This document investigates the synergistic effects of sodium ethyl xanthate (SEX) and ammonium dithiophosphate (ADTP) on nickel concentrate grades and recoveries at Munali Concentrator in Zambia. The objectives are to determine the optimal grind size, reagent dosages, and SEX to ADTP ratios to maximize recoveries and grades. Flotation tests on ground ore samples at different conditions show that a SEX to ADTP ratio of 3:1 with 100gpt total dosage achieves the highest recovery of 77% and grade of 3.6%. In general, higher synergistic ratios increase recoveries while decreasing grades.

1. 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.
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2. 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

3. 2 Problem statement
Concentrator 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.
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4. 3 Main Objective
To investigate the synergic effect of SEX and ADTP
on nickel recoveries and grades on a Munali
concentrator.
Specific Objectives
To determine 80% passing 75microns.
To obtain optimum recoveries and grades.
To investigate the effect of dosages on grades and
recoveries.
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5. 4. Literature Review
It 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

6. 5. Methodology and Materials
5.1 Sample Preparations
Six 1kg samples were each subjected to grind tests.
Each was milled at different times.
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7. 5. Methodology
Figure:5.1 Flow Sheet
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UG Sampling ORE CRUSHING MILLING
FLOTATIONDRYINGFINAL CONCENTRATE

8. 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.
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9. 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.
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10. 5.Methodology
5.4 Reagents Preparations
Table 5.1:Conditioning Stage
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Reagents Dosage (gpt) Addition stage
Collector 100, 120, 150* Conditioning
Guar 500 Conditioning
Frother As required to maintain froth Conditioning
Lime 1000 Conditioning

11. 5. Methodology
5.6 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.
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12. 5. Methodology
5.6 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.
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13. 5. Methodology
5.6 Flotation Tests
Figure: 5.2 Trial
flotation experiment
in a flotation cell.
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14. 5. Methodology
Figure:5.3 Lab flotation test-flow sheet
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15. 6.Results and Discussions
6.1 Establishing 80% passing 75μm
Table 6.1:Results of time and %passing 75μm.
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TIME (MINS) % PASSING 75μm
5 25
10 48
15 64
20 75
25 80
30 90

16. 6. Results
Fig 6.1: Graph of grind of mesh.
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17. 6.Results
Fig 6.2 Graph of grades/recoveries
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18. 6. Results and Discussions.
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19. 6. Results and discussions.
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20. 6. Results and Discussions
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21. 6. Recoveries and Grades
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22. 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.
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23. 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.
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24. 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.
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25. 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.
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