Mining

The mine is considered a modern, low-cost operation and boasts an exemplary safety record. It applies international best practice in the design of its employment, social and environmental policies. It is also the first and largest fully taxpaying mining company in Tanzania. Mining currently takes place through five shafts: Delta, Askiri, Main, CT and Bravo shafts. Shafts are sunk at an angle of 42° along dip of the JWZ mineralisation zone.The shafts are fitted with tracks and material is removed via a hoist and inclined shaft structure. Drives are driven along strike at an angle of ±16° along the plunge of the fold noses. A monorope (endless looped rope and pulley) system is used to remove materials in bags from the mining fronts (in each of the drives, raizes and winzes) towards the inclined shaft ore pass infrastructure.

Ore passes are developed over the shaft to ensure available surge capacity and improved mining efficiencies. Blasting is used as the main method of mine advancement. Once favourable boudin structures are approached pneumatic drilling and handpicking is used to remove tanzanite as carefully as possible. As CEO, Ian Harebottle says, “Our core competence lies in our ability to adapt best practice mining methods to tanzanite’s unique geological environment”. It is anticipated that current enhancements to mining operations aimed at introducing greater mechanisation, including the introduction of a scoop-tram and greater emphasis on selective stoping, will result in a significant increase in material passing through the processing plant and sorthouse.

Production

Processing

Processing and sorting take place on site within purpose-built infrastructure and facilities. The ore treatment plant, which includes a dense media separator (DMS), has a current capacity estimated at approximately 10,000 tonnes per month, on a single shift. The DMS concentrate passes through a fully automated optical sorting system, where after the “super concentrate” is then hand sorted and graded, ready for export. Rough is sorted both manually and using a fully automated rough tanzanite optical sorting and primary grading system, a world first in the coloured gemstone industry.