Hawiah maiden resource estimate and PEA
In addition to developments at Tulu Kapi, KEFI has consistently reiterated its goal that it would report a (maiden) mineral resource estimate at Hawiah in August – a goal that it achieved, when it announced a 19.3Mt resource on 19 August.
Whereas KEFI had initially indicated that it anticipated the total resource to be in the order of 12Mt, in July it increased its estimate to 20Mt. This compared with Edison’s prior estimate (made in March) of 13.3Mt.
The entire deposit comprises three separate zones, which may be summarised as follows:
■
The ‘Camp Lode’: 1,200m long, with an average true width of 7m and confirmed to a depth of 300m below surface.
■
The ‘Crossroads Lode’: 1,000m long, with an average true width of 5m, but confirmed to a depth of only 170m below surface.
■
The ‘Crossroads Extension Lode’: 800m long, with an average true width of 5m and confirmed to a depth of 350m below surface.
A comparison between the maiden resource announced by KEFI on 19 August and Edison’s prior estimate of the potential resource inventory at Hawiah based on the results of the assays already disclosed to the public in March is as follows:
Exhibit 1: Hawiah* maiden mineral resource estimate
Material type |
Category |
Tonnage (kt) |
Cu (%) |
Zn (%) |
Au (g/t) |
Ag (g/t) |
Cu (kt) |
Zn (kt) |
Au (koz) |
Ag (oz) |
Oxide, open pit |
Inferred |
0.1 |
0.1 |
0.03 |
1.7 |
3.9 |
0.1 |
0.04 |
7 |
16 |
Transition, underground |
Inferred |
2.0 |
1.1 |
0.8 |
0.7 |
12.0 |
21 |
16 |
45 |
763 |
Fresh, underground |
Inferred |
17.2 |
0.9 |
0.8 |
0.5 |
10.1 |
147 |
141 |
297 |
5,595 |
Total |
Inferred |
19.3 |
0.9 |
0.8 |
0.6 |
10.3 |
168 |
157 |
349 |
6,373 |
Prior Edison estimate |
N/A |
13.3 |
1.4 |
1.0 |
0.8 |
11.5 |
187 |
133 |
341 |
4,925 |
Uplift of actual vs expected (%) |
|
45.1 |
-35.9 |
-20.0 |
-24.8 |
-10.6 |
-10.1 |
18.0 |
2.3 |
29.4 |
Source: Edison Investment Research, KEFI Gold and Copper. Note: *KEFI 34% beneficial interest; reported in accordance with the Australasian Code for the Reporting of Exploration Targets, Mineral Resources and Ore Reserves, The JORC Code (2012).
In general, it can be seen that, while Edison’s tonnage estimates proved conservative, they were tolerably accurate in terms of metal content (given that, from experience, Edison places a level of accuracy of ±75% on its resource estimates). At prevailing metals prices (US$6,579/t Cu, US$2,424/t Zn, US$1,884/oz Au and US$23.69/oz Ag), the resource contains total metal to a value of US$2.3bn, or the equivalent of 349kt of contained copper or 1.2Moz of contained gold.
The 95km2 Hawiah exploration licence is located in the south-west of the Arabian Shield on the 120km Wadi Bidah Volcanogenic Mineral belt (which is three times as long as the Bisha belt in Eritrea – see Nevsun), on which BRGM and the USGS documented approximately 24 volcanogenic massive sulphide (VMS) deposits and historical workings. The Wadi-Bidah Mineral District is almost unique among the world’s VMS belts in that it remains, to all intents and purposes, undrilled.
In its most recent two phases of exploration, KEFI determined that the Hawiah mineralisation is entirely open at depth, that the VMS style of mineralisation is continuously present directly beneath 4km of the gossanous ridgeline and that it is the source of an extensive and exceptionally strong geophysical anomaly. The massive sulphides intersected in its drill programme are reported to reflect a dominantly pyritic stratiform body containing a variable polymetallic blend of copper, zinc, gold and silver. Highlights of the drilling include:
■
A maximum downhole interval of 29m of mineralisation.
■
A maximum intercept of 4.4% copper over a 6m true width interval, including 5.8% copper over a 3m true width in the supergene zone.
■
A maximum zinc grade of 3.6%.
■
A maximum gold grade of 7.78g/t.
■
A maximum silver grade of 58.50g/t.
Nevertheless, there remains considerable blue-sky potential at Hawiah. To date, the orebody has only been drilled to 350m below ground and remains open at depth. The down-dip continuation of the Camp Lode is of particular interest in this respect, where drilling results to date have reported grade and thickness increasing significantly with depth. The deepest two holes (HWD_005 and HWD_059) returned 1.27% copper over a true width of 9m and 1.55% copper over a true width of 8.7m, respectively and, if intersected in line with expectations, would extend mineralisation to a depth of c 800m and may indicated that resources are nearing the source (vent) of the VMS, where higher grade and thicker massive sulphides and stockwork-style mineralisation may typically be found. Geochemical analysis and volcaniclastic textures within the lodes have also indicated increasing proximity with depth to a potential primary feeder source. Below the Central Zone may also have strong resource potential, as indicated by a strong induced polarisation (IP) anomaly, and planned drilling is targeting mineralisation at a depth of c 450m (cf c 80m tested to date via only a few scout drill holes). Finally, massive sulphides were reported to have been intersected in a drill hole 150m to the north of the Hawiah ridgeline, confirming that the mineralised horizon continues at depth even beyond the northern surface exposure (in the ‘Crossroads extension area’).
Similar potential exists in the upper levels of the deposit, where the gossan portion of the mineralised zone is challenging to sample by drilling by virtue of the weathering patterns and the numerous cavity zones encountered. BRGM drilled these gossans in the 1980s, as a result of which it delineated a resource of 1.2Mt at a grade of 6.4g/t, containing 254koz gold, and management confirms that this oxidised portion of the deposit, which has demonstrated high levels of gold mineralisation, will also be further investigated. To date, initial drilling of these areas has returned an average grade of 1.7g/t gold across seven drill holes with an average vertical depth of 35m.
Based on published literature, KEFI management believes that the Hawiah deposit appears analogous to (albeit already bigger than) the Al Masane polymetallic VMS mine in southern Saudi Arabia, which has reported proven and probable reserves of 7.21Mt at grades of 1.42% copper, 5.31% zinc, 1.19g/t gold and 40.2g/t silver, and a similar metal composition and structural and geological settings. The discovery of the stockwork zone that fed the structure now being drilled would also bring into focus a potentially larger bulk-mineable target analogous to the Jabal Sayid mine operated by Barrick to the north of Hawiah.
The resource reported by KEFI in Exhibit 1 is the equivalent of 19.3Mt at a grade of 1.86% copper equivalent or 1.91g/t gold equivalent, such that each tonne of ore contains US$119 worth of combined metals (at the prices shown on page 4 after Exhibit 1).
Since announcing its maiden resource in August, KEFI has prioritised the completion of a PEA at Hawiah. The PEA was conducted by the KEFI planning team, supported by internationally recognised specialists, including SRK, and included technical analysis, high-level assessments and trade-off studies to establish the likely key components of the mine’s potential development. Among other things, these included:
■
Underground mining using long-hole open stoping, using rib and sill pillars for support.
■
Processing via two-stage flotation to produce separate copper and zinc concentrates, with a cyanide leach circuit to allow for the production of gold doré from the zinc concentrate and tailings stream.
■
Tailings storage and required infrastructure.
The full details of KEFI’s PEA announcement may be found here and Edison has used the operating details provided to construct Edison’s own operating and financial model of the project, both to validate the financial conclusions of KEFI’s model and also to adjust it to reflect Edison’s own long-term assumptions regarding (for example) long-term metals prices. A comparison of the major differences between KEFI’s assumptions and Edison’s is as follows:
Exhibit 2: Comparison of KEFI and Edison assumptions regarding Hawiah
|
KEFI assumption |
Edison assumption |
Metals prices |
|
|
Copper price (US$/t) |
6,603 |
*6,410 |
Zinc price (US$/t) |
2,315 |
*2,315 |
Gold price (US$/oz) |
1,956 |
*1,494 |
Silver price (US$/oz) |
27.50 |
*24.53 |
|
|
|
Other |
|
|
Sustaining capital expenditure |
US$46m |
Seven years at US$8m pa = US$56m |
Source: KEFI Gold and Copper, Edison Investment Research. Note: *Long-term real prices.
Note that, unless specifically indicated to the contrary in the table above, readers may assume that Edison’s assumptions are the same as those detailed in KEFI’s PEA announcement. In addition, in constructing its model, Edison had to make the following assumptions, which were otherwise not specifically disclosed in KEFI’s announcement:
Exhibit 3: Specific Edison assumptions regarding Hawiah
Item |
Edison assumption |
Estimated copper concentrate grade |
35% Cu |
Estimated zinc concentrate grade |
55% Zn |
|
|
Copper treatment charges (TC) |
US$62.00/t |
Copper refining charges (RC) |
US$6.20/lb |
|
|
Zinc treatment charges (TC) |
US$245/t |
|
|
Saudi Arabian income tax rate |
20% |
Item |
Estimated copper concentrate grade |
Estimated zinc concentrate grade |
|
Copper treatment charges (TC) |
Copper refining charges (RC) |
|
Zinc treatment charges (TC) |
|
Saudi Arabian income tax rate |
Edison assumption |
35% Cu |
55% Zn |
|
US$62.00/t |
US$6.20/lb |
|
US$245/t |
|
20% |
Source: Edison Investment Research
Saudi Arabian depreciation is typically conducted over 10 years. However, it may be as low as four to five years for certain machinery items. For the purposes of its model, Edison has assumed that depreciation is conducted over seven years (being the initial life of the proposed mine) and that assets remain fully depreciated at that point, even if the mine’s life is then extended by up to 10 years (see below). We have also ignored accumulated tax losses that would be available.
In its own model, KEFI considers a ‘base case’ scenario, in which the mine operates at a throughput rate of 2.0Mtpa for seven years and an ‘extended’ scenario, in which an further 20Mt is added to the mining inventory ‘at the average grade of the Camp Lode below the 1070m RL elevation’. In the absence of detailed knowledge about the average grade of the Camp Lode, Edison has assumed that this addition to the mining inventory will allow the mining operation to continue at Hawiah for a further 10 years at run-of-mine grades the same as those in the first seven years of the mine’s life (namely 0.87% Cu, 0.78% Zn, 0.53g/t Au and 9.9g/t Ag – see KEFI’s Hawiah PEA announcement).
On the basis of these assumptions, the financial outcomes generated by Edison from its model compare with those generated by KEFI, for both scenarios, as follows:
Exhibit 4: KEFI vs Edison financial model outcomes
Extended mine life scenario |
Scenario |
Base case scenario |
KEFI |
Edison |
Edison |
Model |
KEFI |
Edison |
Edison |
KEFI |
KEFI |
Edison |
Assumptions |
KEFI |
KEFI |
Edison |
|
2.0 |
2.0 |
Ore processing rate (Mtpa) |
2.0 |
2.0 |
2.0 |
|
17 |
17 |
Life of mine (years) |
7 |
7 |
7 |
|
78 |
78 |
Average annual operating costs (US$m) |
79 |
78 |
78 |
|
155.5 |
141.8 |
Annual revenue (US$m) |
153 |
155.5 |
141.8 |
|
86 |
86 |
Average annual all-in sustaining costs (US$m) |
85 |
86 |
86 |
|
69.5 |
55.8 |
Annual steady-state net pre-tax free cash flow (US$m) |
67 |
69.5 |
55.8 |
*362 |
*311.3 |
160.9 |
Post-tax NPV |
*96 |
*99.8 |
25.2 |
28 |
26.6 |
21.1 |
Post-tax IRR |
22 |
20 |
13.3 |
|
222 |
222 |
Pre-production capital expenditure (US$m) |
222 |
222 |
222 |
123.1 |
105.9 |
54.7 |
34% KEFI share of post-tax NPV (US$m) |
32.6 |
33.9 |
8.6 |
6.59 |
5.67 |
2.93 |
Ditto (US cents per share) |
1.75 |
1.82 |
0.46 |
5.18 |
4.46 |
2.30 |
Ditto (pence per share) |
1.37 |
1.43 |
0.36 |
Source: Edison Investment Research, KEFI Gold and Copper. Note: *NPV calculation conducted at an 8% discount rate; otherwise, all other NPV’s conducted at a 10% discount rate.
Several features of these outcomes are noteworthy:
■
The similarity between the outputs of the KEFI model and the Edison model using KEFI assumptions for the ‘base case’ scenario confers confidence upon Edison’s financial model relative to KEFI’s.
■
For the ‘extended mine life’ scenario, the difference between the NPV of the KEFI model and the Edison model using KEFI assumptions is 14.0% (US$311.3m cf US$362m); we regard this as being acceptable within the context of a PEA in which the operating and capital cost estimates are made to a ±50% level of accuracy. In the meantime, we suspect that much of the discrepancy is likely to be attributable to the depreciation of ongoing sustaining capital expenditure over the additional 10 years of mine life (in this case, Edison has assumed zero depreciation of ongoing sustaining capex, which is likely to prove conservative).
■
They compare with Edison’s earlier estimate of a cash margin of US$40/t and, at a mining rate of 1.0–1.3Mtpa over 10 years, a cash margin of US$40–52m pa or US$400–520m over the life of operations (undiscounted etc) after 15% mining dilution and 87% metallurgical recoveries and a posited all-in sustaining cost of US$70/t (see our note Tulu Kapi project started and financings improved, published on 4 March).
In consequence and owing to the tabular and continuous nature of the mineralisation, KEFI anticipates that Hawiah can be advanced to a development decision quickly and at relatively low cost. In particular, if the resource can be expanded to make the ‘extended mine life scenario’ a reality, then KEFI expects that 75% of the project funding could be eligible for debt finance, thereby increasing the project’s (leveraged) post-tax IRR to in excess of 50%.
Following completion of the PEA, KEFI’s immediate priorities towards Hawiah are now as follows:
■
Seeking to double the maiden mineral resource estimate via the next drilling phase to commence in Q420.
■
Undertaking a metallurgical test-work programme.
■
Undertaking an Environmental & Social Impact Assessment (ESIA) baseline and water resources study.
■
Reporting updated PEA results as progress is made, culminating in updates to the PEA financial model prior to commencing a pre-feasibility study (PFS) study for a long-life mining operation.
■
Extending exploration activities into the surrounding district as licensing warrants.
To these ends, the directors of KEFI’s joint venture company in Saudi Arabia, G&M, have resolved to trigger the next stage of the project, comprising:
■
Deeper drilling with a target of doubling the maiden resource in the next drilling phase.
■
Infill drilling to upgrade the existing resources into the indicated category, so as to fully justify mine planning and the estimation of a maiden ore reserve (NB Drill spacing on the Camp and Crossroads Lodes is c 120–140m).
■
Staged studies and surveys to complete a PFS in FY21.
■
Scout drilling for a large stockwork, or ‘feeder’, zone to the massive sulphides already identified; note that this represents a separate, and probably much larger-scale, target than the existing Hawiah resource.