Patent GB-891521-A (GB)
Title: Anionic exchange process for the recovery of uranium and vanadium from carbonate solutions
Inventor: BAILES RICHARD HAZEL
IPC: C01G31/00
Filed: 1954-12-31
Abstract: Uranium and vanadium are recovered from carnotite ores by leaching the roasted ores with alkali metal carbonate solution, for example 5-10% sodium carbonate solution, and absorbing the dissolved uranium and vanadium values on an anion exchange resin from which the uranium and vanadium values are selectively eluted. If the initial ore is roasted with salt, the chloride concentration of the leach liquor must be reduced by adding a base to precipitate uranium and vanadium and impurities, which are separated from the chloride solution and redissolved in a carbonate solution for processing by the anion exchanger. Strongly basic resins are preferred.  Contact with the anion exchanger is preferably effected at about 60 DEG C. and a catalytic amount of hydrogen fluoride may be added to increase the absorption of vanadium.  Separation of the absorbed uranium and vanadium may be effected by three methods: (1) the uranium is first eluted by means of ammonium sulphate solutions having a concentration of 1,5M to saturation, after which the vanadium is eluted with 5M NaCl, saturated ammonium carbonate sodium bicarbonate or 1M caustic soda solution; the residual uranium is also eluted.  Alternatively saturated sulphur dioxide solutions may be employed to elute the vanadium, in which case residual uranium remains on the resin for recovery during recycle.  (2) The vanadium is first eluted by means of concentrated sodium chloride or sulphur dioxide solutions.  After selective elution of the vanadium, the uranium may be eluted with 0,9M ammonium chloride or sodium chloride and 0,1M hydrochloric acid. (3) The initial uranium and vanadium carbonate solution is passed through the ion exchanger to saturate the exchanger and flow is continued after the uranium break-through point until vanadium begins to break through.  The effluent leach liquor is then enriched in uranium and is contacted with a further batch of anion exchange resin which absorbs the uranium; uranium is recovered from the second anion exchange mass by elution with the ammonium sulphate or carbonate, or preferably with a saturated sulphur dioxide solution or acidified ammonium or sodium chloride.  Vanadium retained by the first ion exchange column is removed by sulphur dioxide solution elution, but the column should be pretreated with 0,1M hydrochloric acid, sulphuric acid, sulphur dioxide gas or preferably ammonium sulphate solution.  The vanadium is recovered from the eluates containing it by heating to drive sulphur dioxide if employed, or acidification to eliminate carbonate, followed by treatment with ammonia to precipitate the vanadium values which are heated to 400 DEG C. to convert them to oxide.  If, as in method (1) above, the uranium is obtained by ammonium sulphate elution, the solution is acidified with sulphuric acid to remove carbonate and neutralized with ammonia to precipitate ammonium diuranate. If acidified ammonium chloride has been used for the elution of the uranium, as in method (2), ammonia is added to precipitate the uranium values and the solution is recycled after adding the requisite ammonium chloride and hydrochloric acid.  Precipitated uranium is dried and calcined in 800 DEG C. to obtain U3O8.