Central Asia Metals plc (CAM) said it was continuing to implement its biggest project this year of cut and fill stoping at the zinc-lead mine at Sasa in North Macedonia.
EFFICIENT
In its full year results for the 12 months ended 31 December 2020, the company said that the process would see more than 40% of tailings produced go back into the mining void as paste fill, making the process more environmentally and socially responsible.
CAM added that the method, more efficient than sub-level caving, was expected to come into effect during H2 2022 with approximately 90% of extracted ore using the method by 2024.
SASA
Sasa is an underground mine, with access gained via an adit, that annually produces some 820,000 tonnes of ore.
CAM’s website states that the Svinja Reka deposit is currently mined using a sub-level caving method, which utilises the geotechnical characteristics of the weak hanging wall to allow the rock to cave naturally into the void remaining after ore has been blasted.
From the second half of 2022, the Sasa team will use cut and fill stoping, with approximately 90% of ore due to be extracted using this method by 2024.
“The voids will be backfilled with paste material containing tailings to provide support, rather than allowing the roof to cave as is the case with the current sub-level caving method.
“Tailings from the Sasa processing plant are stored in storage facilities on site.
“With the commencement of cut and fill stoping approximately 45% of Svinja Reka’s life of mine tailings will be stored underground and as of the backfill.
“Then approximately 30% of tailings will be stored in the current Tailings Storage Facility 4.”
PREPARATIONS
The company needs to construct a backfill plant and associated reticulation pipework to transport the material underground, before distribution underground to fill stopes.
A new larger decline will also be developed from surface to offer increased ventilation, easier access and the ability to increase ore production to 900,000 tonnes per year in the medium term.
CAM added it was also looking at dry stacking the remainder tailings and eliminating the future use of tailings dam facilities.