Summary of current risk management

89.2Summary of current risk management

Each state and territory has legislation pertaining to the protection of the environment, waste management, contaminated land, and wildlife protection, supported by Commonwealth legislation, international treaties, and policies.

Environmental media quality assessment guidelines (trigger values) have been published for cyanide in surface waters for the protection of aquatic ecosystems. There is uncertainty regarding the acceptable concentration of cyanide in solutions that are accessible to wildlife. At least one state (NSW) has implemented concentration limits for WAD cyanide to minimise wildlife deaths due to cyanide at mine sites.

Australia does not have sediment or soil quality guidelines for cyanide for the protection of sediment-dwelling or soil-dwelling organisms, respectively.

Recent environment protection initiatives by the mining sector and government include the ICMC (ICMI, 2006), and various best practice guidelines for cyanide management and wildlife protection (NTDME, 1998; Environment Australia, 1998). These are expected to have a major influence on sodium cyanide management and environmental protection by the mining sector in Australia.

It is concluded that existing legislative and voluntary control measures for the manufacture and storage of NaCN are adequate to protect the environment, but that the adequacy of measures to protect the environment during transport should be monitored by the relevant state and territory authorities, particularly when transport incidents involving cyanide occur. The Northern Territory Government initiated a review of the regulatory regime for dangerous goods transport in the Northern Territory as a result of concerns arising from a transport accident in 2007 involving a spill of NaCN. The review report is not yet a public document, but NT WorkSafe advise that the key recommendations from that review were being actioned, including the adoption of the 7th Edition of the Australian Dangerous Goods Code (ADG7) and improvements to coordination across Government agencies, both for compliance monitoring arrangements and for emergency response procedures. NT WorkSafe also indicate that the principal transporters of sodium cyanide in Australia no longer use triple road-trains for the transport of solid sodium cyanide in containers and that configurations now used would be considered lower risk than the configuration used at the time of the 2007 accident.

As noted in Section 64, potential risks to the environment resulting from use of sodium cyanide in gold mining are high, particularly in relation to birds and terrestrial mammals which may imbibe contaminated water. It is concluded that existing legislation and voluntary measures are adequate to protect groundwater and surface water from planned or unplanned releases, and that the risk to the environment from release of HCN to the atmosphere at these facilities is acceptable. However, it is concluded that existing legislation and voluntary measures for the protection of wildlife at gold mines and associated facilities using NaCN are inadequate, particularly as engagement in the ICMC is voluntary. It is proposed that risks could be mitigated by a combination of concentration controls and exposure minimisation measures, as discussed in Section 88.3 and recommended in guidance for the ICMC. The proposed risk control framework is discussed in much greater depth in the recommendations. The recommendations also address wildlife protection at heap leach operations, where concentration controls are not appropriate, and the need for suitable habitat, wildlife and cyanide concentration monitoring, response and reporting programs at both tank leach and heap leach operations. If WAD CN concentration exceeds 10 mg/L, similar standards should apply to wildlife protection at tailings storage facilities at base metal mines using NaCN for flotation.

It is concluded that existing legislative and voluntary control measures for other uses of sodium cyanide are adequate to protect the environment.

90.Conclusions

90.1Use in Australia

Australia is a significant producer, user and exporter of sodium cyanide, with annual production of approximately 100 000 tonnes, compared to around 500 000 tonnes worldwide. As is the case worldwide, sodium cyanide is primarily used in Australia by the gold mining industry, where it is used in the cyanidation process to extract gold from ore. Consequently, greatest use has been in Western Australia (WA), where annual gold production is greater than all the other states and territories. A lesser amount of sodium cyanide is used in Australia for ore flotation and in the electroplating, metal cleaning and metal hardening industries.

As well as a difference in the scale of use, use in mining presents the greatest risk of environmental exposure through transfer of waste to tailings storage facilities or through heap leach operations. In contrast, electroplating and metallurgical processes using cyanide are generally closed systems, where residues in waste can be contained and treated prior to disposal. Release is then to the sewer or to landfills, where further biodegradation of the low level remaining is expected. This risk assessment has therefore focused on gold mining use, as existing management procedures minimise exposure with industrial uses.

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