30. Critically evaluate modern technology in the processing of rubidium and cesium containing rare metal raw materials.
Cesium is found in the minerals pollucite and lepidolite. Pollucite is found in great quantities at Bernic Lake, Manitoba, Canada and in the USA, and from this source the element can be prepared. Most commercial production is as a by-product of lithium production.
Sintering
Rubidium occurs in the minerals pollucite, carnallite, leucite and lepidolite. It is recovered commercially from lepidolite as a by-product of lithium extraction. Potassium minerals and brines also contain rubidium and are another commercial source.
Rubidium Alums, Extraction
31. Analyze the methods of extraction of rubidium and cesium from radioactive waste.The extraction method. The method is based on the ability poliiodiodate, polibrombromaate, dipikrilaminate and certain other compounds of cesium and rubidium concentrate in the organic phase during processing of aqueous solutions of these complex compounds by various extractants.
When using poliiodiodaate Me[I(I)n] the waste solutions neutralized with ammonium carbonate. The precipitate carbonates and hydroxides of iron, aluminum, rare earth, alkaline earth and other elements are filtered, the filtrate was acidified with hydrochloric acid to pH 4-5 and diluted with water to a content of 0.01-0.5 g/l of cesium and rubidium. This solution after the addition of NaI (0.2 mol/L) directed in continuous countercurrent extractors for processing nitrobenzene which containing 0.2 - 0.5 mol/l of iodine. The aqueous solution then used in the dilution step, and nitrobenzene which containing poliiodiodaate cesium, rubidium and potassium, ammonium, alkaline earth metals distills. Distillation precipitation evaporated to dryness and the dry precipitation is calcined at 250-350 °, after which it consists of RbI and CsI.
From waste solutions cesium can be extracted with a nitrobenzene solution of dipicrylamine. Reextracted from the organic phase with 0.01 N HCl; nitrobenzene is recycled and the aqueous solution (after the addition of NaOH and sodium etildiamintetraatsetata) back-extracted with 0.4% with a nitrobenzene solution of dipicrylamine. After reextracted nitrobenzene phase HCl 0.01 N hydrochloric acid solution evaporated to dryness (mixture RbCl and CsCl). Extraction of cesium was 82%.
32. Propose technological processes without waste and low-waste processing.
The concept of non-waste technology is the practical application of knowledge, methods and tools so that within the human needs to ensure the most efficient use of natural resources and protect the environment. Under the non-waste technology we realize a production method that provides the fullest possible use of recyclable materials and of waste resulting therefrom. A more accurate than the "non-waste technology" should be considered the term "low-waste technology", as the principle of "non-waste technology" is not possible because any human technological activities produce waste, at least in the form of energy. Achievement a complete non-waste technology is impossible, because it contradicts the second law of thermodynamics, so the term "non-waste technology" conditions.
As a low-waste production can offer the technological scheme of processing of kaolin.
ПЕРЕВОДЫ НЕКОТОРЫХ СЛОВ ИЗ СХЕМЫ
granulation sintering-грануляционное спекание
flow-through leaching-проточное выщелачивание
sink-слив
shaving-стружка
si-stoff-сиштоф
for mortars-для строительных
reduction roasting-восстановительный обжиг
hydrogen alunite-водородный алунит
ferrous solution-железистый раствор
flushing-промывка
washing water-промывная вода
laundered-отмытый
