Longer wear life and reduced energy consumption at Berezitovy gold mine
A change in the mill lining type and design in a grinding mill at the Berezitovy gold mine in Russia is bringing significant benefits to the whole comminution process. Metso designed the lining to include rubber and Poly-Met materials on both the feed-end head and discharge system and metallic liners on the shell of the aging Metso Allis-Chalmers grinding mill.
Metso’s combination lining has resulted in longer service life, energy savings and a reduced load on the mill bearings and drive.
“After the first four months of grinding gold ore with Metso mill liners in our SAG mill, the results are very positive. The wear rate is low and, based on the first wear measurement, the expected life is about double compared to what we got from our previous all-metallic liners,” says Nikolay Vershinin, head of the mine’s process plant.
According to Vershinin, instead of changing the liners every four months, the mine now plans to extend the change intervals to between 6–7 months. This means a great improvement in grinding uptime and mill lining costs. After four months of using the Metso lining, the mill has been in operation for 2,205 hours and production has so far amounted to 488,867 tons of gold ore.
“The Metso combination lining is some 35 percent lighter compared to full metallic liners, so we now have a much lighter load on the bearings and drive of our old Metso Allis-Chalmers branded grinding mills. The energy consumption has been reduced by 10 percent as a result of the combination of changes made,” Vershinin comments.
“Last, but not least, replacing the Metso rubber and Poly-Met liners is faster and easier than with the previous all-metallic ones. Now, our maintenance crew does not need any special tools for that part of the job,” he adds.
Gold mining in extreme temperatures
Belonging to the globally operating Nordgold group, the Berezitovy mine is located in the Russian Far East, in the northern part of the Taiga forest zone, 2,000 km northwest of the city of Vladivostok. The operating climate consists of extremes, ranging from -50 C in the wintertime and +35 C in the summer.
Berezitovy exploits an open pit with the benching method, targeting the extraction of 1.5 million tons of gold ore in 2013. The average gold content, associated with polymetallic, sulfide-type mineralization, is 2.1 grams per metric ton. Silver, zinc and lead are produced, too. Known reserves allow the mining operation to be continued for at least 8 years to come.
The minerals processing section houses a Russian-made jaw crusher, Metso’s secondary cone crusher and SAG and ball mills, followed by cyanidation, electrolysis and refinery stages. In 2012, the mine produced 3,617 kg (116.3 koz) of gold.
More fines with GP500S cone crusher
After blasting, the extracted gold ore is trucked one kilometer to the primary crusher. Sized down to -300 mm, Metso’s biggest gyratory cone crusher, the Nord-berg GP500S, handles the secondary crushing.
“We have now crushed more than 1.5 million tons with the GP500S and are very pleased with the results. Our crushing capacity has increased from the previous 250 tons per hour to over 440. In addition, we now get more fines, which is beneficial for grinding,” comments Chief Mechanic Evgeny Turanov.
Wear mantles for the GP500S are changed after 6–7 months, depending also on the climate conditions. During extreme cold conditions, crushing frozen gold ore accelerates the wear.
Two teams of 500 workers
Located 50 kilometers from the nearest residential area and over 100 km from the Trans-Siberian railway, the Berezitovy mine faces some extra challenges with its work force and materials logistics.
The mine houses a comfortable camp area that includes accommodation, catering and recreational facilities. The mine communicates with the outside world using a satellite network. Two teams of 500 workers rotate on a month-on/month-off basis.