Dundee Precious Metals is a Canadian-based international mining company with operations in Namibia and Bulgaria and with exploration in Armenia, Bulgaria and Serbia. The Chelopech mine is located in central-western Bulgaria, on the southern flank of the Balkan Ranges. Today the Chelopech mine is best in industry in Bulgaria – operations have been fully upgraded and the resources invested in environmental protection have led to significant improvements. Community investments have largely contributed to the development of the region where mining has been a traditional livelihood for more than a century.
Both Bulgarian and European Union legislation ensures that the management of mine waste in Bulgaria complies with extremely strict guidelines and protocols.
In 2005, the sub-level caving mining method used for over 40 years was substituted by the so-called “long hole stoping with fill” (LHSF) method, given the prevailing Chelopech mine conditions.
This innovative LHSF approach:
- Improves ground stability and prevent ingress of surface runoff into the mine.
- Reduces ore losses and dilution by 20%.
- Ensures 100 % utilisation of waste rock for backfill purposes.
- Reduces by 40 % the amount of tailings deposited to the Tailings Management Facility (TMF).
- Prevents ingress of surface runoff into the mine.
The Long Hole Stoping with Fill method is recommended as the best available technique and is applied worldwide. This innovative system significantly reduces the negative impacts on the surface and subsurface environments.
In essence, the method entails the backfilling of mined stopes with cemented fill.
A Hydraulic Backfill Plant for backfilling of the mined stopes was commissioned in 2008. In 2010 a new paste fill installation was commissioned. The bonding component used in the paste fill allows:
- Better utilisation of flotation tailings.
- Improved quality control.
- Lower speed during backfill transportation.
- Reduction in cement usage.
Waste rock is a type of mining waste. In the past it was hauled to the surface together with the ore, thus forming huge heaps of rock material or the so-called “ore stockpiles”.
With the new mining method, this type of waste material is used for stope backfilling directly underground and is hence fully utilized on the site where it’s been from where it was originally extracted.
The challenges that we will have to face with are as follows:
- Maintain the balance of the cement used in line with the design parameters.
- Increase the free storage capacity to ensure the TMF could store the tailings from the processing of the current proven Mineral Reserve.