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21.10.2019 Mill tailings mixed with cement at Europe’s largest gold mine

Lödige Process Technology, Paderborn, Germany, points out that industries which handle fast-hardening mixing products, where there is risk of significant wear damage, require high throughput rates, but also – and in particular – quick, simple machine cleaning procedures. This certainly applies at Europe’s largest gold mine in northern Finland. Here, the mill tailings are mixed with cement before being pumped back into the cavities created by the excavation. The KM 4200 DW continuous mixer supplied by Lödige has been specially modified to meet these challenges.

Agnico Eagle Finland Oy operates the mine in Lapland. The company, a subsidiary of Canada’s Agnico Eagle Mines Ltd, intends to extract over five tons of pure gold in the Kittilä mine in 2019 alone. It goes without saying that this process generates huge volumes of mill tailings. These are then mixed with water and cement and pumped back into underground cavities created by the gold mining process.

The special challenge of this process is that the mixture of mill tailings, water and cement hardens very quickly. However, many continuous mixers include zones where materials can accumulate. Until now, removing these deposits was extremely time-consuming. For this reason, Agnico Eagle Finland Oy started to look for an effective and reliable solution for mixing mill tailings, which also had to be particularly easy to clean without any residues.

Lödige, which has been manufacturing mixers for 80 years, invented the patented ploughshare shovel and introduced the centrifugal and fluidisation process to mixing technology, which the KM 4200 DW intensive mixer also employs.

To meet the requirements of Agnico Eagle Finland Oy, some modifications were made to a horizontal ploughshare mixer of the type KM 4200 DW. The drum has been designed with an axial division, facilitating hydraulic opening for high-maintenance work. This permits easy access to the entire mixing compartment, making it easy to clean. Due to the pasty-to-liquid consistency of the mixed materials, the greatest challenge was secure sealing of the machine. Lödige solved this problem by developing a new sealing system for sludge-like products. In addition, the Lödige mixer is characterised by low dwell times and high throughput rates. A KM 4200 DW continuous intensive mixer permits throughput rates of 86m³/h.


The specially adapted Lödige KM 4200 DW horizontal ploughshare mixer in Agnico Eagle Finland’s gold mine

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