Operations & exploration

Hunter’s Road

Full name:

Hunter’s Road

Geology and history:

The Hunters Road deposit lies in the upper Bulawayan Group within the Gweru-Midlands South Greenstone belt in central Zimbabwe. The Hunters Road nickel deposit is hosted by a serpentinized cumulate komatite, originally consisting mainly of coarse interlocking magnesium rich olivine grains. In some cases accessory pyroxene, sulphides and chromites are present as intergranular/interstitial/intercumulus material. This cumulate komatite is thus essentially dunitic in composition. The orebody is bi-lobate near to surface but appears to merge at depth to form a single entity as in a scissors fault. Although there are different interpretations on the formation of this structure, the most probable on is that the structure is a result of sinistral shear thrusting and repeating the contact and the mineralisation.

The primary magmatic sulphides, which occur interstitially and intergranular to the olivines, are the main source of extractable nickel. The sulphides consisted of pentlandite (±75%), pyrrhotite (±20%) and possibly minor pyrite (<5%) and traces of chalcopyrite. The deposit has been subject to greenshist metamorphism, supergene alteration, and possibly to other, less readily identifiable alteration. The metallurgical extraction of the nickel is, as a result of the multiple stages of alteration, considered critical to the evaluation of the economic exploitation of the orebody.

The Hunters road deposit was discovered by means of a soil geochemical anomaly and was initially explored through trenches. Substantial drilling has subsequently been completed on the deposit to outline the orebody. This comprised 125 percussion holes, amounting to 4,620m, and 183 diamond drill holes amounting to 41,041m drilled. Recent work on the project involved modelling of the metallurgical domains identified. Currently, Mwana is considering a development programme at the deposit.

A feasibility study for the Hunters Road project was completed in 2008. The project involves development of a probable reserve, estimated based on a nickel price of $7.50 / lb, of some 175,086 tonnes and indicated resource of 53,890 tonnes of contained nickel, and construction of a new concentrator. Production from the first phase of the project, estimated in December 2007 to cost approximately £47.8million, is expected to be approximately 2,500 tonnes of contained nickel per year, with phases two and three bringing total production to 10,000 tonnes of contained nickel per year.

The company is looking at ways to optimise the development of Hunters Road in the context of a restart of operations at BNC.

Geological maps:

Final pit design

 

Reserves and Resources

Note:

• As a result of global decline in nickel prices, exacerbated by the elevated cost of production from BNC’s mines owing to reduced production volumes and the difficult social and economic environment in Zimbabwe, BNC’s mining operations were placed onto care and maintenance in November 2008. Commodity prices prevailing at 31st March 2009 indicated that mining of the resources at Trojan, Shangani and Hunters Road would be uneconomic, and consequently no reserve statement has been included, consistent with the JORC resource management code. Previously stated reserves of 12,385t, 25,109t, 175,086t respectively (stated as of 31st March 2008 and calculated based on a nickel price of $7.50 / lb) have been reclassified as resources.
• The indicated resource at Hunters Road reflects inclusion of the East orebody, which has been drilled out but for which no mine plan or pit design has been prepared. Hunters Road West orebody excludes first 30m of untreatable oxide ore mineralisation. The high grade in the ‘Indicated’ at Trojan is caused by massive sulphide ore below 35/0 level. Confirmatory drilling to verify this high-grade ore has started.
• BNC is investigating options to reduce its cost of production. A statement of reserves will be compiled in due course based on the results of this analysis.