Presentation to the MMMA President’s Technical Seminar JJ Steyn 20 May 2011

1. Presentation to the MMMA President’s Technical SeminarJJ Steyn20 May 2011

2. PRESENTATION CONTENT • Background • UG2 Challenges • Processing of UG2 • Types of UG2 • Lonmin Results on UG2 • Conclusions

3. BACKGROUND • Lonmin’s typical production profile:

4. BACKGROUND • Advantages of UG2 vs. Merensky • More PGM’s per ton (head grade) • More tons per meter advanced (SG) • Disadvantages of UG2 ore vs. Merensky • UG2 reef deeper than Merensky • Less Cu/Ni per ton • More Cr2O3 per ton

5. UG2 CHALLENGES • Smelter Constraints: • Total Cr2O3 in concentrate < 2.2% • Total Cu/Ni in concentrate > 3.8% • UG2 Mineralogy – PGM’s associated with: • Base metal sulphides (±30m BMS grains) • Locked in siliceous minerals (±5m PGM grains) • On gangue and BMS grain boundaries • Classification: • Density difference between chromite and silica host • Reverse classification

6. UG2 ORE PROCESSING • Material report to flotation conc. via two mechanisms • True flotation (dependant on particle surface properties) • Entrainment (dependent on particle size and density) True Flotation: PGM BMS Floatable gangue Entrainment: Chromite Non-floatable siliceous gangue

7. THE UG2 DILEMMA… • Needs fine grinding to liberate PGM’s • 5m PGM’s are locked in gangue • Chromite entrains at fine grinds • Fine particles don’t float well • Reduced chance of particle-bubble collision • Reduced chance of particle-bubble attachment • Increased chance of particle detachment • Gangue surface coatings more detrimental for fines • The result – complicated circuits and innovative designs

8. ACHIEVING A FINE GRIND • Installed Power • Merensky Plant - ± 14 kWh/ton • Karee B & K4 - ± 28 kWh/ton • Dedicated coarse and fine mills • Cleaner circuit milling

9. MINIMISE CHROMITE ENTRAINMENT • Don’t over-grind chromite! • Two-stage flotation - float as coarse as possible in primary rougher • Reverse classification in hydrocyclone • Cyclone classifies on mass • Chromite is a lot denser than siliceous minerals • Results in fine chromite in cyclone underflow • Results in coarse siliceous minerals in cyclone overflow • Solution – mills in open circuit

10. Flotation Flotation Prim Tails Flotation Flotation Prim Tails UG2 MILLING CIRCUITS ROM Primary Mill Secondary Mill

11. FINES FLOTATION • Increase particle-bubble collisions • Frother – finer bubbles • High energy cells – finer bubbles • Increase chance of particle-bubble attachment • High energy cells – particle momentum • Decrease chance of particle detachment • Shallow froths • Clean surfaces • Dispersant • Separate cleaning circuits for fast and slow floating material • MINTEK PROCESS

12. MINTEK PROCESS – CLEANING CIRCUIT • First recover fast floating particles – High Grade • Then focus on slow floating particles – Low Grade • High depressant dosages • High frother dosage • Shallow levels • These conditions also favour water recovery • Thus higher entrainment and chrome recoveries • Running on the edge!

13. EPC FLOW SHEET Primary Mill Primary Roughers To Secondary Mill Secondary Mill Secondary Roughers Final Tails Primary Cleaners (3 Stage) ISA Mill To Secondary Cleaners Final Tails Secondary Cleaners (2 stage)

14. DIFFERENCE TYPES OF LONMIN UG2 • Western UG2 (Karee, Western Platinum) • Eastern UG2 (Eastern Platinum) • Split Reef (WPL) • IRUP (WPL) • Mechanised Ore (mostly EPL)

15. BASIC MINERALOGY OF LONMIN UG2

16. PERFORMANCE OF LONMIN UG2

17. CONCLUSIONS • UG2 needs fine grind for valuable recovery • Lots of power • Two stage milling • Cr2O3 is recovered at fine grinds • Open circuit milling • Fines recovery • Mintek process