GB2198723A

GB2198723A - Separating uranium from uranium bearing materials

Info

Publication number: GB2198723A
Application number: GB08728419A
Authority: GB
Inventors: Ronald David Hancock; Wasyl Michael Sajik
Original assignee: BP PLC
Current assignee: BP PLC
Priority date: 1986-12-18
Filing date: 1987-12-04
Publication date: 1988-06-22
Also published as: GB8728419D0; GB8630316D0

Abstract

Uranium is separated from uranium bearing materials by treating the material with a mineral acid to form a slurry and passing a mixture of sulphur dioxide and oxygen containing gas into the slurry. The uranium solution is then separated from the residual ore material. The mineral acid is suitably dilute sulphuric acid and the volume ratio of sulphur dioxide to oxygen is suitably in the range 1:2 to 1:20.

Description

PROCESS FOR SEPARATING URANIUM FROM URANIUM BEARING MATERIALS The present invention relates to a process for the separation of uranium from uranium bearing materials.

Most uranium minerals are friable and in general are not effectively separated from the gangue or waste constituents by physical methods such as flotation. Uranium can be dissolved from its ores by mineral acids and if uranium is present in the ore in its lower valency reduced state, as is usual, an oxidising agent must also be used in the dissolution process. The most commonly used oxidising agents are manganese dioxide (pyrolusite), sodium chlorate, hydrogen peroxide and Caro's acid.

The present invention relates to a novel process for the separation of uranium from uranium bearing materials that has advantages over known processes under certain conditions.

Thus according to thapresent invention there is provided a process for the separation of uranium from uranium bearing materials comprising the steps of (a) treating the material with a mineral acid to form a slurry, (b) passing a mixture of sulphur dioxide and an oxygen containing gas into the slurry so as to convert the uranium into its higher oxidation state thereby rendering the uranium soluble, and (c) extracting the uranium by a conventional technique. The steps may be performed simultaneously or sequentially.

The mineral acid is suitably dilute sulphuric acid and the mixture of sulphur dioxide to oxygen is suitably in the volume ratio 1:2 to 1:20.

While not wishing to be bound by any theory, as iron containing minerals invariably occur with the uranium ore and sufficient amounts of this iron are soluble in the mineral acid, the function of the added oxidant is generally believed to be the oxidation of ferrous ion to ferric ion, the latter sometimes being referred to as the 'true' uranium oxidant (U4+ + 2Fe3+

U6+ + 2Fe2+).

The action of sulphur dioxide/oxygen containing gas mixtures in effecting this process is surprising as oxygen itself is not a sufficiently strong oxidant for this conversion and sulphur dioxide is well known as a reducing agent.

The invention will now be described by way of example only.

After mining, the uranium ore is crushed and ground and is then leached for several hours in a dilute acid solution through which a sulphur dioxide/oxygen mixture is bubbled. The volume ratio of sulphur dioxide:oxygen is 1:10. The temperature of the slurry may be ambient but elevated temperatures are preferred, e.g. 80 to 950C.

Following the dissolution of the uranium, the uranium bearing solution may be separated from the residual ore solids e.g. by filtration. The solution is then further purified by ion exchange or solvent extraction to obtain uranium of sufficient purity.

Alternatively the slurry may be treated directly e.g. by contact with suitable resins.

The sulphur dioxide and oxygen are suitably pre-mixed and emerge into the solution~by use of a sparge tube.

Claims

Claims:

1. A process for the separation of uranium from uranium bearing materials comprising the steps of (a) treating the material with a mineral acid to form a slurry, (b) passing a mixture of sulphur dioxide and an oxygen containing gas into the slurry so as to convert the uranium into its highest oxidation state thereby rendering the uranium soluble, and (c) extracting the uranium by a conventional technique.

2. A process according to claim 1 in which the steps are performed simultaneously.

3. A process according to claim 1 in which the steps are performed sequentially.

4. A process according to any of the preceding claims in which the volume ratio of sulphur dioxide to oxygen is in the range 1:2 to 1:20.

5. A process according to any of the preceding claims in which the volume ratio of sulphur dioxide to oxygen is 1:10.

6. A process according to any of the preceding claims in which the temperature of the slurry is above ambient temperature.

7. A process according to any of the preceding claims in which the temperature of the slurry is 800C and 950C.

8. A process according to any of the preceding claims in which the resultant uranium bearing solution is separated from the residual ore solids by filtration.

9. A process according to claim 8 in which the separated uranium bearing solution is further purified to obtain uranium by ion-exchange or solvent extraction.

A A process according to any of claims 1 to 7 in which the resultant uranium bearing solution with the residual ore solids is treated with ion exchange resins to recover uranium.

11. A process for separation of uranium from uranium bearing materials as hereinbefore described and with reference to the examples.