Continuous ion exchange process integrated with membrane separation for recovering uranium

Abstract

A continuous ion exchange system and method for recovering uranium from a pregnant liquor solution wherein the method includes the steps of: (a) treating the pregnant liquor solution (16) with a membrane (28) to produce: i) a leach permeate solution (30) at least partially depleted of uranium and carbonate and ii) a leach concentrate solution (30′) having a relatively higher concentration of uranium and carbonate and which is at least partially depleted of chloride; (b) passing the leach concentrate stream (30′) through an ion exchange bed to load uranium onto a strong base anion exchange resin and produce an untreated barren (18) solution depleted of uranium, (c) passing an eluant solution (20) comprising bicarbonate through the loaded ion exchange bed to strip uranium from the strong base anion exchange resin and produce an eluate (22) comprising uranium and bicarbonate, (d) precipitating uranium (24) from the eluate (22) to produce a residual eluant solution (26) depleted of uranium, and (e) repeating steps (a)-(d).

Description

FIELD[0001]The present invention is directed toward a continuous ion exchange process for recovering uranium from pregnant liquor solutions.INTRODUCTION[0002]Continuous ion exchange (CIX) processes have been used since the 1970's to recover uranium from pregnant liquor solutions (PLS). A brief overview of the process is described by: Anton R. Hendriksz and Ronald R. McGregor, “The extraction of uranium from in-situ leach solutions using NIMCIX ion exchange contactor,” Annual Uranium Seminar (proceedings) 1980, 4th, pages 121-124. In general, the CIX process involves the use a uranium recovery circuit including of a plurality of ion exchange beds, commonly arranged in carousal, which repetitively cycle through individual process zones including uranium loading and elution. Various anions (e.g. chloride, sulfate, carbonate, bicarbonate) present in the PLS can also absorb on resin exchange sites during the resin loading phase of the process. The extent to which these anions ultimately ...

AI Technical Summary

Benefits of technology

The present invention is a system and process for recycling uranium from a solution containing uranium, carbonate, and chloride using ion exchange resin. The solution is first treated with a membrane to remove competing anions and produce a purified solution for further treatment. The process involves loading uranium onto a resin, stripping it using an eluant solution, and ultimately precipitating the uranium. The invention achieves efficient and effective recycling of uranium from waste solutions.

Problems solved by technology

The recycling of barrens or residual eluant exacerbates this problem by effectively concentrating these competing anions to the point where they result in a loss of separation efficiency, e.g. lower resin capacity, more frequent resin elution, eluant replacement, dilution of PLS, and the like.

Images