What you should know about Cyanide? Responsible Mining Sustainable Development

Transcription

1 What you should know about Cyanide? Responsible Mining Sustainable Development

2 What is Cyanide? Cyanides are chemical compounds consisting of one carbon atom and one nitrogen atom joined with a triple bond -C N. The 3 principal types of cyanide compounds are: free cyanide, weakly complexed cyanide (WAD) and strongly complexed cyanide. Cyanides occur as solids, liquids and gases. Cyanide for industrial use is normally in the form of sodium cyanide, either as solid briquettes or as a concentrated solution.

3 Cyanide A perspective Cyanide IS acutely toxic. However, like electricity, explosives or highly inflammable materials (including fuel) it is only dangerous IF not managed correctly. Cyanide inhibits respiration, by interfering with the transfer of oxygen around the body. However Cyanide breaks down rapidly (generally within 24 hours) and is dangerous only in case of direct contact without suitable protection. Cyanide compounds occur naturally in trace quantities, mainly formed via photosynthesis. Cyanide is not a cumulative poison; the effect on the body is evaluated on the concentration of the dose, not the number of doses. Non fatal doses detoxify naturally via the body's metabolism (e.g. cigarette smoke contains high levels of cyanide, but it is tar that is harmful). Cyanide is not carcinogenic, nor does it have long term effects.

4 Cyanide levels in common materials Materials Range of levels Chocolate covered almonds Table salt Cigarette smoke Sorghum Almonds Up to 2 ppm Up to 13 ppm Up to 1600 ppm Up to 25 ppm ppm Lima beans 1-31 ppm Road salt Gold Mining Up to 350 ppm Up to 200 ppm (ppm = parts per million concentration) Source - The Management of Cyanide in the Gold Mining Industry Adrian Smith Consulting Inc November 1988

5 Industrial Cyanide Usage ~ 1.1 million metric tons of HCN are produced annually worldwide ~ ONLY 6% is used in the mining industry (North and South America, Europe, Australia etc.) The remaining 94% is other industries (production of plastics, adhesives, fire retardants, cosmetics, pharmaceuticals, food processing, insecticides, chicken feed, electroplating, etc.)

6 Purchased in solid briquettes (safer for transport) Cyanide at Amulsar Solid cyanide mixed with water to form dilute solution (approx. 100ppm) Cyanide solution used to irrigate heap leach facility, as solution has the chemical ability to leach (dissolve) gold and silver from ore A metal- cyanide complex is formed, which is treated to recover the metals in an Adsorption-Desorption-Reaction (ADR) plant. This recovery process destroys the cyanide Residual solution added to dilute cyanide solution (recycled in process as a closed system)

7 The Cyanide Code Cyanide is used in gold mining industry in America, Canada, Australia and elsewhere. The Cyanide Code is a voluntary initiative for the industry and the producers and transporters of the cyanide used in gold mining. It is intended to complement an operation's existing regulatory requirements. Compliance with the rules, regulations and laws of the applicable political jurisdiction is necessary; this Code is not intended to contravene such laws. As it applies to gold mining operations, the Cyanide Code is comprised of two major elements. The Principles broadly state commitments that signatories make to manage cyanide in a responsible manner. Standards of Practice follow each Principle, identifying the performance goals and objectives that must be met to comply with the Principle. The Principles and Practices applicable to cyanide production and transportation operations are included in their respective Verification Protocols. Operations are certified as being in compliance with the Cyanide Code upon an independent third-party audit verifying that they meet the Standards of Practice, Production Practice or Transport Practice.

8 Safe Cyanide Usage Guidelines Amulsar will follow the International Cyanide Management Code (ICMC) standard practices for acquisition, transport, storage and handling of cyanide, such as: Purchase of cyanide from accredited producers in Europe and/or Asia America Transport of cyanide using Cyanide Code certified carrier companies Storage of cyanide in a dry, well ventilated area. Containers will not be let open. Access to storage areas will be restricted to authorised personnel only Cyanide will not be allowed to come into contact with acidic media or oxidising agents Fixed HCN monitors with alarms will be installed where the potential exists for cyanide exposure ph of cyanide solutions during mixing and production maintained at high levels to minimise formation of cyanide gas. Continual monitoring used to verify ph of solutions

9 Cyanide Management at Amulsar Cyanide managed throughout process by Cyanide Management Plan (developed as part of environmental impact assessment) made available to the public Mine designed and operated in compliance with International Cyanide Management Code, with relevant monitoring/inspection procedures and public awareness campaigns, including: Pipes containing cyanide solution will be double lined Ponds will be double lined, with leak detection and collection systems installed Tanks containing hazardous solution will have secondary containment (at least 110% of capacity of tank) ADR plant will have lined containment pond to capture all cyanide solution in plant (in event of highly unlikely incident) Risk assessments will be undertaken (and regularly updated) on all activities concerning the transport, use, storage and handling of cyanide Safety protocols/procedures and plans will be prepared based on risk assessments. Detailed training programs for workers managing cyanide will be prepared and implemented prior to first cyanide shipment Emergency medical procedures will be established and antidote kits made available in the event of exposure to cyanide

10 Closure of Heap Leach Heap will be rinsed with water to remove residual solution and minerals Heap will be covered with clay and topsoil for full rehabilitation Residual cyanide in heap will degrade naturally, via the following processes: Adsorption Oxidation (to form cyanate) Biodegradation Hydrolysis

11 Handling Guidelines for Safety Work is always conducted in well ventilated areas to minimise HCN concentrations Personal Protective Equipment is used to avoid direct contact with cyanide. Examples of PPE are: - full face canister mask - full face shield and safety glasses - elbow length PVC gloves - disposable 'poly' overalls or splash apron - safety rubber boots and or safety boots - safety helmet Portable HCN meter on personnel

12 Responsible Mining Sustainable Development