Optimization of ecological and eco-nomical tasks at processing raw materials obtained from lewisite reaction masses into commercial arsenic oxide. <...> Ключевые слова: технологии переработки, арсенит натрия гидролизный, оксид мышьяка (III), хлорид натрия Izv. <...> Fedorov Anatoliy G. Demakhin State Scientific-Research Institute of Industrial Ecology, Moskovskaya st., 66, Saratov, 410002, Russia E-mail: demakhin@rambler.ru Sergey V. Akchurin () LLC NITC «Ecochim», Moskovskaya st., 66 , Saratov, 410002, Russia E-mail: akchurin.serzh@yandex.ru () Grigori A. Vashchenko LLC UK «UGC», mine «Central», Plast, Chelyabinsk region, 457020, Russia E-mail: grigori1962@mail.ru Valentin A. Fedorov Kurnakov Institute of General and Inorganic Chemistry of RAS, Leninsky prosp., 31, Moscow, 119991, Russia E-mail: fedorov@igic.ras.ru OPTIMIZATION OF ECOLOGICAL AND ECONOMICAL TASKS AT PROCESSING RAW MATERIALS OBTAINED FROM LEWISITE REACTION MASSES INTO COMMERCIAL ARSENIC OXIDE The paper presents original technical solutions for processing the raw materials obtained from the lewisite detoxication products into arsenic (III) oxide. <...> Our optimization of arsenic (V) compounds removal from the system and sodium chloride purification from impurities of arsenic compounds allow improving the economical and ecological parameters of the whole process of hydrolyzed sodium arsenite (HSA) conversion into arsenic (III) oxide. <...> Our improvement of certain technological operations has made possible to optimize the general process scheme. <...> Key words: processing technologies, hydrolyzed sodium arsenite, arsenic (III) oxide, sodium chloride In Russia, lewisite is neutralized by means of high-temperature alkaline hydrolysis to form liquid reaction masses. <...> The main lewisite stock was at the storage facility in the Kambarka town (Udmurt Republic). <...> Prior to transporting that amount to the Gorny settlement (Saratov Region), the masses were evaporated to obtain 12,500 tons of dry salts with a trivial name of hydrolyzed sodium arsenite (HSA). <...> This evaporated product was manufactured according to Russian Technical Specification 2622-159-04872022005. <...> This is a complex multi-component system containing a number of major components, namely: sodium arsenites and arsenates, sodium chloride, water-insoluble substances (mainly bentonite clay), and other compounds in substantially smaller amounts (organic arsenic <...>