Journal of Mining and Metallurgy, 36 (l-2)A (2000) J1 - 22.

INCREASE OF COPPER RECOVERY FROM

POLYMETALLIC ORES

M. Adamovic, S. Radosavljevic" and M. Marinko

Institute for Technology of Nuclear and Other Mineral Raw Materials

Franche d'Eperey 86s, 11000 Belgrade, Yugoslavia

(Received 15 January 2000; accepted 20 March 2000)

Abstract

Selected concentrates minerals of lead with silver, copper and zinc with cadmium areproduced from the polymetallic Pb-Zn-Cu-Ag ores from "Rudnik" mine in the plant forflotation concentration. Copper concentrate is characterized with relatively low recoveryof copper with the significant presence of lead, zinc and iron minerals.

Based on detailed chemical and mineralogical analysis ofproducts and middling ofcopper concentrates, module analysis is done, which pointed to further laboratory investi­gations of the concentration of copper minerals with the main goal of increase of selectiv­ity and recovery of the copper from copper concentrate.

Characteristic results ofthe chemical and mineralogical investigations are shown, soas the investigations on flotation concentration of the copper minerals based on moduleanalysis results. Investigation results showed recovery pointed that with the co-milling ofthe basic concentrate and with selective deprimation of lead, zinc and iron minerals, selec­tive concentrates of copper minerals were got with the much higher recovery of copperfrom the concentrate.

Keywords: polymetallic ore, selective flotation concentrate, flotation concentrate of copper,recovery, Rudnik mine

* Corresponding author

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M. Adamovic et al.

1. Introduction

Polymetallic ore with the variable content of lead, zinc and copper andrelatively high content of silver, bismuth and cadmium is treated in the feedflotation plant "Rudnik". Among mentioned sulfide minerals of iron(pyrrhotine, pyrite) are presented also. Their content is significantly increas­ing with the deeper mining works, while the content of lead, zinc and cop­per is decreasing.

With applying of selective flotation concentration technologic from thementioned ore the following selective concentrates are produced [3, 4]:

Lead concentrate with the lead content of 72-75%, and silver of 1500­2400 glt, with of lead recovery the concentrate is 90-93%, silver is 80­82 %.Copper concentrate with the copper content of 14-17%, and silver of550-600 glt, with of copper recovery in the concentrate is 35-50%, sil­ver is 7-9%Zinc concentrate with the zinc content of 47-49%, and Cd of 3500­5000 glt, with of zinc recovery in the concentrate is 80-83%.High technological effects in the production of lead concentrates and

the satisfying in the production of zinc concentrates significantly reduce theproduced copper concentrate. This is especially emphasized in the caseswhen the copper content in the ore feed is below 0.25%, which causes theconcentrate production below metallurgy standards. Low-quality bulk con­centrates with the 10-14% copper, 8-10% lead, and 10-12% zinc content areproduced in those cases, while the iron content is around 25%. Due to con­stant lowering metal content in the ore it happened that during the longerperiods low-quality copper concentrate is produced. For the determining ofpossibility of improving the technological results (increasing the quality ofcopper concentrate and of copper recovery) large laboratory investigationson flotation concentration were performed which were followed by theproduct and semi-product concentration detailed chemical and mineralogi­cal analysis.

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Increase of Copper Recovery from Polymetallic Ores

2. Technology

Detailed chemical and mineralogical analysis were performed for thedefining basic technology parameters for the following products:

Polymetallic ore feed flotation;Copper rough concentrate;Copper mineral drain slurry flotationCopper concentrate;Refining semi-product.It has to be emphasized that in the technology process of the copper

mineral flotation in the "Rudnik" flotation plant, is done after the flotationof lead minerals and before zinc minerals flotation. Influence of the men­tioned technology processes was not studied, but parameters in the part ofthe process of copper mineral flotation concentration were analyzed [1, 2].

3. Mineralogy

3.1. Methods

The methods for determination in investigated ore and concentratesample are:

Mineralogical investigation, quantitative and qualitative microscopicanalysis (for automatic image analyze is used the program OZARIA2.5 [6];Determination of copper, lead, zinc and sulphur content (for correctionquantitative analyze).

3.2. Mineralogical composition of the ore and the copper concentrate

According to the basic mineralogy analysis in the polymetallic orespecimen, next minerals are determined: pyrrhotine, pyrite, marcasite, gale­na, sphalerite, chalcopyrite, covelline, chalcocite, bornite, tetrahedrite,

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M. Adamovic et al.

arsenopyrite, nature silver, nature bismuth, lead-bismuth sulphosalts, mag­netite, hematite, limonite, cuprite, smithsonite, cerussite, quartz, carbonatesand contact silicates. The content of sulphide minerals was 16.9%, andfrom that amount, the 70.9% were free grain (grinding condition 65% ­74/-lm).

Copper minerals were rarely present. A major copper mineral - chal­copyrite (0.75%) was founded, while covelline, chalcocite, and bornite werepresent in trace amounts. Oxide copper mineral determined was cuprite«0.01 %). Chalcopyrite appears as a free aggregates with 73.2 %. The restof chalcopyrite grains are mostly like simple and complex intergrowth andas disseminated in other minerals.

The predominantly presents sulphide mineral is pyrrhotine (9.3%) and,from that amount, 64.4% are free aggregates. The rest of grains are locatedin all other determinate appearing ways. On the Fig. 1, detailed structureconstruction of mineral aggregates main sulphide minerals is described [5].

According to the basic mineralogy analysis in the copper concentratesample, next minerals are determined: pyrrhotine, pyrite, marcasite, galena,sphalerite, chalcopyrite, covelline, tetrahedrite, arsenopyrite, nature silver,nature bismuth, lead-bismuth sulphosalts, limonite, cuprite, gangue miner­als. The content of sulphide minerals was 85.5%, and from that amount, the79.2% were free grain.

o Free grain • Disseminated III Simple intergrowth t!I Complex intergrowth

Pirrhotine"''::=====:C====::J::::====f.~~~~

Galena_iI======:C====::J::::=======~

Sphalerite.'::=====:C====::J::::======::::::iii':

Chalcopyritek:===:::::;;;:~===:;Z:===:::::;2:::=:::::::=:2==~~0% 20% 40% 60% 80% 100%

Fig. 1. The structure aggregates ratio of chalcopyrite, sphalerite, galena, andpyrrhotine in polymetallic feed flotation "Rudnik".

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Increase of Copper Recovery from Polymetallic Ores

DFree grain • Disseminated II Simple intergrowth III Complex intergrowth

Pirrhotine _lI=====:=t:::::::iiiiiiiiiiiiiiiiiiRiiiiiiiiiiij;iiiliiiiiiiiiiiiiiiii:

Galena_lI======:!!!!!!!!!!!!!!!!!~!!!!!!!!!!!!!!!!!!!!li!!!!!!!!!!!!!!!!!!!!~~

Sphalerite_lI=======C=======:=::!!~!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!~~ ==------"

Chalcopyritek:======~2:::======:;Z=======:Z=======::::Z======~0% 20% 40% 60% 80% 100%

Fig. 2. The structure aggregates ratio of chalcopyrite, sphalerite, galena, andpyrrhotine in copper concentrate.

Copper minerals are present. A major copper mineral - chalcopyrite(25.62%) was founded, while covelline are present in trace amounts. Oxidecopper mineral determined was cuprite «0.01 %). Chalcopyrite appears asa free aggregates with 88.3%. The rest of chalcopyrite grains are mostly likesimple and as disseminated in other minerals

The predominantly presents sulphide mineral is pyrrhotine (15.7%)and, from that amount, 51.6% are free aggregates. The rest of grains arelocated in all other determinate appearing ways. On the Fig. 2, detailedstructure construction of mineral aggregates main sulphide minerals isdescribed.

In Table 1 quantitative mineral composite of the ore feed in flotationplant, "Rudnik" and the copper concentrate are presented. Gangue mineralsare mostly like carbonates, and quartz-silicates.

The following composition was determined by the chemical analysis(in %): 12.57 of lead; 13.40 of copper; 7.15 of zinc; 14.40 of iron; 31.85 ofsulphur; 0.66 of manganese; 0.012 of antimony; 0.085 of bismuth; 571 gltof silver and 0.52 glt of gold.

Chemical and mineralogical analysis was performed on the monthlycomposite production sample for the determination of the present elementscontent and they're interconnection in the low-quality copper concentrate.

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M. Adamovic et al.

Table J. Quantitative mineral composition (in %).

Minerals Polymetallic oreCopper

concentrateGalena 0.20 14.62Sphalerite 4.15 13.01Chalcopyrite 0.75 25.62Pyrrhotine 9.30 15.70Pyrite 1.30 <0.01Marcasite 0.80 1.10Covelline 0.20 0.02Tetrahedrite 0.09 0.03Arsenopyrite 0.11 0.15Bornite 0.02 <0.01Nature silver <0.01 <0.01Nature bismuth <0.01 0.04Pb-Bi sulphosalts 0.02 0.07Magnetite 0.51 <0.01Limonite 0.25 0.03Cerussite 0.04 <0.01Cuprite <0.01 <0.01Gangue minerals 82.23 29.56Total: 100.00 100.01

The most significant elements which reduces the copper concentratequality were 16.8% iron sulfides, about 28% the other major sulfide miner­als (galena and sphalerite) and 29.6% gangue minerals. By the method ofstandard modal analysis the estimation of the liberation degree is evaluated,and the relatively low liberation degree for the most present mineral speciesin the concentrate was founded. During modal analysis the liberation ofminerals for all grain-size distribution classes were estimated.

Modal analysis results emphasized the following recommendations:copper sulfide minerals were liberated with the grinding fineness of 80% ­53 urn with the around of 90%. Copper sulphides formed three classes ofbinary composites: with sphalerite, pyrrhotine and gangue minerals wherecopper sulphides were predominant.

Around 40% of galena with the opening fineness of 80% -53 urn isfree, while the rest was forming binary composites with the pyrrhotine and

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Increase of Copper Recovery from Polymetallic Ores

gangue minerals, and around 20% of galena is included in the structure ofmultiphase mineral associations. Sphalerite was with the mentioned grind­ing fineness free to the level of 80%. Prevailing quantity of unelaboratedsphalerite was in the structural, simple composites and the minor quantitywas in the multiphase.

Pyrrhotine was with the fineness of 80% -53 um liberated with approx­imately 90% while remaining was included in multiphase composites withgalena and gangue minerals, mostly.

4. Copper mineral flotation

According to detailed mineralogical analysis and to other investiga­tions it is found that the main reason of low quality and usability of copperin the concentrate was:

Insufficient liberation of sulfide minerals among each other andbetween minerals in the waste;Recovery technological process of flotation and purification of copperminerals;Inadequate reagent regime;Insufficient deprimating of following sulfide minerals.Considering those facts it is found that the investigations should be

directed to the following:Evaluation of the optimal conditions for the rough flotation of copperminerals (flotation time, flotation reagent regime);Additional grinding of the concentrate of copper minerals to the fine­ness 80% -53 urn (according to the data from the modal analysis) forthe optimal liberation of mineral species;Evaluation of the optimal conditions of the raw concentrates refining;Deprimating of iron and zinc sulphide minerals.

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M. Adamovic et at.

4.1. Copper minerals rough flotation

Flotation tests were performed on the ore samples and drain slurry leadmineral flotation from the production in the feed flotation plant "Rudnik".

Flotation tests were performed in the laboratory Denver cell D-12, andthe grinding test and additional grinding tests in the laboratory mill with thevolume of 17 1. Ore grinding tests were performed to the fineness of 65% ­74 urn (following the plant conditions, and the additional grinding of thebasic concentrate to the fineness of 80% -53 urn (according to the condi­tions of modal analysis). Lead flotation on the ore tests was performedaccording to the production conditions, while the conditions for the coppermineral flotation were changed. With the plant pulp tests (drain slurry leadflotation) conditions were changed in the flotation concentration of the cop­per minerals.

Those investigations showed that the higher usability of copper miner­als could be obtained by the significant increase of the quantity of collectorin the flotation process, which resulted, with the lowering of copper contentin the basic concentrate. The influence of the collector quantity on theusability of copper in the basic concentrate is given on the Fig. 3, and theinfluence of the usability on the copper content in the basic concentrate onthe Fig. 4.

90

85 ~----------==-+-===*==~

R%80 -1---1------------

75 +---,'---------------

70 -f-----------,------,----_

40 60 80 100The collector consumption in 9ft

Fig. 3. Influence of the collector consumption on recovery of copper.

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Increase of Copper Recovery from Polymetallic Ores

100

70 +--------------

90 -~==---------------

R 80 +- ~~----%

60 +--,--------,-.-----,-----,------,-----,

2.0 2.5 3.0 3.5 4.0 4.5 5.0CU%

Fig. 4. Copper content in the rough concentrate.

Based on the tests results it is concluded that the following investiga­tion cycle (additional grinding and purification of the copper basic concen­trate) should be performed with the lower quality rough concentrate (2.5 ­3.0% of copper) what enables higher total copper recovery.

Based on the tests results it is concluded that the following investiga­tion cycle (additional grinding and cleaning of the copper rough concen­trate) should be performed with the lower quality rough concentrate (2.5 ­3.0% of copper) what enables higher total copper recovery.

4.2. Additional grinding of the Cu rough concentrate and the depres­sion of the lead, zinc and iron minerals

Additional grinding of the copper rough mineral concentrate was per­formed to the fineness of 80% -53 urn with the depression addition.Depressions of lead minerals were performed with the K2Cr20 7 and the sul­fide minerals of iron and zinc with the NaCN. Influence of the deprimatorsof lead on the lead content in the copper concentrate is given on the Fig. 5,and the deprimators influence of the sulfides of iron and zinc on the Fig. 6.

4.3. Laboratory tests results

Metal balance of the flotation concentration sum in the plant conditionswas given in the Table 2 and in the Table 3 sum in the laboratory conditions.

J.Min.Met. 36 (1-2)A 2000 19

Pb%

M. Adamovic et al.

6

5 -1-----------~---~~----;

4 +~~---~~-----------------'

3

2 ---~~"""'"=~;::::::==:..

O-t-------r-----,---------i10 20 30 40 50

K2Cr207 consumption in 9ft

Fig. 5. Influence of the KZCrZ07 on the depression of lead minerals.

.. a· . ,Zn

••• II .

~Fe

1412

Fe% 10

and 8Zn% 6

420

20 30 40 50 60

NaCN consumption in 9ft

Fig. 6. Influence of the NaCN on depression of iron and zinc minerals.

Table 2. Metal balance at flotation plant "Rudnik".

Products M,%Content in % Recovery in %

Pb Cu Zn Fe Pb Cu Zn FeInput 100.00 0.20 0.28 2.15 5.20 100.00 100.00 100.00 100.00C/Cu 0.81 5.30 13.80 6.20 28.40 21.46 48.50 2.33 3.64Tailing 99.19 0.15 0.17 2.10 5.01 78.54 51.50 97.67 96.36

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Increase of Copper Recovery from Polymetallic Ores

Table 3. Metal balance obtained through research presented in this paper.

Products M,%Content in % Recovery in %

Pb Cu Zn Fe Pb Cu Zn FeInput 100.00 0.21 0.26 2.12 5.42 100.00 100.00 100.00 100.00C/Cu 0.78 2.45 21.80 3.40 20.48 9.10 65.40 1.25 2.95Tailing 99.22 0.19 0.09 2.09 5.26 90.90 34.60 98.95 97.05

5. Analysis of the results

Flotation of copper minerals in the technology process in the flotationplant "Rudnik" is after the concentration of lead minerals and before theconcentration of zinc minerals. Since concentrations of those minerals aresufficient, scope of the investigations for the improving of technologyparameters in the flotation of copper minerals was directed only to this partof the process with the aim not to change anything in the lead cycle and notto change anything in the concentration process for zinc minerals.Investigations, although limited with the mentioned facts, gave significantimprovements of the technology parameters in the process of flotation con­centration of copper minerals (compare Table 2 and 3).

Additional grinding of the rough concentrate of copper minerals leadto positive liberation of mineral species, so it was enabled the successfuldeprecating of lead, zinc and iron sulfide minerals. Mentioned processesenabled significant improvement of selectivity, and furthermore in theincreasing of the copper content in the concentrate. Minor rounding of theintergrow grains in the process of the basic flotation and clearing enabledsignificant increase of the recovery of copper in the copper concentrate.

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M. Adamovic et al.

References

1. M. Adamovic, Z. Konc, Years of Processing Institute of Mining, 1995, Belgrade, p. 22­

30 (in Serbian).

2. M. Adamovic, 1. Stanojev, B. Brankovic, S. Golubovic, XXIX October Conference,

Bor, 1997, Proceedings p. 357-363. (in Serbian).

3. K. Misic, Proc. of Institute of Mining, No 2, Belgrade, 1984, p. 28-32. (in Serbian).

4. K. Misic, Proc. ofInstitute of Mining, No 1, Belgrade, 1985, p. 18-22. (in Serbian).

5. S. Radosavljevic, Mineralogy analysis of copper concentrates from Rudnik flotation,

Report Institute for Technology of Nuclear and Other Mineral Raw Materials,

Belgrade, 1996, pp. 12. (in Serbian).

6. R. Tomanec, S. Radosavljevic, and P. Jovanic, V Colloquium of Mineral Processing,

Belgrade, 1996, Proceedings p. 73-84. (in Serbian).

22 J.Min.Met. 36 (J-2)A 2000