TABLE OF CONTENTS
1.
INTRODUCTION
3
2.
METHODOLOGY
3
2.1. Sample Preparation
3
2.2. Gravity concentration
3
2.3. Intensive Cyanidation on Gravity Concentrates
4
2.4 CIL
4
2.5 Mineralogical Characterisation
5
3
6
RESULTS
3.1 Head Grade
6
3.2 Gravity Concentration
6
3.3 Intensive Cyanidation on Gravity Concentrate
7
3.4 CIL
8
3.5 Mineralogical Characterization
9
4
SUMMARY AND CONCLUSIONS
10
5
APPENDIX
12
5.1 Sample list
12
5.2 Gravity Test Results
13
5.3 Intensive Cyanidation on Gravity Concentrates
15
5.4 CIL
18
5.5 Mineralogical Report
19
Report Number: A131
Page 2 of 19
PF-ZA-[MINMMN]-[(BYZ)]AN-002
1. INTRODUCTION
Clive Arthur on behalf of Castle Peak Mining Ltd requested SGS South Africa (Pty) Ltd to carry
out metallurgical testwork on gold bearing composite samples. The test programme comprised
of Gravity concentration, Direct cyanidation, Carbon in leach (CIL) and Mineralogical
characterisation.
2. METHODOLOGY
2.1. Sample Preparation
Variable samples were received, these samples were received damp and the initial phase of
the sample preparation was drying. On completion of drying, the samples were composited
according to their gold head grade, composite 1 constituted of the high grade variable samples
whilst composite 2 constituted of the low grade variable samples. A sample list is presented in
Appendix 5.1, indicating which of the variable samples were used in the make-up of the two
composite samples. Each composite sample was screened at 1.7mm; the coarse fraction
(+1.7mm) was crushed to 100% -1.7mm using a cone crusher, following which it was blended
with the initially screened -1.7mm fraction. The 100% -1.7mm samples were further screened
at 75µm, the +75µm fraction was milled to 80% -150µm and blended with the -75µm fraction.
The blended -75µm and 80% -150µm samples were milled to 80% -75µm following which each
of the composite sample was rotary split to remove composite three make-up sub-sample.
Composite three was produced by blending one part composite 1 and two parts composite 2.
A sub-sample was removed from the three composite samples for a head gold analysis (Au in
triplicate); a further 200g sub-sample was removed from composite 1 and 2 for mineralogical
characterisation. The sub-samples were removed by way of rotary splitting.
2.2. Gravity concentration
Five batch gravity tests, two for each composite 1 and 2 and one for composite 3 were
conducted using the SB falcon centrifugal concentrator, as shown in Figure 1. The tests were
conducted using fluidization water at 1.2psi. Gravity concentrate produced for test A
(composite 1 and 2) were subjected to mineralogical characterization, while the gravity
concentrates produced from test B (composite 1, 2 and 3) were subjected to direct cyanidation
using specified Gekko system ILR conditions and the gravity tails were subjected to gold
dissolution using CIL conditions.
Report Number: A131
Page 3 of 19
PF-ZA-[MINMMN]-[(BYZ)]AN-002
Figure 1: Schematic of the SB Falcon centrifugal concentrator
2.3. Intensive Cyanidation on Gravity Concentrates
This test was conducted on the gravity concentrates using specified Gekko Systems ILR
conditions. A sample was weighed into a glass bottle and water added to form slurry at 10%
solids. The dissolution tests were conducted for a period of 24hours, with the filtrate sample
removed at 0, 2, 4, 6, 8, 12 and 24hours.
The cyanide was maintained at 2% throughout the duration of the leach with lead nitrate
addition of 2kg/t and dissolved oxygen maintained at~ 20ppm. The lead nitrate was added to
prevent the passivation film around on the gold surface thereby inhibiting the gold dissolution
The use of elevated dissolved oxygen leads to a higher degree of the formation of the gold
cyanide complex as described by the equation: 4Au + 8CN- + O2 + 2H2O → 4Au(CN)2-
2.4 CIL
The CIL tests were conducted on the gravity tails from test B on all three composite samples.
A 300g sample was weighed into a glass bottle and combined with water to form slurry at 50%
solids; the slurry was agitated by way of bottle rolling as shown in Figure 2. The slurry was
preconditioned for 1hour during which period the pH was adjusted by lime addition to maintain
between 10.5 and 11.
Report Number: A131
Page 4 of 19
PF-ZA-[MINMMN]-[(BYZ)]AN-002
On completion of preconditioning, 2kg/t of cyanide and 20g/l carbon was added, the cyanide
was added in the form of sodium cyanide. The tests were conducted with dissolution times of
2, 4, 8, 12, 24 and 36hours.
On completion of the dissolution tests the slurries were filtered, washed and dried. The
residues, filtrates and carbons were analysed for gold. To establish the residual cyanide and
lime the final filtrates were titrated using silver nitrate and oxalic acid.
Figure 2: Schematic of the bottle roll set up
2.5 Mineralogical Characterisation
In order to gain an understanding of the nature and mode of occurrence of the gold (Au) in the
samples, the following analyses were conducted:
o
Chemical analysis to determine the composition of the ore.
o
General mineralogical characterization of the ore.
o
Exposure and mineral association analysis of the particulate Au grains in the composite
sample.
Report Number: A131
Page 5 of 19
PF-ZA-[MINMMN]-[(BYZ)]AN-002
3
RESULTS
3.1 Head Grade
The gold head assay analysis is presented in Table 1. The analysis was conducted in
triplicate, yielding average gold head assay ranging from 15.2g/t to 0.97g/t.
Table 1: Gold head assay analysis
Head 1
Head 2
Head 3
Average
Head
Au (g/t)
Au (g/t)
Au (g/t)
Au (g/t)
Composite 1
15.8
14.2
15.6
15.2
Composite 2
0.95
1.18
0.77
0.97
Composite 3
9.17
9.16
7.48
8.60
Sample ID
3.2 Gravity Concentration
Gravity concentration results are presented in Table 2 to Table 4. The gold recoveries obtained
ranged from a minimum of 71.5% for composite 2 to a maximum of 87.8% for composite 1, this
signifies the amenability of the ore to gravity concentration.
The concentrate gold grades were derived from the intensive cyanidation tests. Detailed
gravity tests results are presented in Appendix 5.2.
Table 2: Composite 1; gravity concentration results
Fraction
Conc
Tails
Total
Gold
Mass
g
84.5
7920
8005
%
1.1
98.9
100
Cumulative
Grade
Recovery
Mass
Recovery
g/t
1389
2.06
16.7
%
87.8
12.2
100
%
1.1
100
%
87.8
100
Table 3: composite 2; gravity concentration results
Fraction
Conc
Tails
Total
Gold
Mass
g
80.3
7954
8034
%
1.0
99.0
100
Cumulative
Grade
Recovery
Mass
Recovery
g/t
72.0
0.29
1.01
%
71.5
28.5
100
%
1.0
100
%
71.5
100
Report Number: A131
Page 6 of 19
PF-ZA-[MINMMN]-[(BYZ)]AN-002
Table 4: Composite 3; gravity concentration results
Fraction
g
83.5
7961
8044
Conc
Tails
Total
Gold
Mass
%
1.0
99.0
100
Cumulative
Grade
Recovery
Mass
Recovery
g/t
594
0.90
7.05
%
87.4
12.6
100
%
1.0
100
%
87.4
100
3.3 Intensive Cyanidation on Gravity Concentrate
Intensive cyanidation kinetic dissolution results are presented in Figure 3. All three composite
samples yielded recoveries ranging from 99.3% to 99.8%, with composite 3 yielding the
maximum recovery. Appendix 5.3 presents detailed dissolution results.
100
90
80
Au loading (%)
70
60
50
40
30
20
10
0
0
6
12
18
24
Time (Hrs)
Composite 1
Composite 2
Composite 3
Figure 3: Intensive Leach Recovery of Au on Gravity Concentrates for the three composites
Report Number: A131
Page 7 of 19
PF-ZA-[MINMMN]-[(BYZ)]AN-002
3.4 CIL
Carbon in leach kinetic dissolution results are presented in Figure 4. With an initial dissolution
period of 2hours composite 1, 2 and 3 yielded dissolutions of 68.8%, 77.5% and 71.8%
respectively. The dissolution as displayed by the figure increases with an increase in
dissolution period, to yielded maximum dissolutions of 86.6%, 93.6% and 83.8% for composite
1, 2 and 3 respectively. At a dissolution period of 24hours, composite 2 yielded a decrease in
the gold dissolution. The decrease in the dissolution may be attributed to the analytical
inaccuracy. The residues were analyzed by fire assay with AA finish, the equipment has a
detection limit of 0.08g/t and a residue analysis of 0.04g/t was reported, the readability of any
analysis below the detection limit will inadvertently incur analytical errors and hence this
decrease in dissolution.
100
90
80
Calc. Dissolution (%)
70
60
50
40
30
20
10
0
2
8
14
20
26
32
Time (Hrs)
Composite 1
Composite 2
Composite 3
Figure 4: Carbon In Leach
Table 5 presents a summary of the CIL dissolution results. It may be observed that an increase
in dissolution period yielded an increase in reagents consumption; this was true for both lime
and cyanide. All three composite samples yielded maximum cyanide consumption of
~1.90kg/t. The maximum lime consumptions of 0.22kg/t, 0.16kg/t and 0.18kg/t were attained
for composite 1, 2 and 3 respectively. Detailed results are presented in Appendix 5.4.
Report Number: A131
Page 8 of 19
PF-ZA-[MINMMN]-[(BYZ)]AN-002
Table 5: Summary of the CIL dissolution results
Sample ID
Leach
Time
Hrs
Composite 1
Composite 1
Composite 1
Composite 1
Composite 1
Composite 1
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 3
Composite 3
Composite 3
Composite 3
Composite 3
Composite 3
2
4
8
12
24
36
2
4
8
12
24
36
2
4
8
12
24
36
Head
Au
Assayed
g/t
2.06
2.06
2.06
2.06
2.06
2.06
0.29
0.29
0.29
0.29
0.29
0.29
0.90
0.90
0.90
0.90
0.90
0.90
Reagent consumption
Au
Calc'd
g/t
2.04
2.12
2.18
2.06
2.12
2.21
0.27
0.27
0.26
0.31
0.29
0.31
0.92
0.94
0.97
0.89
0.94
0.97
NaCN
kg/t
1.82
1.85
1.87
1.88
1.89
1.91
1.86
1.85
1.88
1.89
1.89
1.91
1.87
1.85
1.87
1.88
1.89
1.90
CaO
kg/t
0.14
0.15
0.15
0.15
0.19
0.22
0.14
0.15
0.16
0.16
0.16
0.16
0.14
0.14
0.15
0.15
0.15
0.18
Au
Dissolution Calc
%
68.8
72.8
75.5
83.6
86.0
86.6
77.5
78.1
92.5
93.5
86.2
93.6
71.8
72.4
81.6
82.3
83.2
83.8
3.5 Mineralogical Characterization
The Au grade for both composites was determined in triplicate. The variable results in
composite 1, suggest that coarse Au grains may be present in significant concentrations, while
the reportability of the grades in composite 2 indicate that coarse gold may not be present in
significant concentrations.
The exposure and association characteristics, for both composite samples, indicated that there
will be good recoveries during cyanidation as the grains are well exposed (with ~99% of the
grains exposed for composite 1 and 94% of the grains exposed for composite 2).
Due to the high levels of the exposure, this material will be amendable to processing by milling
to 80% -75 µm and direct cyanidation. However, the significant presence of coarse gold,
particularly in composite 1 will necessitate extended retention times. These retention times
could be reached by first performing gravity separation with intensive cyanidation of the
concentrate and direct cyanidation of the gravity tailing. A detailed mineralogical report is
presented in Appendix 5.5
Report Number: A131
Page 9 of 19
PF-ZA-[MINMMN]-[(BYZ)]AN-002
4
SUMMARY AND CONCLUSIONS
The gravity concentration test results yielded recoveries of 87.8%, 71.5% and 87.4% for
composite 1, 2 and 3 respectively, whilst the mass pull ranged from 1.0% to 1.1% with
composite 2 and 3 yielding 1.0% and composite 1 yielding 1.1%. The obtained recoveries
suggest that the ore is amenable to gravity concentration. Assayed head grades of 1386g/t,
86.1g/t and 549g/t were obtained on the gravity concentrate for composite 1, 2 and 3
respectively; these assayed head grades were further confirmed by the intensive cyanidation
tests which yielded calculated head grades of 1388.9g/t, 72.0g/t and 593.7g/t for composite 1,
2 and 3 respectively.
The intensive cyanidation test yielded recoveries of 99.3%, 99.7% and 99.8% for composite 2,
1 and 3 respectively. Composite 3 displayed the optimal leach kinetics of all three composite
samples with recoveries of 73.1% and 95.1% obtained after 6 and 12hours of dissolution this
in comparison to recoveries of 67.0% and 90.2% for composite 1 and 50.6% and 71.3% for
composite 2 within the same time interval.
Table 6 presents a summary of the overall recovery for each of the composite sample. The
total recovery is derived from the proportion of gold in the gravity concentrate, gravity tails and
head sample. All three composite samples yielded total recoveries in excess of 90.0%, the
implications thereof being that ore is amenable to the specified processing conditions.
Report Number: A131
Page 10 of 19
PF-ZA-[MINMMN]-[(BYZ)]AN-002
Table 6: Total recovery
Sample ID
Composite 1
Composite 2
Composite 3
Time
Hrs
2
4
8
12
24
36
2
4
8
12
24
36
2
4
8
12
24
36
Recovery from
Gravity
concentrate
%
88
71.0
87.2
Recovery from
CIL- Gravity tails
Total recovery
%
8.39
8.88
9.22
10.2
10.5
10.6
22.1
22.3
26.4
26.7
24.6
26.7
9.08
%
95.9
96.4
96.8
97.8
98.0
98.1
93.1
93.3
97.4
97.7
95.6
97.7
96.3
9.15
10.3
10.4
10.5
96.4
97.5
97.6
97.7
10.6
97.8
Report Number: A131
Page 11 of 19
PF-ZA-[MINMMN]-[(BYZ)]AN-002
5
APPENDIX
5.1 Sample list
SAMPLE ID
205400
205481
205452
203427
200056
205401
205453
205454
205343
203426
205456
200055
205342
205639
203424
200057
200061
200058
200062
205359
205586
205691
205352
205455
205591
205355
205690
205457
205642
205589
203417
205344
203420
205346
203413
COMPOSITE
Composite 1
Composite 1
Composite 1
Composite 1
Composite 1
Composite 1
Composite 1
Composite 1
Composite 1
Composite 1
Composite 1
Composite 1
Composite 1
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
SAMPLE ID
205351
205459
205640
205643
205349
205644
203431
203414
205347
203416
205340
203415
203430
203421
205341
205590
205399
203422
205641
205353
205589
203423
203419
203412
203429
205637
205482
205345
205692
205354
205357
205350
203411
205356
205587
Report Number: A131
COMPOSITE
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Page 12 of 19
PF-ZA-[MINMMN]-[(BYZ)]AN-002
5.2 Gravity Test Results
Composite 1
Test
Grind
Single batch - Comp 1
80% -75µm
Au Head
grade
Test
results
Assayed 15.2
Calc.
16.7
g/t
g/t
Mass
Fraction
g
84.5
7920
8005
Conc
Tails
Total
%
1.1
98.9
100
Grade
g/t
1389
2.06
16.7
15.8
Gold
Recovery
%
87.8
12.2
100
14.2
15.6
Cumulative
Mass
Recovery
%
%
1.1
87.8
100
100
Composite 2
Test
Grind
Single batch - Comp 2
80% -75µm
Au Head
grade
Test
results
Assayed 0.97
Calc.
1.01
Mass
Fraction
Conc
Tails
Total
g/t
g/t
g
80.3
7954
8034
%
1.0
99.0
100
0.95
Gold
Grade
Recovery
g/t
%
72
71.5
0.29
28.5
1.0
100
Report Number: A131
1.18
0.77
Cumulative
Mass
Recovery
%
%
1.0
71.5
100
100
Page 13 of 19
PF-ZA-[MINMMN]-[(BYZ)]AN-002
Composite 3
Test
Grind
Single batch - Comp 3
80% -75µm
Au Head
grade
Test
results
Assayed 8.60
Calc.
7.05
Mass
Fraction
Conc
Tails
Total
g/t
g/t
g
83.5
7961
8044
%
1.0
99.0
100
9.17
Gold
Grade
Recovery
g/t
%
594
87.4
0.90
12.6
7.0
100
Report Number: A131
9.16
7.48
Cumulative
Mass
Recovery
%
%
1.0
87.4
100
100
Page 14 of 19
PF-ZA-[MINMMN]-[(BYZ)]AN-002
5.3 Intensive Cyanidation on Gravity Concentrates
Composite 1
Au Leaching
100
Description:
90
Intense Leach
80
2% NaCN, Oxygen at 20ppm, 2g/kg Pb(NO3 )2
10.0%
NaCN
consumed
Net NaCN
added
0.16 g
2.04 kg/t
Pb(NO3)2
addition
70
2.68 g
33.9 kg/t
16.99 g
219.8 kg/t
NaCN
residual
2.02 %
14.32 g
% leached
Conditions:
Wt % Solids
60
50
40
30
20
NaOH
Consumption
0.30 g
3.85 kg/t
Net NaOH
added
0.30 g
3.8 kg/t
10
0
final
pH
SAMPLE
NAME
12.70
Wt. OR
VOLUME
g
78.9
Sampled Head
SOLUTION
SUB/ADD
g
g
ASSAYS
Au
ppm
1386
Recovery
Au
%
<0.1
62.5
78.4
87.4
87.4
98.2
110.0
117.0
0.0
40.5
53.7
63.1
67.0
78.0
90.2
99.7
Solutions hours
0
1
2
4
6
8
12
24
710
710
710
710
710
710
710
710
50
50
50
50
50
50
0
50
50
50
50
50
50
0
Leach residue
77.3
4.01
Calculated Head
78.9
1389
DO2
NaOH
residual
pH
ppm
initial
5.86
25.6
22.8
26.2
24.3
20.6
21.0
22.0
8.45
12.68
12.78
12.70
12.76
12.74
12.67
12.55
12.70
0
0.00 %
0.00 g
6
12
time (hours)
18
24
sample
Sodium Cyanide
Au
level
added removed
mg
%w/v
g
g
leached
Au
mg
level
%
NaOH
added
g
removed
g
2.000
1.668
2.045
2.031
1.994
1.994
1.958
2.016
44381
58797
69108
73478
85517
98806
109277
0.000
0.000
0.000
0.000
0.000
0.000
1.000
0.000
0.30
-
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.297
0.000
Total
14.20
3.25
1.00
1.00
1.05
1.05
1.29
0.00
0.00
0.83
1.02
1.02
1.00
1.00
0.98
0.00
22.84
5.85
3125
3920
4370
4370
4910
5500
0
310
109587
Report Number: A131
Page 15 of 19
PF-ZA-[MINMMN]-[(BYZ)]AN-002
Composite 2
Au Leaching
100
Description:
90
Intense Leach
80
2% NaCN, Oxygen at 20ppm, 2g/kg Pb(NO3)2
10.0%
NaCN
consumed
Net NaCN
added
0.15 g
2.04 kg/t
Pb(NO3)2
addition
70
3.46 g
46.1 kg/t
16.60 g
225.5 kg/t
NaCN
residual
1.94 %
13.14 g
% leached
Conditions:
Wt % Solids
60
50
40
30
20
NaOH
Consumption
0.30 g
4.04 kg/t
Net NaOH
added
0.30 g
4.0 kg/t
10
0
final
pH
SAMPLE
NAME
12.13
Wt. OR
VOLUME
g
75.1
Sampled Head
SOLUTION
SUB/ADD
g
g
ASSAYS
Au
ppm
86
Recovery
Au
%
<0.1
1.8
2.6
3.0
3.5
4.0
4.6
6.5
0.0
22.5
34.2
41.6
50.6
60.1
71.3
99.3
Solutions hours
0
1
2
4
6
8
12
24
676
676
676
676
676
676
676
676
50
50
50
50
50
50
0
50
50
50
50
50
50
0
Leach residue
73.6
0.51
Calculated Head
75.1
72.0
DO2
NaOH
residual
pH
ppm
initial
6.80
25.0
20.1
19.1
22.0
24.2
21.7
20.4
8.90
12.69
12.54
12.55
12.61
12.62
12.54
12.62
12.13
0
0.00 %
0.00 g
6
sample
Sodium Cyanide
Au
level
added removed
mg
%w/v
g
g
2.001
1.813
1.958
1.987
1.994
1.922
1.886
1.944
Total
13.52
2.21
1.27
1.08
1.04
1.51
1.74
0.00
0.00
0.91
0.98
0.99
1.00
0.96
0.94
0.00
22.38
5.78
90
130
150
175
200
230
0
12
time (hours)
level
%
NaOH
added
g
removed
g
1217
1847
2248
2736
3249
3854
5368
0.000
0.000
0.000
0.000
0.000
0.000
1.000
0.000
0.30
-
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.297
0.000
38
Page 16 of 19
PF-ZA-[MINMMN]-[(BYZ)]AN-002
24
leached
Au
mg
5406
Report Number: A131
18
Composite 3
Au Leaching
100
Description:
90
Intense Leach
80
2% NaCN, Oxygen at 20ppm, 2g/kg Pb(NO3)2
10.0%
NaCN
consumed
Net NaCN
added
0.16 g
2.07 kg/t
Pb(NO3)2
addition
70
2.40 g
30.8 kg/t
16.55 g
216.5 kg/t
NaCN
residual
2.02 %
14.15 g
% leached
Conditions:
Wt % Solids
60
50
40
30
20
NaOH
Consumption
0.30 g
3.89 kg/t
Net NaOH
added
0.30 g
3.9 kg/t
10
0
final
pH
SAMPLE
NAME
12.29
Wt. OR
VOLUME
g
78
Sampled Head
SOLUTION
SUB/ADD
g
g
ASSAYS
Au
ppm
549
Recovery
Au
%
<0.1
25.9
34.2
38.8
41.2
43.2
46.4
49.5
0.0
39.3
54.6
65.3
73.1
80.6
95.1
99.8
Solutions hours
0
1
2
4
6
8
12
24
Leach residue
Calculated Head
702
702
702
702
702
702
702
702
50
50
50
50
50
50
0
50
50
50
50
50
50
0
76.4
1.00
78
594
DO2
NaOH
residual
pH
ppm
initial
5.24
26.4
18.6
23.6
20.5
20.3
19.8
22.0
8.73
12.50
12.39
12.43
12.48
12.49
12.41
12.26
12.29
0
0.00 %
0.00 g
6
sample
Sodium Cyanide
Au
level
added removed
mg
%w/v
g
g
2.001
1.835
1.994
1.958
1.987
1.886
1.994
2.016
Total
14.05
2.11
1.05
1.28
1.09
1.76
1.04
0.00
0.00
0.92
1.00
0.98
0.99
0.94
1.00
0.00
22.38
5.83
1295
1710
1940
2060
2160
2320
0
12
time (hours)
level
%
NaOH
added
g
removed
g
18182
25303
30243
33867
37331
44058
46234
0.000
0.000
0.000
0.000
0.000
0.000
1.000
0.000
0.30
-
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.297
0.000
76
Page 17 of 19
PF-ZA-[MINMMN]-[(BYZ)]AN-002
24
leached
Au
mg
46310
Report Number: A131
18
5.4 CIL
Leach Time
Sample ID
Grind
Composite 1
Composite 1
Composite 1
Composite 1
Composite 1
Composite 1
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 2
Composite 3
Composite 3
Composite 3
Composite 3
Composite 3
Composite 3
80% -75µm
80% -75µm
80% -75µm
80% -75µm
80% -75µm
80% -75µm
80% -75µm
80% -75µm
80% -75µm
80% -75µm
80% -75µm
80% -75µm
80% -75µm
80% -75µm
80% -75µm
80% -75µm
80% -75µm
80% -75µm
Hrs
2Hrs
4Hrs
8Hrs
12Hrs
24Hrs
36Hrs
2Hrs
4Hrs
8Hrs
12Hrs
24Hrs
36Hrs
2Hrs
4Hrs
8Hrs
12Hrs
24Hrs
36Hrs
Test Description
CIL
CIL
CIL
CIL
CIL
CIL
CIL
CIL
CIL
CIL
CIL
CIL
CIL
CIL
CIL
CIL
CIL
CIL
Reagent addition
NaCN
CaO
kg/t
kg/t
2.0
0.17
2.0
0.17
2.0
0.17
2.0
0.17
2.0
0.20
2.0
0.23
2.0
0.17
2.0
0.17
2.0
0.17
2.0
0.17
2.0
0.17
2.0
0.17
2.0
0.17
2.0
0.16
2.0
0.17
2.0
0.17
2.0
0.17
2.0
0.18
NaCN
ppm
174
142
139
116
122
102
160
148
131
122
116
110
151
145
133
122
116
99
Pregnant solution
CaO
pH
ppm
22
11.0
17
10.9
11
10.7
11
10.8
14
10.9
11
10.6
28
11.0
17
10.7
6
10.5
6
10.7
6
10.8
6
10.6
22
11.0
22
10.8
11
10.5
11
10.8
11
10.8
6
10.6
Au
ppm
0.10
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
0.10
<0.1
<0.1
<0.1
<0.1
<0.1
Head
Au Assayed Au Calc'd
g/t
g/t
2.06
2.04
2.06
2.12
2.06
2.18
2.06
2.06
2.06
2.12
2.06
2.21
0.29
0.27
0.29
0.27
0.29
0.26
0.29
0.31
0.29
0.29
0.29
0.31
0.90
0.92
0.90
0.94
0.90
0.97
0.90
0.89
0.90
0.94
0.90
0.97
Report Number: A131
Residue
Assayed
g/t
0.64
0.58
0.54
0.34
0.30
0.30
0.06
0.06
0.02
0.02
0.04
0.02
0.26
0.26
0.18
0.16
0.16
0.16
Carbon
Au
g/t
67
77
81
84
91
93
8
8
11
12
10
14
29
32
41
34
40
40
Reagent consumption
NaCN
CaO
kg/t
kg/t
1.82
0.14
1.85
0.15
1.87
0.15
1.88
0.15
1.89
0.19
1.91
0.22
1.86
0.14
1.85
0.15
1.88
0.16
1.89
0.16
1.89
0.16
1.91
0.16
1.87
0.14
1.85
0.14
1.87
0.15
1.88
0.15
1.89
0.15
1.90
0.18
Page 18 of 19
PF-ZA-[MINMMN]-[(BYZ)]AN-002
Au Dissolution - Assayed
Soln & Carbon
Solid
%
%
68.0
69.1
74.7
72.0
79.9
74.1
83.6
83.6
88.5
85.6
92.7
85.7
70.9
79.4
73.3
79.5
84.0
93.2
98.8
93.1
85.8
86.3
98.8
93.2
73.2
71.3
75.5
71.2
88.0
80.1
81.7
82.4
86.5
82.5
90.6
82.4
Au Dissolution - Calc
%
68.8
72.8
75.5
83.6
86.0
86.6
77.5
78.1
92.5
93.5
86.2
93.6
71.8
72.4
81.6
82.3
83.2
83.8
Accountability
Au
%
98.9
103
106
100
103
107
91.5
93.8
90.7
106
99.5
106
102
104
108
99.3
104
108
5.5 Mineralogical Report
Report Number: 13/A131
Page 19 of 19
PF-ZA-[MINMMN]-[(BYZ)]AN-002
TEST REPORT
SGS South Africa (Pty)Ltd
58 Melville Street
Booysens
Johannesburg
Clive Arthur/ Darren Lindsay
Castle Peak Mining
[email protected]
[email protected]
MINERALOGICAL REPORT No: 12/466 Rev.2
Work Requested By:
Clive Arthur & Darren Lindsay
On Behalf Of:
Castle Peak Mining
Proposal Number:
12/466 Rev.2
Date issued:
05 August 2013
Investigator/s:
Dinah Mosinyi
Detailed Mineralogical Characterisation on Two Composite Samples from Castle Peak
Mining
____________________
______________________
Dinah Mosinyi
Mineralogist
Brandon Youlton
Manager: Mineralogy
This document is issued by the Company under its General Conditions of Service accessible at
http://www.sgs.com/terms_and_conditions.htm Attention is drawn to the limitation of liability, indemnification and
jurisdiction issues defined therein.
WARNING: The sample(s) to which the findings recorded herein (the “Findings”) relate was(were) drawn and/or
provided by the Client or by a third party acting at the Client’s direction. The Findings constitute no warranty of the
sample’s representativity of all goods and strictly relate to the sample(s). The Company accepts no liability with
regard to the origin or source from which the sample(s) is/are said to be extracted. Any unauthorised alteration,
forgery or falsification of the content or appearance of this document is unlawful and offenders may be prosecuted to
the fullest extent of the law.
Report Number: 12/466 Rev.2
PF-ZA-[MINMMN]-[(BYZ)]AN-001 08/11
Page 1 of 22
TABLE OF CONTENTS
1.
INTRODUCTION
3
2.
METHODOLOGY
3
2.1. Head Chemistry
3
2.2. X-Ray Diffraction
3
2.3. Modal Mineralogy
3
2.4. Trace Mineral Search
3
3.
DEFINITIONS
3
4.
RESULTS
4
4.1. Au and Ag Grade of the Composite Samples
4
4.2. Head Chemical Analyses of the Composite Samples
5
4.3. Crystalline Phases by XRD
6
4.4. QEMSCAN Bulk Modal Analysis (BMA)
8
4.5. QEMSCAN Data Validation
10
4.6. Trace Mineral Search Analyses
11
4.6.1. Gold Speciation
11
4.6.2. Gold Deportment
11
4.6.3. Gold Grain Size Distribution
17
4.6.4. Gold Particle Types and Mineral Association
18
4.6.5. Gold Grain Exposure and Mineral Association
20
5.
22
DISCUSSION AND CONCLUSION
Report Number: 12/466 Rev.2
PF-ZA-[MINMMN]-[(BYZ)]AN-001 08/11
Page 2 of 22
1. INTRODUCTION
Clive Arthur, on behalf of Castle Peak Mining, submitted two composite samples for general
mineralogical characterization and chemical analysis.
2. METHODOLOGY
2.1.
Head Chemistry
Split aliquots of ~200 g of the composite samples were pulverized and submitted for Au by fire
assay – AAS finish, silver (Ag) by AAS; major element analysis by borate fusion XRF; base
metals by pyrosulphate fusion XRF; total sulphur and organic carbon (C) by Leco and arsenic
(As) by AAS.
2.2.
X-Ray Diffraction
A ~10 g split aliquot of each of the composite samples was pulverized and the resultant
powder analysed by means of X-ray Diffraction (XRD) in order to identify the major minerals
present in the samples. XRD data collection was done using a Panalytical X’Pert Pro
Diffractometer (employing Co-radiation), and data interpretation was done using High Score
Plus analytical software and the PDF2 database.
2.3.
Modal Mineralogy
Two transverse (90˚ cut) polished sections were made from the composite samples. A Bulk
Modal Analysis (BMA) by QEMSCAN was conducted on the transverse cut polished sections.
2.4.
Trace Mineral Search
QEMSCAN TMS analyses were conducted on 10 polished sections of the gravity
concentrates, in order to quantitatively determine the Au deportment in the sample.
3. DEFINITIONS
QEMSCAN technology is an automated electron beam mineralogical technique, based on a
Scanning Electron Microscope (SEM) with four light-element energy dispersive
X-ray spectrometers (EDS). The QEMSCAN is used in combination with X-ray Diffraction
(XRD) and geochemical analyses to identify and quantify mineralogical characteristics of
geological material.
Please note that the qualitative descriptions and quantitative measurements are based on
observations made in two-dimensional section through polished blocks of the sample. Various
descriptive terms are used in this report; these terms are defined as follows:
•
•
•
Area %: Particles and grains are exposed at the surface of a polished section as twodimensional cross-sections. Any quantification of mineral characteristics is based on
measurements, in pixels, of the exposed areas.
Association: Association refers to adjacency. Two minerals are "associated" if a pixel
of one of the minerals occurs adjacent to a pixel of the other mineral. In this report
association takes into account both vertically- and horizontally-adjacent pixels.
Association Mineral %: The number of pixels of a mineral type adjacent to the
mineral of interest expressed as a percentage of all the pixels associated with the
mineral of interest.
Report Number: 12/466 Rev.2
PF-ZA-[MINMMN]-[(BYZ)]AN-001 08/11
Page 3 of 22
•
Calculated Chemical Composition: The major element chemical composition of the
sample can be calculated taking the SG and theoretical chemical composition of each
mineral into account. The calculated chemical composition is compared to the
measured chemical composition and good agreement serves as validation of the
mineralogical composition. Please note that the calculated and measured chemical
compositions are never exactly similar due to uncertainties in the mineral chemistry.
•
Grain: A mineral grain that consists of a single mineral type. Several grains can make
up a particle. In the case of a liberated grain, the terms grain and particle are
equivalent.
•
Mass %: If a statistical number of mineral grains are measured, then the area % of
each mineral can be converted into mass % taking the SG of each mineral into
account.
•
Particle: Several grains make up a particle. A particle usually refers to a fragment of a
rock or ore, the size of which is dependent on crushing and milling conditions.
4. RESULTS
4.1.
Au and Ag Grade of the Composite Samples
The results of the chemical analyses are given in Table 1. The analytical methods, as well as
the detection limits are also given in the table.
As can be observed in Table 1, the Au grade in Composite 1 is significantly higher than that of
Composite 2at a grade of 14.67 g/t. Composite 2 (low grade composite) had an average grade
of 1.90 g/t. The Ag average grade in both composite samples was 1.00 g/t.
Table 1. Au and Ag Grades of the Composite Samples
Element
Au
Ag
Method
M401
AAS21E
Units
ppm
ppm
Composite 1A
14.40
1.00
Composite 1B
13.90
1.00
Composite 1C
15.70
1.00
14.67
1.00
Composite 2A
1.60
1.00
Composite 2B
2.20
1.00
Composite 2C
1.90
1.00
1.90
1.00
Average
Average
Report Number: 12/466 Rev.2
PF-ZA-[MINMMN]-[(BYZ)]AN-001 08/11
Page 4 of 22
4.2.
Head Chemical Analyses of the Composite Samples
From the head chemistry, it was noted that Composite 1 contained significant amounts of SiO2
at ~65.9% with minor amounts of Al2O3 at ~8.73%, Fe2O3 at 7.02% and CaO at 6.53%. All
other oxides were detected in trace quantities. The LOI (loss on ignition) in the sample was
low (~2.19%), this indicates that the sample contains low amounts of hydrated minerals or
carbonaceous and sulphide minerals, as indicated by the low sulphide (S) (~0.80%) and
organic carbon values shown in Table 3.
Composite 2 contained lower amounts of SiO2, with slightly elevated concentrations of alumina
(Al2O3) at 12.70%, and minor amounts of Fe2O3 at ~9.41%, CaO at ~8.91%, MgO at ~ 8.03%
and the other oxides occurred in trace quantities. The LOI (loss on ignition) for the second
composite was slightly higher relative to Composite 1. This indicates that the sample contains
higher amounts of hydrated minerals or carbonaceous and sulphide minerals, as is indicated
by the slightly higher sulphide content at ~ 0.85%, shown in Table 3. The low arsenic values
for both composites indicate that arsenopyrite may not be present in significant quantities in
the sample.
Given in Table 4 are the base metal results for both composite samples. All base metals, with
the exception of Cr were below detection limit. The low grade composite sample (Composite 2)
contained approximately ~ 0.07% Cr, and Composite 1 contained approximately ~0.05% Cr.
Figure one provides a graphic presentation of the major element distribution for both
composite samples.
Table 2. Head Chemical Composition of the Composite Samples
Element
SiO2
Al2O3
CaO
MgO
Fe2O3
K2O
MnO
Method
XRF79V
XRF79V
XRF79V
XRF79V
XRF79V
XRF79V
XRF79V
Lower Detection
0.05
0.05
0.01
0.05
0.01
0.01
0.01
Upper Detection
100
100
100
100
100
100
100
%
%
%
%
%
%
%
Composite 1
65.90
8.73
6.53
6.91
7.02
0.94
0.10
Composite 2
52.70
12.70
8.91
8.03
9.41
1.23
0.15
Element
Na2O
P2O5
TiO2
Cr2O3
V2O5
LOI
Total
Method
XRF79V
XRF79V
XRF79V
XRF79V
XRF79V
XRF79V
XRF79V
Lower Detection
0.05
0.01
0.01
0.01
0.01
-50
0.01
Upper Detection
100
100
100
100
100
100
100
%
%
%
%
%
%
%
Composite 1
0.94
0.05
0.31
0.08
0.02
2.19
96.13
Composite 2
1.65
0.09
0.40
0.08
0.03
3.07
93.13
Units
Units
Table 3: Total Sulphur, Organic Carbon and Arsenic Assay Values for the Composite Samples
Element
S
Organic C
As
Method
CSA06V
CSA03V
AAS11C
Lower Detection
0.01
0.05
0.01
Upper Detection
100
40
5
%
%
%
Composite 1
0.80
<0.05
0.02
Composite 2
0.85
<0.05
0.02
Units
Report Number: 12/466 Rev.2
PF-ZA-[MINMMN]-[(BYZ)]AN-001 08/11
Page 5 of 22
Table 4: Base Metal Compositions as Determined by Pyrosulphate Fusion XRF
Element
Co
Cr
Cu
Ni
Pb
Zn
Method
XRF77R
XRF77R
XRF77R
XRF77R
XRF77R
XRF77R
Lower Detection
0.02
0.05
0.05
0.05
0.05
0.05
Upper Detection
100
100
100
100
100
100
%
%
%
%
%
%
Composite 1
<0.02
0.05
<0.05
<0.05
<0.05
<0.05
Composite 2
<0.02
0.07
<0.05
<0.05
<0.05
<0.05
Units
Major Element Abundances of Composites 1 & 2
35.00
Distribution (%)
30.00
25.00
20.00
Composite 1
15.00
Composite 2
10.00
5.00
0.00
Si
Al
Ca Mg Fe
K
Mn Na
P
Ti
Cr
V
Element
Figure 1: Major element compositions of the composite samples.
4.3.
Crystalline Phases by XRD
The crystalline phases that were detected by XRD are listed in Table 5, and Figures 2 – 3
shows the diffractograms of composite samples. The following paragraphs provide detailed
descriptions of the mineralogy of the samples. The results of the XRD analyses of the
composite sample agree with the geochemical results.
Composite 1
This composite sample contained quartz, with lesser amounts of amphibole, minor amounts of
plagioclase, mica, chlorite, pyrite and trace amounts of K-feldspar and dolomite. The presence
of K-feldspar and dolomite sets this sample apart from the second composite ( Figure 2). The
results of the major chemical analyses agree with the XRD results, which show a high SiO2
presence, this can be explained by the high concentration of siliceous phases in the sample
namely quartz, amphibole, plagioclase, mica, chlorite and K-feldspar.
Composite 2
Composite 2 contained quartz, with lesser amounts of amphibole, plagioclase, chlorite and
minor amounts of mica, calcite and pyrite. The elevated plagioclase and chlorite concentration,
together with the presence of calcite sets this sample apart from the previous composite
(Figure 2). As with the previous sample, the results obtained by chemical assays agree with
the crystalline phases detected by XRD. The elevated alumina (Al2O3) concentration can be
explained by the slightly higher concentration of plagioclase and chlorite, while the Fe2O3
concentration can be explained by the higher amphibole and pyrite concentrations. It should be
noted that the values presented in Table 5 are indicative only.
Report Number: 12/466 Rev.2
PF-ZA-[MINMMN]-[(BYZ)]AN-001 08/11
Page 6 of 22
Table 5: Crystalline Mineral Phases & Their Approximate Abundance as Determined by X-ray Diffraction
Mineral
Approx. Formula
Composite 1
Composite 2
Quartz
SiO2
20 - 50%
20 - 50%
Amphibole
Ca2(Mg,Fe)5Si8O22(OH)2
10 - 20%
10 - 20%
Plagioclase
NaAlSi3O8
3 - 10%
10 - 20%
K-feldspar
KAlSi3O8
<3%
-
KMg3(Si3Al)O10(OH)2
3 - 10%
3 - 10%
Chlorite
(Mg,Fe)6(Si,Al)4O10(OH)8
3 - 10%
10 - 20%
Dolomite
CaMg(CO3)2
<3%
-
Calcite
CaCO3
-
3 - 10%
Pyrite
FeS2
3 - 10%
3 - 10%
Mica
Quartz
Castle Peak Comp 1
20.0
8.0
6.0
4.0
2.0
d-spacing [Å]
Figure 2: X-ray diffractogram showing the composition of Composite 1.
Report Number: 12/466 Rev.2
PF-ZA-[MINMMN]-[(BYZ)]AN-001 08/11
Page 7 of 22
Mica
Quartz
Pyrite
Amphibole
Quartz
Quartz
Quartz
Amphibole
Quartz
Amphibole
Amphibole
Quartz
Dolomite
Pyrite
0
Quartz
K-feldspar
Amphibole
Plagioclase
Chlorite
Mica
Amphibole
Amphibole
Quartz
Plagioclase
Amphibole
Chlorite
Mica
Chlorite
10000
Amphibole
Counts
40000
Amphibole
Quartz
Amphibole
Quartz
Pyrite
Amphibole
Quartz
Quartz
Amphibole
Quartz
Mica
Amphibole
Amphibole
Quartz
Pyrite
Plagioclase
Amphibole
Calcite
Amphibole
Chlorite
Plagioclase
Amphibole
Chlorite
Mica
Plagioclase
2500
Quartz
Quartz
Castle Peak Comp 2
Chlorite
Amphibole
Counts
10000
Mica
Chlorite
22500
0
20.0
8.0
6.0
4.0
2.0
d-spacing [Å]
Figure 3. X-ray diffractogram showing the composition of Composite 2.
4.4.
QEMSCAN Bulk Modal Analysis (BMA)
The mineralogical composition of the composite samples, as determined by QEMSCAN BMA,
are given in Table 6 and presented graphically in Figure 4. The QEMSCAN modal analyses
confirm most of the minerals detected by XRD mineral identification in Table 5 and Figures 23. The variations between QEMSCAN and XRD are largely due to the XRD being unable to
detect very low mineral concentrations.
The composite samples differed significantly. Composite 1 contained significant amounts of
silicates (~91.5%), with minor amounts of carbonates (~5.54%), and trace amounts of
sulphides (~2.32%). Composite 2 was characterised by elevated concentrations of sulphides
(~16.5%), with slightly lower amounts of silicates (~74.4%), and minor amounts of carbonates
(~8.5%). There was a minor proportion of sulphides (~4%), phosphates/sulphates/carbonates
(~2%), with oxides detected as trace (~0.40%) and other phases at (~0.01%), as illustrated in
Figure 4.
Report Number: 12/466 Rev.2
PF-ZA-[MINMMN]-[(BYZ)]AN-001 08/11
Page 8 of 22
Table 6: Mineralogical Composition of the Composite Samples
Mineral
Approximate Formula
FeS2
Pyrite
Arsenopyrite
Sphalerite
Galena
Chalcopyrite
Other sulphides
AsFeS
ZnS
PbS
CuFeS2
Total Sulphides
SiO2
Quartz
Plagioclase
(Na,Ca)(Al,Si)4O8
KAl3Si3O10(OH)2
Muscovite/K-Feldspar
(Mg,Fe)6(Si,Al)4O10(OH)8
Ca(Mg,Fe)5Si8O22(OH)2
Al2Si4O10(OH)2
Total Silicates
Fe-oxide/hydroxide
Fe2O3 - FeOOH
Total Oxides
Apatite
Ca5(PO4)3(F,Cl,OH)
Chlorite
Amphibole
Pyrophyllite
CaSO4.2H2O
CaCo3
Gypsum
Calcite
CaMg(CO3)2
Ankerite/Dolomite
Total Phosphates/Sulphates/Carbonates
Other
Total
Composite 1
Composite 2
1.94
0.01
0.02
0.23
0.04
0.08
2.32
16.02
0.08
0.18
0.01
0.09
0.09
16.48
40.08
9.08
30.41
14.83
14.54
10.44
8.76
19.00
0.08
91.54
0.10
0.10
0.06
7.83
10.91
0.01
74.43
0.18
0.18
0.06
0.44
0.3
0.00
8.54
5.54
6.04
0.00
0
0.01
100.00
100.00
8.90
Mineral Compositions of Composites 1 & 2
100%
90%
Abundance (%)
80%
70%
Total
Phosphates/Sulphates/
Carbonates
60%
Total Oxides
50%
Total Silicates
40%
30%
Total Sulphides
20%
10%
0%
Composite 1
Composite 2
Figure 4: Bulk mineral composition of the composite samples.
Report Number: 12/466 Rev.2
PF-ZA-[MINMMN]-[(BYZ)]AN-001 08/11
Page 9 of 22
4.5.
QEMSCAN Data Validation
QEMSCAN data validation (Table 7) is based on the BMA results and compares the measured
chemical composition to the calculated chemical composition of the sample, which was
obtained from the abundance of the minerals detected by the QEMSCAN and their estimated
chemical composition. The calculated composition is often slightly different to the measured
chemical composition due to uncertainties in the mineral chemistry.
The calculated chemical composition of the sample compared well with the measured
chemical composition, as shown in Table 7. Please note that the values in Table 7 differ from
those presented in Table 2, as the values in Table 7 are expressed as elements rather than
oxides.
Table 7: Data Validation: Comparing the Calculated Chemical Composition to the Measured Chemical
Composition
Composite 1
Element
Measured (%)
Calculated (%)
Na
Mg
Al
Si
P
K
Ca
Ti
Cr
Mn
0.70
4.17
4.62
30.81
0.02
0.78
4.67
0.18
0.06
0.08
0.68
4.18
4.72
30.77
0.01
0.66
4.78
0.05
0.00
0.08
Fe
4.91
4.98
Composite 2
Report Number: 12/466 Rev.2
Element
Measured (%)
Calculated (%)
Na
Mg
Al
Si
P
K
Ca
Ti
Cr
Mn
1.22
4.84
6.72
24.62
0.04
1.02
6.37
0.24
0.05
0.12
1.28
4.84
6.78
24.71
0.01
1.02
6.33
0.06
0.00
0.10
Fe
6.58
6.49
PF-ZA-[MINMMN]-[(BYZ)]AN-001 08/11
Page 10 of 22
4.6.
Trace Mineral Search Analyses
The aim of the TMS analysis is to characterise the Au occuring in the gravity concentrates of
the samples. The QEMSCAN was set up to find and map particles containing areas of high
backscattered electron (BSE) intensity (including Au grains). Au deportment analysis includes
Au-phase speciation, liberation characteristics, mineral exposure, association characteristics
and Au grain-size distribution.
‘
4.6.1.
Gold Speciation
For the TMS, 5 polished sections for each gravity concentrate were analysed by means of
QEMSCAN in order to describe all the Au-bearing particles present in the analysis plane of
these sections.
Scanning Electron Microscope Energy Dispersive Spectrometry (SEM-EDS) analyses
indicated that the Au occurs mainly as native Au (Ag<25%), with trace amounts of aurostibite
(shown in Table 8) in both concentrates. Due to the low abundance of the other Au-bearing
phase, all the Au will be presented as native Au.
Table 8. Au Elemental Deportment of the Particulate Gold for the Gravity Concentrates of both
composite samples.
Au Deportment-Conc 1
Minerals
Gold
Aurostibite
Mineral Formula
Mass Au (%)
Au (<25% Ag)
99.93
AuSb2
0.07
Au Deportment-Conc 2
Minerals
Gold
Aurostibite
4.6.2.
Mineral Formula
Mass Au (%)
Au (<25% Ag)
99.90
AuSb2
0.10
Gold Deportment
The particle images were analysed using iDiscover 5.2 software. The following twodimensional parameters were measured for each Au-grain:
•
•
•
Area: Size of particles µm2.
Total gold: Size of the Au µm2 occurring in the particles.
Equivalent circular diameter (ECD): Diameter of a circle with the same area as that
of the particles/ grains.
SEM-BSE images, and QEMSCAN particle maps, depicting selected Au containing particles in
the gravity concentrates of the samples, are given in Figures 5A – 6D. Most of the Au grains in
both concentrates are liberated, some are associated with sulphides, and others associated
with silicate minerals.
A total of 100 Au-containing particles were detected, with 1230 Au grains (Table 9). The Aucontaining particle sizes of Gravity Conc 1, showed that the minimum, maximum and average
particle size (ECD in µm) was 1 µm, 309 µm and 35 µm, respectively. As can be observed, the
maximum particle size ECD for composite 1 is three times the maximum particle size (ECD in
µm) of composite 2.
Report Number: 12/466 Rev.2
PF-ZA-[MINMMN]-[(BYZ)]AN-001 08/11
Page 11 of 22
A total of 53 Au-containing particles were detected, with 1011 Au grains in Gravity Conc 2
(Table 9). The Au-containing particle sizes of composite 1, showed that the minimum,
maximum and average particle size (ECD in µm) was 2 µm, 109 µm and 30 µm.
Table 9. Gold Particle Data for the Gravity Concs of Composite 1 and Composite 2
Gravity Conc of Composite 1
No. of Gold
Containing
particles
Ave
Max
100
Min
No. Of Gold
containing
particles
Ave
53
Max
Min
Particle area
2
(µm )
Particle area
(pix)
21347
1644249
3
2640
35
75169
309
2
1
Gravity Conc of Composite 2
Particle area
(pix)
Report Number: 12/466 Rev.2
Particle Size ECD
(µm)
2136
15404
5
Vol % Gold
72
100
0
1230
Particle area
2
(µm )
Particle Size ECD
(µm)
Vol % Gold
1138
8209
3
30
102
2
37
100
0
PF-ZA-[MINMMN]-[(BYZ)]AN-001 08/11
No. of gold
grains
No. of gold
grains
1011
Page 12 of 22
5A
Gold
Plagioclase
Pyrite
Mica
Mica
Element
Weight (%)
Au
100.00
B
Gold
Mica
Plagioclase
Element
Weight (%)
Au
100.00
Figure 5A - 5B. On the right hand side is a QEMSCAN particle map of the gold containing particle and
on the left is the scanning electron microscope image. At the bottom is the EDS-spot analysis and
elemental composition. Shown in Figure 5A is a coarse gold particle approximately ~ 750 µm in size,
associated with plagioclase, mica and pyrite. Figure 5B also shows a coarse gold grain attached to
plagioclase and mica.
Report Number: 12/466 Rev.2
PF-ZA-[MINMMN]-[(BYZ)]AN-001 08/11
Page 13 of 22
C
Mica
Gold
Element
Weight (%)
Au
91.20
Ag
8.80
D
Gold
Mica
Pyrite
Element
Weight (%)
Au
100.00
Figure 5C -5D. On the right hand side is a QEMSCAN particle map of the gold containing particle and
on the left is the scanning electron microscope image. At the bottom is the EDS-spot analysis and
elemental composition. Shown in Figure 5C is a gold particle containing mica. Figure 5D shows a gold
particle containing pyrite and mica.
Report Number: 12/466 Rev.2
PF-ZA-[MINMMN]-[(BYZ)]AN-001 08/11
Page 14 of 22
6A
Chlorite
Gold
Element
Weight (%)
Au
Ag
79.78
20.22
B
Pyrite
Gold
Element
Weight (%)
Au
86.33
Ag
9.82
Fe
3.85
Figure 6A - 6B. On the right hand side is a QEMSCAN particle map of the gold particle and on the left is
the scanning electron microscope image. At the bottom is the EDS-spot analysis and elemental
composition. Shown in Figure 6A is a gold particle containing chlorite. Figure 6B shows a pyrite grain
containing gold.
Report Number: 12/466 Rev.2
PF-ZA-[MINMMN]-[(BYZ)]AN-001 08/11
Page 15 of 22
C
Gold
Element
Weight (%)
Au
89.23
Ag
10.77
D
Pyrite
Pyrrhotite
Mica
Element
Weight (%)
Au
100.00
Gold
Figure 6C - 6D. On the right hand side is a QEMSCAN particle map of the gold containing particle and
on the left is the scanning electron microscope image. At the bottom is the EDS-spot analysis and
elemental composition. Shown in Figure 6C is a small liberated gold particle. Figure 6D shows a gold
grain associated with pyrite, pyrrhotite and mica.
Report Number: 12/466 Rev.2
PF-ZA-[MINMMN]-[(BYZ)]AN-001 08/11
Page 16 of 22
4.6.3.
Gold Grain Size Distribution
The Au-grain size distributions (GSD) of the gravity concentrates are presented in Table 10and
graphically shown in Figure 8. A majority of the Au grains in gravity concentrate 1, were <2 µm
ECD, however, this only accounts for ~0.15% of the Au distribution. Thirteen Au grains, sized
>=100 µm ECD, contribute to ~57% of the Au in the sample.
Most of the Au grains in Gravity Concentrate 2 were detected as <2µm ECD, however this only
accounts for 5.12% of the Au distribution. Two Au grains sized between 60 and 80 µm ECD
accounted for ~33.4% of the Au distribution.
Table 10. Gold Grain Size Distribution for the Particulate Gold in the Gravity Concentrates of the
Composite Samples
Gold Size Distributions GSD of Composite 1
Size Classes (µm ECD)
N
Area
Distr. (%)
<2
>= 2 < 5
>= 5 < 10
>= 10 < 20
>= 20 < 30
>= 30 < 40
>= 40 < 50
>= 50 < 60
>= 60 < 80
>= 80 <1 00
932
76
60
61
32
11
13
8
14
10
1275
1289
4901
19759
28945
19177
38213
35258
97735
119606
0.15
0.15
0.57
2.31
3.39
2.25
4.47
4.13
11.44
14.01
>= 100
13
487822
57.12
1230
853980
100.00
Total
Gold Size Distributions GSD of Composite 2
Size Classes (µm ECD)
<2
>= 2 < 5
>= 5 < 10
>= 10 < 20
>= 20 < 30
>= 30 < 40
>= 40 < 50
>= 50 < 60
>= 60 < 80
>= 80 <1 00
>= 100
Total
Report Number: 12/466 Rev.2
N
Area
Distr. (%)
964
26
5
8
4
0
1
2
1
0
1403
275
497
2537
4302
0
3264
9139
5963
0
5.12
1.00
1.82
9.27
15.71
0.00
11.92
33.38
21.78
0.00
0
0
0.00
1011
27380
100.00
PF-ZA-[MINMMN]-[(BYZ)]AN-001 08/11
Page 17 of 22
Gold Grain Size Distribution
Distribution (%)
60.00
50.00
40.00
30.00
20.00
10.00
Composite 1
>= 100
>= 80 <1 00
>= 60 < 80
>= 50 < 60
>= 40 < 50
>= 30 < 40
>= 20 < 30
>= 10 < 20
>= 5 < 10
>= 2 < 5
<2
0.00
Composite 2
Size (micron ECD)
Figure 7. Gold grain size distribution for Gravity Concentrate 1 and Gravity Concentrate 2.
4.6.4.
Gold Particle Types and Mineral Association
The liberation and association characteristics of the Au grains for the composite samples
sample are given in Table 11.
The Au containing particles were classified into the following classes:
• Liberated (Lib): More than 80 area % of the particle is strictly that mineral.
• Middling (Midd) Au/Sulp/Sil/CarbPhosSulphates: Between 30 area % and 80 area
% of the particle is Au, sulphide, silicates or carbonates phosphates sulphates.
• Poly phase particles: Au containing particle is composed of several minerals, none of
which dominates.
The mass % Au distribution for the particulate Au is given in Table 11.
Approximately 82% of the particulate Au grains in the gravity concentrate of Composite 1
sample were considered liberated, with ~75% of the grains completely liberated and ~7.4%
partially liberated (middling). About 18% of the Au was associated with other mineral phases,
particularly the silicates (~11.2%).
Approximately 61% of the particulate Au grains in the gravity concentrate of Composite 2 were
considered liberated, with ~40.2% of the grains completely liberated and ~20.5% partially
liberated (middling). About 39.4% of the Au was associated with other mineral phases,
particularly the sulphides (~18%).
Report Number: 12/466 Rev.2
PF-ZA-[MINMMN]-[(BYZ)]AN-001 08/11
Page 18 of 22
Table 11. Mass Distribution of Particulate Gold per Gold Containing Particle Class
Particle Types Au
Conc 1
Quantity (N)
Class
Liberated Au (>=80%)
Middling Au (>=30%<80%)
Liberated Au Grains
Liberated Sulp (>=80%)
Midd Sulp (>=30%<80%)
Lib Sil (>=80%)
Midd Sil (>=30%<80%)
Lib Ox (>=80%)
Midd Ox (>=30%<80%)
Lib CarbPhosSulphates
Midd CarbPhosSulphates
Poly phase particles
Total
Area
(pixel)
837057
125843
962900
358584
26701
769401
1469
0
15609
0
0
0
74.63
7.36
81.98
5.43
0.92
11.24
0.05
0.00
0.38
0.00
0.00
0.00
767936
67276
835212
980
4398
12265
341
0
784
0
0
0
290
2134664
100.00
853980
Quantity (N)
Area
(pixel)
Mass % Gold
Area (µm )
15
7
22
9
0
5
1
0
16
0
0
0
17825
13033
30858
39627
0
27704
5
0
15029
0
0
0
40.17
20.46
60.63
17.97
0.00
9.93
0.00
0.00
11.47
0.00
0.00
0.00
17330
7781
25111
361
0
521
1
0
1386
0
0
0
53
113223
100.00
27380
Conc 2
Class
Total
Report Number: 12/466 Rev.2
2
Area (µm )
187
36
223
14
6
36
7
0
4
0
0
0
Particle Types Au
Liberated Au (>=80%)
Middling Au (>=30%<80%)
Liberated Au Grains
Liberated Sulp (>=80%)
Midd Sulp (>=30%<80%)
Lib Sil (>=80%)
Midd Sil (>=30%<80%)
Lib Ox (>=80%)
Midd Ox (>=30%<80%)
Lib CarbPhosSulphates
Midd CarbPhosSulphates
Poly phase particles
Mass % Gold
PF-ZA-[MINMMN]-[(BYZ)]AN-001 08/11
2
Page 19 of 22
4.6.5.
Gold Grain Exposure and Mineral Association
The Au-grain exposure and association characteristics for both gravity concentrates are given
in Table 12. The exposure of Au is directly related to the ability of Au to be leached during
cyanidation.
The Au containing particles were classified into following classes;
•
•
•
•
•
•
Exposed (≥80%): More than 80% is exposed (>80% surrounded by background).
Exposed (≥10%<80%): Between 80 and 10% is exposed (10%-80% surrounded by
background).
Exposed (<10%): Less than 10% is exposed (<10% surrounded by background).
Locked in mineral (100%): 100% surrounded by sulphides, silicates, oxides or
carbonates/phosphates/sulphates.
Locked on the boundary: locked between two minerals with no exposure.
Locked on polymineral boundary: If the Au-grain is locked on multiply grain
boundaries with no exposure and does not fall into the above categories.
The total exposure of particulate Au in the gravity concentrate of Composite 1 was very high,
with ~99.9% of the particulate Au having greater than 80% exposure. Only ~0.07% of the Au
grains were locked in gangue, oxides accounting for most of the gangue (0.04%).
Approximately ~0.04% of the Au was locked on a poly-mineral boundary.
The total exposure of particulate Au in the gravity concentrate of Composite 2 was similar to
that of composite 1 as it was also greater than 90%. Approximately 87.8% of the particulate Au
had greater than 80% exposure. Only ~4.52% of the Au grains were locked in gangue, oxides
accounting for most of the gangue (3.33%). Approximately ~1.72% of the Au was locked on a
poly-mineral boundary.
Report Number: 12/466 Rev.2
PF-ZA-[MINMMN]-[(BYZ)]AN-001 08/11
Page 20 of 22
Table 12. Gold Grain Size Distribution for the Particulate Gold in the Gravity Concentrates of the
Composite Samples
Exposure & Association Characteristics
Conc 1
2
Area (µm )
Class
Quantity
Gold Dist. %
Exposed (>=80%)
307
275170
32.22
Exposed (>=10%<80%)
339
577787
67.66
Exposed (<10%)
6
58
0.01
Total Exposed Gold
652
853015
99.89
Locked in sulphide (100%)
8
46
0.01
Locked in silicate (100%)
92
108
0.01
Locked in oxide (100%)
260
376
0.04
Locked in carb/phos/sulphates (100%)
0
0
0.00
Locked on sulphide-silicate boundary
6
8
0.00
Locked on sulphide-oxide boundary
6
55
0.01
Locked on sulphide-carb/phos/sulphates boundary
0
0
0.00
Total Locked in Gangue
372
593
0.07
Locked on silicate-oxide boundary
1
1
0.00
Locked on silicate-carb/phos/sulphates boundary
1
1
0.00
Locked on poly-mineral boundary
204
370
0.04
Total locked on Mineral Boundary
206
372
0.04
Total
1230
853980
100.00
Exposure & Association Characteristics
Conc 2
2
Area (µm )
Class
Quantity
Gold Dist. %
Exposed (>=80%)
27
24047
87.83
Exposed (>=10%<80%)
68
1391
5.08
Exposed (<10%)
3
235
0.86
Total Exposed Gold
98
25673
93.77
Locked in sulphide (100%)
8
71
0.26
Locked in silicate (100%)
0
0
0.00
Locked in oxide (100%)
671
913
3.33
Locked in carb/phos/sulphates (100%)
0
0
0.00
Locked on sulphide-silicate boundary
0
0
0.00
Locked on sulphide-oxide boundary
8
243
0.89
Locked on sulphide-carb/phos/sulphates boundary
8
10
0.04
Total Locked in Gangue
695
1237
4.52
Locked on silicate-oxide boundary
0
0
0.00
Locked on silicate-carb/phos/sulphates boundary
0
0
0.00
Locked on poly-mineral boundary
218
470
1.72
Total locked on Mineral Boundary
218
470
1.72
Total
1011
27380
100.00
Report Number: 12/466 Rev.2
PF-ZA-[MINMMN]-[(BYZ)]AN-001 08/11
Page 21 of 22
5. DISCUSSION AND CONCLUSION
Two composite samples from Castle Peak Mining were submitted for general mineralogical
characterization and chemical analysis. This was done to gain an understanding of the nature
and mode of occurrence of the gold (Au) in the samples. In order to achieve the objectives of
the study, a gold deportment and chemical analysis were conducted on both composites.
Both composite samples contained significant amounts of SiO2, with variable amounts of
Al2O3, CaO, MgO, and Fe2O3. The total S concentration for composite 1 is 0.80% and 0.85%
for composite 2, with pyrite being the significant sulphide phase for both composites. The As
concentration for both composite samples is very low, this can be attributed to the low
concentrations of arsenopyrite or any other arsenic-bearing phase in the composite samples.
The organic C concentrations for both composite samples were below detection limit. The low
concentration suggests that possible preg robbing constituents may be absent, and that
roasting may not be necessary.
Results of the X-ray diffraction (XRD) showed that both composite samples were silica rich as
they contained quartz, amphibole, variable amounts of plagioclase, mica and chlorite, with
minor to trace amounts of dolomite, calcite and pyrite.
From the data validation studies, it was noted that both composite samples contained
significant amounts of silicates, variable amounts of carbonates, sulphides and trace amounts
of oxides. Although mineralogically similar, the sulphide content of the composite samples
differed significantly. Composite 1 contained trace amounts of sulphides, while the pyrite
content in composite 2 was elevated significantly. The absence of pyrrhotite and copperbearing phases indicates that pre-oxidation before cyanidation will not be necessary.
The results of gravity concentration test work are shown in Table 2 – 3 of the metallurgy report
number A131. From the data it can be deduced that both composite samples are strongly
amenable to gravity upgrading of the gold as 87.8% (1389 g/t Au) of the gold reported to the
gravity concentrate in Composite 1 and 71.5% (72.0 g/t Au) reported to the gravity concentrate
in Composite 2. Please note that the gold has upgraded from 16.7 (g/t Au) from the head
grade to 1389 g/t in the gravity concentrate of Composite 1. Very little gold remains in the
tailings (~12.2%) which has been downgraded to 2.06 g/t Au.
The gold in Composite 2 has also upgraded from 1.01 from the head grade to 72.0 g/t in the
gravity concentrate of Composite 2. Little gold remains in the tailings (~28.5%) which has been
downgraded to 0.29 g/t Au.
It is important to note that the coarse grained nature of the gold leads to a nugget effect during
assaying. It is recommended that assaying be done in one of the following ways:
• Screen File Assay: Screen at least 500 g of the milled ore at 106 µm. Assay the coarse
fraction in totality and the fines in triplicate.
In conclusion the ore is highly amenable to gravity upgrading and cyanidation and high
recoveries are expected (>95%).
Report Number: 12/466 Rev.2
PF-ZA-[MINMMN]-[(BYZ)]AN-001 08/11
Page 22 of 22