This document summarizes an investigation into optimizing the flotation behavior of upper east and lower mine ores at the Bulyanhulu gold processing plant. Kinetic flotation tests were conducted on samples from the two ore sources as well as a composite feed. Results showed the lower mine ore and composite feed recovered over 90% of gold within 30 minutes, while the upper east ore recovered around 80%. Copper recovery curves flattened at 300g/t PAX dosage with 95% recovery. Gold recovery continued increasing past 300g/t PAX, yielding 81% recovery and 25g/t concentrate grade. Recommendations included mineralogical analysis and decreasing the proportion of problematic upper east ore in the composite feed.

1. Investigation Of Flotation Behaviour Of Upper East
And Lower Mine Ores At Bulyanhulu Gold Plant
By:
Emmanuel E. Mmole
IPT Student - University of Dar es Salaam

2. Outline
• Introduction
• Project Objectives
• Methodology
• Results
• Conclusion
• Recommendations

3. Introduction
• The flotation ore feed at Bulyanhulu gold processing plant has a
complex mineralogy
• It is mainly comprised of pyrite (FeS2) and chalcopyrite (CuFeS2)
• The ore feed includes the Lower Mine (high grade) and the
Upper East (low grade) ores.
• This feed causes pulp spillages at the cleaner flotation cells due
to its probable mineralogy and flotation characteristics

4. Project Objectives
• To optimize the production of gold, copper and silver at the
flotation circuit by determining the flotation behavior of the
Lower Mine and Upper East ores
• Improving gold (and copper) recovery with the subsequent
reduction of gold losses in tails
• Optimizing the flotation feed treatment
• Reduction of operating costs

5. Methodology
• Kinetic flotation testwork on the Lower mine and Upper East
ore samples, as well as the flotation feed as the control sample.
• Pulp density: 35% solids
• Air flowrate: 5 L/min
• pH: Natural ore pH (8 - 9)
• Reagents dosages:
PRODUCT PAX (g/t) Aerophine (g/t) Frother (g/t)
Flotation feed 300 22 27
Lower Mine Ore 300 22 27
Upper East Ore 600 50 27

6. Results
0.00
62.94
81.58
89.78 90.96 91.65 92.70 93.64
0.00
68.39
79.02
86.22 87.37 88.14 88.88 90.10
0.00
39.33
62.84
75.20
78.01 78.91 80.37
82.91
0.00
10.00
20.00
30.00
40.00
50.00
60.00
70.00
80.00
90.00
100.00
0 5 10 15 20 25 30 35
%AuRecovery
Flotation Time (min)
Au recovery vs time curves for Lower Mine ore, Upper East ore and
Flotation feed
Lower Mine Ore Upper East Ore Flotation Feed

7. Results (cont.)
0.00
66.29
82.00
89.01
90.23 90.98 92.00
92.89
0.00
59.08
68.59
76.32
78.50
81.65
83.91
87.74
0.00
48.27
72.95
86.28
88.75 89.55 90.65 92.11
0.00
10.00
20.00
30.00
40.00
50.00
60.00
70.00
80.00
90.00
100.00
0 5 10 15 20 25 30 35
%CuRecovery
Flotation Time (min)
Cu recovery vs time curves for Lower Mine ore, Upper East ore and
Flotation feed
Lower Mine Ore Upper East Ore Flotation Feed

8. Results (cont.)
10.00
15.00
20.00
25.00
30.00
0.00
20.00
40.00
60.00
80.00
100.00
150 225 300 375 450 525
Augrade(g/t)
Aurecovery(%)
PAX dosage (g/t)
Au Recovery vs PAX dosage for Flotation feed
Au Recovery Au grade

9. Results (cont.)
0.000
5.000
10.000
15.000
20.000
80.00
85.00
90.00
95.00
100.00
150 225 300 375 450 525
Cugrade(%)
Curecovery(%)
PAX dosage (g/t)
Cu Recovery vs PAX dosage for Flotation feed

10. Conclusion
• Flotability of gold and copper bearing minerals in both types of
ores is relatively fast. At least 70% of these minerals can be
recovered in the first 10 minutes of flotation after which the rate
of flotation starts to decrease.
• The recovery curve of PAX optimization for copper seems to
flatten at around 300 g/t PAX with a recovery of about 95% and
concentrate grade around 3%.
• For gold, the recovery keeps increasing past 300 g/t PAX giving
recovery of about 81% and a concentrate grade of 25 g/t.

11. Recommendations
• The project is commendable because it would help to:
 Alleviate additional costs incurred due to usage of excessive
reagents to treat the troublesome ore feed.
 Optimize the flotation feed treatment, thereby improving the
flotation circuit recovery (and concentrate grade).

12. Recommendations (cont.)
• I therefore recommend the following:
 Mineralogical analysis of the flotation feed should be done.
 Decrease the amount of Upper East ore in the composite
flotation feed.
 Further tests should be done by a proper design of
experiment so as to determine the interaction of the reagents
on the response (recovery or concentrate grade).