METHOD FOR CONVERSION OF REACTION MASSES PRODUCED IN ALKALINE HYDROLYSIS OF LEWISITE INTO TECHNICAL PRODUCTS Russian patent published in 2010 - IPC A62D3/37 A62D101/02 C01G28/00 

FIELD: chemistry.

SUBSTANCE: invention relates to the field of chemical weapons destruction, namely to methods for conversion of reaction masses (RM) produced in process of lewisite destruction by method of alkaline hydrolysis, and also products produced from RM in evaporation - "hydrolytic sodium arsenite" (HAS), or in electrolysis of RM - spent catholyte. Method includes filtering of initial product from water-insoluble substances, concentration of filtrate by evaporation to produce solution of sodium arsenite in concentration of 25.0-30.0 wt %, separation of sodium chloride deposit by means of filtration, neutralisation of sodium arsenite solution to produce arsenic oxide and its treatment by method of repulping, dissolution of sodium chloride deposit in water and treatment of produced solution from arsenic compounds, at the same time sodium chloride solution is cleaned from arsenic compounds by means of their recovery into element arsenic, recovery agent is represented by thiourea dioxide, or sodium or zinc dithionite, or their mixtures, which is taken in the ratio of 2.1-2.5 per 1 relative to total arsenic, and process of recovery is carried out in the range of temperatures from 20 to 100°C, produced element arsenic is cleaned by method of repulping. In process of arsenic oxide production, arsenic compounds (V) are recovered in arsenic compounds (III) at pH of medium equal to 3-4 with a recovery agent taken in the ratio of 1.5-2.5 per 1 relative to arsenic (V), at the same time recovery agent is represented by sulphite, or bisulphite, or sodium pyrosulphite, or rongaite or their mixtures. Process of arsenic oxide and element arsenic repulping is carried out with diluted solutions of mineral acids and water in ultrasonic field. On completion of element arsenic repulping process solution is filtered, deposit of element arsenic is washed on the filter with ethyl alcohol, then pressed in die with pressure of at least 70 kN and finally dried in vacuum at the temperature from 20 to 200°C. Solutions are filtered through a layer of microcellulose and carbon-fibre fabric of 0.5-3.0 cm, which makes it possible to separate water-insoluble substances, dying admixtures and metal admixtures.

EFFECT: invention makes it possible to increase efficiency and to simplify process, to expand assortment and to improve quality of produced technical products, to improve ecological safety of the process.

5 cl, 7 ex, 1 dwg