The method of disposal of lewisite with obtaining metal arsenic

 

(57) Abstract:

The invention relates to chemical technology disposal of toxic substances, in particular, lewisite and receiving on its base metal arsenic. The inventive pre-mixed steam-gas mixture of hydrogen gas and lewisite in a molar ratio of 2/1 9/1 at 800-1000C undergoes parolise. By passing through the reaction device, the gas-vapor mixture is decomposed mainly to metallic arsenic, and hydrogen chloride. The output from the reaction device of the mixture flows into the deposition chamber, where the cold surface of the chamber in the deposition of metallic arsenic. The pyrolysis reaction lewisite to metallic arsenic is a gas-phase reaction, the speed of which depends on the temperature of the process and the hydrogen concentration in the original steam-gas mixture. The method allows to dispose of lewisite to produce metallic arsenic is not less than 99.9% of theoretical yield, the process is carried out in one stage, while the lewisite concentration at the outlet of the reaction device is below the maximum permissible concentration of lewisite in the air of working zone of production areas. 1 C. p. F.-ly.

The invention relates to him the ical arsenic.

The problem of utilization of lewisite acquires exceptional importance.

Accumulated huge stocks of lewisite and disposal of lewisite in metallic arsenic would satisfy all requirements. Arsenic is the starting substance for the manufacture of semiconductor compounds, in particular for the production of gallium arsenide, and also finds application in agriculture and glass production.

Lewisite belongs to the group "S" with skin-naravni common toxic effect. Lewisite is an oily, dark-brown liquid with a strong obsession for the smell of geranium. Usually get technical product is not an individual matter and is a mixture of michalkaronski compounds of the following approximate composition:

75-85% of the weight-lewisite;

5-15% weight-lewisite;

20-10% by weight arsenic trichloride.

-lewisite, 2-chlorovinyldichloroarsine, chemical formula ClC2H2AsCl2. A heavy, colorless, water-insoluble liquid storage acquires a violet shade. Smell-lewisite like the smell of geraniums. Molecular weight 207,4 boiling point 196,6aboutWith a Density at 25aboutWith 1,8793 g/cm3Solubility>H2)2AsCl. Colorless liquid, insoluble in water. Molecular weight 233,4 boiling point 230aboutWith a Density at 25aboutWith 1,6884 g/cm3Trichloride arsenic, AsCl3(Choral music theatre).

Oily, steaming liquid. Molecular weight 181,4 boiling point 130,4aboutWith Density at 20aboutWith 2,1668 g/cm

The level of engineering and technology in the field of chemical industry at present is that there is not any effective and technologically waste destruction process of lewisite with obtaining necessary for the industry of metallic arsenic.

However, of particular interest is the processing of lewisite method of chlorination in arsenic trichloride and subsequent processing into pure arsenic for commercial use [1] This method consists of two stages: the interaction of lewisite with gaseous chlorine and isolation from the reaction mass trichloride arsenic [2]

The disadvantages of the prototype method are:

the need to work with large amounts of lewisite;

a high degree of residual lewisite (up to 3), therefore, the concentration of lewisite in the reaction mass at some time AsCl3(Choral music theatre), MAC 10-3mg/m3;

storage and transportation must meet the requirements of storage and transportation of toxic substances;

the need to create a special vacuum separation unit choral music theatre and tetrachloroethylene (TAE) in connection with the closeness of their boiling points;

low productivity of the process lewisite destruction per unit of reaction volume;

the need for additional stages of the technological process (recovery choral music theatre) for processing choral music theatre in metallic arsenic.

The technical result of the invention is

the increase in the degree of conversion of lewisite to values that ensure the exposure of the working area of industrial premises (<2-lewisite, lewisite.

When the temperature of the process 800aboutWith along with the hydrogenolysis reactions of lewisite happen reactions of thermal decomposition of lewisite. In reaction mass accumulates arsenic trichloride, is the formation of acetylene. The degree of decomposition of lewisite is small and the concentration of lewisite significantly higher than the MPC (if 700aboutWith the degree of decomposition of lewisite 99,3%). A higher degree of transformation of lewisite at the temperature holding process is less than the ri temperatures above 1000aboutWith the process carried out is impractical because the degree of decomposition of lewisite does not increase, the technical difficulties are greatly increased.

The molar ratio of hydrogen to lewisite less 2/1 reduces the degree of decomposition of lewisite to 99,94% which is significantly higher than the MPL. The molar ratio of hydrogen to lewisite above 9/1 reduces the yield of metallic arsenic.

The best variant of the proposed method is as follows.

P R I m e R 1. Pre-mixed gas-vapor mixture of hydrogen and lewisite in a molar ratio of 5.3/1 in the amount of 1.32 kg/h at 900aboutTo be served at the entrance of the reaction device. Gas-vapor mixture passes the reaction device and enters the chamber of the deposition of metallic arsenic from the gas mixture. The lewisite concentration at the outlet of the reaction device 0,48210-12mol/l (110-7mg/l), which corresponds to the calculation of the degree of conversion of lewisite with precision 710-10. At the outlet of the reaction device get 0,451 kg/h of metallic arsenic with the release of 99.97% of theoretical.

P R I m m e R 2. Pre-mixed gas-vapor mixture of hydrogen, nitrogen and lewisite, in a molar ratio of hydrogen:lewisite 5,3:1 number of 5.25 kg/the t input of the reaction device. The lewisite concentration at the outlet of the reaction device 0,48210-7mg/l), which corresponds to the calculation of the degree of decomposition of lewisite with precision 710-10. At the outlet of the reaction device get 1,805 kg/h of metallic arsenic with the release of 99.97% of theoretical.

P R I m e R 3. Pre-mixed gas-vapor mixture of hydrogen and lewisite in a molar ratio of 7.9/1, the number 5,38 kg/h at 800aboutTo be served at the entrance of the reaction device. The lewisite concentration at the outlet of the reaction device 0,48210-12mol/l (110-7mg/l), which corresponds to the calculation of the degree of conversion of lewisite with precision 710-10. At the outlet of the reaction device get 1,805 kg/h of metallic arsenic with the release of 99.97% of theoretical.

P R I m e R 4. Pre-mixed gas-vapor mixture of hydrogen and lewisite in a molar ratio of 5.3/1, in the amount of 5.25 kg/h at 700aboutTo be served at the entrance of the reaction device. The lewisite concentration at the outlet of the reaction device 0,9310-5mol/l, which corresponds to the degree of decomposition of lewisite 0,993. At the outlet of the reaction device get 1,59 kg/h of metallic arsenic with access 88,28% of theoretical.

P R I m e R is g/h at 1100aboutTo be served at the entrance to the reaction device. The lewisite concentration at the outlet of the reaction device 0,48210-12mol/l (110-7mg/l), which corresponds to the calculation of the degree of decomposition of lewisite with precision 710-10. At the outlet of the reaction device get 1,805 kg/h of metallic arsenic with the release of 99.97% of theoretical.

P R I m e R 6. Pre-mixed gas-vapor mixture of hydrogen and lewisite in a molar ratio of 1.2/1, in the amount of 5.05 kg/h at 1000aboutTo be served at the entrance of the reaction device. The lewisite concentration at the outlet of the reaction device 0,1110-5mol/l, which corresponds to the degree of decomposition of lewisite 99,94% At the outlet of the reaction device is to obtain 1,803 kg/h of metallic arsenic with out 99.9% of theoretical.

P R I m e R 7. Pre-mixed gas-vapor mixture of hydrogen and lewisite in a molar ratio of 10.5/1, the number 5,51 kg/h at 1000aboutTo be served at the entrance of the reaction device. The lewisite concentration at the outlet of the reaction device 0,48210-12mol (110-7mg/l), which corresponds to the degree of conversion of lewisite with precision 110-10. At the outlet of the reaction device get 1,804 kg/h metallic arsenic is Yak tested in the pilot installation. When the temperature of the process 800-1000aboutWith a molar ratio of hydrogen to lewisite 2/1 9/1--and a molar ratio of nitrogen: hydrogen is not less than 3.2:1 lewisite concentration at the outlet of the reaction device 110-7mg/l, which is below the maximum permissible concentration of lewisite in the air of working zone of production areas; exit metallic arsenic least 99.9% of theoretical; increased productivity decomposition lewisite per unit reaction volume; the recycling process lewisite to metallic arsenic is carried out in one stage in one reaction device; a received batch of metallic arsenic. Refined metal arsenic is directed to the production of gallium arsenide. At one of the factories for storage S plan to create a pilot plant disposal lewisite to metallic arsenic capacity of 40-50 tons per year, followed by the creation of industrial production.

1. The METHOD of DISPOSAL of LEWISITE WITH OBTAINING METAL ARSENIC interaction of lewisite with gaseous component, characterized in that the interaction is carried out at 800 to 1000oWith in a homogeneous gas phase, and as a gaseous component using hydrogen at a mole is tlaut in phlegmatizers atmosphere of nitrogen at a molar ratio of nitrogen:hydrogen is not less than about 3.1:1.

 

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