EDSON CHENJERAI
RioZim Metallurgical Services
RIOZIM-METALLON PILOT PLANT
FLOTATION TEST WORK
Bulk Concentrate Production and Optimization Test Work
Contents
...............................................................................................................................................................0
1.0 INTRODUCTION...........................................................................................................................1
2.0 BULK CONCENTRATE PRODUCTION......................................................................................1
2.1 Methodology................................................................................................................................2
2.2 Challenges...................................................................................................................................3
2.3 Results and Discussion................................................................................................................3
3.0 OPTIMIZATION TEST WORK.....................................................................................................4
3.1 Challenges...................................................................................................................................4
3.2 Results and Discussion................................................................................................................5
Test A – Variation of amount of reagents added............................................................................5
Test B – Variation of reagent suites...............................................................................................5
Test C – Variation of amount of Frother........................................................................................5
Test D – Variation of pH...............................................................................................................6
Test E – Variation of pulp density.................................................................................................6
Test F – Variation of grind............................................................................................................6
4.0 CONCLUSIONS.............................................................................................................................7
4.1 Bulk Concentrate Production.......................................................................................................7
4.2 Optimization Tests.......................................................................................................................7
5.0 RECOMMENDATIONS...........................................................................................................7
5.1 Flotation plant........................................................................................................................7
5.2 Metallurgical Laboratory Services.........................................................................................8
6.0 APPENDICES.................................................................................................................................9
6.1 Optimization tails assays.............................................................................................................9
6.2 Bulk concentrate assays.............................................................................................................10
6.3 Optimization tests concentrate assays........................................................................................10
1.0 INTRODUCTION
A flotation plant is scheduled to be commissioned at Cam and Motor Mine for the treatment
of run-of-mine ore. Test work is currently underway for the determination of the optimum
operating conditions for the plant as well as the subsequent treatment of the concentrate.
A sample of approximately 1.2 tonnes of the Cam sulphide ore was prepared for transport to
the Metallon flotation pilot plant in Mazoe. The aim of this project was to produce a bulk
concentrate of the Cam and Motor sulphide or as well as to perform flotation optimization
tests on both sulphide and transitional ore samples. The bulk concentrate is to be sent for
further test work at another facility.
2.0 BULK CONCENTRATE PRODUCTION
The Technical Services Department supplied the Cam sulphide and transitional ore samples
to Metallurgical Services. The sulphide sample was crushed to 0.3mm and subsequently
pulverised to 55% passing 75µm. It was then transported to Mazoe for the production of the
bulk concentrate as well as optimization tests.
The bulk concentrate was produced in a flotation pilot plant capable of continuous processing
of ore supplied. The basic flow diagram for the plant is as shown in Figure 1 below.
Figure 1: Pilot Plant flow diagram
However, given that the sample had been pulverized to 50% passing 75µm, the milling
section of the plant was by-passed and the concentrate was produced in a batch process. See
Figure 2 for the flotation cells used in the batch process.
Figure 2: Flotation cells used for production of bulk concentrate
The reagent suite used in the production of the bulk concentrate was SIBX and PAX. This
reagent suite is readily available as it is currently in use at RioZim’s Renco facility; previous
test work conducted also indicated its suitability in treating the Cam sulphide.
2.1 Methodology
The flotation cells were capable of processing 18kg of ore at a pulp density of 30%. Based on
this capacity, the operation procedure was developed as follows:
Reagent Concentration Weight (g) Dilution Measured
(g/t) volume volume
CuSO4 90 18 100ml 9ml
SIBX 45 9 100ml 9ml
PAX 23 4.6 100ml 9ml
D070 68 1.44 1.44ml
D233 68 2.16 2.16ml
Do-Froth 3ml
1. Weigh 18kg of the sample
2. Split into two 20-litre buckets for easier handling
3. Add water to create pulp
4. Add pulp to feeder tank and top with water to achieve 30% solids
5. Condition pulp as follows:
a. Measure 9ml of CuSO4 and condition for 5 minutes
b. Measure 9ml of SIBX and condition for 3 minutes
c. Measure 9ml of PAX and condition for 3 minutes
6. Pump conditioned mixture into flotation cells then add DO-Froth and condition for 5
minutes
7. Start-up compressor and float for 10 minutes
8. Collect rougher concentrate and tails and retain for assay
2.2 Challenges
In order to produce the required amount of the bulk concentrate, it was necessary to run
approximately 12 batches of the samples a day during the five-day trip. However, the process
did not proceed smoothly for a larger part of the week due to power outages and inadequate
water supplies. Another challenge face by the team was the handling of the tails produced
during the flotation runs; large amounts of pulp from the tails needed to be prepared for
transported as the tests progressed. Shift work would have been a viable option but there was
a limited number of personnel on the team. The team managed to organize and complete the
task despite the fatigue that came as a result of having to work long hours in order to
compensate for time lost during power and water outages.
2.3 Results and Discussion
Figure 3 below shows the froth produced during flotation of the bulk sample. It can be
observed that the bubble tenacity was good with large bubbles formed. The froth stability was
also good. In terms of colour, the concentrate was grey-black. The tails produced were off-
white.
Figure 3: Flotation of Cam sulphide
Composite samples of the Cam sulphide ore, bulk concentrate and tails were sent for assay at
the Metallon Laboratory as well as the RioZim Analytical Laboratory.
Table 1 below shows the results of the production of the bulk concentrate based on the assays
done at both the Metallon Laboratory and RioZim Analytical Laboratory.
Table 1:Bulk concentrate assay results and analysis
head conc tail
feed grade mass % mass conc enrichmen Conc grade Recovery
Sample mass(g) (g/t) (g) pull grade(g/t) t ratio Ratio (g/t) %
bulk sulphide( Metallon
Assays) 846000 6.57 61000 7.21 56.0 9 15 2.95 58.16%
bulk sulphide( Rio
Assays) 846000 9.79 61000 7.21 70.7 7 9 2.14 80.58%
Due to the variation in the assays from the two laboratories, the samples will be re-submitted
to other assays labs.
3.0 OPTIMIZATION TEST WORK
Optimization tests were also conducted using the smaller flotation cells, the variables were
pH, reagents, particle size and pulp density.
3.1 Challenges
The main challenge faced while running the optimization tests was the unavailability of assay
services; analysis of results during tests runs would have been useful in making informed
decisions concerning parameter adjustments. Another challenge faced was a generally high
mass pull for all the tests due to the high air flow in the flotation cells; the same compressor
used in the larger cells was in use on these smaller ones.
3.2 Results and Discussion
The main reagent suite tested was PAX and SIBX. However, one set of tests (Test B) was a
comparison of different reagent suites. The results are tabulated below with brief
commentary:
Test A – Variation of amount of reagents added
Table 2 shows that good recoveries can be obtained for the 1*R and ½ of the reagent dosage
although the mass pull would have to be reduced to 10-15% in order attain a higher
concentrate grade.
Table 2: Variation of reagent dosage
head conc tail
feed grade mass % mass conc enrichmen Conc grade Recovery
Sample mass(g) (g/t) (g) pull grade(g/t) t ratio Ratio (g/t) %
Test A 1xR 3000 9.79 957 31.90 17.2 2 2 1.79 91.21%
Test A 1/2xR 3000 9.79 938 31.27 17.0 2 2 1.52 92.79%
Test A 1/4xR 3000 9.79 229 7.63 45.7 5 7 4.17 63.17%
Test B – Variation of reagent suites
Four reagent suites (including PAX and SIBX) were tested at the same dosage as the 1XR run
in Test A described above. The best reagent was D233 which yielded a concentrate grade of
27.1 g/t with a mass pull of 19.53%. PAX and SIBX also yielded satisfactory results with
27.5 g/t with a mass pull of 31.9%. This results indicates that reduction in the mass pull
would yield an even higher concentrate grade.
Table 3: Variation of reagents suites
head conc tail
feed grade mass % mass conc enrichmen Conc grade Recovery
Sample mass(g) (g/t) (g) pull grade(g/t) t ratio Ratio (g/t) %
Test B PAX SIBX 3000 9.79 957 31.90 27.5 3 3 1.79 87.40%
Test B D070 3000 9.79 365 12.17 20.7 2 4 6.23 52.05%
Test B D233 3000 9.79 586 19.53 27.1 3 3 2.2 84.39%
Test B SNPX CO-
COLLECTOR 3000 9.79 263 8.77 19.9 2 3 4.42 70.55%
Test C – Variation of amount of Frother
The two tests shown in Table 4 indicate that the more Frother added, the higher the
concentrate grade yielded and the lower the mass pull; further optimization tests can still be
conducted to determine whether the trend continues at much higher Frother dosages.
Table 4: Variation of Frother dosage
head conc conc tail
feed grade mass % mass grade(g/t enrichment Conc grade Recovery
Sample mass(g) (g/t) (g) pull ) ratio Ratio (g/t) %
1.5ml frother 18000 9.79 1890 10.50 14.5 1 1
3ml frother 18000 9.79 1450 8.06 19.2 2 2
Test D – Variation of pH
Table 5 below shows that the optimum pH for floating our ore using PAX and SIBX is 8.5.
Although the mass pull was high (31.9%), the concentrate grade was 17.2 g/t which can
increased by reducing the mass pull. This result is favourable because this optimum pH is
close to the natural pH which is 8.3.
Table 5: pH variation
head conc tail
feed grade mass % mass conc enrichment Conc grade Recovery
Sample mass(g) (g/t) (g) pull grade(g/t) ratio Ratio (g/t) %
Test D pH 7.5 3000 9.79 1540 51.33 8.6 1 1 1.63 102.81%
Test D pH 8.5 3000 9.79 957 31.90 17.2 2 2 1.79 91.21%
Test D pH 9.5 3000 9.79 551 18.37 15.4 2 2 1.7 92.90%
Test D pH 10.5 3000 9.79 882 29.40 15.0 2 2 1.47 94.20%
Test E – Variation of pulp density
Table 6 below shows that the optimum pulp density is 30% solids which yielded 17.2 g/t
concentrate grade. Although the mass pull was higher than that obtained in the other two,
decreasing it would yield an even higher concentrate grade.
Table 6: Pulp density variation
head conc conc tail
feed grade mass % mass grade(g/t enrichmen Conc grade Recovery
Sample mass(g) (g/t) (g) pull ) t ratio Ratio (g/t) %
Test E 30% pulp
density 3000 9.79 957 31.90 17.2 2 2 1.79 91.21%
Test E 40% pulp
density 4000 9.79 1200 30.00 15.5 2 2 1.27 94.78%
Test E 50% pulp
density 5000 9.79 2500 50.00 7.2 1 1 2.84 117.77%
Test F – Variation of grind
The optimum grind of the three tested was 55% passing 75 µm with a concentrate grade of 56
g/t. The tests using 80% passing 75 µm show that the smaller cell tended to produce a higher
mass pull (31.9% for the 3,000g sample and 9.06% for the 18,000g in the larger cell). This
larger mass pull in likely due to the high air flow as the same size compressor was utilized in
both cells.
Table 7: Variation of grind
head conc tail
feed grade mass % mass conc enrichmen Conc grade Recovery
Sample mass(g) (g/t) (g) pull grade(g/t) t ratio Ratio (g/t) %
Test F 55%
-75µm 846000 6.57 61000 7.21 56.0 9 15 2.95 58.16%
Test F 70%
-75µm 3000 9.79 1050 35.00 23.1 2 3 1.43 91.03%
Test F 80%
-75µm 3000 9.79 957 31.90 17.2 2 2 1.66 91.91%
4.0 CONCLUSIONS
4.1 Bulk Concentrate Production
A bulk concentrate was successfully produced at a recovery of 80.58% and a concentrate
grade of 70.68 g/t. The concentrate weight produced was 61kgs which indicates a mass pull
of 7.21% of the bulk feed floated.
4.2 Optimization Tests
The optimization tests that were run parallel to the production of the bulk concentrate gave a
clear indication of the optimum parameter for flotation of the Cam sulphide. Although the
mass pull obtained for each test was generally high due to the high air flow in the cells, trends
in the results were clear.
For each test (A-F), the following parameters yielded the best results:
1. 30% solids for pulp density
2. pH of 8.5
3. 60% passing 75µm grind
4. ¼ of initial dosage of reagents used
5. 3ml of Frother
D233 performed well in comparison to other reagents suites yielding 27.1 g/t with a lower
mass pull than PAX and SIBX (19.5% versus 31.9% at 27.5 g/t)
5.1 RECOMMENDATIONS
5.2 Flotation plant
The geology of the Cam and Motor ore constitutes of massive trans-sulphide zones,
according to the pilot plant results, raw transitional and sulphide ore floated well at the
conditions below,
30-40% solids for pulp density
pH of 8.5
60% passing 75µm grind
45Hz (2700rpm agitators)
CuSO4, SIBX, PAX and DO Froth was the reagent suite which yielded good flotation
concentrate grade of 70.68g/t at a recovery of 80.58%, which is an indication that if these
reagents were to be adopted in the main plant as well as those conditions from the pilot plant,
the concentrate grade and recoveries would fall along that range. Leaching the raw sulphide
ore before floating it gave a recovery of 17.5% and floating the leach tails gave a recovery of
86.8%, which indicates that less than 20% of the trans- sulphide gold is recoverable by the
CIL plant prior to flotation circuit.
5.3 Metallurgical Laboratory Services
It is recommended that the optimization tests be repeated using flotation cells whose air flow
can easily be adjusted. This will reduce mass pull and give better indications of the
concentrate grades that can be achieved. The air supply should also have a gauge so that
uniformity can be maintained while running these tests.
It is also recommended that a similar set of optimization tests be run for the different reagent
suites in order to determine the best treatment method for the Cam sulphide.
6.0 APPENDICES
6.1 Optimization tails assays
RIOZIM LIMITED
CENTRAL ANALYTICAL LABORATORY
EIFFEL FLATS
SOLIDS & CARBONS
BATCH SAMPLE ANALYSIS SAMPLE Au
NO. DATES DATE DESCRIPTION ppm
20180131747 26.01.2018 01.02.2018 Solids: A1 Test E 50% 2.84
" " " B1 Test A 1/2XR 1.52
" " " C1 Trans 2 4.65
" " " D1 Test F 80% < 75 µm 1.66
" " " E1 Test E 40% 1.27
" " " F1 Test B D070 6.23
" " " J1 Test F 70% < 75µm 1.43
" " " Q1 Test B SNPX 2.87
" " " K1 Test D Ph 7.5 1.63
" " " L1 Test D Ph 9.5 1.70
" " " M1 Test A 1XR 1.79
" " " N1 Test B D233 2.20
" " " O1 Leach Tails before float 8.08
" " " P1 Test B SNPX with co-collector 4.42
" " " R1 Test D Ph 10.5 1.47
" " " S1 Trans 1 3.98
" " " T1 Test A 1/4XR 4.17
20180131747 26.01.2018 Carbon: Leach *
Comment:*To follow
CHEMIST/SNR.CHEMIST
6.2 Bulk concentrate assays
CUSTOMER: O Dhlamini
RIOZIM LIMITED
CENTRAL ANALYTICAL LABORATORY
EIFFEL FLATS
CONCENTRATES & SOLIDS
BATCH SAMPLE ANALYSIS SAMPLE Au Cu Ni As Sb
NO. DATES DATE DESCRIPTION ppm ppm ppm ppm ppm
20180201016 01.02.2018 01.02.2018 Concentrate L Bulk 1st batch concentrate 74.68 1184 276 84480 11112
" " " L1 Bulk 2nd batch conentrate 66.67 818 244 94040 8704
" " " L2 Composite Bulk Concentrate 81.10 896 250 100880 9880
" " " Solid L3 Sulphide Head 9.79 134 78 11734 1922
" " L4 Leach Float Tails 1.24 118 74 2072 1022
L5 80% through 75 0.60 80 54 1308 694
6.3 Optimization tests concentrate assays
CUSTOMER: Mrs O Dhlamini/T Dangeni
RIOZIM LIMITED
CENTRAL ANALYTICAL LABORATORY
EIFFEL FLATS
SOLIDS
BATCH SAMPLE ANALYSIS SAMPLE Au
NO. DATES DATE DESCRIPTION ppm
20180131738 26.01.2018 31.01.2018 A Test E 50% 7.15
" " " B Test A 1/2XR 16.96
" " " C Trans 2 37.78
" " " D Test F 80% < 75 µm 27.51
" " " E Test E 40% 15.53
" " " F Test B D070 20.67
" " " G 1.5 ml frother 14.49
" " " I 80% < 75 large cell 24.33
" " " J Test F 70% < 75µm 23.11
20180131738 26.01.2018 31.01.2018 H 3ml frother 19.16
E. DANGENI
CHEMIST/SNR.CHEMIST CHIEF CHEMIST
CUSTOMER: Mrs O Dhlamini/T Dangeni
RIOZIM LIMITED
CENTRAL ANALYTICAL LABORATORY
EIFFEL FLATS
SOLIDS(CONCENTRATES)
BATCH SAMPLE ANALYSIS SAMPLE Au
NO. DATES DATE DESCRIPTION ppm
20180131746 26.01.2018 31.01.2018 K Test D Ph 7.5 8.61
" " " L Test D Ph 9.5 15.30
" " " M Test A 1XR 17.12
" " " N Test B D233 27.07
" " " O Leach Tails before float 50.20
" " " P Test B SNPX with co-collector 19.86
" " " Q Test D Ph 10.5 31.94
" " " R Trans 1 15.03
" " " T Test A 1/4XR 45.71
20180131746 26.01.2018 31.01.2018 U Test E 50% 7.35
E. DANGENI
CHEMIST/SNR.CHEMIST CHIEF CHEMIST
