Stratoni silver, lead, and zinc mine is an underground mine located in Stratoni village of Greece.
The mine is jointly owned by Eldorado Gold (95%), and Aktor Enterprises (5%), a subsidiary of ELLAKTOR. It is part of the Kassandra mines properties owned by Eldorado Gold and include the Olympias and Skouries mines.
The Stratoni mine was earlier owned by several companies including TVX Gold, and Hellas Gold, a subsidiary of European Goldfields, before being acquired by Eldorado Gold in 2012. The mine is estimated to have a life of four years.
Stratoni mine location, geology, and mineralisation
The Stratoni mine is located in the Halkidiki Peninsula of northern Greece within an area of 38km2. The deposit is found within the south-dipping Stratoni Fault, a mineralising corridor situated in the center of the Stratoni region.
The Stratoni deposit is a silver-lead-zinc carbonate replacement deposit occurring within the marble of Kerdilya Formation, which is separated by the Stratoni Fault. Pyrite, galena and sphalerite are the main ore minerals occurring in the deposit.
The area for mineralisation extends for 8km along the Stratoni Fault and is close to Madem Lakkos deposit to the east of Mavres Petres, and Piavitsa to the west.
Stratoni silver-lead-zinc mine reserves and production
The mine has a proven and probable reserve of 768,000t grading 154g/t Ag, 6% Pb and 8.4% Zn. Contained metal is estimated at 3.8 million ounces (Moz) of Ag, 46,000t of Pb and 65,000t of Zn.
The measured and indicated resources of the mine are estimated at 807,000t grading 185g/t Ag, 7.2% Pb and 10.1% Zn. Contained metal is estimated at 4.8Moz of Ag, 58,000t of Pb and 82,000t of Zn.
The inferred resources are estimated at 1.56 million tonnes (Mt) grading 169g/t Ag, 6.6% Pb and 9.6% Zn. Contained metal is estimated at 8.5Moz of Ag, 103,000t of Pb and 150,000t of Zn.
Piavitsa, a satellite deposit to Stratoni, is estimated to contain inferred mineral resources of 1.93Moz grading 5.70g/t Au and 19.15Moz grading 57g/t Ag.
In 2019, Eldorado Gold mined 174,866 tonnes (t) of ore was mined. The total concentrate produced was 37,153t.
Mining at Stratoni
Conventional drill and blast mining using a combination of transverse and longitudinal drift-and-fill methods with rock breaking is employed at Stratoni. The ore is removed from the stope after blasting using load haul dump trucks.
The stoped area is backfilled with cemented tailings from the surface through 120mm and 150mm pipes at a rate of 40 cubic metres per hour. Backfilling is essential to ensure safe operation.
The mined ore is dumped in an ore storage area and transported to a crushing plant. The ore is dry crushed in three stages to a size of minus 12mm using a primary jaw crusher, a standard secondary crusher and two shorthead tertiary crushers.
The crushed ore is sent to a fine ore bin and crushed to a nominal size of 80% minus 200 microns in a conventional rod mill/ball mill circuit and sent to a differential flotation circuit.
Lead is floated first in the floatation circuit and then zinc minerals are recovered from lead circuit tailing. The lead circuit includes conditioning, roughing, scavenging and cleaning, while the zinc includes the same stages with an additional stage of cleaning.
The lead concentrate is dewatered using a 13m diameter thickener and a 1m diameter disc filter. The zinc concentrate is cleaned using two 10m diameter thickeners and 1m diameter disc filer.
The concentrates are weighed and sent to the storage sheds for transportation to the smelter.
Stratoni mine is located 100km from Thessaloniki city and is accessible by road. The mine features warehousing facilities including a central warehouse, a mill warehouse and two buildings for chemicals and reagent storage.
The water requirements for the process plant are provided through the public system for domestic use, while treated water is used for industrial purposes. Electricity for the mine is supplies from a 10km-long, 20kV overhead line operated by the Public Electricity Supply Company (PPC).