OJSC “Giredmet”

V. V. Apanasenko, Leading Researcher, e-mail: asla_new@rambler.ru

There is considered the process of the waste gas purification by sodium carbonate solution in the range of temperatures from 0 to 60 ^oC. The waste gas contains the hydrogen chloride, trichlorosilane, silicon tetrachloride and dichlorosilane with 10 and 17% wt. It is established by the calculation, that the crystallization of obtained sodium hydrocarbonate might take place in the course of process. The amount of precipitated NaHCO₃ grows with the increasing of Na₂CO₃ concentration in the initial solution and decreases with the growth of temperature and extremely depends on degree of soda use in the process of gas purifying. In the generated suspension, the peak value of weight of solid salts fraction reaches, when soda is half used. That means that sodium carbonate completely transforms into hydrocarbonate and makes up to 10,9% (conditions: 17% of soda solution, t = 0 ^oC, HCl is the only hazardous substance in waste gases). At the temperature 60 ^oC the maximum of salt crystallization decreases to 5,4% (other conditions are the same). There are computed the properties such as density and viscosity for obtained solutions and suspensions (when solid salt is precipitated). The flows' density and viscosity decreases, with increasing of soda use degree, which improves the mass exchange in a neutralization process. There is formed the precipitate of silicic acid, along with solid sodium hydrocarbonate in a purifying process of waste gases, which contain clorosilanes. The amount of this precipitate grows with the increase of the degree of soda use and thus increases the lump of precipitation. It is also shown that under the temperature less than 20 ^oC, Na₂CO₃·10H₂O might precipitate as well. The amount of the precipitate of sodium carbonate decahydrate is calculated in terms of the temperature, soda concentration and degree of its use. The formation of solid salt phases might significantly complicate the utilization process of the waste gas in production conditions. It has to be taken into account in choosing the equipment for gas purifying system.

1. Naumov A. V. Materialy Elektronnoy Tekhniki. Izvestiya Vuzov – Materials of Electronic Technics. Bulletin of Universities. 2009. No. 2. pp. 4–12.

2. Kozhemyakin V. A., Pochtarev A. N. Tsvetnye Metally – Non-ferrous metals. 2008. No. 10. pp. 65–68.

3. Strelnikov A. S. Ekologiya i promyshlennost Rossii – Ecology and industry of Russia. 1999. No. 1. pp. 8–12.

4. Kozhemyakin V. A., Zubchenko G. V., Mitnik V. L., Vaks G. L. Malootkhodnye protsessy i okhrana okruzhayushchey sredy v metallurgii redkikh metallov (Low-waste processes and environmental protection in the metallurgy of rare metals). Moscow : Metallurgiya, 1991. 160 p.

5. Dorokhova E. N., Prokhorova G. V. Zadachi i voprosy po analiticheskoy khimii (Problems and questions on analytical chemistry). Moscow : Mir, 2001. 267 p.

6. Ayler R. Khimiya kremnezema. V dvukh chastyakh (Chemistry of silica. In two parts). Moscow : Mir, 1982. 1128 p.

7. Apanasenko V. V., Voldman G. M. Tsvetnye Metally – Non-ferrous metals. 2010. No. 9. pp. 59–66.

8. Zdanovskiy A. B., Soloveva E. F., Lyakhovskaya E. I. et al. Eksperimentalnye dannye po rastvorimosti mnogokomponentnykh vodno-solevykh sistem : spravochnik (Experimental data on dissolubility of multicomponent water-and-salt systems : reference book). Saint Petersburg : Khimizdat, 2003. Vol. 1, Book 1. 608 p.

9. Zdanovskiy A. B., Soloveva E. F., Lyakhovskaya E. I. et al. Eksperimentalnye dannye po rastvorimosti mnogokomponentnykh vodno-solevykh sistem : spravochnik (Experimental data on dissolubility of multicomponent water-and-salt systems : reference book). Saint Petersburg : Khimizdat, 2003. Vol. 2, Book 1. 640 p.

10. Sokolovskiy A. A., Yakhontova E. L. Primenenie ravnovesnykh diagramm rastvorimosti v tekhnologii mineralnykh soley (Application of balanced solubility diagrams in the technology of mineral salts). Moscow : Khimiya, 1982. 264 p.

11. Zaytsev I. D., Aseev G. G. Fiziko-khimicheskie svoystva binarnykh i mnogokomponentnykh rastvorov neorganicheskikh veshchestv (Physical and chemical properties of binary and multycomponent solutions of non-organic substances). Moscow : Khimiya. 1988. 416 p.

12. Spravochnik khimika (Chemist`s reference book). Under the editorship of B. P. Nikolskiy et al. Leningrad : Khimiya, 1968. Vol. 5. 976 p.