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Possible to extract more from existing mines

Published: 20 March 2019

To extract metals and industrial carbonates from the same mine would reduce the amount of waste while at the same time increasing the economic benefit. In a project, researchers at Luleå University of Technology are investigating the geological conditions for broadening the production in existing mining areas.

– It is clearly possible. In the Bergslagen mining district in southern Sweden, you can potentially extract industrial carbonates and base metal sulphides in the same mining area, says Nils Jansson, researcher in ore geology at Luleå University of Technology and leader of the project VectOre, a unique collaboration between the university, the metal-producing industry and the carbonate-mining industry.

In Sweden – as well as in most of the world – the extraction of minerals for the production of copper, silver and zinc takes place separate from the extraction of industrial carbonates.

Maximize extraction in existing mining areas

The green transition and electrification increase demand for metals, while society is still dependent on industrial carbonate as an important component in cement, paper production, liming of soils and in steel production.
Strict environmental requirements, protracted permit processes and a growing focus on sustainability increase the incentives to maximize extraction in existing mining areas, says Nils Jansson.

– Waste is one of the biggest issues for the mining industry. An increased diversification at existing mines could lessen the amount of waste while at the same time increasing the economic value. Part of the material that today ends up in tailing ponds could potentially be used as industrial minerals, he says.

Only a few hundred meters from the old silver mine in Sala, in Tistbrottet, high-quality dolomite is currently being mined. High-quality carbonate deposits and sulphide deposits commonly occur adjacent to each other in Bergslagen. An improved understanding of their relationship may stimulate diversification at existing mines or extend their life-time by adding value to rocks now regarded as waste.

Better understanding of geological processes

All three active metal mines in Bergslagen, the Lovisa mine, Garpenberg and Zinkgruvan, occur in or directly adjacent to dolomitic rock units, Nils Jansson points out.
– Our research indicates that the ancient geological processes that once formed the sulphide ores, locally also upgraded surrounding limestone units to a very light and clean variety of dolomite. A better understanding of these geological processes can contribute to new mineral discoveries. This means that production can be diversified in other places where ore is mined near dolomitic strata, and thus the mining areas' lifetime can be extended.

According to Nils Jansson, the geological prerequisites for such a diversification exist, but there are a number of challenges to tackle. In Sweden, metal-producing companies and carbonate-mining companies are subject to different legislation and have limited knowledge of each other's raw materials, needs and markets.
– The carbonate-mining companies do not invest as much in exploration as the metal-producing companies. On the other hand, they do not spend as much resources on characterizing the waste rock. There is a lot to gain from a knowledge exchange between the two industries, says Nils Jansson, adding:
– It is possible to produce more in existing mines. I hope this project will increase the knowledge of how to do it.

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