Integrated Annual Review 2012 Annual Financial Report 2012 Mineral Resources and Mineral Reserves Regional overview  

5.3.4 Managing materials responsibly

We are committed to the safe and responsible management of our materials.

Our most significant input materials include timber, blasting agents, hydrogen chloride, lime, cement and caustic soda (sodium hydroxide). However, cyanide represents the most potentially hazardous input material, meaning we place particular emphasis on its management. All our eligible operations1 have full certification under the International Cyanide Management Code (ICMC). This certification extends to our transport providers.

Our most significant output materials include tailings, waste rock, chemical waste and hydrocarbon waste.

Land rehabilitation at Damang,
Land rehabilitation at Damang, Ghana

Tailings and waste rock management

All of our operations have life of mine tailings management plans. Their Tailings Storage Facilities (TSFs) and associated pipeline and pumping infrastructure are subject to ISO 14001 certified, externally audited tailings management systems – as well as daily inspection and formal annual reporting. In addition, our TSFs are inspected for technical integrity by independent engineers at least once every three years (see below) – or more frequently where required by local circumstances or relevant permit or licence conditions.

In addition, our TSFs are subject to a range of measures to minimise the risks they pose to the environment, including robust physical modelling and engineering. Specific risk management measures include:

  • Pollution containment facilities to capture any runoff
  • Recycling systems to enable tailings water to be reused in metallurgical processes (including closed circuit systems)
  • Dust and erosion control measures, including vegetation and/or dust suppressants on slope faces

Although most of our tailings are stored in TSFs, a proportion is recycled as paste fill (in combination with cement) in line with best practice rock engineering requirements. In South Africa we recycle a substantial proportion of our waste rock through reprocessing (p95) and its utilisation in construction projects. The remainder is kept in managed waste rock dumps (WRDs), which are subject to comprehensive rehabilitation.

Case study: New tailings storage facility at Cerro Corona – a major feat of innovative engineering

Figure 5.21: Group input materials (pre-unbundling)   Figure 5.22: Group mining waste
Figure 5.21: Group input materials (pre-unbundling)   Figure 5.22: Group mining waste (pre-unbundling)
1 i.e. excluding Cerro Corona, which produces a copper concentrate    

Audit of Tailings Storage Facilities

During 2012, we commissioned an external expert review of all our ‘live’ Tailings Storage Facilities (TSFs).This is built on a similar audit exercise carried out in 2009. The latest review found that all TSFs were generally stable, the management of freeboard is strong, and permits are in place and being complied with. Nonetheless, the review identified opportunities for improvement around:

  • The existence of large bodies of water on TSFs at our Tarkwa and St Ives mines
  • Rehabilitation and slope erosion in South Africa (in the context of our ongoing evaluation of our Surface Treatment Strategy (see below))
  • Physical monitoring and management
  • Groundwater modelling

Surface Treatment Strategy in the South Africa Region

We are continuing to examine potential opportunities around the reprocessing and centralisation of our current and historical TSF and Waste Rock Dumps (WRDs) in the West Wits area into a new Centralised Tailings Storage Facility (CTSF) adjacent to South Deep’s existing Doornpoort TSF, or equivalent arrangements at alternative locations. This work falls under the joint venture with Gold One. The project would not only produce additional gold (and potentially uranium) at an attractive NCE margin, but would also help reduce our long-term tailings management costs and minimise our future environmental liabilities.

For example, (like South Deep’s Doornpoort TSF) the CTSF would sit on non-dolomitic geological strata that minimises groundwater pollution risks. This compares to eight out of 13 current TSFs in the West Wits area, which sit on dolomitic rock that hosts naturally occurring aquifers. In addition, the CTSF (or equivalent facilities in alternative locations) would integrate similar design features as the Doornpoort TSF, which would help minimise any potential environmental impacts. These include pre-isolation of the most acidic water for treatment, on-site water treatment facilities, full plastic lining of the return water dam, extensive bunding (i.e. physical controls) and catchment paddocks.

Whilst we are now satisfied with our ability to meet the relevant technical requirements – including the integration of innovative Python processing plants to help concentrate WRD material (p94) – we are developing a portfolio of potential commercial options, both under our 2011 memorandum of understanding with Gold One and on a unilateral basis. We are likewise analysing the potential social and environmental requirements that would need to be satisfied for the project to proceed.

Should the requisite returns on investment be identified and development of the project proceed, joint surface resources (which amount to more than 700 million tonnes) – as well as the potential integration of neighbouring TSFs – could make a material contribution to Group production. The joint venture project with Gold One is now a responsibility of the Sibanye Gold management team.

West Africa tailings capacity

During 2012, our Damang mine received approval from Ghana’s Environmental Protection Agency (EPA) for three critical infrastructure projects required to sustain production at the mine. These include:

  • The raising of its existing East TSF, which will offer sufficient capacity to 2014
  • Construction of the mine’s Far East TSF, which will be needed from 2014 onwards
  • Construction of the new Huni WRD, which is due for completion by the end of 2013 and will have the capacity to hold 66 million m3 of waste rock

This follows extensive negotiation with the EPA and removes a significant risk to future production capacity. Furthermore, it demonstrates the maintenance of constructive relations with the EPA, despite the suspension of our heap leach activities at our neighbouring Tarkwa mine (p91).

At Tarkwa, various options are being investigated to provide additional tailings storage capacity, including the upgrading of TSF1 and TSF2, as well as the possible construction of a new TSF5. A decision on these options is expected by mid-2013.