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Dec 12, 2019

Outotec Thickened Tailings and Paste Plant decreases environmental footprint at UMMC's Uchalinskiy

The Ural Mining Metallurgical Company (UMMC) mining and processing plant in Uchaly, Russia was faced with a significant and potentially costly challenge relating to tailings disposal. The existing disposal pond was close to capacity, and constructing a new facility would be costly, time consuming, and significantly expand the mine’s environmental footprint. Outotec® Thickened Tailings and Paste Plant was constructed on site to reduce the mine’s environmental footprint by eliminating the need for a new tailings pond and enabling reclamation of the depleted open-pit crater.

Turning waste into environmentally friendly paste

UMMC is one of the leading Russian producers of major commodities including copper, zinc, coal, gold, and silver, with over 40 operations in Russia and abroad and more than 80 000 employees. Its Uchalinskiy mining and processing plant processes copper-pyrite ores and produces copper and zinc concentrates. The plant accounts for over 65% of all zinc concentrate produced in Russia.

The plant used the traditional impoundment method to dispose of tailings, and by 2014 the existing tailings pond was almost full. There were two options: either a new tailings pond could be built, or the depleted open pit could be used to store tailings.

UMMC chose to implement an Outotec® HCT paste thickening plant to turn concentrator waste into an environmentally friendly paste product (reclaimant) that can be used to restore the depleted crater of the site’s open pit.

Outotec Thickened Tailings and Paste Plant at Uchaly.
Outotec Thickened Tailings and Paste Plant at Uchaly.

Ensuring the safety of ongoing mining operations

The existing mine was at a depth of 400–600 meters under the open pit, meaning safety was of the utmost importance in this project.

To ensure safety, several factors had to be considered:
• reducing the amount of water in the tailings to minimize mine drainage
• increasing the solids content from 20% to 68-70%.

The open pit of the Uchalinskiy copper-pyrite deposit.
The open pit of the Uchalinskiy copper-pyrite deposit.

A sustainable solution for managing tailings

The Outotec Thickened Tailings and Paste Plant not only reduces the area occupied by the tailings pond and the risk of environmental pollution, but it also allows efficient recovery of process water for reuse and reduces the energy consumption of slurry and water pumping.

In addition, by moving away from the traditional method of disposal, the operating life of the tailings pond is increased from 20 to 50 years.

Main project implementation stages

Together with our partner, the Institute of the Urals Branch of the Russian Academy of Sciences in Yekaterinburg, we developed an approach that would meet all project requirements and avoid the underflow flooding into the underground space.

Work began in 2010 when the first laboratory tailings thickening tests were performed. Pilot tests were carried out in autumn 2011 and the first technical and commercial quotation was prepared in 2012. In 2014, our joint engineering solution successfully passed state expert appraisal. In 2017 the plant successfully passed all the tests. The desired solids content of 70% was achieved almost immediately after startup of the paste tailings plant.

Backfilling solution enables land reclamation

When mixed with cement the paste from the thickening plant can be used for backfilling the depleted open pit or underground mine space. This both decreases the area of the tailings pond and increases safety by improving the stability of the mine.

Project scope

• Basic engineering
• Two Outotec HCT paste thickeners
• Automation for paste tailings plant


*Metso Outotec was formed July 1, 2020 when Metso and Outotec merged into one company. This case study has been written prior to the merger under the old company name.

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