The next stop on our KGHM tour was a visit at the mill and labs located at their Rudna Mine. The geology of the ore body is comprised of Dolomite, Shale and Sandstone. The high grade copper is located in the shales, with low grade within the dolomite and sandstone. This has created difficulties in processing, particularly the grinding, as the dolomite and sandstone are tricky to differentiate, yet it is required to grind these two ore types at different specifications.
We were welcomed by a team of KGHM representatives as well as a lovely surprise of tea, coffee and juice. After a quick introduction and presentation we geared up and were on our way!
First stop: the geological sample preparation lab. We were fortunate enough to witness first hand advanced automated sampling robots. Very few of these robots are yet to be employed in the industry, with KGHM running the only lab of this kind in Europe. Clearly KGHM is on the forefront of technology, constantly looking to improve and optimize their operations. 2 parallel robotic arms transported samples from small crushers to drying ovens as well as pulverizing stations. The capacity of this system is 1000 samples per day. Unfortunately photography was not permitted in the lab.
We were then whisked away to the next lab which completed mineralogical analysis on samples from all 3 of KGHM’s local mines. We observed and impressive Scanning Electronic Microscope (SEM) as well as a mineral identification database.
Our tour of the processing plant began with observing a large vibrating screen; the oversize was returned to the crushing circuit, the undersize continued to the rod mills for further grinding.
The next stop on the tour was the crushing circuit. From here, we continued on to the grinding circuit. The grinding circuit is comprised of rod, ball and hammer mills, various specifications of grinding media were employed. After grinding, the ore was passed through hydro cyclones and spiral classifiers for further classification. In the picture below the rod mills can be seen on the right and the spiral classifiers on the left. A large overhead crane was used to transport pallets and other heavy loads to various locations in the mill.
The class then ventured back outside to the train receiving yard. Here ore is delivered daily from KGHM’s Lubin and Polkowice mines for processing.
Then it was on to the flotation circuit where there were banks and banks of flotation cell which were used to float the valuable minerals using differential wettability. A series of rougher, cleaner and scavenger cells were used to optimize the recovery. KGHM also employed an automated monitoring system which measured the size and the height of the froth bubbles. Below is a photo of a scavenger cell.
While touring the facilities, KGHM conducted interviews showcasing the ‘Faces of Mining’, interviewing a few students as well as a professor. They were interested in our reasoning for choosing Poland as a destination for our grad trip as well as some of the differences between Canadian and Polish mining and milling.
After the interviews, we were escorted to the dewatering and thickening tanks. The moisture content of the thickened concentrate was still too high for transport and must therefore be sent through a series of filter presses and a large drum dryer. After drying, at temperatures up too 500 degrees celcius, the final moisture content is approximately 8.5%. The concentrate final grade is typically 22.75%.
The tour concluded with a question period as well as a delicious lunch kindly provided by KGHM. We then boarded the bus for ‘home’ and spent the rest of the day touring the city of Wroclaw, hunting for Gnomes..
– Danielle & Kim