In each case, sample widths of 1.0 meter were taken to include some hanging wall and footwall dilution around the veins and represent a minimum mining width
. Veins comprise white chalcedonic quartz and minor adularia with dark grey banding due to the inclusion of silver sulphides and gold.
Table 1 also shows how these areas carry high grade over thicknesses in excess of the minimum mining width
defined in the Beta Hunt Mine Preliminary Economic Assessment (PEA) Technical Report dated March 4, 2016.
The mining width
in the setup notch was enlarged by 6 in.
Second phase drilling has indicated that the average UG2 Reef grade on Winnaarshoek is 7.44g/t of three platinum group metals (platinum, palladium, rhodium plus gold) over a mining width
of 87 cm: a healthy but medium-sized claim.
Although the proposed pit model showed possible difficulties in conforming with these indicated schedules, due to insufficient mining width
and other practical considerations, the period outlines derived this way are, nonetheless, very useful starting points for more detailed scheduling work.
Beyond the general assumption thatminingwould take place underground using decline access and trackless haulage the only particular mining assumption that was made for the resource estimate was a 5 metre minimum mining width
, reflected in the block width.
A minimum mining width
has been set at 3 m so that all mining can be fully mechanized, safe and efficient.
Restrictions with the creeping cone arise, however, with the minimum mining width
necessary to maintain a breaking face in longhole stoping and to allow compacted ore to run down the cone.
Grade thickness was determined by applying the reported minimum mining width
of 2.0 meters to the M&I grade of 17 g/t Pt+Pd for an average grade-thickness of approximately 34 gram-meter (g-m).
If the mechanized jumbo drills and LHDs require more operating room, the minimum horizontal mining width
for mechanized equipment will become 10 ft, and slusher mining will be used in areas of less than 10 ft horizontal width.
The average J-M Reef mining width
is approximately 3.7 m, whereas Merensky's average mining width
is just some 0.9 m.
The mine plan is based on a 4.9-g/mt gold cutoff at a minimum mining width
of 1.6 m.