Water balance of a boreal black schist heap leach operation

The Terrafame (formerly Talvivaara) mine in northern Finland uses oxidative heap leaching in temperatures which can fall below -30 degrees C, and there is also an annual net precipitation of water. The sulphide ore is very reactive, causing problems with mine water and heating of the heap. The actual water balance during 2017 and 2018 is compared with simulations of annual precipitation and evaporation in a highly arid climate (the Antofagasta Mountains, Chile) and in an area of no excess heat generation in the heap. The discharge requirement and therefore the water footprint of the Terrafame plant was shown to be highly dependent on the climatic conditions. Heat generation in the heap leach operation was shown to be vital for water management operations and therefore the management of discharge. Climate change scenarios show that the need for water discharge from the site would only increase by 5% in the wettest years, whereas raw water utilisation would increase by 46-83% during the driest years. The results suggest that although the heat generation is ore- and process-specific, the water consumption as well as discharge to the surrounding environment is highly dependent on the climatic conditions (precipitation, temperature) in the geographical location.
The Terrafame (formerly Talvivaara) mine in northern Finland uses oxidative heap leaching in temperatures which can fall below -30 degrees C, and there is also an annual net precipitation of water. The sulphide ore is very reactive, causing problems with mine water and heating of the heap. The actual water balance during 2017 and 2018 is compared with simulations of annual precipitation and evaporation in a highly arid climate (the Antofagasta Mountains, Chile) and in an area of no excess heat generation in the heap. The discharge requirement and therefore the water footprint of the Terrafame plant was shown to be highly dependent on the climatic conditions. Heat generation in the heap leach operation was shown to be vital for water management operations and therefore the management of discharge. Climate change scenarios show that the need for water discharge from the site would only increase by 5% in the wettest years, whereas raw water utilisation would increase by 46-83% during the driest years. The results suggest that although the heat generation is ore- and process-specific, the water consumption as well as discharge to the surrounding environment is highly dependent on the climatic conditions (precipitation, temperature) in the geographical location.