BAT PRACTICE AT OVACIK GOLD MINE G. ÖNAL

Transcription

1 BAT PRACTICE AT OVACIK GOLD MINE G. ÖNAL Istanbul Technical University Faculty of Mines Mineral Processing Engineering Dept Istanbul-TURKEY 1. Introduction In this presentation, the BAT application has been outlined in Ovacık Gold- Silver mine in Turkey. This BAT application was accepted as best one in Europe by Euro mines. 2. Location And Project Futures of Mine Mine is located in Western Anatolia near the antique city Pergamon. Fig. 1, fig. 2. Ovacık Mine s project features Ore type : Epithermal low sulphidation quartz + breccia veins Host rock : Andesite Reserve : 13 million 4.36 gr/ton Au) & 4.5 g/ton Ag Resource : million 5.01 gr/ton Au & 2.20 g/ton Ag Mining : Open Pit & Underground Process : CIP cyanide leach Plant capacity : 900,000 t/y ore Gold & silver output : 5 t/y Au & 4.5 t/y Ag Mine life : min 15 years Tailings treatment :Chemical destruction (INCO SO 2 /Air + Ferric sulphate) + natural degradation 1

2 Figure 1. Location of Ovacık Gold Mine Figure 2. View of Ovacık Gold Plant 2

3 In the mine was produced 53 tons gold and 50 tons silver between May 2001 and December The flow-sheet of processing plant is shown in Fig 3. The recovery of gold is 93-93% and silver is 70-75%. Figure 3. Flow sheet of Ovacık Gold Plant 3. Best Practice in Environmental Management System and Best Available Technology Environmental Management System General Management Plan Environmental Management System Occupational Safety and Health Plan Tailings Pond Management Plan Mine Closure & Rehabilitation Plan Emergency Action Plan Rapid Response System BAT Practice Measures Mining Drilling - Machines equipped with dust collectors 3

4 Blasting -Controlled blasting: -Preventing dust and rock-fly -Reduced blast noise down to 115 db on the average as opposed to 130 db permissible level -Reduced vibration down to 2 mm/sec as opposed to permissible 13 mm/sec. (Measurement nearest residence) Loading -Ore water sprayed before loading Hauling -Water sprayed hauling roads Mine water -Non. Rainwater pumped to the tailings pond. -Run-off water around the mine is collected into a water pond for settling and used as surface-spraying agent. Crushing & Screening -Water spraying at Primary Crushing -Total dust collection system -2 x wet scrubbers (dust emission is reduced to 1/10 of permissible long and short term particulate levels of 150 and 300 g/m 3 air respectively) -Bag Filter on lime silo (~ zero dust particulate emission) -Computer control operation and lock system. -Camera control of critical locations. Milling -Computerized fail-safe process control and sequential activation. -Machine operation lock system -Process parameters (ph, active capacity, levels in tanks, chemical concentration, emission level) -Chemical destruction of sodium cyanide (INCO SO 2 / AIR) -Chemical treatment for spills (HYPOCHLORITE) -Heavy metal stabilization (FERRIC SULPHATE) -Gas scrubber for carbon activation furnace fume -HCN detection devices -Cyanide storage in closed building. -Fail-safe cyanide solution preparation -Hourly manual monitoring along with computerized control Waste rock -Used as embankment building material 4

5 Tailings Dam -Built to ICOLD standards -Equipped with a composite liner system: -70 cm clay -1,5 mm HDPE geomembrane -20 cm gravel-sealing the drainage system draining water to the collection tower -Decant water collection tower circulating water back to the mill -Run-off water collection channel around the pond -Downstream monitoring wells Figure 4. Tailing Pond Figure 5. Chemical Destruction at Plant 5

6 Other measures -5 Units of precipitated dust monitoring devices located around the mine -3 Units of particulate dust monitoring devices around the mine. -Vibration & noise monitoring devices 4. Risk Assessment And Audit Risk Assessment Before operation Ovacık Mine Tailings Dam risk assessment Ovacık Mine Cyanide Cycle risk assessment Ovacık Gold Mine Assessment Report During operation Ovacık Mine Tailings Dam risk assessment (Golder Associates Ltd.) Ovacık Mine Cyanide Cycle risk assessment (Golder Associates Ltd.) In house risk mitigation plan Audit İzmir Governorship Monitoring & Auditing Committee Ministry of Health- İzmir Health Directorate Ministry of Environment General Directorate of Preventing & Controlling Environmental Pollution Turkish Mining Affair Euromines European Miners Association audit Quarterly internal audit Annual external audit of the international independent audit firms 5. Rehabilitation The mining sites are rehabilitated prior to the final CLOSURE of the mining operations as per commitments to the Authorities Open pits are filled with extractive waste material and reclaimed following the expiration of the operation, e.g. Ovacık and Küçükdere. All concrete and steel structures at the plant will be removed and those areas will be arranged Tailings Pond will be dewatered and a revegetated top cover will be emplaced. Forest area will be reforested Other areas will be used for agriculture and cattle-dealing Surface and Groundwater Quality will be monitored for a minimum of 10 years. 6

7 6. Transparency Open door policy for all stakeholders Community access to relevant and accurate information Publishing the results of the environmental measurements Addressing to the civil society the environmental & health impacts and economic & social benefits of the Ovacik mine Encouraging representatives of the local community participating the audit team Written commitment to the government about the mining activities on site Informing immediately the government about the developments at the mine site 7. Conclusion Ovacık gold mine is in operation since 12 years. Their applications have been inspected by national and international authorities. Turkish ministry of Environment, Euromines, Golden Associates Turkish Scientific Counsel appreciated their application for BAT and Environmental management. Ovacık gold mine was the first gold mine in Turkey. This mine has been an example for the other gold and silver mines in Turkey. Sources 1. Turkish Scientific Counsel Report, Golder Associates Ltd., Golder Associates Ltd., Güven Önal presentation in EU Brussels, Annual report of Koza Company,