Border with Scoping Study

The Border Zinc-Lead deposit was originally discovered in the early 1970s by Etosha Petroleum Ltd (‘Etosha’). Etosha conducted a limited program of broad spaced diamond drilling and estimated an exploration target of 15-30 Million Tonnes @ 2-5% Zn+Pb to a depth of 300 metres below surface.

Following Sabre's acquisition of the project area in 2007, Sabre set out to test this target and define a JORC resource for the deposit, with the aim of bringing the deposit into production in a suitable economic environment.
 

A model of the mineralisation at Border looking from the east along the strike of the Pavian Trend

Border is a modified Mississippi Valley-Type (MVT) deposit and consists primarily of coarse galena (lead) and sphalerite (zinc) mineralisation within dolomitic host rocks. No pyrite or any other sulphides are present, and weathering is almost non-existent. The deposit dips at 60° to the north, stretches along strike for over 2,400 metres and extends up to 390 m beneath surface (with the bulk of the tonnage and grade within 150 m of surface). The ore body varies between 10 metres and 85 metres in thickness (with an average thickness of 25 metres).
A combination of Reverse Circulation and Diamond drilling has resulted in the estimation of an Inferred Resource (JORC) for the Border Zinc-Lead deposit of:


16.2 Million Tonnes @ 2.12 % Pb+Zn & 4.76 gpt Ag (at a 1.25% Pb+Zn cut-off)*

*The inferred mineral resource estimate is based on a nominal 0.5% Pb+Zn wireframe cut-off with a maximum internal dilution of five metres. Grade was interpolated using an inverse distance weighting squared (IDW2) technique.

The sizeable resource at Border allowed Sabre to conduct a high level scoping study over the deposit. This study included metallurgical test work, mine optimisation and cost estimation.

Course Sphalerite (Light Brown - Zn) and Galena (Metallic Grey - Pb) in drill core from the Border deposit

Border Metallurgy

Sabre has completed detailed metallurgical test work on the Border deposit. The test work was based upon the premise that the mineralisation would respond well to initial upgrading via Dense Media Separation (DMS), thereby greatly reducing ‘downstream’ mineral processing costs. The test work proved to be highly successful.

The beneficiation test work showed exceptional upgrading of the ore, producing in excess of 80 times the original lead content, and around 37 times the original zinc content when DMS is followed by grinding and flotation. Final concentrate grades are around 65 % lead and 61.5 % zinc (from an ore grading 0.77 % Pb and 1.66 % Zn), with final recoveries of 86.9 % and 81.7 % respectively.

The optimised test results show:

In summary, after DMS and flotation 81.7 % of the total zinc and 87.8 % of the total lead, as well as 89 % of the total silver, can be expected to be recovered. Most importantly for the economics of the project, only 17 % of the mined ore would require grinding and flotation.

Results of the Scoping Study

Initial results of the scoping study are positive. The findings indicate that the Border deposit may be profitable in its own right. Sabre envisages that the Border deposit in conjunction with other deposits on the Pavian Trend (such as South Ridge and Nosib H), in addition to the Driehoek deposits on the Hoek Trend, could be used to feed a centrally located plant built on the Pavian Trend to treat all ore.

Several open pit scenarios were postulated for mining at Border, ranging from 500,000 tonnes per annum (tpa) to 2 million tpa. For a 1 million tpa mine, key findings from the Border scoping study are as follows:

*Note that these figures are preliminary in nature and may vary by ± 30%, as is the nature of such high-level scoping studies.

1. Prices used for calculation were at a 5% discount to metals prices listed on the London Metals Exchange on 18/1/2012. The actual values used in the calculation are Zn: US$1870/t, Pb: US$1960/t, Ag: US$28/oz.

2. Mining cost of ore is calculated from the general mining cost per tonne (~$3.80 per tonne) and the strip ratio (here a nominal 1.65:1 based on the geometry of the deposit).

 

 

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