1. What is the difference between the Resin-in-pulp and Carbon-in-pulp process? Why does PHM use the Resin-in-pulp process?
The Resin-in-pulp process is an alternative to the carbon process; resins have many features that make them more attractive or applicable for their use in mining. Not only will they concentrate the target aurocyanide complex but can also remove all cyanide complexes as well. As opposed to the carbon-in-pulp process, the prime advantages of the resin-in-pulp process is the ability to provide precious metal recovery, cyanide recycling, and tailings treatment all in one process. When using carbon, the final discharge tail still contains cyanide / metals which have to be chemically treated prior to discharge. Resin systems also increase absorption kinetics, allow for higher metal loadings, and are easier to screen / handle than carbon, thus lowering capital and operational plant costs.
3. How safe is the tailings dam at the Pokrovskiy mine?
Cyanide is mostly destroyed at Pokrovskiy using a formaldehyde process prior to being piped in an insulated double-layer slurry pipeline to the tailings dam. Emergency containment ponds have been constructed along the pipeline route in case of a pipe rupture. The tailings dam has a natural clay liner 5-10m thick and the design of the dam has been approved and registered by the Federal authorities and is designed to meet World Bank Group guidelines. In its Environmental Review of Pokrovskiy, the International Finance Corporation observed that Cyanide levels in the tailings dam at Pokrovskiy are regularly monitored in both the surface and groundwater sampling points around the tailings dam and fall well below allowable limits and that to date, no cyanide contamination of surface or ground waters has been detected since the commencement of operations in 1999.
4. Is it dangerous to use cyanide for gold production?
One of the major uses of cyanide worldwide is in the mining industry for extracting gold from ore. The most significant environmental risk from the cyanide solutions used in gold mining is the possible leaching into soil and groundwater of cyanide at toxic concentrations, or catastrophic cyanide spills that might inundate an ecosystem with toxic levels of cyanide. However, mining enterprises take precautions to prevent the cyanide solution used from escaping into the environment; the layers of ore and ground up rock are contained in special leach pads lined with a plastic membrane to prevent the cyanide from leaching into the soil. The cyanide is captured and recycled and in order to minimise the environmental impact of cyanide that is not recycled, mining facilities treat the cyanide waste through several processes. They will allow it to degrade naturally, which will occur in sunlight (photodegredation) and through hydrolysis and oxidisation, among other natural processes. Mine managers can also seek to enhance this natural degradation, as well as using non-natural methods to accelerate the cyanide breakdown.
5. What are the recovery rates at the resin-in-pulp plant at Pokrovskiy?
A c.91% recovery rate was achieved in 2007.
6. Do cold temperatures during the winter period affect the processing operations of the Group?
The processing operations are not affected by the cold temperatures during the winter as the processing plant is indoors. The heap leach operations are however affected by the cold temperatures and are therefore seasonal operations. Mining operations are also affected by the cold temperatures as the ground can be frozen and additional blasting is therefore required.
The Resin-in-pulp process is an alternative to the carbon process; resins have many features that make them more attractive or applicable for their use in mining. Not only will they concentrate the target aurocyanide complex but can also remove all cyanide complexes as well. As opposed to the carbon-in-pulp process, the prime advantages of the resin-in-pulp process is the ability to provide precious metal recovery, cyanide recycling, and tailings treatment all in one process. When using carbon, the final discharge tail still contains cyanide / metals which have to be chemically treated prior to discharge. Resin systems also increase absorption kinetics, allow for higher metal loadings, and are easier to screen / handle than carbon, thus lowering capital and operational plant costs.
3. How safe is the tailings dam at the Pokrovskiy mine?
Cyanide is mostly destroyed at Pokrovskiy using a formaldehyde process prior to being piped in an insulated double-layer slurry pipeline to the tailings dam. Emergency containment ponds have been constructed along the pipeline route in case of a pipe rupture. The tailings dam has a natural clay liner 5-10m thick and the design of the dam has been approved and registered by the Federal authorities and is designed to meet World Bank Group guidelines. In its Environmental Review of Pokrovskiy, the International Finance Corporation observed that Cyanide levels in the tailings dam at Pokrovskiy are regularly monitored in both the surface and groundwater sampling points around the tailings dam and fall well below allowable limits and that to date, no cyanide contamination of surface or ground waters has been detected since the commencement of operations in 1999.
4. Is it dangerous to use cyanide for gold production?
One of the major uses of cyanide worldwide is in the mining industry for extracting gold from ore. The most significant environmental risk from the cyanide solutions used in gold mining is the possible leaching into soil and groundwater of cyanide at toxic concentrations, or catastrophic cyanide spills that might inundate an ecosystem with toxic levels of cyanide. However, mining enterprises take precautions to prevent the cyanide solution used from escaping into the environment; the layers of ore and ground up rock are contained in special leach pads lined with a plastic membrane to prevent the cyanide from leaching into the soil. The cyanide is captured and recycled and in order to minimise the environmental impact of cyanide that is not recycled, mining facilities treat the cyanide waste through several processes. They will allow it to degrade naturally, which will occur in sunlight (photodegredation) and through hydrolysis and oxidisation, among other natural processes. Mine managers can also seek to enhance this natural degradation, as well as using non-natural methods to accelerate the cyanide breakdown.
5. What are the recovery rates at the resin-in-pulp plant at Pokrovskiy?
A c.91% recovery rate was achieved in 2007.
6. Do cold temperatures during the winter period affect the processing operations of the Group?
The processing operations are not affected by the cold temperatures during the winter as the processing plant is indoors. The heap leach operations are however affected by the cold temperatures and are therefore seasonal operations. Mining operations are also affected by the cold temperatures as the ground can be frozen and additional blasting is therefore required.
