Virtual Curtain Limited

Transcription

1 Virtual Curtain Limited Superior outcomes for treatment of contaminated & mine acid drainage water 1. Removes radionuclides and heavy metals 2. Reduces sludge volume by up to 90% 3. Long term stable repository for radionuclides via calcination 4. Acid drainage/leakage control of abandoned mine sites and waste rock 5. Enables treated water to be efficiently purified by reverse osmosis for release to the environment or recycled 6. Provides sub-surface treatment of contaminated aquifers by creation of a virtual barrier or curtain 7. Very low capital cost

2 Contacts: Jeff Moore Virtual Curtain Limited Suite 1, 45 Ord Street West Perth Western Australia 6005 Dr Grant Douglas CSIRO Private Bag5 Wembley Western Australia 6913

3 Virtual Curtain Water Treatment and Remediation Technology Virtual Curtain technology represents a new cost-effective method to treat acidic and contaminated mining and industrial wastewater to a standard suitable for discharge into the natural environment or for re-use. The treatment involves the synthesis and application of hydrotalcites a layered double hydroxide mineral, primarily composed of magnesium and aluminium. Simple, generally one-step application methodology suitable for: in situ, one-off treatment of large contaminated open-pit lakes; batch treatment ( pump and treat ) of contaminated open-pit lakes using satellite pits; in circuit treatment and remediation of process plant waste water, and; sub-surface treatment of contaminated aquifers by the creation of a virtual barrier or virtual curtain. The technology uses commercially available additives to create synthetic hydrotalcite-minerals which can remediate and neutralise acidic wastewater and capture a broad suite of toxic heavy metals including uranium, copper, lead, cadmium and anions such as chromate and arsenate. Virtual Curtain technology offers superior outcomes to the traditional use of lime-based additives to remediate acidic and contaminated waste water, with advantages including: significantly reduced sludge volumes, by up to 90 per cent compared with limebased precipitated sludges; hydrotalcites form at approximately ph 6 or greater, settle rapidly and can be easily removed using centrifugation which contrasts to lime-based precipitated sludges which often require additional treatment to effectively dewater; hydrotalcite precipitates have been demonstrated to contain high concentrations of uranium, rare earth element, copper and other valuable metals which can be reprocessed to recover valuable commodities and offset remediation costs, and; hydrotalcites can be further stabilized via calcining to form a stable long-term repository for a range of radionuclides liberated during or after cessation of uranium mining. Emerging global market as increasingly strict environmental management legislation impacts: existing/abandoned mine sites with acidic drainage/leakage, including mining waste heaps with oxidising sulphide minerals such as pyrite; in-situ uranium leach mine sites ( ISL ), including leakage from thousands of cold warera uranium injection/extraction bores in Europe and the US, and; current mine closure policies are becoming increasingly rigid with requirement for longterm solutions for leakage of toxic by-products. In the first commercial application of the Virtual Curtain technology, metal contaminants were removed from an acid pit lake at a Queensland copper mine and approximately 50ML of rainwaterquality solute was safely discharged into a sensitive receiving environment.

4 Virtual Curtain technology treatment produced only a fraction of the amount of sludge compared to a conventional lime-based method while also producing an ore grade precipitate, said CSIRO scientist, Dr Grant Douglas. Commercial Scale Application of Virtual Curtain Technology at Copper/Tin/Silver/Indium Mine Pit lake prior to treatment Addition of hydrotalcite forming reagents (treatment completed in ca. 2 weeks) Dewatered pit and hydrotalcite mineral ore grading 8% copper and 4% zinc Recommencement of mining operations

5 Radionuclide Removal Radionuclide activities at Beverley North Uranium Deposit: In barren and treated lixiviant (Bq/L) In HT-based precipitate (Bq/kg) Radionuclide Barren lixiviant (Bq/L) Treated lixiviant (Bq/L) Percent removal HT precipitate (Bq/g) 238 U Th Th Ra Pb Bi Pb

6 Summary of ph, major (mg/l), trace element (µg/l) and rare earth element (REE) of Beverley North Uranium Deposit Barren Lixiviant (BL), and post-hydrotalcite treatment BL compositions. Analyte Barren lixiviant (BL) BL + MgCl 2 /NaOH ph (~8.5) Major elements (mg/l) Na K Ca Mg S Cl Total Alkalinity <5 19 Trace elements (µg/l) Al As Ba Cd 193 <0.2 Co 750 <1 Cr 900 <100 Cs Cu 2900 <100 F Fe Ga Ge 50 <1 Hf 2 <0.05 Li Mn 800 <100 Mo Ni 1600 <100 Pb 220 <5 Rb Sb Sc 200 <100 Si Sn 20 <1 Sr Th 1286 <0.05 Ti 200 <100 Tl U V W Zn <100 Zr 8 <0.2 Rare Earth Elements (REE) + Y (µg/l) La 976 <0.02 Ce 2502 <0.02 Pr 345 <0.01 Nd 1368 <0.02 Sm Eu 37 <0.01 Gd Tb 68 <0.01 Dy 371 <0.02 Ho 71 <0.01 Er 190 <0.01 Tm 25 <0.01 Yb 152 <0.02 Lu Y 1514 <0.05

7 Summary: Virtual Curtain Technology Hydrotalcite formation to neutralise acidity and capture radionuclides and heavy metals

8 SEM image of hydrotalcite botryoids formed from Beverley uranium mine barren lixiviant Hydrotalcite precipitate formed from a laboratory trial using a Cu-Zn acid mine water Close up of the botryoids showing individual hydrotalcite platelets formed from Beverley uranium mine barren lixiviant Hydrotalcite precipitate containing approximately 8% Cu and 4% Zn (green) recovered after the in situ treatment of a Cu-Zn acid mine water