Langer Heinrich is a calcrete-hosted secondary uranium deposit associated with valley-fill sediments in an extensive Tertiary palaeodrainage system. Uranium occurs as carnotite, an oxide mineral containing both uranium and vanadium, deposited as thin films lining cavities and fracture planes and as grain coatings and disseminations. The deposit extends over a 15 km length. Mineralisation is nearsurface, between one and thirty metres thick, and between 50 and 1,100 metres wide depending on the width of the palaeovalley. After calcrete development and mineralisation, parts of these sediments were eroded because of uplift that caused rejuvenated river flows - the largest being the Gawib River that in part follows the palaeovalley and has dissected and modified both the calcrete and associated mineralisation.

The current mineral resource is modelled to be approximately 16Km in strike, 0m to 100m in depth and varies in width from 300m to 900m depending on the position of the paleochannel walls.

Mining method is conventional open pit mining as was used successfully at the operation until mining ceased.

No mining dilution or ore loss is applied to ROM stockpile recovery as dimensions are well known. The ROM stockpile floors are surveyed prior to build and no blasting is required.

Based on the back analysis of existing data and a factor of safety assessment, the pit slope design parameters are recommended:

Parameter Wall Height <60 m 60 m < Wall Height < 90 m
Batter face angle 62° 62°
Bench height 9 m 9 m
Berm width 5 m 5 m
Overall slope angle 45° 41°
Geotechnical berm width N/A 15 m

The H pits consist of five mining areas, totaling 17.6 Mt of Ore Reserves at 484 ppm U3O8 and an average strip ratio of 4.1:1.

The F pits consist of two mining areas, totaling 10.6 Mt of Ore Reserves at 540 ppm U3O8 with an average strip ratio of 1.4:1.

The G pits consist of four mining areas, totaling 9.3 Mt of Ore Reserves at 436 ppm U3O8 with an average strip ratio of 1.9:1.

The J pits consist of four mining areas, totaling 20.8 Mt of Ore Reserves at 478 ppm U3O8 with an average strip ratio of 1.8:1.

The study considered the infrastructure requirements associated with the conventional contractor based truck and shovel mining operation including crushing and beneficiation, ore transportation and ship loading. Existing infrastructure includes established open pits, waste dumps, ore pads, haul roads, workshops and offices, water and power supply, an established processing facility and operational tailings storage facilities.

Crushing and Screening
Ore grade material on the ROM pad is fed through two ROM bins with vibrating grizzly feeders and crushed in two crushers to minus 80 – 110mm (depending on the ore type being processed). One bin feeds the Stage 1 & 2 circuit, and the other Stage 3.

Crushed material is conveyed to three scrubbers which break down the calcrete that holds the agglomerates together, liberating the uranium as well as removing the uranium bearing coating from the quartz pebbles.

After scrubbing, screened oversize, plus 10mm, is discharged to a recycle crushing circuit where it undergoes another screening process at 45mm, splitting the material into a plus 45mm fraction deporting to the secondary crusher and a minus 45mm portion which is fed to the tertiary crusher.

The minus 10mm crushed ore from the secondary crusher and the minus 8mm product from the tertiary crusher combine and are fed over a 10mm vibrating screen.

The minus 10mm ore is transferred onto the scrubber feed conveyor while the plus 10mm is conveyed back to the tertiary crusher for re-crushing.

There is one primary crusher and two scrubbers in Stages 1 and 2 and there is an additional crusher and scrubber for Stage 3. The Stage 3 scrubber is gear-driven rather than, as for the older units, tyre-driven.

The recycle (secondary and tertiary crushing) circuit, consisting of one cone crusher for each duty, have been augmented by a second tertiary crusher.

The Stage 3 section was designed to handle 270tph of fresh feed while the Stages 1 and 2 equipment was designed for 200tph combined. It is possible to handle up to 550tph with both circuits and 300tph with the Stages 1 and 2 equipment.

A mineral processing plant and supporting infrastructure exists at the site. Operating parameters for the plant are based on historical performance and updated modelling. An allowance is made for minor plant refurbishments and flowsheet improvements to be applied on restart.

Processing method is based on the existing processing plant using conventional methods including crushing and screening, ore beneficiation, alkaline leaching, counter-current decantation, ion exchange, precipitation and calcining. Final product is dried and drummed for sale.

The flowsheet will not change materially from the existing model. Cut-off grades were set at 250ppm as this is more suited to known processing plant performance. 18 months is allowed to achieve plant startup. Metallurgical recovery is based on historical data and updated analysis. Plant improvements include the following items that are costed and budgeted for in the Restart Plan Update:
• ROM bin modifications
• ........