COMBINATION OF CARRIER-MAGNETIC-SEPARATION AND A FURTHER SEPARATION FOR MINERAL PROCESSING

Abstract

The present invention relates to a process for concentrating desired particles comprising a carrier-magnetic-separation comprising the following steps a) providing a feedstock which contains the desired particles and an undesired material; b) adding hydrophobic magnetic particles to the feedstock which results in a loaded feedstock containing agglomerates of the magnetic particles and the desired particles or of the magnetic particles and the undesired material; c) separating the agglomerates from the loaded feedstock by a separation method which results in isolated agglomerates, where the separation method is selected from sorting, electric separation, magnetic separation, screening, classification, gravity concentration, and flotation; d) breaking up the isolated agglomerates to obtain a suspension comprising the magnetic particles in desagglomerated form; and e) separating the magnetic particles from the suspension obtained in step d) by a separation method selected from sorting, electric separation, magnetic separation, screening, classification, gravity concentration, and flotation.

Claims

1-18. (canceled)

19. A process for concentrating desired particles comprising a carrier-magnetic-separation comprising the following steps, a) providing a feedstock which contains the desired particles and an undesired material; b) adding hydrophobic magnetic particles to the feedstock which results in a loaded feedstock containing agglomerates of the magnetic particles and the desired particles or of the magnetic particles and the undesired material; c) separating the agglomerates from the loaded feedstock by a separation method which results in isolated agglomerates, where the separation method is selected from sorting, electric separation, magnetic separation, screening, classification, gravity concentration, and flotation; d) breaking up the isolated agglomerates to obtain a suspension comprising the magnetic particles in desagglomerated form; and e) separating the magnetic particles from the suspension obtained in step d) by a separation method selected from sorting, electric separation, magnetic separation, screening, classification, gravity concentration, and flotation; and f) optionally re-introducing the magnetic particles obtained in step e) to step b); g) provided that at least one separation method of steps c) or e) is a magnetic separation, and where the process comprises at least one further separation before or after the steps a), b), c), d) or e), and where the further separation is selected from sorting, electric separation, screening, classification, gravity concentration, and flotation.

20. The process according to claim 19, wherein the gravity concentration is achieved with jigs, spiral concentrators, shaking tables, centrifugal concentrators, sluices, cones, fluidized bed separators, dense medium separators or elutriators.

21. The process according to claim 19, wherein the gravity concentration is achieved with jigs selected from the group consisting of Harz jig, IHC radial jig, in line pressure jig, Denver mineral jig and air-pulsated jig, spiral concentrators selected from the group consisting of Humpreys spiral, souble start and spiral concentrator, shaking tables selected from the group consisting of sand tables, slime tables, Duplex concentrator, and Mozley laboratory separator, centrifugal concentrators selected from the group consisting of Kelsey centrifugal jig, Knelson concentrator, Falcon concentrator and multi-gravity separator, pinched sluiced, Reichert cone, fluidized bed separators selected from the group consisting of, CrossFlow separator, and Reflux Classifier, dense medium separators selected from the group consisting of gravitational vessels like drum separators, Wemco cone separator, Drewboy bath, Norwalt washer; centrifugal separators like dense medium cyclones, water-only cyclones, Vorsyl separator, large coal dense medium separator, Dyna whirlpool separator, and Tri-Flo separator, or elutriators selected from the group consisting of teetered bed separator, Floatex density separator, HydroFloat separator, and allflux separator.

22. The process according to claim 19, wherein where the flotation is achieved with mechanical flotation machines, pneumatic flotation machines, hybrid flotation machines, flotation columns, reactor/separator flotation machines, flash flotators, Hydrofloat separator, or Stack cells.

23. The process according to claim 19, wherein the sorting is achieved by hand or sensor based sorting, where the sensor type is selected from color in visible light, ultraviolet, gamma radiation, neutron radiation, conductivity, X-ray fluorescence, X-ray luminiscence, infrared, Raman, or microwave attenuation.

24. The process according to claim 19, wherein the electric separation is achieved by charging via ion or electron bombardment, conductive induction, or triboelectric charging.

25. The process according to claim 19, wherein the magnetic separation is achieved by low-intensity, high-intensity, high-gradient, or superconducting magnetic separators.

26. The process according to claim 19, wherein the classification is achieved with centrifugal classifiers or gravitational classifier, such as sedimentation classifier, counter flow classifier, or air classifier.

27. The process according to claim 19, wherein the screening is achieved with vibrating screens, static grizzlies, Mogensen Divergators, trommes, bradford breaker, roller screens, flip-flow screen, rotaspiral, Pansep screen, sieve bends, or tumbler screens.

28. The process according to claim 19, wherein the separation method in step c) is selected from sorting, electric separation, magnetic separation, screening, classification, gravity concentration, and where in case the further separation is flotation then the flotation is not made in step c) or not between step c) and step d).

29. The process according to claim 19, wherein the further separation is made before the step b), in between the step b) and the step d), or after the step d).

30. The process according to claim 19, wherein the further separation is selected from gravity concentration, which is made before the agglomeration step b), after the separation step e), or after step b), and optionally the gravity concentration is excluding elutriation.

31. The process according to claim 19, wherein the further separation is selected from screening, which is made before the agglomeration step b), after the separation step e) or after step b).

32. The process according to claim 19, wherein the further separation is selected from classification, which is made before the agglomeration step b), after the separation step e), or after step b).

33. The process according to claim 19, wherein the further separation is selected from sorting and is made before step b).

34. The process according to claim 19, wherein the further separation is selected from classification and is made before step b).

35. The process according to claim 19, wherein the further separation is made before step a).

36. The process according to claim 19, wherein the further separation is selected from sorting and electric separation and is made in dry state before step a).

Description

EXAMPLES

Example 1—Rougher

[0162] The process according to the invention may be used as rougher as shown in Scheme 1a and 1 b. The advantage of the use as rougher is that the process requires only a small area in a mining area.

Example 1a

[0163] In this example the mined ore is treated by comminution and separation operations to provide a feedstock material for step a) of the inventive process. The sequence of steps a) to f) wherein in steps c) and e) a magnetic separation is employed constitute a rougher separation. This requires that the feed provided in step a) has been treated in a way that the target material that will be agglomerated in step b) with magnetic particles has the right particle size distribution and degree of liberation i.e. that there is enough free surface of the target material available to allow the adsorption of collector agents. The treatment of the feed before step a) is done by a sequence of crushing and grinding and a further separation. This further separation can be any one or any combination of sorting, electric separation, screening, classification, gravity concentration, dense medium separation and flotation. In addition to further separations of the present invention an additional magnetic separation can be employed before step a) in cases where the ore contains magnetic or magnetizable mineral species like magnetite or pyrrhotite.

##STR00001##

[0164] The further separation before step a) will produce a target material that ultimately will constitute the feedstock for step a) and a tailing material that is either dumped directly or is fed to further grinding and separation stages or recycled to the grinding and further separation stage before step a).

[0165] The tailings of step c) is a rougher tailing that may dumped directly or may be further treated by any concentration process known in the art or by those described in the present invention namely those of the following examples 2) (Scavenging).

[0166] The product of step e) is a rougher concentrate that may be further treated by any concentration process known in the art or by those described in the present invention namely those of the following examples 3) (Cleaning)

Example 1b

[0167] In this example the further separation that is introduced as in scheme 1a) before step a) of the inventive process produces at least two different fractions of the feed ore that may be treated in parallel at least one fraction by the process of steps a) to e) and optionally f) of which either step c) or e) or both are magnetic separations and at least one second fraction by a process selected from the further separations of the present invention and a magnetic separation. The further separation before step a) may be one that produces 2 fractions differing mainly in particle size and particle weight i.e. separations like screening, classification or gravity separations. Thus, one fraction may be better suited to a conventional flotation while the other fraction may be too fine for conventional flotation and may be advantageously processed by the process comprising steps a) to e) and optionally f). Such a process may be described by the following scheme:

##STR00002##

[0168] Alternatively the further separation before step a) may produce different fractions differing in the mineral composition e.g. one fraction containing predominantly mineral type 1 and the other mineral type 2. Separations that may sort according to the mineral composition are sorting, electro separation, flotation, magnetic separation and dense medium separation.

[0169] The products of step c) and e) are a rougher tailing and a rougher concentrate of one fraction respectively and a rougher tailing and a rougher concentrate of the other fraction. Both concentrates and both tailings may be further treated by any other concentration process known in the art or the inventive process namely those described in examples 2) and 3).

Example 1c

[0170] In the foregoing examples the process according to steps a) to e) and optionally f) steps c) and e) are magnetic separations. Alternatively either step c) or step e) can be further separation processes that are no magnetic separations. In step c) a flotation may be performed which is intensified by the agglomeration with magnetic particles in step b). The flotation concentrate containing these agglomerates is then introduced to step d) where the agglomerates are broken and the magnetic particles are separated by a magnetic separation in step e).

Example 1d

[0171] Another example is a process as described in examples 1 a) and 1b) where within the process steps a) to e) and optionally f) step e) is a further separation i.e. no magnetic separation. The concentrate obtained by magnetic separation in step c) will be desagglomerated in step d). The slurry obtained in step d) containing the target minerals and the magnetic particles can be processed by a flotation step relying on the hydrophobic properties of the magnetic particles which will be collected in the flotation froth.

Example 2—Scavenger

[0172] The process according to the invention may be used as scavenger. The starting material is usually a tailing from another stage and contains low concentration of the desired material. The preceeding separation stage may be any concentration process known in the art or a process of the present invention resulting in a tailing. The tailing can be treated by grinding in order to liberate so far non-liberated target minerals. The resulting material will be the feedstock provided in step a) of the inventive process. The further treatment according to steps b) to e) and optionally f) can be done analogously as described in examples 1a), 1b), 1c) and 1d).

Example 3—Cleaner

[0173] The process according to the invention may be used as cleaner. The starting material is usually a concentrate from a preceeding separation stage. Usually the corresponding feed material that will be introduced in step a) is rich in target minerals. The preceeding separation stage may be any concentration process known in the art or a process of the present invention resulting in a concentrate. The concentrate can be treated by grinding in order to liberate so far non-liberated target minerals. The resulting material will be the feedstock provided in step a) of the inventive process. The further treatment according to steps b) to e) and optionally f) can be done analogously as described in examples 1a), 1b), 1c) and 1d).

Example 4—Coarse Particle Workup

[0174] The process according to the invention may be used during coarse particle workup as shown in the following scheme. During the mineral processing often grinding/classification circuits are installed in order to optimize the liberation of the desired material. Typically, after grinding the fine particles are further processed in other steps, whereas the coarse particles are returned to grinding. Prior to the return of the coarse particles to grinding they can be concentrated by the coarse particle workup as shown in the scheme. Advantage is that coarse particles which contain no desired material are not ground again and thus the efficiency of the grinding is increased.

Example 4a

[0175] ##STR00003##

Example 4b

[0176] ##STR00004##

Example 5—Slime Workup

[0177] During the various mineral processing steps the formation of slimes may occur. Usually, such slimes are difficult to separate, and may even be disadvantagous for many separation steps because they increase foaming (Pickering effect). Slimes are preferably separated by hydrocyclones. The carrier-magnetic-separation is one of the few suitable methods for concentration of the desired material in slimes, e.g. from slimes resulting from hydrocyclones or other classification steps.

[0178] Thus, the process according to the invention may be used during slime workup as shown in the following scheme.

##STR00005##