The document discusses sulphate removal from mining effluents in the Southern Hemisphere. It covers regulations for sulphate discharge limits internationally and in various countries. Technologies for concentrating, solidifying, and separating sulphate from effluents are reviewed, including conventional lime precipitation and more advanced membrane, ion exchange, and biological processes. The key factors in selecting treatment technologies are effluent characterization, discharge criteria, and sludge handling. An optimal system requires integrating concentration, sulphate removal, and solids separation steps.

1. Sulphate Removal from Mining Effluents Current Developments in the Southern Hemisphere Raymond Philippe, Hatch Water, Chile Deon Nel, Hatch Water, South Africa Trevor Clarke, Hatch Water, Australia

4. Effluent Discharge Regulations 2400 - 500 (Class 1-3) - (Class 4) 3000 500 (Cat 4) TDS mg/l 250 (Class 1-3) - (Class 4) Resolution 357 Brazil 1000 NCADE Lib VI, 1 Ecuador 70 - 150 - Water Act 1998 South-Africa 1000 ANZECC 2000/General Water Use Stakeholders / Trigger Values Australia 300 (Cat 3) DS-002-2008-MINAM** Peru 1000-2000 250-500 250 DS90 DS46 NCh1333 Chile Conductivity mS/m [SO 4 ] -2 mg/l Legal Instrument Country

11. Advanced Sulphate Treatment Concept Separation Step Solidification Step Concentration Step Effluent Solids Treated effluent 2500 mg/l SO 4 <200 mg/l SO 4 5000 mg/l SO 4 2500 mg/l SO 4 CaO CaSO 4 .2H 2 O Advanced Treatment Technologies Black Box

16. Examples:Industrial Advanced Sulphate Treatment Operations Conventional (lime) treatment: 1600-2000 mg/l SO 4 <500 2008 235 NF/RO&evotransp Chile Collahuasi (Anglo/Xstrata) 2009 2005 1994 2006 2007 Year SO 4 discharge mg/l Q (m3/h) Technology Country Operation < 95 (200 μ S/cm) 290 Lime & NF & RO Aus ERA Ranger 1360 120 416 830 <30 NF/RO US Mosaic, Florida < 10 NF&RO&evap Aus Kwinana Nickel (BHP) <200 Biosure SA Ancor Works <200 RO & Lime SA eMalahleni (BHP/Anglo)