuum pumping device arranged outside the reaction furnace, after extraction of reaction waste gas of the purification tank is finished, driving the exhaust pipe to reset by the push cylinder, and synchronously closing the exhaust pipe; and
step nine, the ejection of compact, treat that exhaust emission is complete the back, through the row of material pipe of reacting furnace bottom is driven by the promotion cylinder that corresponds and is docked with the inlet pipe of purification tank bottoms portion, and is synchronous, the rack of installation on the promotion cylinder with the rotary gear cooperation of inlet pipe, rotary valve will the inlet pipe is opened, and the graphite powder after the purification passes through the inlet pipe is arranged the material pipe output through arranging, treats the ejection of compact back that finishes, the promotion cylinder drives arrange the material pipe and reset, close in step the inlet pipe.
In the first step, the purity of the graphite powder input into the purification tank is 60% -90%.
As an improvement, in the third step, after the vacuum pumping treatment is finished, the pressure in the purification tank is 0.2-3 kPa.
As an improvement, in the fifth step, the power mechanism includes:
the driven gear is sleeved on a rotating shaft in the middle of the mounting bracket for mounting the purification tank; and
and the driving motor is arranged on the side wall of the reaction furnace and correspondingly assembled with the driven gear through a driving gear.
As an improvement, in the fifth step, the air supply switch includes:
the fixed switch plate is arranged in a semicircular shape and is fixedly arranged on the branch pipe;
the switch cylinders are sleeved on the corresponding branch pipes and synchronously rotate along with the gas supply gears; and
the movable switch plate is arranged on the switch cylinder and seals the branch pipe when being mutually complemented with the fixed switch plate.
As an improvement, in the fifth step, the communication position of the branch pipe and the storage bin on the purification tank is close to the communication position of the material storage area and the material receiving area.
As an improvement, an annular exhaust head is arranged in the storage bin and communicated with the branch pipe, and graphite powder output to the material receiving area from the material storing area penetrates through the annular center of the exhaust head.
As an improvement, in the sixth step, the circulation switch includes:
the fixed sealing plates are arranged in a semicircular shape and fixedly arranged on the first circulating branch pipe and the second circulating branch pipe;
the mounting cylinder is sleeved on the corresponding first and second circulating branch pipes and synchronously rotates along with the circulating gear; and
and the movable sealing plate is arranged on the mounting cylinder and seals the corresponding first circulation branch pipe and the second circulation branch pipe when being mutually complemented with the fixed sealing plate.
As an improvement, in the sixth step, filter screens are arranged at the communication positions of the first circulation branch pipe and the second circulation branch pipe with the storage bin.
The invention has the beneficial effects that:
(1) according to the invention, through the rotary reaction step and the gas circulation step and the cooperation of the purification tank arranged in the shape of an hourglass, graphite powder slowly falls in the purification tank like sand and is uniformly reacted with the input purified chemical gas, so that the graphite powder entering the purification tank can be completely mixed and reacted with the purified chemical gas, metal impurities in the graphite powder are removed, the uniform and continuous purification processing of the graphite powder is realized, and the graphite powder is simpler to purify and has lower cost;
(2) in the rotary reaction step, the annular exhaust head is utilized, so that the graphite powder entering the material receiving area from the material storage area passes through the annular middle part of the exhaust head, and the purified chemical gas exhausted by the exhaust head just surrounds the graphite powder to react, so that the reaction is more uniform, and the purification effect is better;
(3) in the gas circulation step, the gas circulation mechanism is used for communicating the material storage area and the material receiving area, so that the air pressure balance between the material storage area and the material receiving area is realized, and the graphite powder in the material storage area can still smoothly enter the material receiving area even if purified chemical gas enters the purification tank.
In conclusion, the method has the advantages of uniform reaction, high purity of purified graphite, good continuity, low cost and the like, and is particularly suitable for the technical field of preparation of high-purity graphite.
Drawings
FIG. 1 is a schematic flow chart of the preparation method of the present invention;
FIG. 2 is a first schematic view of a front view structure of the present invention;
FIG. 3 is a schematic perspective view of the present invention;
FIG. 4 is a schematic perspective view of a first purification tank according to the present invention;
FIG. 5 is a schematic perspective view of a rotary valve according to the present invention;
FIG. 6 is a second schematic front view of the present invention;
FIG. 7 is a schematic perspective view of a second embodiment of the purification tank of the present invention;
FIG. 8 is a schematic perspective view of the gas supply switch of the present invention;
FIG. 9 is a schematic three-dimensional view of the purification tank of the present invention;
FIG. 10 is a front view of the gas circulation mechanism of the present invention;
FIG. 11 is a schematic cross-sectional view of a circulation switch according to the present invention;
fig. 12 is a schematic sectional view of a purification tank according to the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations and positional relationships based on those shown in the drawings, and are used only for convenience of description and simplicity of description, and do not indicate or imply that the equipment or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be considered as limiting the present invention.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.
The first embodiment is as follows:
as shown in fig. 1, a preparation process of high purity graphite powder for semiconductor grade SiC powder synthesis comprises the following steps:
step one, charging, wherein a feeding pipe 11 at the top of a reaction furnace 1 is driven by a corresponding pushing cylinder 15 to be in butt joint with a feeding pipe 211 at the top of a purification tank 2, synchronously, a rack 16 arranged on the pushing cylinder 15 is matched with a rotating gear 242 of the feeding pipe 211, a valve 241 is rotated to open the feeding pipe 211, graphite powder to be purified is input into the purification tank 2 through the feeding pipe 11 via the feeding pipe 211, and after the feeding is finished, the pushing cylinder 15 drives the feeding pipe 11 to reset, and the feeding pipe 211 is synchronously closed;
step two, pressurizing and drying, namely driving the gas feeding pipe 12 at the top of the reaction furnace 1 to be in butt joint with the gas feeding pipe 212 at the top of the purification tank 2 through the corresponding pushing cylinder 15, synchronously, matching a rack 16 arranged on the pushing cylinder 15 with a rotating gear 242 of the gas feeding pipe 212, rotating a valve 241, opening the gas feeding pipe 212, introducing argon gas into the purification tank 2 through the gas feeding pipe 12 and the gas feeding pipe 212 by an external gas source, after gas transmission is finished, driving the gas feeding pipe 12 to reset by the pushing cylinder 15, synchronously closing the gas feeding pipe 212, starting an electric heater arranged in the reaction kettle 1, heating the purification tank 2, and drying the graphite powder;
step three, vacuumizing, after drying is completed, the exhaust pipe 213 at the top of the purification tank 2 is butted with the exhaust pipe 13 at the top of the reaction furnace 1 driven by the corresponding push cylinder 15 through the exhaust pipe 13 at the top of the reaction furnace 1, synchronously, the rack 16 arranged on the push cylinder 15 is matched with the rotating gear 242 of the exhaust pipe 213, the valve 241 is rotated, the exhaust pipe 213 is opened, vacuumizing equipment arranged outside the reaction furnace 1 performs vacuumizing treatment on the purification tank 2 through the exhaust pipe 13, after the vacuumizing treatment is completed, the push cylinder 15 drives the exhaust pipe 13 to reset, and the exhaust pipe 213 is synchronously closed;
heating, and after vacuumizing is completed, heating the purification tank 2 by an electric heater arranged on the reaction kettle 1 to raise the temperature in the purification tank 2 to 2200-2600 ℃;
step five, performing rotary reaction, wherein a power mechanism 5 arranged on the reaction furnace 1 drives the purification tank 2 to rotate 180 degrees around a horizontal axis, graphite powder in a material storage area 22 of the purification tank 2 is uniformly conveyed to a material receiving area 23 below, synchronously, along with the rotation of the purification tank 2, a gas supply gear 35 in the gas supply mechanism 3 is matched with a gas supply rack 36, and a branch pipe 311 communicated with the material receiving area 23 in the gas supply mechanism 3 is opened through a rotary gas supply switch 32, the branch pipe 311 communicated with the material storage area 22 is closed, an external purified chemical gas source is input to the graphite powder falling in the material receiving area 23 through a branch pipe 311 through an opened main gas pipe 33, and the impurities in the graphite powder are removed;
step six, gas circulation, synchronous with the step five, along with the rotation of the purification tank 2, a circulation gear 45 and a circulation rack 46 in the gas circulation mechanism 4 are matched to open a first circulation branch pipe 42 communicated with the material storage area 22 and a second circulation branch pipe 43 communicated with the material receiving area 23 in the gas circulation mechanism 4 through a rotation circulation switch 44, and the material storage area 22 and the material receiving area 23 form gas circulation;
step seven, repeating the reaction, and repeating the step five and the step six for 2-3 times after all the graphite powder in the material storage area 22 is conveyed into the material receiving area 23 until the graphite powder completely reacts with the purified chemical gas;
step seven, cooling, after the reaction is completed, closing the electric heater in the reaction kettle 1, and cooling the purification tank 2 to room temperature;
step eight, discharging waste gas, after cooling, driving the waste gas to be butted with an exhaust pipe 213 at the top of a purification tank 2 through an exhaust pipe 13 at the top of the reaction furnace 1 by a corresponding push cylinder 15, synchronously, matching a rack 16 arranged on the push cylinder 15 with a rotating gear 242 of the exhaust pipe 213, rotating a valve 241, opening the exhaust pipe 213, performing air extraction treatment on the purification tank 2 through the exhaust pipe 13 by a vacuum pumping device arranged outside the reaction furnace 1, and after extraction of reaction waste gas of the purification tank 2 is finished, driving the exhaust pipe 13 to reset by the push cylinder 15, and synchronously closing the exhaust pipe 213; and
step nine, the ejection of compact, treat that exhaust emission is complete the back, through row of material pipe 14 of retort 1 bottom is driven by the promotion cylinder 15 that corresponds and is docked with the inlet pipe 211 of purification jar 2 bottoms, and is synchronous, the rack 16 of installation on the promotion cylinder 15 with the rotary gear 242 cooperation of inlet pipe 211, rotary valve 241, will inlet pipe 211 is opened, and the graphite powder after the purification passes through inlet pipe 211 is arranged the output of material pipe 14, treats the ejection of compact back that finishes, promotion cylinder 15 drives row of material pipe 14 resets, closes in step inlet pipe 211.
Wherein, in the first step, the purity of the graphite powder input into the purification tank 2 is 60% -90%.
Further, in the third step, after the vacuum pumping treatment is finished, the pressure in the purification tank 2 is 0.2-3 kPa.
In addition, in the fifth step, the power mechanism 5 includes:
the driven gear 51 is sleeved on the rotating shaft 201 in the middle of the mounting bracket 20 for mounting the purification tank 2; and
and the driving motor 52 is installed on the side wall of the reaction furnace 1, and the driving motor 52 is correspondingly installed and matched with the driven gear 51 through a driving gear 53.
Further, in the fifth step, the air supply switch 32 includes:
a fixed switch plate 321, wherein the fixed switch plate 321 is arranged in a semicircular shape and is fixedly installed on the branch pipe 311;
the switch cylinder 322 is sleeved on the corresponding branch pipe 311 and synchronously rotates along with the air supply gear 35; and
a movable opening and closing plate 323 installed on the opening and closing cylinder 322, which seals the branch pipe 311 when being complemented with the fixed opening and closing plate 321.
Furthermore, in the fifth step, the communication position between the branch pipe 311 and the storage bin 21 on the purification tank 2 is close to the communication position between the material storage area 22 and the material receiving area 23.
It is worth to be noted that, in the fifth step, in the process of rotating the purification tank 2, the graphite powder originally located in the lower bin 21 is switched to the upper portion, and in order to ensure that the purified chemical gas is introduced into the lower receiving area 23 all the time, the present application opens the branch pipe 311 located in the lower receiving area 23 all the time and closes the branch pipe 311 located in the upper receiving area 22 through the cooperation of the gas supply gear 35 and the gas supply rack 36, and in addition, no matter how the purification tank 2 rotates in the present application, the storage area 22 located in the upper portion and the receiving area 23 located in the lower portion do not change due to the rotation of the purification tank 2.
In a preferred embodiment, an annular exhaust head 37 is disposed in the storage bin 21 and is communicated with the branch pipe 311, the graphite powder output from the storage area 22 to the receiving area 23 passes through the annular center of the exhaust head 37, and the purified chemical gas exhausted by the exhaust head 37 intensively reacts with the graphite powder toward the center of the exhaust head 37.
Further, in the sixth step, the circulation switch 44 includes:
a fixed closing plate 441, wherein the fixed closing plate 441 is semicircular and is fixedly installed on the first and second circulation branch pipes 42 and 43;
the installation cylinder 442 is sleeved on the corresponding first and second circulation branch pipes 42 and 43, and rotates synchronously with the circulation gear 45; and
and a movable sealing plate 443 attached to the mounting cylinder 442, the movable sealing plate 443 sealing the corresponding first and second circulation branch pipes 42 and 43 when being complementary to the fixed sealing plate 441.
In the sixth step, filter screens 47 are disposed at the positions where the first circulation branch pipe 42 and the second circulation branch pipe 43 are communicated with the storage bin 21.
It should be noted that, in order to ensure that after the purified chemical gas is introduced into the material receiving region 23, the air pressure in the material receiving region 23 does not affect the graphite powder discharge of the material storage region 22, the material receiving region 23 and the material storage region 22 are communicated by the gas circulation mechanism 4, so that the air pressures in the two regions are kept balanced, and the filter screen 47 is used for filtering the graphite powder.
Example two:
as shown in fig. 2 to 5 and 12, a preparation apparatus of high purity graphite powder for semiconductor grade SiC powder synthesis includes:
the reaction furnace 1 is arranged in a sealed manner, and an electric heater is arranged in the reaction furnace 1;
the purification tank 2 is arranged in an hourglass shape, is rotatably arranged on the reaction furnace 1 through a mounting bracket 20, and comprises two funnel-shaped storage bins 21 which are oppositely arranged, a material storage area 22 is arranged in the storage bin 21 at the upper part, and a material receiving area 23 is arranged in the storage bin 21 at the lower part;
the gas supply mechanism 3 is arranged in the reaction furnace 1, is communicated with an external gas source and is used for inputting purified chemical gas into the material receiving area 23; and
and the gas circulation mechanism 4 is arranged in the reaction furnace 1, is just opposite to the gas supply mechanism 3 arranged on the other side of the purification tank 2, and is used for communicating the material storage area 22 with the material receiving area 23.
Wherein, open feed pipe 211, intake pipe 212 and outlet duct 213 on the smooth lateral wall that sets up of feed bin 21, just all be provided with valve member 24 on feed pipe 211, intake pipe 212 and the blast pipe 213.
Further, the valve assembly 24 includes:
the valve 241 is rotatably installed on the corresponding feed pipe 211, the corresponding intake pipe 212 and the corresponding exhaust pipe 213; and
and a rotating gear 242, wherein the rotating gear 242 is sleeved on the rotating shaft of the valve 241.
Further, the top of reacting furnace 1 is provided with feed pipe 11, gas tube 12, exhaust tube 13, the bottom of reacting furnace 1 is provided with row material pipe 14, feed pipe 11, row material pipe 14 with the coaxial setting of inlet pipe 211, gas tube 12 with the coaxial setting of intake pipe 212, exhaust tube 13 with the coaxial setting of outlet duct 213, just feed pipe 11, gas tube 12, exhaust tube 13 and row material pipe 14 are by the flexible setting of the promotion cylinder 15 drive that corresponds, should promote to be provided with on the propelling movement end of cylinder 15 with rotatory gear 242 corresponds complex rack 16.
As shown in fig. 6, a power mechanism 5 for driving the purification tank 2 to rotate is disposed at a position where the purification tank 2 is rotatably mounted and connected to the reaction furnace 1, and the power mechanism 5 includes:
the driven gear 51 is sleeved on the rotating shaft 201 in the middle of the mounting bracket 20; and
and the driving motor 52 is installed on the side wall of the reaction furnace 1, and the driving motor 52 is correspondingly installed and matched with the driven gear 51 through a driving gear 53.
As shown in fig. 7, 8 and 12, the gas supply mechanism 3 includes, as a preferred embodiment:
the tail ends of the air supply pipes 31 are respectively communicated with the bins 21, the air supply pipes rotate synchronously with the purifying rollers 2, and an air supply switch 32 is arranged on a branch pipe 311 communicated with the corresponding bin 21;
the main air pipe 33, the main air pipe 33 is connected with the middle part of the air supply pipe 31 in a rotating and sealing way, the air supply pipe 31 can rotate along the axial direction of the main air pipe 33, the main air pipe 33 is communicated with an external air source, and the main air pipe 33 is provided with a main valve 34;
the air supply gear 35 is sleeved on the corresponding air supply switch 32, and rotates synchronously with the air supply switch 32; and
and the gas supply racks 36 are respectively arranged at the top and the bottom of the reaction furnace 1, are matched with the corresponding gas supply gear 35, and are switched on and off corresponding to the gas supply switch 32.
Further, the air supply switch 32 includes:
a fixed switch plate 321, wherein the fixed switch plate 321 is arranged in a semicircular shape and is fixedly installed on the branch pipe 311;
the switch cylinder 322 is sleeved on the corresponding branch pipe 311 and synchronously rotates along with the air supply gear 35; and
a movable opening and closing plate 323 installed on the opening and closing cylinder 322, which seals the branch pipe 311 when being complemented with the fixed opening and closing plate 321.
Furthermore, the connection position between the air supply pipe 31 and the storage bin 21 is close to the connection position between the material storage area 22 and the material receiving area 23, and an annular exhaust head 37 is arranged in the storage bin 21 and is connected with the air supply pipe 31.
It should be noted that, when the graphite powder is discharged from the material storage region 22 to the material receiving region 23 and reacts with the purified chemical gas introduced into the material receiving region 23, during the process of purifying the graphite powder, the purification tank 2 rotates to make the graphite powder entering the material receiving region 23 return to the material storage region 22 again, and during the process of rotating the purification tank 2, the bin 21 is switched between the material storage region 22 and the material receiving region 23, which results in that it is necessary to ensure that the branch pipe 311 of the bin 21 located on the material receiving region 23 can be opened to input the purified chemical gas into the purification tank 2, and during the process of rotating the purification tank 2, the branch pipe 311 located on the material storage region 22 is closed and the branch pipe 311 located on the material receiving region 23 is opened by the cooperation of the gas supply gear 35, the gas supply rack 36 and the gas supply switch 32.
It is further described that the graphite powder output from the material storage region 22 to the material receiving region 23 passes through the annular central position of the gas discharge head 37, the purified chemical gas discharged from the gas discharge head 37 intensively reacts with the graphite powder uniformly toward the central position of the gas discharge head 37, the graphite powder reacts with the purified chemical gas sufficiently, the accumulation of the graphite powder does not occur, and the graphite powder at the bottom cannot react with the purified chemical gas.
As shown in fig. 9 and 11, in a preferred embodiment, the gas circulation mechanism 4:
a main circulating air pipe 41, wherein the main circulating air pipe 41 is vertically arranged on the mounting bracket 20 and synchronously rotates with the purification tank 2;
the first circulating branch pipes 42 are symmetrically communicated with two axial end parts of the main circulating gas pipe 41, are respectively communicated with the corresponding storage bins 21, and are respectively positioned at the top and the bottom of the purification tank 2;
the second circulation branch pipes 43 are arranged between the symmetrical first circulation branch pipes 42, one ends of the second circulation branch pipes 43 are communicated with the main circulation gas pipe 41, the other ends of the second circulation branch pipes 43 are communicated with the corresponding storage bins 21, and the second circulation branch pipes 43 are arranged closer to the communication positions of the material storage area 22 and the material receiving area 23 than the first circulation branch pipes 42;
the circulation switch 44 is arranged on the axial direction of the first circulation branch pipe 42 and the second circulation branch pipe 43, and controls the on-off of the first circulation branch pipe 42 and the second circulation branch pipe 43;
the circulating gear 45 is sleeved on the corresponding circulating switch 44, and the first circulating branch pipe 42 and the circulating gear 45 on the second circulating branch pipe 43 which are positioned on the same side are meshed;
circulation racks 46, the circulation racks 46 being respectively installed at the top and bottom of the reaction furnace 1, and engaged with the circulation gears 45 on the first circulation branch pipes 42; and
and the filter screen 47 is installed at the position where the first circulation branch pipe 42 and the second circulation branch pipe 43 are communicated with the storage bin 21.
Further, the circulation switch 44 includes:
a fixed closing plate 441, wherein the fixed closing plate 441 is semicircular and is fixedly installed on the first and second circulation branch pipes 42 and 43;
the installation cylinder 442 is sleeved on the corresponding first and second circulation branch pipes 42 and 43, and rotates synchronously with the circulation gear 45; and
and a movable sealing plate 443 attached to the mounting cylinder 442, the movable sealing plate 443 sealing the corresponding first and second circulation branch pipes 42 and 43 when being complementary to the fixed sealing plate 441.
It should be noted that, in order to ensure that after the purified chemical gas is introduced into the material receiving region 23, the air pressure in the material receiving region 23 does not affect the graphite powder discharge of the material storage region 22, the material receiving region 23 and the material storage region 22 are communicated by the gas circulation mechanism 4, so that the air pressures in the two regions are kept balanced, and the filter screen 47 is used for filtering the graphite powder.
It is further described that, during the process of purifying graphite powder, the purification tank 2 rotates to make the graphite powder entering the material receiving area 23 return to the material storage area 22 again, and during the process of rotating the purification tank 2, the storage bin 21 is switched between the material storage area 22 and the material receiving area 23, and in order to ensure that the gas entering the material storage area 22 through the gas circulation mechanism 4 is always located at the upper part of the graphite powder, the first circulation branch pipe 42 located in the material storage area 22 is opened, the second circulation branch pipe 43 located in the material storage area 22 is closed, the second circulation branch pipe 43 located in the material receiving area 23 is opened, the first circulation branch pipe 42 located in the material receiving area 23 is closed by the arrangement of the circulation gear 45, the circulation rack 46 and the circulation switch 44, so that the purified chemical gas entering the material receiving area 23 and the waste gas generated by the reaction are formed, the second circulation branch pipes 43 passing through the material receiving area 23 enter the top of the purification tank 2 through the first circulation branch pipes 42 of the material storage area 22, and the second circulation branch pipes 43 are arranged close to the top of the material receiving area 23, so that the influence of gas flow on the graphite powder entering the material receiving area 23 is avoided.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (9)
1. A preparation process of high-purity graphite powder for synthesizing semiconductor-grade SiC powder is characterized by comprising the following steps:
step one, charging, wherein a feeding pipe (11) at the top of a reaction furnace (1) is driven by a corresponding pushing cylinder (15) to be butted with a feeding pipe (211) at the top of a purification tank (2), synchronously, a rack (16) arranged on the pushing cylinder (15) is matched with a rotating gear (242) of the feeding pipe (211), a rotating valve (241) is used for opening the feeding pipe (211), graphite powder to be purified is input into the purification tank (2) through the feeding pipe (11) through the feeding pipe (211), and after the feeding is finished, the pushing cylinder (15) drives the feeding pipe (11) to reset, and the feeding pipe (211) is synchronously closed;
step two, pressurizing and drying, namely driving an air feeding pipe (12) at the top of the reaction furnace (1) to be in butt joint with an air feeding pipe (212) at the top of a purification tank (2) through a corresponding pushing cylinder (15), synchronously, matching a rack (16) arranged on the pushing cylinder (15) with a rotating gear (242) of the air feeding pipe (212), rotating a valve (241), opening the air feeding pipe (212), introducing argon gas into the purification tank (2) through the air feeding pipe (12) and the air feeding pipe (212) by an external air source, resetting the air feeding pipe (12) by the pushing cylinder (15) after gas transmission is finished, synchronously closing the air feeding pipe (212), starting an electric heater arranged in the reaction kettle (1), heating the purification tank (2) to raise the temperature, and drying the graphite powder;
step three, vacuumizing, after drying is completed, the exhaust pipe (213) at the top of the purification tank (2) is butted with the exhaust pipe (13) at the top of the reaction furnace (1) through the driving of a corresponding push cylinder (15), synchronously, a rack (16) arranged on the push cylinder (15) is matched with a rotating gear (242) of the exhaust pipe (213), a valve (241) is rotated, the exhaust pipe (213) is opened, vacuumizing equipment arranged outside the reaction furnace (1) performs vacuumizing treatment on the purification tank (2) through the exhaust pipe (13), and after the vacuumizing treatment is completed, the push cylinder (15) drives the exhaust pipe (13) to reset, and the exhaust pipe (213) is synchronously closed;
heating, and after vacuumizing is completed, heating the purification tank (2) by an electric heater arranged on the reaction kettle (1) to raise the temperature in the purification tank (2) to 2200-2600 ℃;
step five, performing rotary reaction, wherein a power mechanism (5) arranged on the reaction furnace (1) drives the purification tank (2) to rotate 180 degrees around a horizontal axis, graphite powder in a material storage area (22) of the purification tank (2) is uniformly conveyed to a material receiving area (23) below, synchronously, and with the rotation of the purification tank (2), an air supply gear (35) in an air supply mechanism (3) is matched with an air supply rack (36) to open a branch pipe (311) communicated with the material receiving area (23) in the air supply mechanism (3) and close the branch pipe (311) communicated with the material storage area (22) through a rotary air supply switch (32), and an external purified chemical gas source is input to the graphite powder falling in the material receiving area (23) through an opened main air pipe (33) through the branch pipe (311) to react to remove impurities in the graphite powder;
step six, gas circulation is performed, synchronous with the step five, and along with the rotation of the purification tank (2), a circulation gear (45) and a circulation rack (46) in the gas circulation mechanism (4) are matched to open a first circulation branch pipe (42) communicated with the material storage area (22) and a second circulation branch pipe (43) communicated with the material receiving area (23) in the gas circulation mechanism (4) through a rotary circulation switch (44), and the material storage area (22) and the material receiving area (23) form gas circulation;
step seven, repeating the reaction, and repeating the step five and the step six for 2-3 times after all the graphite powder in the material storage area (22) is conveyed into the material receiving area (23) until the graphite powder and the purified chemical gas completely react;
seventhly, cooling, after the reaction is completed, closing the electric heater in the reaction kettle (1), and cooling the purification tank (2) to room temperature;
step eight, discharging waste gas, after cooling, driving the waste gas to be butted with an exhaust pipe (213) at the top of a purification tank (2) through an air suction pipe (13) at the top of the reaction furnace (1) by a corresponding push cylinder (15), synchronously, matching a rack (16) arranged on the push cylinder (15) with a rotating gear (242) of the exhaust pipe (213), rotating a valve (241), opening the exhaust pipe (213), performing air extraction treatment on the purification tank (2) through the air suction pipe (13) by a vacuum extraction device arranged outside the reaction furnace (1), and after finishing extraction of reaction waste gas of the purification tank (2), driving the air suction pipe (13) to reset by the push cylinder (15), and synchronously closing the exhaust pipe (213); and
step nine, the ejection of compact, treat that exhaust emission is complete the back, through row of material pipe (14) of reacting furnace (1) bottom is driven by corresponding promotion cylinder (15) and is docked with inlet pipe (211) of purification jar (2) bottom, synchronous, rack (16) of installation on the promotion cylinder (15) with rotary gear (242) cooperation of inlet pipe (211), rotary valve (241), will inlet pipe (211) are opened, and the graphite powder after the purification passes through inlet pipe (211) is arranged material pipe (14) output, treats the ejection of compact back of finishing, promotion cylinder (15) drive it resets to arrange material pipe (14), closes in step inlet pipe (211).
2. The process for preparing high-purity graphite powder for synthesizing semiconductor-grade SiC powder according to claim 1, wherein in the first step, the purity of the graphite powder input into the purification tank (2) is 60-90%.
3. The process for preparing high-purity graphite powder for synthesizing semiconductor grade SiC powder according to claim 1, wherein in the third step, after the vacuum pumping is finished, the pressure in the purification tank (2) is 0.2-3 kPa.
4. The process for preparing high-purity graphite powder for semiconductor-grade SiC powder synthesis according to claim 1, wherein in the fifth step, the power mechanism (5) comprises:
the driven gear (51), the said driven gear (51) is fitted on the spindle (201) of the middle part of the mounting bracket (20) to mount the said purifying tank (2); and
the driving motor (52) is installed on the side wall of the reaction furnace (1), and the driving motor (52) is correspondingly installed and matched with the driven gear (51) through a driving gear (53).
5. The process for preparing high-purity graphite powder for semiconductor-grade SiC powder synthesis according to claim 1, wherein in the fifth step, the gas supply switch (32) comprises:
the fixed switch plate (321) is arranged in a semicircular shape and is fixedly arranged on the branch pipe (311);
the switch cylinder (322) is sleeved on the corresponding branch pipe (311) and synchronously rotates along with the gas supply gear (35); and
a movable shutter plate (323), said movable shutter plate (323) being mounted on said switch cylinder (322) and sealing said branch pipe (311) when complementary to said fixed shutter plate (321).
6. The process for preparing the high-purity graphite powder for synthesizing the semiconductor-grade SiC powder according to the claim 1, wherein in the fifth step, the communication position of the branch pipe (311) and the bin (21) on the purification tank (2) is close to the communication position of the stock area (22) and the material receiving area (23).
7. The process for preparing the high-purity graphite powder for synthesizing the semiconductor-grade SiC powder according to claim 6, wherein an annular exhaust head (37) is arranged in the stock bin (21) and is communicated with the branch pipe (311), and the graphite powder output from the stock region (22) to the material receiving region (23) passes through the annular center of the exhaust head (37).
8. The process for preparing high purity graphite powder for synthesis of semiconductor grade SiC powder according to claim 1, wherein in the sixth step, the circulation switch (44) comprises:
the fixed sealing plate (441), the said fixed sealing plate (441) is set up in the form of semicircle, it is fixed on said first circulation branch pipe (42) and second circulation branch pipe (43);
the mounting cylinder (442) is sleeved on the corresponding first circulation branch pipe (42) and second circulation branch pipe (43) and rotates synchronously with the circulation gear (45); and
and the movable sealing plate (443) is arranged on the mounting cylinder (442), and seals the corresponding first circulation branch pipe (42) and the second circulation branch pipe (43) when being complemented with the fixed sealing plate (441).
9. The process for preparing the high-purity graphite powder for synthesizing the semiconductor-grade SiC powder according to claim 1, wherein in the sixth step, filter screens (47) are arranged at the communication positions of the first circulation branch pipe (42) and the second circulation branch pipe (43) and the storage bin (21).
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