PROCESS OF CLEARING OF ALKALI METALS AND ALLOYS BASED ON SODIUM, POTASSIUM AND CESIUM FROM IMPURITIES Russian patent published in 1998 - IPC

FIELD: technology and metallurgy of alkali metals. SUBSTANCE: process refers to clearing from impurities of alkali metals based on sodium, potassium and cesium meant for nuclear power engineering when preparing liquid-metal heat transfer agent. Alkali metals and alloys based on sodium, potassium and cesium from impurities, for instance, calcium, are cleared by treatment of molten metal or alloy with gaseous nitrogen followed by filtration. In this case treatment of molten metal or alloy with gaseous nitrogen is conducted at temperature above 350 C with amount of nitrogen not less than 2.4 l/kg of technical sodium. Filtration is carried out at temperature 300-350 C through filter having porosity not more than 12 μm. EFFECT: increased efficiency of clearing of alkali metals and alloys, decreased cost of clearing and enhanced safety of technology of extraction and dewatering of sediments. 3 cl