METHOD OF COMPLEX PROCESSING AND DEACTIVATION OF RADIOACTIVE WASTE AT RARE METAL PRODUCTION Russian patent published in 2008 - IPC C22B59/00 C22B60/00 C22B3/20 G21F9/28 

FIELD: metallurgy.

SUBSTANCE: invention refers to metallurgy, particularly to hydrometallurgical methods of processing and deactivation of radioactive waste at rare metal production. The method includes hydro washing away of spent melt of saline spraying filter (SSF), the chlorination process of loparit concentrates, treatment of produced suspension with alkaline reagent, mixing with iron containing shop flush waters, separation of radioactive sediment from the mother solution and transporting of radioactive sediment into a special waste storage (SWS). Prior to treatment with the alkaline reagent the suspension, produced after hydro washing away of spent melt SSF, is mixed at a ratio 1:(0.8-1.2) with the solution, containing 250-300 g/dm³ chlorides of alkali metals, and is heated to 85±5°C. With the use of solution of sodium hydroxide as the alkaline reagent treatment of the suspension is performed to pH 2.0+0.5, then this solution is held for 0.5+0.1 hr, then solution of high molecular flocculant- hydrolysed oilacrilamid - is introduced and is held without mixing for 2.0±0.5 hrs. After that the thickened part of the suspension is fed to a nutsch-filter, the produced sediment - rare metal concentrate - is dried, tempered and transfered to chlorination of source loparit concentrates. Filtrate is combined with clarified portion of the suspension, heated to 80±10°C and treated with solution of sodium hydroxide to pH 12.0±0.5. Produced oxihydrate pulp is held at 80±10°C for 1.0±0.5 hrs and is fed to a filter-press-I; the extracted radioactive sediment is washed out at the filter-press-I 3-4 volumes of water, and process water is merged with shop flush water. The washed out sediment is blown out with a compressed air at the filter-press-I, then unloaded and transported to SWS, while mother solution is mixed at a ratio of 1:(10-20) with iron containing shop flush water. Produced radioactive chloride solution is heated to 80±10°C and treated with solution of sodium hydroxide to pH 12.0±0.5, the resulted pulp is held at 80±10°C and pumped to a filter-press-II with production of deactivating solution, which is discharged to a shop drainage, and with production of sediment; the latter is merged with the sediment - rare metal concentrate, extracted out of suspension after dissolving of the spent melt SSF; the said sediment is heat treated and partially neutralized, then dried, tempered and transferred to chlorinating in saline chlorinators together with the source loparit concentrate.

EFFECT: upgraded degree of deactivation of solutions and discharge waters and additional extraction of valuable elements.

2 dwg, 1 ex