Mineral Resource Update - P-Q Weathered Zone
|
27 March 2013 |
|
Bushveld Minerals Ltd
("Bushveld" or the "Company")
Mineral Resource Update - Weathered portion of Bushveld Iron Ore Project's P-Q Zone
Bushveld Minerals Limited (AIM: BMN), a mineral development company focused on iron and tin projects in southern Africa, is pleased to provide an operations update on its iron ore project in Limpopo Province, South Africa.
The results of 2012 drilling, metallurgical test work and JORC (2012) compliant mineral resource estimation of the weathered zone of the P-Q Iron and titanium ('Ti-magnetite') Layers are reported here.
Highlights:
· 38 million tonne Indicated Mineral Resource (~5% of the combined Indicated and Inferred Mineral Resource) of friable, potentially 'free-dig' (lower mining cost) material established in the weathered zone, shallower than 30 m
· Preferential weathering of the silicate gangue minerals and minimal alteration of Ti-magnetite in the weathered zone
· Detailed delineation of the weathered resource with its lower SG (density) has resulted in a slight decrease in the total tonnages in the P-Q zone from 752 million tonnes to 716 million tonnes
· >86% recoveries and >53% Fe in concentrate grades for massive ore from the weathered zone, comparable to the fresh ore for both the massive and disseminated ore types
Following the Mineral Resource Update on the P-Q Zone last month which upgraded and extended the deposit along strike, the Company is pleased to publish results from 1,038 metres of drilling carried out recently on the near-surface weathered portions of the P-Q layer. The slight change in the overall tonnage is to be expected, owing to the lower SG (density) of the weathered zone, and better definition of the P-Q Zone at shallow depths (previous Mineral Resource Estimates projected the mineralised packages to surface). Significantly, the delineation of the weathered zone, which may require less blasting and crushing, allows for the definition of a potential 'free-dig' portion of the resource with lower mining and processing costs.
Fortune Mojapelo, CEO, commented: "More than providing better definition of the outcrop zone of the Bushveld Iron Ore project, the potential of the weathered resource lies in its lower "free-dig" mining cost proposition. The size of this resource, at 38 million tonnes in the indicated resource category, vindicates our efforts to proceed with metallurgical test work, whose results demonstrate high recoveries for a good quality concentrate product.."
Results of weathered P-Q Magnetite Layer drilling
In 2012 a 1,525 metre diamond drilling programme was undertaken on the fresh, unweathered P-Q Zone in order to extend the mineral resource along strike and improve the level of geological confidence. The results of this programme were incorporated into an updated mineral resource model, which resulted in an increase of the P-Q resource to 752 million tonnes comprising 378 million tonnes in the Indicated category and to 374 million tonnes in the Inferred category (as announced in the P-Q Zone Mineral Resource Update on the 7th of February 2013).
Following this, a further 1,038 metres of drilling was carried out on the near-surface, oxidized and weathered portions of the P-Q layer. This drilling was aimed at gaining an understanding of the depth of weathering of the P-Q Zone, quantifying the tonnage and grade of Ti-magnetite in the weathered horizon, and better defining the subcrop position of the P-Q Zone. A number of east-west fence lines were drilled across the interpolated outcrop position of the P-Q Zone at a close spacing (between 10 m and 50 m) to ensure complete testing of the weathered zone. Visual assessment of the borehole core (average recovery of 95%) indicates that the weathered zone extends to depths ranging from 3 m to 30 m with an average of approximately 25 m over the P-Q Zone. Ti-magnetite remains largely unaffected by the weathering process whereas the interstitial gangue minerals feldspar and pyroxene have been partly altered to secondary hydrous silicates.
Assay results for intersections through the weathered P-Q Zone reveal that the grade of the Fe mineralisation is comparable to the unweathered material.
Results for each borehole intersection are reported below:
|
Borehole ID |
Fence Line |
BH Depth (m) |
Top of P-Q intersection (m) |
Base of P-Q intersection (m) |
Intersection width |
Avg Fe (%) |
Avg V2O5 (%) |
Avg TiO2 (%) |
Avg P2O5 (%) |
Avg SiO2 (%) |
Avg Al2O3 % |
S% |
|
VKW10 |
A |
40 m |
2.00 |
6.00 |
4 m |
21.0 |
0.15 |
4.2 |
0.02 |
34.9 |
13.8 |
0.01 |
|
VKW11 |
A |
60 m |
3.00 |
31.00 |
28 m |
31.4 |
0.21 |
9.5 |
0.03 |
23.4 |
10.3 |
0.02 |
|
VKW32 |
B |
15 m |
1.40 |
18.00 |
16.60 m |
33.9 |
0.13 |
9.6 |
0.04 |
21.8 |
9.2 |
0.01 |
|
VKW25 |
C |
82 m |
3.00 |
40.00 |
37 m |
29.9 |
0.16 |
8.5 |
0.04 |
21.1 |
9.0 |
0.14 |
|
VKW23 |
C |
20 m |
2.00 |
20.00 |
18 m |
22.9 |
0.19 |
5.9 |
0.04 |
32.2 |
13.9 |
0.01 |
|
VKW27 |
D |
50 m |
2.00 |
14.00 |
8 m (excluding a 4 m sill) |
28.7 |
0.23 |
6.3 |
0.02 |
29.3 |
12.0 |
0.01 |
|
VKW28 |
D |
20 m |
5.00 |
31.00 |
26 m |
34.7 |
0.23 |
10.6 |
0.03 |
21.2 |
10.2 |
0.01 |
|
VKW29 |
E |
50 m |
2.00 |
50.00 |
48 m |
30.8 |
0.19 |
8.3 |
0.03 |
26.0 |
11.2 |
0.01 |
|
VKW30 |
E |
50 m |
9.00 |
21.00 |
12 m |
25.0 |
0.19 |
4.7 |
0.03 |
33.8 |
13.2 |
0.01 |
|
VKW9 |
A |
30 m |
Not sampled - used for metallurgical testing |
|||||||||
|
VKW11.2 |
A |
100 m |
Not sampled - used for metallurgical testing |
|||||||||
|
VKW24 |
C |
50 m |
Not sampled - used for metallurgical testing |
|||||||||
|
VKW26 |
D |
50 m |
Not sampled - used for metallurgical testing |
|||||||||
|
VKW1- VKW8 |
A |
15-20 m |
Not intersected |
|||||||||
|
VKW12-VKW22 |
B |
15-45 m |
Note intersected - drilled Phosphate Zone |
|||||||||
|
VKW31 |
E |
30 m |
Not intersected |
|||||||||
Mineral Resource Estimation for the weathered portion of the P-Q Zone
The results of the 2012 drilling programme were incorporated into a mineral resource estimation specifically for the weathered P-Q Zone. The 3 m to 5 m thick overburden soil horizon was excluded from the mineral resource estimation, which was conducted by The MSA Group in Johannesburg, South Africa and reported in accordance with the JORC Code, 2012 Edition.
Indicated Mineral Resources for the weathered P-Q Zone as of 8 March 2013
|
Layer |
Million Tonnes |
SG (g/cm3) |
Fe (%) |
Fe2O3 (%) |
TiO2 (%) |
V2O5 (%) |
SiO2 (%) |
Al2O3 (%) |
P2O5 (%) |
S (%) |
|
Q3 |
10.20 |
3.47 |
33.0 |
47.2 |
9.4 |
0.12 |
23.2 |
9.0 |
0.05 |
0.17 |
|
Q2 |
8.83 |
3.77 |
40.2 |
57.5 |
13.5 |
0.23 |
14.5 |
6.9 |
0.02 |
0.10 |
|
Q1 |
4.47 |
3.40 |
30.2 |
43.2 |
7.9 |
0.23 |
25.8 |
10.5 |
0.02 |
0.11 |
|
PMAG |
4.42 |
3.41 |
31.5 |
45.1 |
8.4 |
0.27 |
23.3 |
11.0 |
0.03 |
0.25 |
|
PFWDISS* |
10.38 |
3.29 |
27.5 |
39.3 |
6.0 |
0.22 |
30.4 |
12.5 |
0.03 |
0.09 |
|
TOTAL |
38.30 |
|
||||||||
* = Layer reported at a 35% Fe2O3 cut-off
Using the results from the modeling of the weathered zone, the combined weathered and unweathered Indicated Mineral Resources to a vertical depth of 200 m as of 8 March 2012 are as follows:
|
Layer |
Million Tonnes |
SG (g/cm3) |
Fe (%) |
Fe2O3 (%) |
TiO2 (%) |
V2O5 (%) |
SiO2 (%) |
Al2O3 (%) |
P2O5 (%) |
S (%) |
|
Q3 |
138.63 |
3.61 |
31.7 |
45.5 |
10.2 |
0.13 |
25.2 |
9.9 |
0.06 |
0.40 |
|
Q2 |
81.17 |
4.01 |
41.9 |
59.1 |
15.2 |
0.28 |
12.6 |
6.5 |
0.02 |
0.27 |
|
Q1 |
26.36 |
3.59 |
32.5 |
45.6 |
10.5 |
0.28 |
22.3 |
9.9 |
0.02 |
0.27 |
|
PMAG |
34.44 |
3.62 |
32.4 |
45.4 |
10.1 |
0.29 |
21.3 |
10.5 |
0.03 |
0.80 |
|
PFWDISS* |
67.28 |
3.38 |
26.9 |
38.5 |
7.1 |
0.22 |
30.1 |
12.8 |
0.03 |
0.33 |
|
TOTAL |
346.19 |
|
||||||||
* = Layer reported at a 35% Fe2O3 cut-off
Thus, the weathered zone accounts for approximately 9% of the Indicated mineral resource on the P-Q Zone calculated to a vertical depth of 200 m, or approximately 5% of the overall Indicated and Inferred Mineral Resource. The friable and potentially 'free-dig' nature of the weathered zone, as visually determined in drill core, may allow for lower mining and processing costs.
The P-Q Zone (Non-weathered) Inferred Mineral Resources (200 m to 400 m vertical depth) as of 8 March 2013 are as follows:
|
Layer |
Million Tonnes |
SG (g/cm3) |
Fe (%) |
Fe2O3 (%) |
TiO2 (%) |
V2O5 (%) |
SiO2 (%) |
Al2O3 (%) |
P2O5 (%) |
S (%) |
|
Q3 |
139.03 |
3.59 |
30.2 |
43.3 |
8.8 |
0.09 |
28.3 |
10.3 |
0.13 |
0.61 |
|
Q2 |
92.64 |
3.99 |
40.2 |
57.5 |
14.1 |
0.23 |
15.3 |
7.6 |
0.02 |
0.55 |
|
Q1 |
23.42 |
3.64 |
32.7 |
46.8 |
10.8 |
0.27 |
22.2 |
10.6 |
0.02 |
0.36 |
|
PMAG |
38.28 |
3.58 |
30.6 |
43.7 |
9.8 |
0.26 |
23.5 |
11.5 |
0.04 |
0.74 |
|
PFWDISS* |
76.51 |
3.37 |
26.8 |
38.3 |
6.9 |
0.21 |
30.2 |
12.8 |
0.03 |
0.43 |
|
TOTAL |
369.88 |
|
||||||||
* = Layer reported at a 35% Fe2O3 cut-off
Owing to the fact that shallow drilling has provided better definition and more geological information with regards to stratigraphic contacts, and the fact that the density is lower in the weathered horizons, there is a slight change in the overall tonnages in both the Indicated and Inferred categories, with mineral resources in the Indicated category now totaling 346 million tonnes (previously 378 million tonnes), and mineral resources in the Inferred category now 370 million tonnes (previously 374 million tonnes).
Results of weathered P-Q Magnetite Layer metallurgical tests
In order to confirm that Ti-magnetite recovery in the weathered zone is similar to that in the fresh P-Q Zone, a testwork programme of screening, scrubbing and Davis Tube Tests was undertaken at SGS Laboratories in Johannesburg on the weathered P-Q Zone. In the borehole core, the weathered material is friable and the Ti-magnetite appears to be visually similar to the unweathered mineralisation while the gangue feldspars and pyroxenes are partly altered to secondary hydrous silicates. Scrubbing was therefore identified as a potential step for the upgrading of weathered material.
Following wet screening to determine whether silicates and associated gangue minerals report preferentially to any size fraction, the >500 µm fraction was selected as the best for scrubbing tests. The scrubbing tests were carried out for three time intervals, ranging from 30 minutes to one hour, although the difference in results from the 30 minute scrub to the one hour scrub was negligible. A noticeable reduction in undesirable contaminants was achieved with SiO2 grades being reduced by more than 2% for both the massive and disseminated samples. The increase in iron content was, however, fairly small. There is a noticeable difference between the massive and disseminated ore samples, with the disseminated sample having a significantly lower grade, although the absolute difference between feed and product grades were fairly similar for the two types of material.
Massive Ti-magnetite sample scrubbing feed and product grades:
|
|
SiO2 (%) |
Al2O3 (%) |
CaO (%) |
MgO (%) |
Fe (%) |
TiO2 (%) |
|
Feed grade |
10.5 |
5.8 |
2.3 |
1.2 |
43.1 |
16.1 |
|
Product grade |
7.7 |
5.1 |
1.7 |
1.0 |
46.0 |
17.5 |
Disseminated Ti-magnetite sample scrubbing feed and product grades:
|
|
SiO2 (%) |
Al2O3 (%) |
CaO (%) |
MgO (%) |
Fe (%) |
TiO2 (%) |
|
Head grade |
24.6 |
9.6 |
7.9 |
2.3 |
27.0 |
8.3 |
|
Product grade |
21.8 |
9.2 |
6.3 |
2.2 |
31.0 |
10.3 |
Davis Tube Tests were also carried out on the samples to establish whether Ti-magnetite recovery in the weathered material is similar to the fresh material. Ti-magnetite recoveries for the weathered zone compare favourably with the fresh material, with recoveries of 80 - 85% possible in the massive material, and 60 - 65% in the disseminated material.
Massive Ti-magnetite Davis Tube grades and recoveries at varying size fractions:
|
Sample |
Fe (%) |
Recovery (%) |
TiO2 (%) |
Recovery (%) |
SiO2 (%) |
Recovery (%) |
Al2O3 (%) |
Recovery (%) |
CaO (%) |
Recovery (%) |
MgO (%) |
Recovery (%) |
|
Head |
41.9 |
|
15.7 |
|
10.9 |
|
5.69 |
|
2.34 |
|
1.23 |
|
|
500 µm |
53.0 |
86.9 |
19.4 |
84.9 |
2.1 |
13.2 |
2.9 |
35.0 |
0.15 |
4.4 |
0.7 |
39.7 |
|
212 µm |
53.5 |
86.9 |
19.6 |
85.0 |
1.8 |
11.0 |
2.8 |
33.1 |
0.12 |
3.5 |
0.7 |
36.0 |
|
106 µm |
52.7 |
82.9 |
19.2 |
80.6 |
1.6 |
9.7 |
2.7 |
31.0 |
0.13 |
3.7 |
0.6 |
31.6 |
|
75 µm |
51.9 |
78.3 |
18.4 |
74.1 |
3.4 |
19.7 |
3.2 |
36.0 |
0.47 |
12.7 |
0.7 |
38.0 |
|
53 µm |
52.6 |
74.3 |
18.6 |
70.1 |
2.5 |
13.7 |
2.9 |
30.4 |
0.28 |
7.1 |
0.6 |
29.8 |
Disseminated Ti-magnetite Davis Tube grades and recoveries at varying size fractions:
|
Sample |
Fe (%) |
Recovery (%) |
TiO2 (%) |
Recovery (%) |
SiO2 (%) |
Recovery (%) |
Al2O3 (%) |
Recovery (%) |
CaO (%) |
Recovery (%) |
MgO (%) |
Recovery (%) |
|
Head |
27.8 |
|
8.9 |
|
22.6 |
|
9.2 |
|
7.0 |
|
2.0 |
|
|
500 µm |
51.5 |
62.5 |
17.4 |
66.1 |
4.6 |
6.9 |
3.8 |
14.0 |
0.7 |
3.5 |
0.9 |
15.2 |
|
212 µm |
52.6 |
61.5 |
17.5 |
63.9 |
2.7 |
3.9 |
3.2 |
11.4 |
0.5 |
2.2 |
0.8 |
12.7 |
|
106 µm |
54.0 |
62.6 |
17.8 |
64.5 |
2.2 |
3.1 |
3.1 |
10.8 |
0.4 |
1.8 |
0.8 |
12.2 |
|
75 µm |
53.6 |
61.7 |
17.6 |
63.4 |
2.0 |
2.8 |
3.1 |
10.7 |
0.4 |
1.7 |
0.7 |
10.8 |
|
53 µm |
53.5 |
61.2 |
17.3 |
61.9 |
2.2 |
3.1 |
3.1 |
10.8 |
0.4 |
2.0 |
0.7 |
11.4 |
Map of the P-Q Weathered Zone:
http://www.rns-pdf.londonstockexchange.com/rns/9547A_-2013-3-26.pdf
Enquiries: info@bushveldminerals.com
|
Bushveld Minerals Fortune Mojapelo |
+27 (0) 11 268 6555 |
|
Fox Davies Jonathan Evans |
+44 (0) 20 3463 5000 |
|
Tavistock Communications Jos Simson/ Jessica Fontaine |
+44 (0) 20 7920 3150 |
|
Tielle Communications Stéphanie Leclercq |
+27 (0) 83 307 7587 |
Notes to the editor
Bushveld Minerals Limited is a mineral development company focused on the Bushveld Iron Ore Project and the Mokopane Tin Project, both located on the northern limb of the Bushveld Complex, South Africa.
The Company was admitted to the Alternative Investment Market of the LSE in March 2012.
Competent Persons Report
The scientific and technical information relating to mineral resource estimation contained within this announcement has been reviewed and approved by Mr. Jeremy Witley, a professional geologist with more than 20 years' experience in base and precious metals exploration and mining as well as Mineral Resource evaluation and reporting. He is Principal Resource Consultant for the MSA Group and has the appropriate relevant qualifications, experience, competence and independence to be considered a "Competent Person" under the definitions provided in the JORC Code 2012 Edition.
The scientific and technical information relating to metallurgical testwork contained within this announcement has been reviewed and approved by Jan Rabe, Senior Process Engineer at PESCO, the metallurgical advisor to the Company. Rabe has an honours degree in metallurgy and over 11 years' experience as a practising metallurgical engineer.
Glossary
Alteration - a change in the chemistry and mineralogy of a rock, typically involving the addition of water or other fluids
Feldspars - a group of minerals comprising variable proportions of SiO2, Al2O3, K2O, Na2O and CaO
Free-dig - material that can be mined without the need for blasting, and which may therefore have lower mining and processing rock
Friable - rock that is semi-consolidated and disintegrates easily
Gangue - material or minerals within a mineralised zone regarded as waste
Hydrous silicates - silicate minerals that have been affected by alteration and have incorporated water into their chemical composition
Pyroxenes - a group of minerals comprising variable proportions of FeO, MgO, SiO2, Al2O3 and CaO
Scrubbing - a physical beneficiation process where ore is tumbled with water and interparticle attrition removes fine particles such as clays
SG - specific gravity (i.e. the density of the rock)
Silicate - a mineral with a composition which contains Si (silicon). Silicates are common rock-forming minerals
This information is provided by RNS
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