Method for separating a defined mineral phase of value from a ground ore

Abstract

A defined mineral phase is separated from a ground ore having several chemical phases and being present in a heterogeneous particle size distribution by classifying the ore according to a defined particle diameter into at least two fractions, a first fraction having particles essentially larger than the defined particle diameter and a second fraction having particles essentially smaller than the defined particle diameter, and the defined mineral particles of value being present in both fractions, floating the first fraction having the greater particle diameters and selecting the defined mineral particles of value in a flotation concentrate, selectively admixing the defined mineral particles of value in the fraction having the smaller particle diameters with magnetizable particles, applying a magnetic separation process to the second fraction having smaller particle diameters, and separating a concentrate with an enrichment of the defined mineral phase of value.

Claims

1. A method for separating useful material from a ground ore having several chemical phases and heterogeneous grain sizes, the method comprising: classifying ore particles of the ground ore into one of two fractions, the ore particles in a first fraction having first particle diameters substantially larger than a defined particle diameter and the ore particles in a second fraction having particle diameters substantially smaller than the defined particle diameter, both the first and second fractions containing mineral particles of the useful material; subjecting the first fraction to a flotation process to produce a flotation concentrate including enriched particles of the useful material; mixing the second fraction with magnetizable particles; separating bonded particles of the useful material in the second fraction that have bonded with the magnetizable particles from unbonded magnetizable particles that have not bonded with the mineral particles of the useful material; and separating the mineral particles of the useful material in the second fraction, that have bonded with the magnetizable particles and have been separated from the unbonded magnetizable particles, from the magnetizable particles to produce a magnetic separation concentrate containing the particles of the useful material.

2. The method as claimed in claim 1, wherein the flotation process produces a tailing stream, and wherein the method further comprises combining the tailing stream with the second fraction after said classifying.

3. The method as claimed in claim 2, wherein the defined particle diameter is less that 70 μm.

4. The method as claimed in claim 3, wherein the defined particle diameter is less that 50 μm.

5. The method as claimed in claim 1, wherein the classifying is performed using a hydrocyclone.

6. The method as claimed in claim 5, wherein the mineral particles of the useful material are derived from salts of the lanthanides.

7. The method as claimed in claim 1, wherein the mineral particles of the useful material are derived from layers of the rare earths.

8. The method as claimed in claim 1, wherein the defined particle diameter is less that 70 μm.

9. The method as claimed in claim 1, wherein the defined particle diameter is less that 50 μm.

10. The method as claimed in claim 1, wherein the mineral particles of the useful material are derived from salts of the lanthanides.

11. The method as claimed in claim 1, further comprising, prior to said mixing, chemical conditioning the second fraction so that organic substances are attached to the surfaces of the mineral particles of the useful material in the second fraction.

12. The method as claimed in claim 11, wherein the flotation process produces a tailing stream, and wherein the method further comprises combining the tailing stream with the second fraction during the chemical conditioning.

13. The method as claimed in claim 11, wherein the classifying is performed using a hydrocyclone.

14. The method as claimed in claim 11, wherein the mineral particles of the useful material are derived from layers of the rare earths.

15. The method as claimed in claim 11, wherein the mineral particles of the useful material are derived from salts of the lanthanides.

16. The method as claimed in claim 11, wherein the defined particle diameter is less that 70 μm.

17. The method as claimed in claim 11, wherein the defined particle diameter is less that 50 μm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) These and other objects and advantages will become more apparent and more readily appreciated from the following description of the various embodiments, taken in conjunction with the accompanying drawings of which:

(2) FIG. 1 shows a process for the separation of a mineral particle of useful material, that is a ground ore, making use of a combination of flotation and magnetic separation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(3) Reference will now be made in detail to the various embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout.

(4) Referring to FIG. 1, an embodiment of the method for separating out a phase of a useful material 2 from a ground ore 4 is described below by way of example. The ore 4 is ground in accordance with a known process, in which a heterogeneous distribution of grain sizes for the individual particles inevitably arises. The grinding classification, and with it the extent or level of exposure, are dependent on the deposit, or on the phase sizes present in it, of the useful material phase 2 which is to be separated out. However, even for these phase sizes of the useful material phase 2 there is also a phase size distribution curve, so that it is expedient to classify the ground ore 4 into two fractions. This takes place in a classification facility 6, in which on the one hand a first fraction 8 is produced, this having a distribution of grain sizes which is essentially larger than 50 micrometer. Further, in the classification facility 6, which can take the form of a hydrocyclone, a second fraction 10 is separated out, this having particle sizes which lie essentially below 50 micrometer. It is basically possible to produce yet further fractions which have different grain size distributions, if it is thereby possible to optimize technically the selection process.

(5) The first fraction 8 with the larger diameter particles is now passed into a flotation facility 11, which represents a known flotation facility. The flotation produces a flotation concentrate 12, which contains an enrichment of the useful material phase 2. Depending on the flotation method, and depending on the nature and constitution of the ground ore, the level of the yield of the useful material phase 2 in the flotation concentrate will vary. For this reason, it may be expedient to apply the flotation process 11 more than once.

(6) In parallel with this, the second fraction 10 of the ground ore 4 is passed to a magnetic separation process. For this purpose, a chemical conditioning 20 of the particles in the fraction 10 is first carried out, where this conditioning 20 is known per se and will therefore not be further discussed here. It will only be said that the particles of useful material are brought together with organic substances which have a selective effect, which attach themselves to the surface of the particles of useful material and hence influence the characteristics of their surface. Also introduced during the conditioning is surface treated magnetite (Fe.sub.3O.sub.4) or some other magnetic phase, which is taken up by the selectively surface treated particles of useful material 2. In a downstream magnetic separation reactor 15, the particle agglomerates, including magnetite particles 14 and the particles of useful material 2, are separated out. In the course of this, a tailing flow 19 arises, which can be fed once again into the magnetic separation process. This will depend on how high the yield is, of particles of useful material, after the first separation process in the separation reactor 15. After the magnetite particles have been separated out from the second fraction 10 in a separation apparatus, the magnetite particles 14, which are bonded to the particles of useful material 2, are separated off again at separation 22 from the particles of useful material 2, so that on one side a magnetic separation concentrate 16 with particles of useful material 2 results, on the other side the magnetite particles 14 are retrieved and fed back again to the conditioning process 20.

(7) For various ores it has been found that if the tailing stream 18, which arises from the flotation 11, still contains a high enough proportion of particles of useful material 2 it is also expedient to feed this additionally to the magnetic separation process. On the other hand, this implies of course that in this case the yield from the flotation 11 was not yet at a satisfactory level. It has been found that, in respect of a wider distribution of grain sizes, magnetic separation 15 is less temperamental than flotation 11. Basically however, the tailing flow 18 can also be discarded in the form of 18′ and stored permanently in an appropriate disposal site, or at this point it is also possible to separate out particles of other alternative useful materials.

(8) It has further been established that environmentally critical substances in the ground ore 4, in particular radioactive particles such as uranium oxide or thorium dioxide, are also present with a very fine distribution in the ground ore 4, so that a large proportion of these environmentally damaging substances accumulate in the second fraction 10. These are then left behind in the tailing flow 19 and can be permanently stored separately from the tailing flow 18. This is particularly advantageous because of the fact that the tailing flow 19 which results from the magnetic separation has, by comparison with to the tailing flow 18 or the tailing flow 18′ which results from the flotation process, a comparatively smaller volume. If the enrichment of the environmentally damaging substances in this tailing flow 19 is greater, this comparatively small tailing flow can be stored separately in a disposal site selected for this purpose, so that the environmentally damaging products which arise with the mining of rare earth elements can be stored separately in a smaller fraction, which significantly reduces the environmental impact.

(9) The various embodiments have been described in detail with particular reference and examples, but it will be understood that variations and modifications can be effected within the spirit and scope of the various embodiments covered by the claims which may include the phrase “at least one of A, B and C” as an alternative expression that means one or more of A, B and C may be used, contrary to the holding in Superguide v. DIRECTV, 69 USPQ2d 1865 (Fed. Cir. 2004).