The Kisladag Mine, owned by Eldorado Gold through its Turkish subsidiary Tuprag Metal Madencilik Sanayi ve Ticaret, produced 179,195 ounces of gold through the first three quarters of 2011. This set a new record for the largest gold mine in the country. In addition to turning out a healthy supply of gold, Kisladag also has drawn in thousands of visitors who show up to see what a well-run cyanide heap leach operation looks like.
The ore is abundant but low grade, with Proven and Probable Reserves of 430 million tonnes at a grade of 0.74 g/t, and Measured and Indicated Resources of 560 million tonnes at 0.68 g/t. So heap leaching is the only economically viable method for extraction. After drilling and blasting, a gyratory crusher and four cone crushers prepare the run-of-mine ore, and a conveyor system transfers it to a leach pad.
In 2011, 12.5 million tonnes of ore went through the process at Kisladag. Liberating the sulphide ores that form the bulk of the deposit takes 100 to 120 days, with a recovery rate of 64 per cent. A carbon adsorption plant recovers the gold and the final product is shipped out as doré bars.
Kisladag works hard to manage the risks in its operations. The deposit contains an amount of oxide waste, which is used to encapsulate sulphide waste and prevent acid mine drainage. “I’ve not seen it at any mine I’ve ever been at,” comments the mine’s general manager, Bill Crabtree. Both sulphide and oxide waste rock are hauled to a waste rock dump area in 150-tonne trucks. The oxide waste is dumped second so that it covers the sulphide waste rock like a metre’s worth of icing on a very large cake. Topsoil capping follows the oxide waste. This process has been repeated continuously from the project’s start.
As the pit is excavated more deeply, the oxide ore will eventually run out, which Crabtree estimates at 40 per cent of run-of-mine in 2011 and 30 per cent in 2012. In anticipation, work is underway to compose a different cover mixture.
Kisladag is also handling the leaching process for ore from its new gold mine, Efemcukuru, near the city of Izmir. Crabtree explains that it was wiser to avoid any problems relating to cyanide use by producing concentrate at Efemcukuru and trucking it to Kisladag where the relevant permits were already in place. He points out, however, that environmental concerns have been dying out over the years. “Early on it was a concern, only because of what others did in the past,” he says. “With companies coming in that have expertise, it’s changed a lot.”
Environmental concerns did delay the project initially. In 2007, less than a year after production began, a legal challenge to environmental approval set the mine at a standstill for seven months. But Kisladag kept on all of its employees, intensifying their training and waiting for the court case resolution. Meanwhile, the price of gold continued to rise. Ultimately, Crabtree says, the case cleared the courts and Kisladag restarted with greater local respect and a higher price for its product.
Expanding as planned
Gold price permitting, Kisladag could be in operation for at least the next 10 years. It was planned in staged expansions, beginning with commercial production in 2006. The pit has a total surface footprint of 125 hectares, to be mined out over the life of the mine.
In the initial stages of development, Eldorado used a local contractor with smaller trucks to haul waste. As big trucks and major mining equipment arrived in 2008, the mine hired on the workers who had been brought in and trained for the job. The local contractor continues to do other work around the site.
In 2011, additional capacity was added to the crushing and conveying circuits. The next step is expansion Phase IV, which should add another 12.5 million tonnes to the leach pad and bump up production to about 475,000 ounces a year after its completion in 2014. A supplementary environmental impact assessment remains to be submitted and approved in 2012. New crushing, stacking and conveyor systems will arrive in the next few years, along with more trucks, shovels and drill rigs. A dewatering system will be installed once the pit is developed below the water table in 2014.
Although the company was initially concerned that Kisladag’s location might limit the available equipment, Crabtree says that they were pleasantly surprised. For its Caterpillar equipment, Kisladag found dealers in both Istanbul and Izmir. Engine manufacturer Cummings, too, has a dealership in Istanbul. “We found out that there was a lot more here than we even dreamed of,” says Crabtree. Even with the larger trucks and shovels – Kisladag brought in the first local 785 Cat trucks – there was adequate support. The first two people hired to operate the Hitachi EX-3600 shovels had 18 years of experience with large shovels.
Crabtree adds that some components, like those for conveyor lines, can be easily custom built in Turkey. “You can go to Ankara and you can take things to machine shops, give them one of the parts, and tell them, ‘Make me one of those, I’ll be back in a few weeks,’” he says. “It’s amazing.”
Building a reputation