KR101264252B1 - Apparatus for refining silicon and method thereof - Google Patents

Abstract

The present invention is a reaction tank for removing impurities contained in the silicon powder by reacting the supplied silicon powder and acid solution; A solid-liquid separator connected to the reactor and receiving a mixed solution of the silicon powder and the acid solution from the reactor, and separating the mixed solution into solid-phase high-purity silicon and liquid waste liquid by centrifugation; And it provides a silicon refining device comprising a harmful gas treatment unit for processing and discharge the harmful gas discharged from the reaction tank and the solid-liquid separator.
According to the present invention, high purity solar-grade silicon can be produced by removing metal impurities contained in silicon through acid treatment.

Description

Silicon refining apparatus and its method {APPARATUS FOR REFINING SILICON AND METHOD THEREOF}

The present invention relates to a silicon refining apparatus and a method thereof, and more particularly, to a silicon refining apparatus and a method for producing a solar-grade silicon of high purity by removing metal impurities contained in the silicon through acid treatment. will be.

In general, in the case of silicon used as a wafer for semiconductors or solar cells, a carbon reducing agent such as silica (SiO ₂ ) and coke in a natural state is obtained by a thermal carbon reduction method of reacting at high temperature using an arc or the like. do. However, the silicon obtained at this time contains a large amount of impurities and has a purity of about 99%. Thus, the semiconductor wafer (purity 99.99999999% (10N)) or the solar cell wafer (purity 99.9999% (6N)) must be further refined. It can be used as.

Here, silicon used for semiconductor applications is manufactured by converting metallurgical grade metal silicon having a purity of about 98% obtained by reducing silica into silicon chloride, and then distilling the silicon chloride and then thermally decomposing it. Complex manufacturing processes and extremely tight process control are required, which inevitably leads to high manufacturing costs. For this reason, the silicon for this semiconductor use is not suitable for the use of the solar cell which is required to reduce cost with increase of demand because the quality is too high and manufacturing cost is too high.

Therefore, various methods of refining, that is, removing impurities contained in silicon with a purity of 6N or higher, suitable for solar cells, have been proposed, using metallurgical metal silicon of low cost as a raw material.

Disclosure of Invention The present invention has been made to solve the above-mentioned problems, and the object of the present invention is to provide a silicon refining apparatus and a method for producing a solar-grade silicon of high purity by removing metal impurities contained in silicon through acid treatment. It is done.

The present invention is a reaction tank for removing impurities contained in the silicon powder by reacting the supplied silicon powder and acid solution; A solid-liquid separator connected to the reactor and receiving a mixed solution of the silicon powder and the acid solution from the reactor, and separating the mixed solution into solid-phase high-purity silicon and liquid waste liquid by centrifugation; And it provides a silicon refining device comprising a harmful gas treatment unit for processing and discharge the harmful gas discharged from the reaction tank and the solid-liquid separator.

Here, the raw material supply unit is connected to the reaction tank for supplying the silicon powder and the acid solution to the reaction tank, wherein the raw material supply for supplying the silicon solution and the acid solution mixed with the distilled water supplying the silicon powder It is also characterized by an acid solution feeder.

In addition, the reactor is formed of a double structure of the inner wall and the outer wall, the heat medium oil is injected and circulated between the inner wall and the outer wall is characterized by.

At this time, it is also characterized in that it further comprises an oil heater for heating the heat medium oil connected to the reaction tank and supplied to the reaction tank.

In addition, the reaction tank is characterized in that it is provided with a device for generating any one of stirring, bubble, ultrasonic waves or pressure to promote the reaction of the silicon powder and the acid solution.

On the other hand, the present invention comprises the steps of preparing a silicon powder and an acid solution; Reacting the silicon powder with the acid solution to remove impurities contained in the silicon powder; And centrifuging the mixed solution of the silicon powder and the acid solution into a solid silicon powder and a liquid waste solution.

Here, there is also a feature that further comprises the step of washing the silicon powder centrifuged.

According to the present invention, high purity solar-grade silicon can be produced by removing metal impurities contained in silicon through acid treatment.

1 is a block diagram showing a silicon refining apparatus according to the present invention.
2 is a process flowchart showing the silicon refining method according to the present invention in the order of process.

Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

Next, the silicon refining apparatus according to the present invention will be described with reference to FIG. 1.

Referring to FIG. 1, the silicon refining apparatus 100 according to the present invention is a refining apparatus for removing metal impurities contained in a low purity silicon powder through acid treatment in order to manufacture high purity solar class (6N) silicon. , Reaction tank 120, solid-liquid separator 130 and harmful gas treatment unit 140 is formed. In this case, the silicon refining apparatus 100 may include a raw material supply unit 110 supplying silicon powder and an acid solution to the reaction tank 120.

The raw material supply unit 110 is a device for supplying silicon powder and an acid solution to the reaction tank 120, and is connected to the reaction tank 120. At this time, the silicon powder and the acid solution are respectively supplied to the reaction tank 120 and mixed in the reaction tank 120. Therefore, the raw material supply unit 110 may be composed of a silicon supply 111 and the acid solution supply 112 for this purpose. That is, the silicon supply 111 is filled with silicon powder, the particle size may be approximately 5㎛ or more, the amount of the silicon powder supplied to the reactor 120 may be 3 ~ 10kg. In addition, in order to prevent the scattering of the silicon powder supplied to the reaction tank 120, distilled water is supplied to the silicon feeder 111, it is preferably supplied in the form of a silicon slurry.

In addition, the acid solution supplier 112 is configured in a form in which the acid solution, such as hydrochloric acid, nitric acid, hydrofluoric acid is filled in each cylinder. At this time, the acid solution supplied to the reaction tank 120 may be approximately 30 ~ 120L, this acid solution supply amount is set in consideration of the supply amount of the silicon powder and the storage capacity of the reaction tank 120. The acid solution is supplied to the reaction tank 120 in a mixed state with distilled water.

In addition, the silicon powder and the acid solution are moved by the pumping action of the pump 150 installed in each piping line, and whether or not the supply and the amount of supply to the reaction tank 120 is applied to various valves installed in the piping line. Can be controlled.

The reactor 120 provides a space in which the reaction between the silicon powder and the acid solution proceeds. That is, the low purity silicon powder containing impurities is mixed with an acid solution such as hydrochloric acid, nitric acid, and hydrofluoric acid in the reaction tank 120, and impurities contained in the silicon powder are removed by chemical reaction between these acid solutions and impurities. .

Each injection hole is formed at the top or side of the reactor 120 so that the silicon powder and the acid solution can be injected. In addition, the reaction tank 120 may be formed in a dual structure consisting of an inner wall and an outer wall to create a smooth reaction environment between the silicon powder and the acid solution, that is, to maintain a constant inside of the reaction tank 120.

And heat medium oil is injected between the inner wall and the outer wall, the temperature inside the reaction tank 120 through the circulation of the heat medium oil can be kept constant. At this time, the heat medium oil may be injected into the reaction tank 120 by the oil heater 122.

That is, the oil heater 122 is connected to the reaction tank 120 to heat the heat medium oil to continuously circulate along the circumference of the reaction tank 120. At this time, the circulation of the heat medium oil may be made by the pump 150. And it is a matter of course that the oil heater 122 has a sufficient heating capacity for heating the heat medium oil circulating through the reaction tank (120).

For example, the oil heater 122 should have a heating capacity that can heat the heat medium oil up to 110 ℃ in consideration of the temperature of the reaction tank 120 is 100 ℃. In addition, the oil heater 122 should be able to block overheating due to abnormal heating, and in connection with the temperature measurement result of the thermocouple installed inside the reactor 120, based on this temperature correction Through it can be formed to heat the heat medium oil to an appropriate temperature.

On the other hand, when the silicon powder and the acid solution in the reaction tank 120, the harmful gas is inevitably generated in this process. Therefore, an outlet for discharging the harmful gas to the harmful gas processing unit 140 is formed in the upper portion of the reaction tank 120.

In addition, the reaction tank 120 should be formed of a material having acid resistance to a strong acid solution such as hydrochloric acid, nitric acid, hydrofluoric acid, and the like.

As mentioned above, the plurality of portions including the upper and side portions of the reaction tank 120 measure the internal temperature during the reaction between the silicon powder and the acid solution, and a temperature for temperature correction with the oil heater 122 for adjusting the temperature of the heat medium oil. Couples may be installed.

In addition, a viewing window may be formed on the upper side or side of the reaction tank 120 so that an operator may observe the inside of the reaction tank 120.

In addition, the reaction tank 120 may be formed in a separate type to promote convenience for internal cleaning. At this time, the separation and coupling portion of the reaction tank 120 should ensure a sufficient sealing force for safety from harmful gases.

On the other hand, the silicon powder and the acid solution supplied to the reaction tank 120 is a chemical reaction occurs when contacted with each other, it is preferable to artificially mix to further promote this reaction. Therefore, the reaction tank 120 may be provided with a stirrer or a device such as a bubble generator, an ultrasonic generator, or a pressurizer to promote a reaction between the silicon powder and the acid solution. Accordingly, FIG. 1 illustrates a state in which a stirrer 121 is installed in the reaction tank 120 as a reaction promoting device. However, this is only one embodiment of the above-described bubble generator, ultrasonic generator or pressurizer can be installed to replace the stirrer 121, of course.

The stirrer 121 is an apparatus for stirring these for promoting the reaction of the silicon powder and the acid solution. The stirrer 121 may be formed to include a motor 121a, a rotating shaft 121b, and an impeller 121c. Here, the motor 121a is disposed above the outer side of the reaction tank 120 and imparts rotational force to the rotating shaft 121b rotatably connected thereto. The rotation shaft 121b rotatably connected to the motor 121a is disposed in the reaction tank 120 along the length direction of the reaction tank 120. And the impeller 121c is coupled to the lower end of the rotating shaft 121b to rotate in conjunction with the rotation of the rotating shaft 121b, so that the silicon powder and the acid solution are mixed as a whole by the swirling airflow generated by the impeller 121c. To facilitate their reaction. At this time, the rotary shaft 121b and the impeller 121c in direct contact with the silicon powder and the acid solution should be formed of a material having acid resistance so as not to contaminate the silicon powder in the stirring process.

The rotational speed of the stirrer 121 may be formed to be adjustable in units of rpm. And the stirrer 121 should have a sufficient heat resistance for the reaction temperature up to 110 ℃, have a stirring capacity capable of sufficiently stirring the acid solution of approximately 30 ~ 120L, and stagnated inside the reaction tank 120 when stirring The size of the impeller 121c and its rotational speed should be set so that there is no area.

The solid-liquid separator 130 is a device for separating the mixed liquid consisting of the silicon powder and the acid solution into a solid high-purity silicon powder and a liquid waste liquid. The solid-liquid separator 130 may be a centrifuge. That is, the solid-liquid separator 130 is a device for separating by using the difference in density between the solid silicon powder and the liquid acid waste liquid, it is possible to separate the high-purity silicon powder from which impurities are removed from the mixed liquid using a centrifugal force in a short time. . At this time, the solid-liquid separator 130 is preferably provided with a throughput of 20L / min or more. The solid-liquid separator 130 is connected to the reaction tank 120 through a pipe line, the inflow of the mixed liquid discharged from the reaction tank 120 may be made through the pumping action of the pump 150. On the other hand, the solid-liquid separator 130 is connected to the waste liquid collection box 131 by the pipe, the waste liquid collection box 131 is to collect the waste liquid separated from the silicon powder by centrifugation.

In addition, the solid-liquid separator 130, like the reaction tank 120, of course, should be formed of a material having acid resistance and heat resistance. And the harmful gas generated during the operation of the solid-liquid separator 130 is discharged to the harmful gas processing unit 140.

The noxious gas treatment unit 140 is generated during the centrifugal process of the noxious gas and the solid-liquid separator 130 generated during the reaction between the noxious gas generated and discharged during the process, that is, the silicon powder and the acid solution in the reaction tank 120. It is a device to treat and discharge harmful gas.

The noxious gas treatment unit 140 may include a condenser 141 and a scrubber 143. Here, the condenser 141 is connected to the outlet of the reaction vessel 120 and the pipe line and is located above the reaction vessel 120. The condenser 141 primarily filters the harmful gas discharged from the reaction tank 120 before reaching the scrubber 143. In this case, a chiller 142 including a pump 150 for circulating and supplying coolant may be connected to the condenser 141. Accordingly, the condenser 141 may supply coolant circulated and supplied by the chiller 142. To cool and purify the hot exhaust gases.

In addition, the scrubber 143 is a device for cleaning the noxious gas in a dry or wet manner, and is connected to the condenser 141 through a pipe. That is, the scrubber 143 is a device that finally purifies and discharges harmful gas passing through the condenser 141. Such a scrubber 143 should be designed to handle the harmful gas generated from up to 120L of acid solution. At this time, the scrubber 143 may be introduced into the harmful gas discharged from the solid-liquid separator 130 in addition to the reaction tank (120). The exhaust gas purified through the scrubber 143 is discharged to the outside through a hood or the like.

Hereinafter, a silicon refining method according to the present invention will be described with reference to FIG.

2 is a process flowchart showing the silicon refining method according to the present invention in the order of the process. Referring to FIG. 2, the silicon refining method according to the present invention first includes calcium (Ca), iron (Fe), aluminum (Al), etc. To prepare a silicon powder containing a metal impurity and an acidic solution such as hydrochloric acid, nitric acid, hydrofluoric acid to react with the silicon powder to remove the metal impurities. In this step, approximately 3 to 10 kg of a silicon powder having a particle size of 5 µm or more is prepared. The supply amount of such silicon powder may vary depending on, for example, the capacity of the reaction tank 120 in which the reaction is performed. And acidic solution is prepared to approximately 30 ~ 120L to match the supply of silicon powder to be reacted.

Next, the silicon powder prepared by quantitative reaction with the acid solution is removed to remove impurities contained in the silicon powder through the acid solution. Here, it is preferable to mix distilled water with the acid solution before mixing the silicon powder and the acid solution. In addition, in order to promote the reaction between the silicon powder and the acid solution, they may be agitated or may generate ultrasonic waves, pressure, bubbles, and the like, and the stirrer 121 may be used.

On the other hand, the harmful gas generated during the reaction between the silicon powder and the acid solution is discharged to the outside. At this time, the harmful gas must be passed through the condenser 141 and the scrubber 143 to be purified in several stages and then discharged into the air.

Next, the mixed solution of the silicon powder and the acid solution from which the metal impurities are removed is separated from each other. In this step, for example, they are centrifuged using the solid-liquid separator 130. Here, the high purity silicon powder separated from the mixed solution is washed several times to finally obtain a high purity silicon powder. Meanwhile, the acidic waste liquid separated from the silicon powder is collected in a container such as a waste collection container 131 and then disposed of.

Although the present invention has been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also included in the scope of the present invention. It belongs.

100: silicon refining device 110: raw material supply unit
111: silicon supply 112: acid solution supply
120: reactor 120a: inner wall
120b: outer wall 121: agitator
121a: motor 121b: axis of rotation
121c: impeller 122: oil heater
130: solid-liquid separator 131: waste liquid collection
140: harmful gas processing unit 141: condenser
142: chiller 143: scrubber
150: pump

Claims (7)

A reaction tank for reacting the supplied silicon powder with an acid solution to remove impurities contained in the silicon powder;
A solid-liquid separator connected to the reactor and receiving a mixed solution of the silicon powder and the acid solution from the reactor, and separating the mixed solution into solid-phase high-purity silicon and liquid waste liquid by centrifugation; And
To include a harmful gas processing unit for processing and discharge the harmful gas discharged from the reaction tank and the solid-liquid separator,
The harmful gas processing unit,
A condenser to which cooling water is circulated and connected to the reaction tank to cool and purify the harmful gas primarily;
And a scrubber connected to the condenser and the solid-liquid separator to purify and discharge the harmful gas passed through the condenser and the harmful gas discharged from the solid-liquid separator. The method of claim 1,
A raw material supply part connected to the reaction tank and supplying the silicon powder and the acid solution to the reaction tank,
And the raw material supply unit comprises a silicon feeder for supplying the silicon powder and an acid solution feeder for supplying the acid solution mixed with distilled water.
The method of claim 1,
The reactor is formed of a dual structure of the inner wall and the outer wall,
Silicon refining apparatus, characterized in that the heat medium oil is injected and circulated between the inner wall and the outer wall.
The method of claim 3,
And an oil heater connected to the reactor and heating the heat medium oil supplied to the reactor.
The method of claim 1,
The reactor is equipped with a device for generating any one of stirring, bubble, ultrasonic waves or pressure to promote the reaction of the silicon powder and the acid solution.
Preparing a silicon powder and an acid solution;
Reacting the silicon powder with the acid solution in a reaction tank to remove impurities contained in the silicon powder; And
Centrifuging the mixed liquid of the silicon powder and the acid solution into the solid silicon powder and the liquid waste liquid in the solid-liquid separator,
Cooling and purifying the harmful gas discharged from the reaction tank through a condenser connected to the reaction tank, the harmful gas passed through the condenser through the scrubber connected to the condenser and the solid-liquid separator and the discharged from the solid-liquid separator A silicon refining method comprising purifying and discharging harmful gas. The method according to claim 6,
The silicon refining method further comprises the step of washing the centrifuged silicon powder.

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