Langer Heinrich is a surficial calcrete type uranium deposit containing a Mineral Resource of 53,937t U3O8 at a grade of 0.046% U3O8 in the Measured and Indicated categories (including RoM stockpiles) in seven mineralized zones designated Detail 1 to 7 along the length of the Langer Heinrich valley within the 15km length of a contiguous paleo drainage system. The deposit is located in the Namib Desert, approximately 80km from the major seaport of Walvis Bay.
The Mineral Resource is detailed below at a cut-off grade of 250ppm U3O8.
Mineral Resource Estimate (depleted for mining at end of June 2018)
|Measured & Indicated
(Figures may not add due to rounding and are quoted inclusive of any Ore Reserves, and have been depleted for mining to the end of June 2018 and are quoted on a 100% basis)
Economic analysis on this resource has indicated a break-even cut-off grade of 250ppm.
Ore Reserve Estimate (250ppm U3O8 Cut-off)
|Proved Ore Reserve
|Probable Ore Reserve
|Total Ore Reserve
(Ore Reserve has been depleted for mining to the end of June 2018 and are quoted on a 100% basis)
The Ore Reserve was estimated from the original un-depleted Measured and Indicated Mineral Resource of 151.8Mt at a grade of 0.054% U3O8. The Mineral Resource estimate for the project was updated to incorporate all the additional drilling completed on site since 2010. The additional Reverse Circulation (RC) drilling amounted to some 29,954 holes for 1,044,922m added to the resource dataset. It also allowed for an important increase in the definition of the non-mineralised basement profile. This updated basement profile was then used to further refine the Ore Reserve pit design. The Mineral Resource estimate was completed using Multi-Indicator Kriging and incorporates a specific adjustment based on expected mining parameters which have now been adjusted from those used in the 2010 Mineral Resource to incorporate information derived from actual mining. As a result, additional dilution and mining recovery are not included in the Ore Reserve estimation.
Changes from the 2010 Mineral Resource have been a significant transfer of material from Indicated to Measured category and a substantial reduction in Inferred material due to the increased drilling density. Overall there was a less than 1% reduction in contained metal. Differences between the updated Ore Reserve are related to depletion due to mining, refinement of the pit design based on the new basement profile and better definition of mineralisation edges due to increased drilling density and removal of material from the Ore Reserve as a result of on-going conversion of existing pits to tailings facilities. There has been no change to either the Mineral Resource or Ore Reserve cut-off grades, both remaining at 250ppm.
These reserves form the basis of the continuing life of mine plan for the Project. The revised mine plan allows a project life of 20 years, based on current processing feed rates
ML 172, previously EPL3500, covers the western extension of the mineralised Langer Heinrich paleochannel. An application to convert the EPL to a mining lease has now been granted. During the year a follow-up test passive seismic survey was conducted in order to cost effectively determine the likely basement location with promising results. It is expected that the survey area will be significantly expanded in the 2018 financial year.