GB679546A - Improved process for the extraction of rhenium and analogous elements - Google Patents

Abstract

Elements of column VII of the Periodic classification, particularly manganese, technecium, rhenium and neptunium are extracted from raw materials containing them, even in traces, by attacking the material with an oxidizing chemical to form a solution containing the elements as anions, adding to the solution a water-soluble salt of an organic base <FORM:0679546/IV (b)/1> wherein R1-RIV are organic radicals, M is an element of column V of the Periodic classification (N, P, As, Sb, Bi, &) and Ss an anion, so as to form compounds containing anions of the elements and cations of the organic base, and extracting said compounds with an organic solvent, e.g. chloroform, bromoform or dichloroethane. Rhenium is thus extracted as a perrhenate, manganese as a permanganate, chlorine as a perchlorate and iodine as an iodide, iodate or periodate Rhenium and technecium should be extracted in an alkaline medium when molybdenum is present, and rhenium and manganese in an acid medium when they are to be separated from a solution containing iron. The invention is particularly described with reference to the extraction of rhenium from molybdenite ore.ALSO:Elements of column VII of the Periodic Classification, particularly manganses, technetium, rhenium and neptunium, are extracted from raw materials containing them, even in traces by attacking the materials with an oxidising chemical to form a solution containing the elements as anions, adding to the solution a water soluble salt of an organic base <FORM:0679546/III/1> wherein R1-R1v are organic radicals, M is an element of column V of the Periodic Classification (N, P, As, St, Bi &c.) and Ss an anion, sco as to form compounds containing anions of the elements and cations of the organic base, and extracting said compounds with an organic solvent, e.g. chloroform, bromoform or dichloroethane. Rhenium is thus extracted as a perrhenate, manganese as a permanganate, chlorine as a perchlorate, and iodine as an iodide, iodate or periodate. Rhenium and technetium should be extracted in an alkaline medium when molybdenum is present, and rhenium and manganese in an acid medium when they are to be separated from a solution containing iron. The invention is particularly described with reference to the extraction of rhenium from molybdenite ore, which is attacked by fuming nitric acid at 60-80 DEG C, or with sodium dioxide. In the first case, excess nitric acid is removed, and then the solution is brought to, say pH9. The organic reagent, e.g. tetraphenylarsonium or phosphonium chloride, or triphenylbenzyl phosphonium chloride, is added, and the mixture then shaken with the organic solvent. The organic solution is dried with calcium chloride, and agitated with 12N hydrochloric acid, or with a concentrated acid and a reducing agent such as stannous chloride, or with a concentrated solution of a metal chloride, whereby rhenium passes into the aqueous phase whilst the organic solvent contains the organic reagent. Alternatively, the organic base may be precipitated by adding N/10 perchloric acid. The rhenium-containing solution is evaporated until perrhenic acid begins to distil, the solution is neutralized with soda or ammonia and evaporated to dryness, and the residue reduced to rhenium by hydrogen at 1000 DEG C. Another example describes the extraction of technetium, produced by irradiating molybdenum trioxide with neutrons. The irradiated material is dissolved in caustic soda, the pH adjusted to 9-11, and the extraction is effected with triphenyl arsonium chloride. The metal is produced as indicated for rhenium. A further example refers to the solubitly of tetraphenyl arsonium chlorate and periodate in water and chloroform.ALSO:A hydrochloric acid solution containing perrhenate ions is evaporated until perrhenic acid begins to distil, the solution is neutralized with soda or ammonia and evaporated to dryness, and the residue reduced to rhenium in hydrogen at 1000 DEG C. Metallic technecium is similarly produced.