AU2008201799B2

AU2008201799B2 - Differential flotation of mixed copper sulphide minerals

Info

Publication number: AU2008201799B2
Application number: AU2008201799A
Authority: AU
Inventors: Graeme Heyes
Original assignee: HEYES CONSULTING Pty Ltd
Current assignee: HEYES CONSULTING Pty Ltd
Priority date: 2007-04-23
Filing date: 2008-04-23
Publication date: 2012-04-05
Anticipated expiration: 2028-04-23
Also published as: AU2008201799A1

Abstract

- 21 A method of separating copper-containing minerals in an ore that contains two or more than two different 5 copper-containing sulphide minerals is disclosed. The method includes processing a slurry of the ore in a series of flotation stages and controlling the flotation stages to separate the minerals in the ore selectively based on the mineral type. The method takes advantage of different 10 inherent flotabilities of copper-containing minerals, such as chalcopyrite and chalcocite, to separate the minerals from a mixed sulphide mineral ore that contains the minerals.

Description

AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION Standard Patent Applicant (s): Heyes Consulting Pty Ltd Invention Title: DIFFERENTIAL FLOTATION OF MIXED COPPER SULPHIDE MINERALS The following statement is a full description of this invention, including the best method for performing it known to me/us: P71419AU.1 Pa_SetFiling Application 2008-4-23.doc (M) - 2 DIFFERENTIAL FLOTATION OF MIXED COPPER SULPHIDE MINERALS The present invention relates to separating copper-containing sulphide minerals from an ore that 5 contains two or more than two different copper-containing sulphide minerals. The present invention also relates to producing copper from an ore that contains two or more than two 10 different copper-containing sulphide minerals. The term "ore" is understood herein to include blends of ores mined from different locations. 15 The present invention relates particularly, although by no means exclusively, to separating copper containing sulphide minerals in the form of chalcopyrite and chalcocite (and optionally other copper-containing sulphide minerals, such as bornite) from a mixed sulphide 20 ore that contains these minerals to form at least a chalcopyrite-rich concentrate with a first, lower Cu:S ratio and a chalcocite-rich concentrate with a second, higher Cu:S ratio. 25 The present invention also relates particularly, although by no means exclusively, to producing copper from mixed sulphide ores that contain chalcopyrite and chalcocite (and optionally other copper-containing sulphide minerals such as bornite) in the ores. 30 One particular application for the present invention is the Olympic Dam Operations of BHP Billiton Limited. The ore contains chalcopyrite, chalcocite, bornite and other copper sulphide minerals. While in the 35 past the mined ore has contained approximately equal amounts of chalcopyrite, chalcocite, and bornite, currently the Cu:S ratio is steadily decreasing and this N:\Melbourne\Cases\Patent\71000-71999\P71419.AU.1\Specis\Differential Flotation.doc -3 trend is likely to continue with proposed expansions of the mining operations. This downward trend in the Cu:S ratio indicates an increase in the level of chalcopyrite relative to the other two above-mentioned minerals in the 5 ore. The downward trend in Cu:S ratio is relevant because the smelting process currently used at Olympic Dam Operations requires a concentrate having a Cu:S ratio well 10 above that of chalcopyrite. The blister smelter currently being used at Olympic Dam Operations was designed for a minimum Cu:S ratio of 1.6:1. Operating the smelter below a Cu:S ratio of 1.6:1 results in significant loss of copper recovery and increased smelter costs. A selective 15 mining method is currently used at Olympic Dam Operations to control the Cu:S ratio at the mine and supply the smelter with ore having a controlled Cu:S ratio. However, the cost of selective mining is high and it is clear that such selective mining is increasingly a less viable 20 option, particularly with the trend of increasing levels of chalcopyrite in the ore, and is a problem that needs to be solved as part of the proposed expansion of the mine. The present invention is concerned with 25 addressing the above problem. According to the present invention there is provided a method of separating copper-containing minerals in an ore that contains two or more than two different 30 copper-containing sulphide minerals, which method includes processing a slurry of the ore in a series of flotation stages and controlling the flotation stages to separate the minerals in the ore selectively based on the mineral type and thereby producing at least a first concentrate of 35 the copper-containing minerals having a comparatively low Cu:S ratio and a second concentrate of the copper containing minerals having a higher Cu:S ratio. N:\Melbourne\Cases\Patent\71000-71999\P71419.AU.1\Specis\Differential Flotation.doc -4 The present invention is based on a realisation that different inherent flotabilities of copper-containing minerals, such as chalcopyrite and chalcocite, provide an 5 opportunity to separate the minerals from a mixed sulphide mineral ore that contains the minerals on the basis of mineral type. Hence, in the case of a mixed sulphide mineral 10 ore containing chalcopyrite, chalcocite and other copper sulphide minerals, the present invention processes an ore in a series of flotation stages that are controlled to separate minerals from the ore selectively based on the mineral type and produces (a) a first concentrate of the 15 copper-containing minerals having a comparatively low Cu:S ratio in which chalcopyrite is a major component of the concentrate and (b) a second concentrate of the copper containing minerals having a higher Cu:S ratio in which chalcocite is a major component of the concentrate. 20 Hence, in the case of a mixed sulphide mineral ore containing chalcopyrite and chalcocite (and optionally other minerals such as bornite), preferably the method includes processing the slurry and producing (i) the 25 above-mentioned first concentrate of the copper-containing minerals having the comparatively low Cu:S ratio in which chalcopyrite is a major component of the concentrate (hereinafter referred to as "the first chalcopyrite-based concentrate") and (ii) the above-mentioned second 30 concentrate of the copper-containing minerals having the higher Cu:S ratio in which chalcocite is a major component of the concentrate (hereinafter referred to as "the second chalcocite-based concentrate"). 35 The second chalcocite-based concentrate has a Cu:S ratio well above the minimum of 1.6:1 required by the current blister smelter at the Olympic Dam Operations and N:\Melbourne\Cases\Patent\71000-71999\P71419.AU.1\Specis\Differential Flotation.doc -5 can be used as a feedstock for the smelter without difficulty. The first chalcopyrite-based concentrate having 5 the comparatively lower Cu:S ratio can be used as a feedstock for another downstream processing operation for recovering copper from the concentrate. For example, the first concentrate can be used in a known 2-stage smelter that requires a Cu:S ratio of 0.9:1 to 1.3:1 in the 10 feedstock for the furnace. The method may include exploiting the natural floatability of some minerals versus other minerals. 15 Specifically, the method may include controlling at least one flotation stage on the basis that chalcopyrite has greater natural floatability than chalcocite (and bornite). 20 The method may include controlling at least one flotation stage to exploit the natural floatability of some minerals versus other minerals. For example, the method may include controlling 25 collector addition to the slurry in at least one flotation stage to exploit the natural floatability of some minerals versus other minerals and thereby selectively float a particular mineral type. 30 For example, the method may include aerating the slurry in a flotation stage or stages to control the environment of the slurry to float chalcopyrite. For example, the method may include adding 35 collectors, such as a xanthate, to at least one flotation stage to promote/enhance flotation of chalcocite versus chalcopyrite. N:\Melbourne\Cases\Patent\71000-71999\P71419.AU.1\Specis\Differential Flotation.doc - 6 One embodiment of the present invention includes processing the slurry in a first flotation stage under conditions that exploit the natural floatability of 5 chalcopyrite and floating the chalcopyrite to form the first chalcopyrite-based concentrate and an output slurry containing chalcocite and other copper-containing minerals, processing the output slurry in a second flotation stage under conditions that enhance/promote 10 floatability of chalcocite and other copper-containing minerals and floating the chalcocite and forming the second chalcocite-based concentrate. Another, although not the only other, embodiment 15 of the present invention includes the steps described in the preceding paragraph and further includes the steps of forming a bulk concentrate of the first chalcopyrite-based concentrate and the second chalcocite-based concentrate, treating the bulk concentrate by grinding and/or leaching 20 the bulk concentrate, and processing the treated bulk concentrate in another flotation stage under conditions that exploit the floatability of chalcopyrite and floating the chalcopyrite and forming a chalcopyrite-based concentrate and an output slurry containing chalcocite and 25 other copper-containing minerals. According to the present invention there is provided a method of producing copper from an ore that contains two or more than two different copper-containing 30 minerals, which method includes: (a) processing a slurry of the ore in a series of flotation stages and controlling the flotation stages to separate the minerals in the ore selectively based on 35 the mineral type and thereby producing at least two concentrates which have different Cu:S ratios; and N:\Melbourne\Cases\Patent\71000-71999\P71419.AU.1\Specis\Differential Flotation.doc - 7 (b) processing the first concentrate and the second concentrate and producing copper. In the case of a mixed sulphide mineral ore 5 containing chalcopyrite and chalcocite (and optionally other minerals such as bornite), preferably the method produces a first concentrate of the copper-containing minerals having a comparatively low Cu:S ratio in which chalcopyrite is a major component of the concentrate and a 10 second concentrate of the copper-containing minerals having a higher Cu:S ratio in which chalcocite is a major component of the concentrate. The downstream processing of step (b) may 15 include concentrate smelting, such as via a blister smelter or a 2-stage smelter. The downstream processing of step (b) may include other options such as hydrometallurgical-based processing 20 such as leaching. Preferably the downstream processing of step (b includes smelting at least one concentrate and hydrometallurgically processing at least another of the 25 concentrates. The present invention is described further by way of example with reference to the accompanying drawings, of which: 30 Figure 1 is a flowsheet of one embodiment of a method of separating copper-containing minerals in a mixed sulphide ore in accordance with the present invention; 35 Figure 2 is a flowsheet of another embodiment of the method of separating copper-containing minerals in a mixed sulphide ore in accordance with the present N:\Melbourne\Cases\Patent\71000-71999\P71419.AU.1\Specis\Differential Flotation.doc -8 invention; and Figure 3 is a flowsheet of another, although not the only other, embodiment of the method of separating 5 copper-containing minerals in a mixed sulphide ore in accordance with the present invention. The following description of the flowsheets of Figures 1 to 3 is in the context of processing an ore or 10 blend of ores containing two particular copper-containing minerals, namely chalcopyrite and chalcocite. However, the present invention is not confined to these particular minerals and extends generally to copper 15 containing minerals. With reference to Figure 1, a slurry of an ore that contains chalcopyrite and chalcocite, with a Cu:S ratio of 1.2:1, is supplied to a first flotation stage, 20 which may be of any suitable type of mechanical or pneumatic cell, and is processed in the stage. The first stage is operated to take advantage of the greater natural floatability of chalcopyrite compared to chalcocite. In particular, collectors are not required to promote/enhance 25 flotation of chalcopyrite. The concentrate produced in the first stage contains chalcopyrite as a major component of the concentrate and has a low Cu:S ratio of the order of 0.9 30 1.3:1. The concentrate produced in the first stage is transferred from the first stage for further processing in a leach circuit to recover other metals from the 35 concentrate. The tailing from the first stage is transferred N:\Melbourne\Cases\Patent\71000-71999\P71419.AU.1\SpeciS\Differential Flotation.doc - 9 to a second stage. A suitable collector, such as a xanthate, to promote/enhance flotation of chalcocite is added to the pulp either upstream of or in the second stage and the cell is operated in this second stage of the 5 method to float the remaining copper-containing minerals in the pulp. The concentrate produced in the second stage contains chalcocite as a major component of the 10 concentrate and has a higher Cu:S ratio than the first stage of the order of 2.4:1. The concentrate is transferred from the second stage for further processing in a leach circuit to recover 15 other metals from the concentrate. The tailings are discharged from the second stage as a final tails stream. 20 In the Figure 1 flowsheet the concentrates from the first and the second stages are processed separately, with the selection of the processing options being based at least in part on the Cu:S ratios of the concentrates. 25 The method shown in the Figure 2 flowsheet includes the same basic method steps as the method shown in the Figure 1 flowsheet, save that the concentrates from the two cells are combined together and processed as shown in the Figure. 30 Specifically, the resultant bulk concentrate slurry is passed through a grinding mill and ground to reduce the size of particles in the concentrate. Thereafter, the bulk concentrate is transferred to a 35 cleaner stage and this stage is operated to exploit the natural floatability of chalcopyrite compared to chalcocite. N:\Melbourne\Cases\Patent\71000-71999\P71419.AU.1\Specis\Differential Flotation.doc - 10 The resultant concentrate produced in the cleaner stage contains chalcopyrite as a major component of the concentrate and has a Cu:S ratio of the order of 0.9 5 1.3:1. The resultant pulp produced in the cleaning stage contains chalcocite as a major component of the concentrate and has a Cu:S ratio of the order of 2.4:1. 10 The products from the cleaner stage are then processed separately, with the selection of the processing options based at least in part on the Cu:S ratios of the concentrates. 15 The method shown in the Figure 3 flowsheet includes the same basic method steps as the method shown in the Figure 2 flowsheet, save that differential flotation is performed after production and leaching of a 20 final mixed sulphide concentrate. In order to test the method of the present invention a number of ore samples were collected with the Cu:S ratio varying over a range of 1.0:1 to 1.8:1. 25 One of the samples, with a Cu:S ratio of 1.4:1, was chosen for a preliminary study. The selected sample contained chalcocite at about 30 20% of the copper-containing minerals in the sample and chalcopyrite at the remainder of the copper-containing minerals in the sample. PRELIMINARY TESTS - GENERAL DISCUSSION 35 The selected sample used was prepared for flotation test work. N:\Melbourne\Cases\Patent\71000-71999\P71419.AU.1\Specis\Differential Flotation.doc - 11 A suitable grind time was established. The grind size required for the flotation tests was a Peao of 75 microns. Initially grinding was done in a standard 5 laboratory mill. Grinding was done at a pulp density of 60% solids. A series of flotation tests were carried out in a Galigher laboratory flotation cell, operating at 950 RPM. 10 Roughing was done in a 5L cell and cleaning in a 2.5L cell. Air was used as the flotation gas and laboratory tap water was used in all tests. The pulp level was set constant for each test and the froth was removed at a constant rate using a preset scraper. 15 The reagent scheme for the tests was similar to that being used at Olympic Dam Operations: i.e. pH 8.2 and collector, SEX, at about 50 g/t, total addition. The frother used was the one in common use in the laboratory; 20 namely Teric H407 - a polypropylene glycol type frother. The results of the tests are summarised in Table 1. 25 Table 1 TEST 1 Wt Assay% Distribution % Cu:S Fract Cu S Fe Cu S Fe Con 1 0.060 15.9 12.1 31.2 78.5 71.2 7.4 1.26 Con 2 0.077 2.33 2.26 21.6 15.6 17.0 7.9 1.03 Tail 0.863 0.08 0.14 24.9 5.9 11.8 84.7 Calc Hd 1.000 1.156 1.02 25.4 100.0 100.0 100.0 1.13 Assay 1.29 1.20 25.6 1.08 Hd TEST 2 Wt Assay% Distribution % Cu:S Fract Cu S Fe Cu S Fe N:\Melbourne\Cases\Patent\71000-71999\P71419.AU.1\Specis\Differential Flotation.doc - 12 Con 1 0.105 8.65 8.53 29.4 71.2 79.5 11.7 1.01 Con 2 0.010 28.7 10.7 20.4 22.5 9.5 0.8 2.68 Tail 0.885 0.09 0.14 26.1 6.3 11.0 87.5 Calc Hd 1.000 1.28 1.13 26.4 100.0 100.0 100.0 1.13 Assay 1.29 1.20 25.6 1.08 Hd I I _II In Table 1 the test products are grouped into two concentrates, one with a Cu:S ratio close to chalcopyrite and the other containing the rest of the copper-containing 5 minerals. SUMMARY OF TESTS TEST 1. This was a reference test using a standard 10 procedure with roughing/scavenging and cleaning. Grinding was done in a standard laboratory mill. TEST 2. For this test the natural floatability of the chalcopyrite mineral was exploited to try and 15 achieve separation. Grinding was done in a standard laboratory mill. DISCUSSION - PRELIMINARY TESTS 20 It is understood that the two major copper containing minerals are chalcopyrite and chalcocite, with minor amounts of bornite. The Cu:S ratios for these minerals are as 25 follows: 0.99:1 for chalcopyrite, 2.48:1 for bornite, and 3.87:1 for chalcocite. The smelter requires a concentrate with a Cu:S ratio of 1.6:1 or higher. Simplistically, assuming that 30 only chalcopyrite and chalcocite are present in the ore, N:\Melbourne\Cases\Patent\71000-71999\P71419.AU.1\Specis\Differentia Flotation.doc - 13 this means that a concentrate containing chalcopyrite and chalcocite in a ratio of 60:40 is required by the smelter to achieve 1.8:1 Cu:S ratio. Such a product would have an assay of 52% Cu, 20% Fe and 29% S, assuming no other 5 contamination, a Cu:Fe ratio of 2.6:1, and a S:Fe ratio of 1.45:1. In test 1, where the sample was treated in a standard procedure, i.e. roughing, scavenging and 10 cleaning, the first stage of the cleaner concentrate did appear to show some selectivity with respect to chalcocite with a Cu:S ratio of 1.26:1. However, to put this in perspective, it should be noted that the rougher/scavenger concentrate had a Cu:S ratio of 1.21:1. That is, the 15 upgrading of the concentrate relative to the head was probably due to rejection of pyrite (or similar) to the tail. For test 2, an attempt was made to exploit the 20 natural floatability of the two minerals; i.e. chalcopyrite floats naturally in the normal environment of a flotation cell whereas chalcocite does not float in this environment. The results in Table 1 show that it was possible to recover about 23% of the copper into a product 25 with a Cu:S ratio of 2.68:1 and about 71% of the copper into a product with a Cu:S ratio very close to that of chalcopyrite. 30 CONCLUSIONS - PRELIMINARY TESTS The preliminary tests indicates that it is possible to make a separation of chalcopyrite from chalcocite and other copper sulphides in the ore from 35 Olympic Dam. FURTHER TESTS N:\Melbourne\Cases\Patent\71000-71999\P71419.AU.l\Specis\Differential Flotation.doc - 14 Following the above preliminary tests another 3 tests were carried out on a different sample of ore in accordance with the procedure summarised below. 5 The results of the tests are presented in Table 2. The concentrate was cleaned once (product called 10 chalcopyrite con in Table 2) and then the other sulphides were collected in a separate rougher concentrate (product called chalcocite con in the Table). In Table 2 set out below these two products are combined (product called Ro/Sc con) to show how the process compares, overall, with 15 the present concentrator operation at Olympic Dam Operations. The Ro/Sc concentrate had an average grade of 13.3% Cu and the average recovery of Cu for each of these 20 tests was 94.1%, making it comparable with the current concentrator flowsheet for Olympic Dam Operations. Table 2. 25 Separation of chalcopyrite from the other sulphides in Olympic Dam Operations ore. Test 1 Product % Weight % Cu Cu/S Recovery % Cu Chalcopyrite Con 4.32 27.0 1.29 45.71 Chalcocite Con 12.68 9.68 2.38 48.07 Ro/Sc Con 17.00 14.0 1.67 93.78 Ro/Sc Tail 83.00 0.19 6.22 Calc Head 100.00 2.55 1.69 100.00 Assay Head 2.76 30 N:\Melbourne\Cases\Patent\71000-71999\P71419.AU.1\Specis\Differential Flotation.doc - 15 Test 2 Product % Weight % Cu Cu/S Recovery % Cu Chalcopyrite Con 4.43 27.1 1.26 46.21 Chalcocite Con 14.65 8.51 2.37 48.01 Ro/Sc Con 19.08 12.8 1.65 94.22 Ro/Sc Tail 80.92 0.19 5.78 Calc Head 100.00 2.60 1.67 100.00 Assay Head 1 2.76 Test 3 5 Product % Weight % Cu Cu/S Recovery % Cu Chalcopyrite Con 4.51 26.7 1.30 45.56 Chalcocite Con 14.67 8.77 2.40 48.71 Ro/Sc Con 19.18 13.0 1.70 94.26 Ro/Sc Tail 80.82 0.19 5.74 Calc Head 100.00 2.64 1.71 100.00 Assay Head 2.76 It is evident from Table 2 that the results of the three tests are remarkably similar, showing that the separation is very robust. 10 As well, the separation was very effective. The chalcopyrite concentrate had a Cu/S ratio of about 1.28:1 and the chalcocite concentrate had a Cu/S ratio of about 2.38:1, compared to the bulk product which has a Cu/S 15 ratio of about 1.69:1. Since chalcopyrite has a Cu/S ratio of about 1.00:1, it is probable that further cleaning of the chalcopyrite concentrate would improve the grade and the 20 Cu/S ratio. Also, given that the combined concentrate is N:\Melbourne\Cases\Patent\71000-71999\P71419.AU.l\specis\Differential Flotation.doc - 16 similar to the current concentrator rougher/scavenger concentrate produced at Olympic Dam Operations, it follows that the chalcocite rich concentrate could be upgraded to an acceptable final concentrate. 5 The results in Table 2 show that the mixed sulphides present in Olympic Dam Operations ore were separated into a chalcopyrite rich concentrate with a Cu/S ratio of 1.28:1 and another concentrate containing the 10 other sulphides with a Cu/S ratio of 2.38:1, while maintaining the recovery expected using the present separation process of Olympic Dam Operations. In addition, the preliminary and further test 15 work showed that the separation is independent of the Cu:S ratio of the copper minerals in the feed. Many modifications may be made to the embodiments of the method of separating copper-containing minerals in 20 a mixed sulphide ore in accordance with the present invention shown in the Figures without departing from the spirit and scope of the invention. References 25 Heyes, G.W. and Trahar, W.J., 1977. The natural flotability of chalcopyrite. Intl. J. Miner. Process., 4:317-344. 30 Heyes, G.W. and Trahar, W.J., 1979. Oxidation-reduction effects in the flotation of chalcocite and cuprite. Intl. J. Miner. Process., 6:229-252. N:\Melbourne\Cases\Patent\71000-71999\P71419.AU.1\Specis\Differential Flotation.doc

Claims

1. A method of separating copper-containing minerals in an ore that contains two or more than two different 5 copper-containing sulphide minerals, which method includes processing a slurry of the ore in a series of flotation stages and controlling the flotation stages to separate the minerals in the ore selectively based on the mineral type and thereby producing at least a first concentrate of 10 the copper-containing minerals having a comparatively low Cu:S ratio and a second concentrate of the copper containing minerals having a higher Cu:S ratio.

2. The method defined in claim 1 wherein, in the 15 case of a mixed sulphide mineral ore containing chalcopyrite and chalcocite (and optionally other minerals such as bornite), the method includes processing the slurry and producing (i) the first concentrate of the copper-containing minerals having the comparatively low 20 Cu:S ratio in which chalcopyrite is a major component of the concentrate (hereinafter referred to as "the first chalcopyrite-based concentrate") and (ii) the above mentioned second concentrate of the copper-containing minerals having the higher Cu:S ratio in which chalcocite 25 is a major component of the concentrate (hereinafter referred to as "the second chalcocite-based concentrate").

3. The method defined in claim 2 wherein the second chalcocite-based concentrate has a Cu:S above 1.6:1. 30

4. The method defined in any one of the preceding claims includes using the first chalcopyrite-based concentrate having the comparatively lower Cu:S ratio as a feedstock for another downstream processing operation for 35 recovering copper from the concentrate.

5. The method defined in claim 4 includes using the N:\Melbourne\Cases\Patent\71000-71999\P71419.AU.1\Specis\Differential Flotation.doc - 18 first concentrate in a 2-stage smelter that requires a Cu:S ratio of 0.9:1 to 1.3:1 in the feedstock for the furnace. 5

6. The method defined in any one of the preceding claims includes exploiting the natural floatability of some minerals versus other minerals.

7. The method defined in any one of the preceding 10 claims includes controlling at least one flotation stage on the basis that chalcopyrite has greater natural floatability than chalcocite (and bornite).

8. The method defined in any one of the preceding 15 claims includes controlling at least one flotation stage to exploit the natural floatability of some minerals versus other minerals.

9. The method defined in any one of the preceding 20 claims includes controlling collector addition to the slurry in at least one flotation stage to exploit the natural floatability of some minerals versus other minerals and thereby selectively float a particular mineral type. 25

10. The method defined in any one of the preceding claims includes aerating the slurry in a flotation stage or stages to control the environment of the slurry to float chalcopyrite. 30

11. The method defined in any one of the preceding claims includes adding collectors, such as a xanthate, to at least one flotation stage to promote/enhance flotation of chalcocite versus chalcopyrite. 35

12. The method defined in any one of the preceding claims includes processing the slurry in a first flotation N:\Melbourne\Cases\Patent\71000-71999\P71419.AU.1\Specis\Differential Flotation.doc - 19 stage under conditions that exploit the natural floatability of chalcopyrite and floating the chalcopyrite to form the first chalcopyrite-based concentrate and an output slurry containing chalcocite and other copper 5 containing minerals, processing the output slurry in a second flotation stage under conditions that enhance/promote floatability of chalcocite and other copper-containing minerals and floating the chalcocite and forming the second chalcocite-based concentrate. 10

13. The method defined in claim 12 further includes the steps of forming a bulk concentrate of the first chalcopyrite-based concentrate and the second chalcocite based concentrate, treating the bulk concentrate by 15 grinding and/or leaching the bulk concentrate, and processing the treated bulk concentrate in another flotation stage under conditions that exploit the floatability of chalcopyrite and floating the chalcopyrite and forming a chalcopyrite-based concentrate and an output 20 slurry containing chalcocite and other copper-containing minerals.

14. A method of producing copper from an ore that contains two or more than two different copper-containing 25 minerals, which method includes: (a) processing a slurry of the ore in a series of flotation stages and controlling the flotation stages to separate the minerals in the ore selectively based on 30 the mineral type and thereby producing at least two concentrates which have different Cu:S ratios; and (b) processing the first concentrate and the second concentrate and producing copper. 35

15. The method defined in claim 14 wherein, in the case of a mixed sulphide mineral ore containing N:\Melbourne\Cases\Patent\71000-71999\P71419.AU.1\Specis\Differential Flotation.doc - 20 chalcopyrite and chalcocite (and optionally other minerals such as bornite), the method produces a first concentrate of the copper-containing minerals having a comparatively low Cu:S ratio in which chalcopyrite is a major component 5 of the concentrate and a second concentrate of the copper containing minerals having a higher Cu:S ratio in which chalcocite is a major component of the concentrate.

16. The method defined in claim 14 or claim 15 10 wherein the downstream processing of step (b) includes concentrate smelting, such as via a blister smelter or a 2-stage smelter.

17. The method defined in claim 14 or claim 15 15 wherein the downstream processing of step (b) includes other options such as hydrometallurgical-based processing such as leaching.

18. The method defined in claim 14 or claim 15 20 wherein the downstream processing of step (b includes smelting at least one concentrate and hydrometallurgically processing at least another of the concentrates.

19. A method of separating copper-containing 25 minerals in an ore that contains two or more than two different copper-containing sulphide minerals substantially as hereinbefore described with reference to the accompanying drawings. 30

20. A method of producing copper from an ore that contains two or more than two different copper-containing minerals substantially as hereinbefore described with reference to the accompanying drawings. N:\Melbourne\Cases\Patent\71000-71999\P71419.AU.l\Specis\Differential Flotation.doc