INVESTIGATE THE SYNERGIC EFFECTS OF SODIUM ETHYL XANTHATE (SEX) AND AMONIUM DITHIOPHOSPHATE (ADTP) ON NICKEL CONCENTRATE

GRADES AND RECOVERIES AT MUNALI CONCENTRATOR.BY

NYENDWA JANNY (METALLURGY STUDENT, UNZA 2015)

Supervisor Dr Witika.

1

1. Introduction Munali Nickel Mine is the only nickel mine in

Zambia located about 80km south of Lusaka.The mine owns a processing plant which

treats sulphide nickel ore in the form of petlandite (NiFe)9S8.

Other minerals present include chalcopyrite,talc and pyrrhotite.

900,000tons of sulphide nickel ore per annum to produce 8,500-9,000tpG of nickel concentrate with an average 10% Ni grade.2

2 Problem statementConcentrator department ordered more than

100t of ADTP.This was done without any test work in the

plant or lab to ascertain suitability of ADTP as a flotation reagent for Munali ore.

The use of ADTP as a collecting reagent resulted in poor grades and recoveries for flotation.

3

3 Main Objective To investigate the synergic effect of SEX and

ADTP on nickel recoveries and grades on a Munali concentrator.

Specific ObjectivesTo determine 80% passing 75microns.To obtain optimum recoveries and grades.To investigate the effect of dosages on

grades and recoveries.4

4. Literature ReviewIt is well documented that ADTP when used

with other collectors in the correct proportion or synergy enhances Ni recoveries and improves grades. (CYTEC, 2010)

ADTP gives an improved selectivity in the flotation of sulphide ore especially when used in synergy with some xanthates.

Low pH conditions affect grades (Wills, 2006).Synergy improves properties such as collecting

power and selectivity.5

5. Methodology and Materials 5.1 Sample Preparations

Six 1kg samples were each subjected to grind tests.

Each was milled at different times.

6

5. MethodologyFigure:5.1 Flow Sheet

7

UG Sampling ORE CRUSHING MILLING

FLOTATIONDRYINGFINAL CONCENTRATE

5. Methodology 5.1 Establishing 80% -75μm

The pulp sent to the oven to remove water for 24hrs.

100g of the sample was homogenized. Employed the wet screen analysis.Grind size is a critical parameter for optimum

recoveries and grade.To achieve the grinding tests, milling was done at

different residence time.80% -75mμ is recommended for flotation for

Munali ore. 8

5. Methodology 5.1 Chemical Reagents

Sodium ethyl xanthate (SEX) and Ammonium Dithiophosphate.-collection of nickel and other valuable minerals.

Guar gum depressant-depressant of pyrite and talc

Lime-ph adjustment.Frother-froth stabilization Ore Prep F-549.

9

5.Methodology 5.4 Reagents Preparations

Table 5.1:Conditioning Stage

10

Reagents Dosage (gpt) Addition stage

Collector 100, 120, 150* Conditioning

Guar 500 Conditioning

Frother As required to maintain froth Conditioning

Lime 1000 Conditioning

5. Methodology5.6 Flotation Tests

1kg ore was milled for 25mins.The pulp was taken to the flotation cell for

flotation.And reagents were added accordingly.Conditioning was done for 2mins before

flotation.And collection was done at every 3mins

between every successful roughers.11

5. Methodology5.6 Flotation Test Cont.

Flotation tests were done using a lab flotation cell at 650rpm and air blown at a volumetric flow rate of 3.0l/min.

Four different rougher concentrates were collected.

12

5. Methodology5.6 Flotation Tests

Figure: 5.2 Trial flotation

experiment in a flotation cell.

13

5. MethodologyFigure:5.3 Lab flotation test-flow sheet

14

6.Results and Discussions6.1 Establishing 80% passing 75μm

Table 6.1:Results of time and %passing 75μm.

15

TIME (MINS) % PASSING 75μm

5 25

10 48

15 64

20 75

25 80

30 90

6. Results Fig 6.1: Graph of grind of mesh.

16

6.ResultsFig 6.2 Graph of grades/recoveries

17

6. Results and Discussions.

18

6. Results and discussions.

19

6. Results and Discussions

20

6. Recoveries and Grades

21

6. Results and Discussions• Increase in synergic ratios resulted in increase of

recoveries.• Increase in synergies yielded a general decrease in

grades.• There were inconsistent grades at 120gpt.• Dosages generally resulted in increased recoveries

and decreased grades.• Synergies yielded higher recoveries than pure a

collector at 1:0 compared to 1:1, 2:1, and 3:1.22

7.Conclusion and Recommendations

• Optimum results were at 100gpt 3:1, recovery 77% and grade 3.6%.

• Optimum recoveries were obtained at 120gpt ratio 1:1 .

• Optimum grades were obtained at 100gpt ratio 3:1• Maximum recovery was obtained 150gpt ratio 3:1• Unmonitored pH and selectivity of collectors are

suspected contributors to poor grades.• Increased recoveries were as a result of synergies.

23

7. Conclusions and Recommendations

• Use of a pH meter is recommended to ascertain the results.

• The project should be revisited with the same parameters but with new chemicals.

• The concentrate should be assayed for various minerals including pyrite and talc.

• The mineralogy of the concentrate should be investigated.

24

8. References• Mining Chemicals HANDBOOK. (2004). CYTEC.• Rao T. C., Govindarajan, B., and Barnwal, J. P. (1995), “A Simple Model for Industrial Coal Flotation Operation”, High-Efficiency Coal

Preparation (Kawatra, ed.), Society for Mining, Metallurgy, and Exploration, Littleton, CO, pp. 177-185.• Wills, B. (2006). Mineral Processing Technology. 6th ed. Oxford:Butterworth-Heinemann.• Zulu, H. (2011). Munali Nickel Mine Flotation Report.

25