JPS60114328A - Treatment of gas containing hydrogen arsenide - Google Patents

Abstract

PURPOSE:To treat the titled gas by a dry process being a simple process with the usage of an easily obtainable adsorbent by passing a gas containing AsH3 through a packed layer of bleaching powder or the mixture of bleaching powder, iron compound, and diatom earth after humidifying the gas and by oxidizing and adsorbing the AsH3. CONSTITUTION:An adsorbent consisting of simple high test hypochlorite Ca(OCl)2 or the mixture of hypochlorite, iron compound such as FeCl3, and diatom earth is packed into a packed layer. After humidifying a gas containing AsH3 by bubbling the gas in water or a spraying nozzle, etc., the gas is passed through the packed layer. The AsH3 contained in the gas is oxidized and adsorbed by the adsorbent.

Description

Detailed Description of the Invention This invention relates to the use of metal hydrides such as hydrogen arsenide and hydrogen phosphide as doping gases in the manufacturing process of semiconductors and integrated circuits in the semiconductor electronics industry. This invention relates to a method for dry processing of hydrogen arsenide-containing gas discharged from industry.

Hydrogen arsenide (Arsine/AsH3) and hydrogen phosphide (phosphine/PHa) are highly toxic, and if these toxic gases are released into the atmosphere from the process without being treated, they will have a very negative impact on human health, resulting in the worst In some cases, there is a possibility that it may pose a danger to life, so it is naturally necessary to detoxify it.

Currently, the methods used to treat exhaust gas containing hydrogen arsenide emitted by the semiconductor electronics industry or other chemical industries can be roughly divided into solid adsorption methods, potassium permanganate oxidation and absorption methods, and combustion decomposition methods. is proposed.

The outline of these treatment methods is as follows.A typical example of the solid adsorption method is as seen in Japanese Patent Publication No. 58-34178. Exhaust gas is purified by using a purifying agent composition in which a porous material is infiltrated with a solution prepared by adding cupric oxide, cupric oxide, magnesium chloride, and mercuric chloride as auxiliary materials and water. This purification method is described in detail in the same publication as AsHa+5FeC13+4(20-+6F
eC12+6HC1+H3As03 (1) 3MCI+Fe(OH)3-+FeCIa+3H20(
It consists of an absorption mechanism and a regeneration mechanism (2). In this method, when mercuric chloride is used as an auxiliary material, Hg is contained in the treated wastewater and treated waste, and its treatment becomes a problem.

Permanganese acid power! J (KMnOa) oxidation absorption method
This is a method in which an aqueous MnO4 solution is passed through an absorbent and absorbed and removed according to the following reaction formula.

AsH3+2KMnO4→KzHAs04+Mn 20
3+H20 In this method, manganese oxide is produced and there are problems such as clogging due to deposition in the absorption device.

The combustion decomposition method is a method in which ASH3 is oxidized and decomposed at about 3000 ml, and has the problem of complicated operation management and high cost.

Each of the above processing methods has its own advantages and disadvantages, and generally tends not to be justified in terms of technical efficiency and economic efficiency.

This invention aims to reduce treatment costs by using adsorbents that are easy to operate and obtain, and does not contain harmful substances in treated waste. (3) Problems such as treatment of secondary chemical damage are avoided It was developed with the aim of providing a method for processing gas containing a small amount of hydrogen arsenide.

The feature of this invention is that after the hydrogen arsenide-containing gas is humidified, it is passed through a packed bed of an adsorbent made of bleaching powder alone or a mixture of this powder and an iron compound or diatomaceous earth to remove hydrogen arsenide from the gas. The purpose is to oxidize and adsorb it.

The main component of highly bleached powder is primary calcium hypochlorite (Ca(O
CI)2) 1 It is preferable for the treatment of AsH3 because it has a larger amount of available chlorine than normal bleached powder (CaOCI2), but normal bleached powder can also be used if necessary. This is because the main component of bleached powder is said to be a mixed salt of calcium chloride and calcium hypochlorite.

The iron compounds mentioned in this invention are added to collect the generated As and prevent it from eluting out of the system, and include iron monoxide (Fe203) and ferric chloride (FeCl3).
〇Diatomaceous earth is added to prevent the adsorbent from turning into mud due to humidification (A'+).The amount of diatomaceous earth added is 2 to 4 times the amount of bleaching powder. Further, the amount of iron compound added is 2 to 174 times the amount of bleached powder.

The oxidation efficiency of bleached powder can be increased by humidifying the hydrogen arsenide-containing gas in advance. Humidification operations include bubbling into the water, spray nozzles, and other methods. The degree to which the humidity is increased is determined by considering processing conditions such as the amount of adsorbent packed and the hydrogen arsenide concentration in the gas.

Next, examples of this invention will be shown.

Example: Hydrogen arsenide-containing gas (
Introducing AsH31ppm, humidity 0, temperature 25C),
After bubbling, 15 mm × 150 mm) (
4g of highly bleached powder (available chlorine 60%), F
The gas was passed through a packed bed filled with a mixture (15 g) of 31 g of eCl and ±10 g of diatomaceous material at a flow rate of 2.4 l/Hr. The humidity in the gas at the inlet of the packed bed was 0% and 65% at a temperature of 25C, respectively. The results of the implementation (tk) are shown in the attached figure.

As shown in the figure, by humidifying the hydrogen arsenide-containing gas, the hydrogen arsenide concentration in the treated gas can be reduced to 0. We were able to reduce the O to 5 ppm or less.

Example 2 To understand the arsenic adsorption performance of Ca(CIO)2.

Arsenic was generated in an arsenic generator (Asia + Zn + KI) and entrained in the introduced air (humidity 67% - temperature 26C), and a 15mm x 150+U+H adsorption tower was filled with 10g of highly bleached powder (available chlorine 60%). 2 l in layer
/Hr, and the exhaust gas is distributed to a cylinder containing a silver diethyldithiocarbamate solution,
When the concentration of As was measured, the results shown in the table below were obtained. If the method of this invention is followed, the process is simplified compared to the wet method, so operation management is extremely easy, and hazardous substances are processed and disposed of. Since it does not mix with materials, there are few problems in secondary processing, and since an easily available adsorbent is used and the amount of utility consumed is small, it brings benefits such as a reduction in processing costs.

[Brief explanation of drawings]

The drawings are diagrams illustrating the results of the embodiments of the present invention. (7) Outlet gas distribution gas ICI/Hr)

Claims (1)

[Claims] The feature is that after humidifying the hydrogen arsenide-containing gas, it is passed through a packed bed of an adsorbent made of bleaching powder alone or a mixture of this powder and an iron compound or diatomaceous earth to oxidize and adsorb the hydrogen arsenide in the gas. A method for treating hydrogen arsenide-containing gas.