7th Oct 2013 07:01
7 October 2013
Mwana Africa PLC
("Mwana" or the "Company")
Completion of Competent Persons Report and 28% Increase in Ore Reserves at Trojan Nickel Mine
Mwana is pleased to announce the completion of a competent person's review by SRK Consulting (UK) Limited ("SRK") of Bindura Nickel Corporation's ("BNC") business plan for the re-start of operations at Trojan. SRK reviewed the updated mine plan targeting the higher grade ore zones in the early years of production at Trojan. The report is independent confirmation that the plan is realistic and achievable and enables BNC to update its Ore Reserves statement to total proven and probable reserves of 3.168Mt at an average grade of 1.04% for 32,975 tonnes of nickel, a 28% increase to the previously reported Trojan reserves as at 31 March 2010 of 25,810 tonnes of contained nickel.
The table below presents BNC's latest Mineral Resource and Ore Reserve Statements for Trojan as at 30 June 2013, audited by SRK and reported in accordance with the JORC Code.
Table 1:SRK Audited Mineral Resource and Ore Reserve Statement at 30 June 2013
Ore Reserve | Mineral Resource | |||||||
Tonnage | Grade | Nickel | Tonnage | Grade | Nickel | |||
Category | (kt) | (%) | (t) | Category | (kt) | (%) | (t) | |
Proved | 2,166 | 0.89 | 19,254 | Measured | 2,235 | 1.01 | 22,572 | |
Probable | 1,002 | 1.37 | 13,721 | Indicated | 1,946 | 1.52 | 29,583 | |
Total | 3,168 | 1.04 | 32,975 | Sub-total | 4,181 | 1.25 | 52,155 | |
Inferred | 4,038 | 1.63 | 65,817 | |||||
Total | 8,219 | 1.44 | 117,971 |
(1) Ore Reserves are reported as delivered to the concentrator and exclude all metallurgical recoveries.
(2) Mineral Resources are stated inclusive of Ore Reserves.
(3) Ore Reserves are restricted to 37L and above.
(4) Mineral Resource and Ore Reserve depleted for actual mining during April to June 2013.
The Trojan deposit has been subject to a number of resource estimate updates over the years of its operation. Most recently a resource estimate was prepared by Digital Mining Services (DMS), Harare, and is valid as of 31 March 2013. The current resource estimate extends between Level 31 (31L) and Level 49 (49L), a vertical extent of some 517m. BNC's Business Plan is based on the exploitation of the Measured, Indicated and Inferred Resources on and above 49L which are projected to support mining for some 10 years. The construction of the infrastructure required to access deeper levels has already commenced.
The data used to derive the latest resource estimate comprises information collected from underground drilling (and a limited amount of underground chip sampling) from 31L to the base of the drilling at 47L. The Trojan mine geologists interpret the orebody outlines on level plans some 15m apart. The orebody outlines are grade defined, based on a 0.45% nickel grade cut-off, and have been linked together to produce solid wireframe envelopes of the mineralised zones. The wireframe solids derived in this way were then provided to Digital Mining Services, Harare (DMS) who undertook the remainder of the resource estimation process using Surpac software. A total of 13 separate mineralised zones have been modelled based on the mineralisation type, strike and host lithology. These are broadly categorised into 3 orebodies (or domains); termed Main (which includes the Massives), Hanging Wall NW (HWNW) and Hanging Wall NE (HWNE) respectively. The Main domain comprises 7 sub-zones, the HWNW domain is comprised of 3 sub-zones, and the HWNE domain comprises only one zone. The Massive Domain consists of two zones, differentiated as either between 3% and 10% Ni and a high grade Massive core with grades greater than 10% Ni.
While a cut-off grade of 0.45% Ni was used in the generation of the wireframe outlines, no selective mining within these is envisaged, except for the massive ore, given the sub-level caving mining method planned and the Mineral Resource simply comprises all mineralisation within the orebody wireframes below 31L up to and including 49L after taking into account depletion from historical mining activities.
The Ore Reserve incorporates the Measured and Indicated Mineral Resources above 37L that have been used to derive Proved and Probable Ore Reserves respectively. The Ore Reserve statement reflected above includes appropriate modifying factors in terms of ore losses, extraction ratios and dilution associated with the drawpoint management of the sub-level caving mining method. The modifying factors are based on experience from a long operating history and reconciliation with the process plant. There is potential to increase the quantum of the Ore Reserve by improving the confidence in the Inferred Mineral Resource following further drilling as the mine progresses to deeper levels. Furthermore, the orebody remains open along strike to the east at depths below 37L and so there is also potential for strike extensions.
SRK has reviewed the Business Plan for the re-start of operations at Trojan and considers the plan to be both realistic and achievable. While the inclusion of Inferred Resources in the 10 year Business Plan does present a risk, this is not untypical for steep dipping underground orebodies such as this. Furthermore, given that this material does not become prominent in the production schedule until after four to five years from re-start there is sufficient time available for BNC to undertake a phase of drilling to increase the confidence in this material prior to its mining. SRK notes that this has been normal practice over the life of the Trojan mine historically and is a function of access to drill sites which become available as lower levels are developed.
While the Business Plan runs for a 10 year period, SRK considers that the orebody is open along strike to the east at depths below 37L and that there is a good likelihood that with further exploration drilling and technical studies, further resources will be delineated which will in due course enable this to be extended beyond this period.
The Business Plan forecast projections commence with production of ore from the mine in July 2013 at a rate of some 68,000 tonnes and increases to some 78,000 tonnes in August 2013. Over the LoM the mining rate then varies between 63,000 tonnes per month (tpm) and 77,000 tpm and averages around 73,000 tpm.
The production schedule is based on a combination of Ore Reserves and modified Measured, Indicated and Inferred Mineral Resources. As noted above, the Ore Reserves declared have been restricted to the Measured and Indicated portion of the resources above 37L and SRK has undertaken sufficient checks to verify the economic potential of the declared Ore Reserves.
SRK notes that up to April 2016 the schedule is almost entirely comprised of modified Measured and Indicated Resources, however, beyond this point the proportion of Inferred Resources mined increases steadily until the majority of ore mined in the latter months is currently classed as Inferred. Over the life of mine (LoM) the Inferred material makes up some 45% of the total tonnage mined and SRK notes that beyond May 2019 the Inferred material consistently comprises at least 75% of the tonnage mined. While this does represent a risk to the production schedule in the Business Plan, SRK notes that this is an unavoidable function of the underground mining methods where exploration drilling can only be undertaken for a limited depth below the current workings and that BNC plans to undertake further infill drilling ahead of mining in order to increase the confidence in the Inferred material to Indicated or Measured as appropriate.
For the purposes of the Business Plan projections running from July 2013, the mill matches the mining schedule. SRK notes that as part of the re-start programme and commissioning, the actual tonnage of ore fed to the mill from February to June 2013 is recorded by BNC as some 210kt of ore in total and achieving around 55kt in both April and May 2013, which supports the assumption that the planned feed tonnages over the coming months can be achieved. Ore will be processed through the existing concentrator plant, which incorporates a new flotation circuit. Nickel recovery is expected to vary from 77.8% to 82.4% at steady state, averaging 82.3% over the LoM plan. The forecast nickel recovery has been adjusted upwards from that achieved historically to reflect the increase in head grade and the improved performance expected from the new flotation circuit.
The nickel concentrate is assumed to have a grade of 9.2% with between 240t and 940t of nickel being recovered to concentrate per month and an average of some 650t nickel recovered per month over the LoM. The initial concentrate is assumed to have a moisture content of 15% which is assumed to be reduced to 8% through drying and prior to bagging for shipment. The amount of concentrate (at 8% moisture) that is assumed to be produced varies between 3,000t and 12,000t per month and averages some 8,300tpm over the LoM.
SRK has reviewed the production schedule on which the Trojan Business Plan is based and while this incorporates a portion of Inferred material, and therefore has a higher element of risk than if this was not the case, considers this to have been appropriately derived from the Mineral Resource model.
An offtake agreement has been signed with Glencore which gives clarity on the revenue assumptions made going forward. SRK is satisfied that the terms of this have been appropriately reflected in the BNC Business Plan.
BNC has developed operating costs from first principles and using experience from previous operating history at the mine, processing and administration facilities. SRK has reviewed the operating and capital cost assumptions and considers these to have been developed in a thorough manner and to be reasonable for the purposes of the Trojan Business Plan.
For further information contact:
Mwana Africa PLC Kalaa Mpinga |
Tel: +44 (0) 20 7654 5580 |
Nominated Adviser and Broker Peel Hunt LLP Matthew Armitt / Ross Allister |
Tel: +44 (0) 7418 8900 |
Public & Investor Relations Tavistock Communications Ed Portman / Simon Hudson / Mike Bartlett |
Tel: +44 (0) 20 7920 3150 |
The information in this press release that relates to Ore Reserves and Mineral Resources is based on information compiled under the direction of John Miles CEng and Dr Mike Armitage C Eng respectively. Mr Miles and Dr Armitage are both a Member of the Institute of Materials, Minerals and Mining which is a 'Recognised Overseas Professional Organisation' (ROPO) included in a list promulgated by ASX from time to time.
Dr Armitage is a full time employee of SRK and Mr Miles is an associate of SRK. Both have sufficient experience which is relevant to the style of mineralisation and type of deposit under consideration and to the activity which he has undertaken to qualify as a Competent Person as defined in the 2004 Edition of the 'Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves' (the JORC Code) and for the purposes of the AIM Rules. Dr Armitage and Mr Miles have reviewed this press release and consent to the inclusion in the press release of the matters based on his information in the form and context in which this appears.
About Mwana Africa PLC
Mwana Africa PLC is a pan-African, multi-commodity mining and development company. Mwana's principal operations and exploration activities cover gold, nickel, copper and diamonds in Zimbabwe, the DRC and South Africa.
Mwana's Freda Rebecca gold mine in Zimbabwe, having restarted operations in 2009, produced 65,350 ozs of gold in the 12 months to March 2013.
In October 2013, Mwana announced that the gold mineral resource at its Zani Kodo project in Democratic Republic of Congo had increased to 2.975 million ounces.
In February 2013, Mwana announced it had signed a Joint Venture Agreement with Zhejiang Hailiang Company Limited to jointly explore some of its copper license areas in the Katanga Province of the DRC.
The restart of operations at The Trojan Nickel Mine (owned by Mwana's Zimbabwe subsidiary Bindura Nickel Corporation ("BNC")) followed four years during which all of the BNC assets were on care and maintenance. In September 2012, BNC carried out a restructuring and recapitalisation involving US$23m being invested into BNC which has allowed it to restart the Trojan mine. First sale of concentrate to Glencore took place in April 2013.
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