CS263243B1 - Process for preparing an elution solution for regeneration of strongly basic ion exchangers - Google Patents

Abstract

The solution relates to a method of preparing an elution solution for the regeneration of strongly basic pyridine-type anions or divinylbenzene-based anions, saturated with uranium during hydrometallurgical processing of uranium ores. The solution obtained after elution of the ion exchange is first adjusted to the pH value necessary for the destruction of the uranyl tricarbonate complex, which is pH 3.0 to 4.5. Then, ammonium sulfate from waste production and sodium carbonate are added to the solution obtained after precipitation and removal of the precipitate in an amount corresponding to a total sulfate ion concentration of 90 to 180 g/1 and a carbonate content of 4 to 40 g/1. The elution solution thus prepared is then used again for the regeneration of the ion exchange.

Description

(54) A process for preparing an elution solution for regenerating strongly basic ion exchangers

The invention relates to a process for the preparation of an elution solution for the regeneration of strongly basic anion exchangers of the pyridine type or of an anion exchange resin based on uranium saturated with divinylbenzene in the hydrometallurgical treatment of uranium ores. In the solution obtained after elution of the ion exchanger, it is first adjusted to the pH necessary for breaking the uranyl tricarbonate complex, which is a pH of 3.0 to 4.5.

Ammonium sulphate from waste production and sodium carbonate in an amount corresponding to a total sulphate ion concentration of 90 to 180 g / l and a carbonate content of 4 to 40 g / l are then added to the solution obtained after precipitation and removal of the precipitate. The elution solution thus prepared is then reused for ion exchange regeneration.

(51) Int a /

B OH 49/00

263 243

BACKGROUND OF THE INVENTION The present invention relates to a process for the preparation of an elution solution for the regeneration of strongly basic pyridine-type ion exchangers or urinyl-saturated divinylbenzene ion exchangers in the hydrometallurgical treatment of uranium ores.

The regeneration of a strongly basic uranium saturated ion exchanger is generally carried out in a sulphate-carbonate alkaline elution condition with a solution containing a mixture of sodium and ammonium sulphate, basified with sodium carbonate or ammonium carbonate or mixtures of these carbonates, including the hydrolyzed forms of these carbonates. The recovered eluate is enriched in uranium which is present in the form of uranyltricarbonate ^X Λ complex of UO ₂ (CO ₃ ) ₃ '. In the eluate, the concentration of the sulphate component is reduced by the loss of sulphate ion due to ion exchange and other salt losses, for example due to ion exchange manipulation in the regeneration circuit. The uranium from the solution is recovered as a precipitate by first destroying the uranyltricarbonate ion with concentrated sulfuric acid according to equation (1) and then precipitating the solution with ammonia gas according to equation (2).

(NH ₄ ) ₄ (UO ₂ (CO ₃ ) ₃ ) + 3H ₂ SO ₄ ----- b 3CO ₂ + 3H ₂ O + UO ₂ SO ₄ +2 (NH ₄ ) ₂ SO ₄

UO ₂ SO ₄ + 6NH ₃ + 3H ₂ O —---> (ΝΗ ₄ ) ₂ υ ₂ Ο _? + 2 (NH _{4) 2} SO ₄ (2)

It follows from both equations (1) and (2) that these operations simultaneously add to the solution the sulphate ion deficit in the form of ammonium sulphate. Since the loss of sulfate ion in regeneration generally exceeds the amount of sulfate ion replenished by both of the above reactions, it is necessary to replenish the sulfate ion into the solution by another operation to a technologically effective level. In practice, the sulphate ion is replenished according to equation (3) by directly neutralizing the eluate acidified with sulfuric acid with ammonia gas. Usually proceed

2 2S3 243

H ₂ SO ₄ + 2 NH ₃ ---- (NH ₄ ) ₂ SO ₄ (3) in that the acidification of the eluate according to equation (1) is carried out at a lower pH than the uranyl tricarbonate complex destruction technology, The uranium precipitate is then removed from the solution by sedimentation or filtration after the ammonia precipitation, and the clarified solution is returned to prepare the eluent for ion exchange regeneration. Prior to that, part of the volume surplus generated is usually discharged outside the recovery circuit. Sulfate ion losses also occur as a result of moisture being drawn off from the uranium precipitate system. The regenerating agent is prepared by adding sodium or ammonium carbonate or mixtures thereof to the recycled sulfate solution.

The disadvantage of this process is that the technologically necessary concentration of the sulphate ion component is produced in the precipitation operation, i.e. outside the process of preparation and immediate application of the eluent, and therefore with a considerable time lag. The logical consequence is the scattering in the sulfate ion concentration at the inlet to the regeneration, which affects the operability of the process control. Another disadvantage is the costly preparation of a portion of ammonium sulfate according to equation (3) from concentrated sulfuric acid and ammonia, where part of the volume with the technological level of the sulfate ion component is often discharged as excess balance without participating in any active technological process or the concentration of sulphates with the uranium precipitate moisture outside the system. At the same time, the increased salinity of the uranium concentrate adversely affects its quality.

The above process is largely eliminated by the process of preparing the elution solution for the regeneration of the strongly basic ion exchange resins according to the invention, which first consists in adjusting the pH of the solution obtained after elution of the ion exchanger to a necessary value for breaking the uranyltricarbonate complex present. to 4.5. Ammonium sulphate from waste production and sodium carbonate in a quantity corresponding to a total sulphate ion concentration of 90 to 180 g / l and a carbonate content of 4 to 40 g / l are then added to the solution obtained after precipitation and removal of the precipitate, and the elution solution thus prepared is reused. for ion exchange regeneration.

In carrying out the method of the invention, the process is an upset

- 3 ~

263 243 of the urenyltricarbonate complex is guided in the optimum technological mode so that in the longer time the uranium present is precipitated from the solutions, i.e. at a pH in the range of 3.0 to 4.5. The sulphate ion concentration is adjusted at a technologically effective level only after removal of the volumetric excess, in the elution agent pretreatment operation, so that waste ammonium sulfate is metered into the solution in the required amount. In practice, for example, solid ammonium sulphate from waste production is dosed directly, for example pneumatically, into a solution for the elution of the eluent, or a more concentrated ammonium sulphate stock solution from waste production is prepared from the above-balance solution and is then metered of the eluent. Ammonium sulphate from waste production can also be dosed into a stock solution of soda prepared from the above-balance solution. This arrangement makes it possible to reduce the loss of sulfate ion in the uranium ore recovery operation and to ensure optimum technological mode conditions in the preparation of the eluent. Since the sulphate ion is also prepared from waste products, the consumption of primary chemicals - sulfuric acid and ammonia - is reduced.

Example 1

To the solution obtained after elution with a uranium-saturated ion exchanger w

With a content of 110 g / l of SO ^ ion in the form of a mixture of ammonium and sodium sulphates, concentrated sulfuric acid is added to a final pH of 3.0 to 4.0, and carbon dioxide is released from the solution during decomposition of the present uranyltricarbonate complex carbonates. Ammonia gas was fed to the solution thus obtained and a uranium precipitate precipitated at a pH of 7.0-7.2. The resulting precipitate was removed by sedimentation, and solid waste ammonium sulfate and sodium carbonate were added to the clarified solution to a total sulfate ion concentration of 140 g / l and a carbonate content of 10 g / l. This solution was used to regenerate the saturated ion exchange resin with an efficiency of 98%. The urate was removed from the obtained eluate in the form of uranium effort and the solution was used for the next elution cycle after prolonged replenishment of the sulphate and carbonate component. Again, a regeneration efficiency of 98% was achieved and found that any number of cycles could be performed by this procedure and verified that the cycles could

- 4 repeat without restriction.

Example 2 283 243

To a portion of the solution obtained after the separation of the metal as in Example 1 was added solid ammonium sulfate from the waste production so that the total concentration of sulfate ion was 450 g / l. A portion of the solution thus prepared was used to adjust the sulfate ion concentration in the eluent, which was also prepared from the solution obtained after separation of the uranium precipitate, in which the carbonate concentration was adjusted to 5 g / l. The amount of added solution was such that the total sulfate ion concentration in the eluent to be prepared was 145 g / l. This solution regenerated the saturated ion exchanger with uranium with an efficiency of 98%.

Claims (4)

OBJECT OF THE INVENTION 263 243 A process for the preparation of an elution solution for the regeneration of strongly basic ion exchangers of the pyridine type or anion exchangers based on uranium saturated with uranium ores in hydroraetallurgical treatment of uranium ores, characterized by first adjusting the pH of the solution obtained after ion exchange is 3.0 to 4.5 and then ammonium sulphate from waste production and sodium carbonate in an amount corresponding to a total sulphate ion concentration of 90 to 180 g / l and a carbonate content of 4 to 40 g / l are added to the solution obtained after precipitation and removal of the precipitate. then the prepared elution solution is reused for ion exchange regeneration. 2. A process according to claim 1, wherein solid waste ammonium sulfate is added directly to the elution solution in an amount corresponding to a total concentration of 90 to 180 g / l of the sulfate ion present in the solution. 3. A process according to claim 1, characterized in that solid ammonium sulphate from waste production is added to a portion of the solution after separation of the metal and a stock solution of 200-600 g / l of sulphate ion is prepared to adjust the total leachate solution. sulphate concentration up to 180 g / l. 4. A process according to claim 3, characterized in that solid sodium carbonate in an amount of 50 to 350 g / l is dissolved in a portion of the solution containing solid ammonium sulfate from the waste product and the solution is used to prepare the elution solution.