Method for preparing uranium concentrates by fluidised bed precipitation, and preparation of UO3 and U3O8 by drying/calcining said concentrates

摘要

The invention relates to a method for preparing a uranium concentrate in the form of solid particles, by precipitation from a uraniferous solution using a precipitation agent in a vertical reactor (1) which comprises a base (7), a top, a central portion (2), an upper portion (3) and a lower portion (6), wherein the solid particles of the uranium concentrate define a fluidised bed as a result of an ascending liquid current that flows from the base (7) towards the top of the reactor (1) after consecutively passing through the lower portion (6), the central portion (2), and the upper portion (3) of the reactor (1), and which is generated by supplying, at the base (7) of the reactor (1), a recycling liquid current (11) tapped from a first predetermined level (A) in the upper portion (3) of the reactor and fed back without settling to the base (7) of the reactor (1), a liquid excess being further discharged via an overflow (10) located at a second predetermined level (B) in the upper portion (3) of the reactor, and wherein the upper limit (C) of the solid-particle fluidised bed is controlled so as to be at a level lower than the first and second predetermined levels.