The focus on dry-stack tailings is increasing rapidly in mining, not only because of greater scrutiny on mine tailings following several high profile wet tailings impoundment failures, but also because of the recently developed Global Industry Standard on Tailings Management.
Dry stacking merits are several, relating to both environmental and safety advantages: the high density allows the material to occupy less space, reducing the environmental footprint of a tailings facility. Water removed from tailings can be recycled, reducing water use. And the tailings solidity significantly improves safety and stability during flooding or seismic events.
Some mining companies innovated early on, before stakeholder scrutiny, recognising the benefits and that it was the right thing to do. Eldorado Gold is one such group; the company pioneered the use of dry-stack tailings technology in Turkey and Greece. Their experience with the best-available technology goes as far back as 2006, when Eldorado began assessing the use of dry-stack tailings for the Efemçukuru project (now an underground gold mine) in Turkey. At the time, Eldorado was one of only a handful of mining companies evaluating the technology, and it became the first to permit and construct a dry-stack tailings facility in Turkey.
Eldorado was also the first to deploy the best-available technology in Greece. At Kokkinolakkas, Eldorado’s US$100 million tailings management facility in Halkidiki, dry tailings from Eldorado’s Olympias (underground gold-silver-lead-zinc mine) and Stratoni (underground silver-lead-zinc mine) are stacked and separated from the surrounding environment by a 4-layer impermeable liner. Tailings from previous mining activities in the area are also being cleaned up and transported to the central Kokkinolakkas facility. This is part of Eldorado’s commitment to facilitate wider environmental rehabilitation in the Halkidiki area. The state-of-the-art facility is monitored 24 hours a day, 7 days a week, helping to keep dry-stack tailings stable and secure. Water diversion channels direct non-contact water away from the Kokkinolakkas facility, keeping tailings dry and immobile, while preventing water contamination.
Then on April 29, 2021 the company announced that the Greek Ministry of Energy and Environment had approved a modification to the Kassandra Mines Environmental Impact Assessment (EIA) to allow for the use of dry stack tailings disposal at the Skouries project (open pit & underground gold and copper mine, also in Halkidiki). Skouries is currently on care and maintenance pending a full re-start of construction. It is approximately 50% constructed and requires approximately 2.5 years to complete.
“Receipt of this approval is a major milestone for the Skouries project and the use of dry-stack technology results in a number of safety, environmental and economic benefits,” said George Burns, President and CEO. “Investment in dry stack at Skouries demonstrates our commitments to using best available environmental technologies at our mines and to ensuring the safety and protection of people and the environment. This approval is one of the key items required to restart construction at Skouries. We continue to advance other work on the project, including the completion of a feasibility-level update to the capital cost estimate. Skouries is a world class asset and once in production will add significant value for our investors, local communities and the Greek State.”
“Eldorado is an industry leader in using dry stack tailings as a best-available technology. We’ve deployed dry stack tailings at most of our mines, and pioneered this technology in Turkey and Greece. We’re excited to be able to use this technology at Skouries,” added Joe Dick EVP & Chief Operating Officer in the company’s recently published 2020 Sustainability Report.
Looking at Eldorado’s other operations, the Kışladağ open pit gold mine in Turkey uses heap leaching, so all of the water that enters the ore is removed or evaporates, thus the material remains dry and stable and no tailings are produced. The company is also studying alternative tailings methods such as dry stack technology as well as potential paste tailings disposal for future use at its Lamaque underground gold mine located in Val-d’Or, Quebec. Currently, Lamaque stores slurried tailings in the Sigma Tailings Facility, which is expected to reach the end of its life in the coming years.
