CN1139588A

CN1139588A - Method for treating waste gas containing arsenic and arsenic compound

Info

Publication number: CN1139588A
Application number: CN 96104510
Authority: CN
Inventors: 闻瑞梅; 刘任重; 邓礼生; 梁骏吾
Original assignee: Institute of Semiconductors of CAS
Current assignee: Institute of Semiconductors of CAS
Priority date: 1996-04-11
Filing date: 1996-04-11
Publication date: 1997-01-08
Anticipated expiration: 2016-04-11
Also published as: CN1053596C

Abstract

The present invention discloses a kind of method for treating the waste gas containing arsenic and arsenic compounds produced in the semiconductor process. The oil vapor in the waste gas is firstly removed, then the waste gas is undergone the foaming and back spraying treatment by using mixed solution of KIO3, KI and H2SO4, then the mixed solution of CuSO4 and H2SO4, and mixed solution of KMnO4 and NaOH are used separately to make the back spraying treatment to the waste gas. The overpressure protection and alarm measure are adopted in order to treat the gas when the air course is blocked. Said method features high efficiency for removing the toxic component in the waste gas, eliminating the possibility of destruction of arsine and safe in operation.

Description

Method for treating waste gas containing arsenic and arsenic compound

The present invention relates to a method for treating waste gas containing arsenic and arsenic compounds in semiconductor industry and research.

In semiconductor research and production, during the preparation of semiconductor materials containing arsenic by methods such as Chemical Beam Epitaxy (CBE), Metal Organic Chemical Vapor Deposition (MOCVD), and the like, waste gases containing arsenic and arsenic compounds are generated. These components are toxic and therefore the exhaust gas must be treated before it can be discharged. The national environmental protection standard has specific regulation on the content of toxic gas in the discharged waste gas, and the treated waste gas can be discharged only after reaching the standard.

The treatment of waste gases containing arsenic and arsenic compounds is usually carried out by absorbing the toxic components with a treatment solution, and usually with an oxidizing agent. There are two absorption modes, one is bubbling and the other is reverse spraying. The bubbling is to introduce the waste gas below the liquid level of the treatment liquid, and the gas overflows from the treatment liquid under the action of the pressure of the waste gas, and the reverse spraying is to move the gas from bottom to top in the reverse spraying device, and the treatment liquid is sprayed from top to bottom to contact with the gas to react. The treatment equipment for such waste gas currently on the market adopts either a spraying method or a bubbling method.

Generally, the exhaust gas to be treated contains oil vapor, and the oil adheres to the surroundings of the arsenic particles, so that the contact efficiency between the arsenic particles and the treatment liquid is lowered, thereby affecting the treatment effect. And the oil enters the treatment fluid, which also shortens the service life of the treatment fluid. Another disadvantage of the existing processes is the potential for arsine explosions. The waste gas contains arsine, and when the concentration of arsine reaches a certain value, spontaneous explosion can occur when air is encountered. In addition, the exhaust gas contains larger particles and some solid matter is generated in the device during the treatment process, so that the exhaust gas channel has the possibility of blockage, and no proper measures are available in the prior art for preventing the possible damage caused by the blockage.

Because of the components and the proportion of the treatment fluid adopted in the prior art, the treatment effect is poor when the content of arsenic and arsenic compounds in the waste gas is high, and the service life of the treatment fluid is short.

The invention aims to provide a novel method for treating waste gas containing arsenic and arsenic compounds, which has better treatment effect and is safe.

The invention is realized in such a way. Adopts the methods of oil separation, overpressure protection and alarm, reverse spraying and bubbling combination and multi-stage treatment. Firstly, the poisonous waste gas enters an oil separation device to remove oil vapor in the waste gas, and then the waste gas is introduced into KIO₃、KI、H₂SO₄Bubbling in the mixed solution, namely introducing waste gas below the liquid level of the treatment solution to enable the waste gas to overflow from the treatment solution by self pressure, then carrying out reverse spraying by adopting the same treatment solution, and then adopting CuSO₄、H₂SO₄The mixed solution carries out second-stage reverse spraying treatment on the waste gas, and KMnO is adopted₄And carrying out third-stage reverse spraying on the waste gas by using the NaOH mixed solution. If the waste gas channel is blocked, the waste gas enters the activated carbon adsorption device through the overpressure protection and alarm device.

After the method is adopted to treat the waste gas containing arsenic and arsenic compounds, the toxic component As in the waste gas₂、As₄、AsH₃The content of (A) is less than 0.04mg/m³The product reaches the national environmental protection standard and can not generate self-explosion of arsine. When the exhaust gas channel is blocked, the condition that the exhaust gas leaks into the air can not occur, thereby being safer. Meanwhile, the average service life of the treatment fluid is prolonged from one month to three months in the prior art.

The technical scheme of the invention is further explained by combining the attached drawings.

FIG. 1 is a schematic view of a method for treating waste gas containing arsenic and arsenic compounds

In the figure, 1, an oil separating device

2. Overvoltage protection and alarm device

3. Activated carbon adsorption device

4. First-stage treatment box

5. Second-stage treatment box

6. Third-stage treatment box

7. Toxicity monitoring and alarming device for discharged tail gas

8. Overvoltage alarm device

9. First-stage reverse spraying device

10. Second-stage reverse spraying device

11. Third-stage reverse spraying device

The toxic waste gas containing arsenic and arsenic compounds is first passed into the oil separator 1 to remove the engine oil vapor from the waste gas, thereby improving the efficiency of the subsequent treatment process. Then, the exhaust gas is introduced into the KIO tank₃、KI、H₂SO₄The mixed solution is bubbled below the liquid level in the first-stage treatment tank 4, during which toxic components in the exhaust gas react with the treatment liquid. Most of the arsine is absorbed, and after the waste gas overflows from the treatment liquid, even if the waste gas contacts air flowing in the reverse direction along the pipeline, because the concentration of the arsine is very small, the arsine cannot explode.

The waste gas overflows from the treatment liquid under the action of the self pressure and then enters the first-stage reverse spraying device 9 upwards, the treatment liquid in the first-stage treatment box 4 is lifted to the upper part of the device 9 under the action of a pump, and then is sprayed from top to bottom and then returns to the first-stage treatment box 4, and the circulation is carried out. In the reverse spraying device 9, the treating liquid sprayed from top to bottom contacts with the waste gas moving from bottom to top, and reacts to absorb toxic components in the waste gas.

The waste gas after the first-stage bubbling and spraying treatment enters the second-stage treatment box 5 from the upper part of the reverse spraying device 9 through a pipeline. The waste gas is not introduced below the liquid level of the treatment liquid in the second-stage treatment tank 5, but directly enters the second-stage reverse spraying device 10 along the upper part of the liquid level. CuSO is filled in the second-stage treatment box 5₄And H₂SO₄The mixed solution was used as a treatment solution. As in the first stage of spraying treatment, the treatment liquid is lifted to the upper part of the device 10 under the action of a pump, then sprayed from top to bottom in the device to contact with the waste gas moving from bottom to top, and then returned to the second stage treatment tank 5, and the circulation is carried out.

Exhaust gasFrom the upper part of the second stage reverse spray treatment box 10, the reverse spray treatment box enters the third stage treatment box 6 through a pipeline and flows along the KMnO contained in the treatment box₄NaOH mixed solution enters the lower part of the third-stage reverse spraying device 11 above the liquid level, and KMnO is the same as the previous two-stage reverse spraying treatment process₄And the NaOH solution is sprayed in the third-stage reverse spraying device 11 to contact with the waste gas for reaction, and the treatment solution returns to the treatment box 6 for circulation.

Finally, the waste gas is discharged from the upper part of the device 11 through a pipeline, and an exhaust tail gas toxicity detection alarm device 7 is arranged at an outlet so as to detect the content of toxic components in the waste gas and alarm when the content exceeds the standard.

The principle of treating arsenic and arsenic compounds with the various treatment liquids described above is as follows. The arsenic in the exhaust gas was analyzed to be present in the form of As₂、As₄、AsH₃The reaction principle of these components with the treatment solution is as follows:

in the process of treatment, once the waste gas channel is blocked, the waste gas which is not processed by bubbling and spraying enters the overpressure protection and alarm device 2, the device is opened and closed under normal conditions, when the gas pressure is increased to a certain limit, the gas channel is automatically opened and an alarm is generated, the waste gas enters the activated carbon adsorption device 3, and the activated carbon absorbs toxic components in the waste gas, so that the time is provided for treating the blockage or taking other measures. An overpressure alarm device 8 is arranged at the gas outlet of the activated carbon adsorption device 3, and when waste gas is discharged, the device gives an alarm.

In a preferred embodiment of the invention, the concentrations of the various treatment fluids are such. The solution contained in the first-stage treatment tank is KIO₃KI, saturated solution, 1-5% of H₂SO₄A solution; the solutions contained in the second stage treatment tank 5 were: 1% -5% of CuSO₄Solution and 1% -5% H₂SO₄A solution; the solutions contained in the third-stage treatment tank 6 were: 1% -5% NaOH solution and 1% -5% KMnO₄And (3) solution.

The sequence of the second-stage reverse spraying treatment and the third-stage reverse spraying treatment can be exchanged. That is, KMnO may be used first₄Treating the waste gas with NaOH solution, and then using CuSO₄、H₂SO₄The solution is processed.

Claims

1. A process for treating the waste gas containing As and As compounds includes such steps as ① removing oil vapour from said waste gas, ② introducing said waste gas containing 1-5% H₂SO₄Solution and saturated KIO₃③ waste gas overflows from the mixed solution and enters into the first stage reverse spraying device from bottom to top, the mixed solution is sprayed from top to bottom in the device and contacts with the waste gas to absorb arsenic and arsenic compounds in the waste gas, ④ the waste gas is guided into the second stage reverse spraying device from bottom to top and moves, and the waste gas contains 1% -5% H₂SO₄And 1% -5% of CuSO₄The treating liquid of the solution is sprayed from top to bottom in the second stage reverse spraying device to contact with the waste gas for treating the waste gas, ⑤ the waste gas is finally led into the third stage reverse spraying deviceThe device moves from bottom to top and contains 1% -5% KMnO₄And treating liquid of 1-5% NaOH solution is sprayed from top to bottom in the third stage reverse spraying device and contacts with the waste gas to treat the waste gas, ⑥ and then the waste gas is discharged.

2. The method of claim 1 wherein said steps of ④ and ⑤ can be reversed by first using said KMnO-containing solution₄And NaOH, and then adopting the CuSO-containing treating fluid to treat the waste gas₄And H₂SO₄The waste gas is treated by the treating fluid.

3. A method as claimed in claim 1 or claim 2, wherein the untreated waste gas is passed through a further channel to an overpressure protection and alarm device which normally closes, automatically opens the channel when the pressure increases to a certain limit and alarms, and from there can be passed to the activated carbon adsorption unit for disposal.