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Mining Waste - LTU - Susanne Nigéus
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Residues from the pulp industry can provide more environmentally friendly mines

Published: 13 March 2018

Susanne Nigéus is a PhD student in applied geochemistry at Luleå University of Technology, and she is investigating whether green liquor dregs may be a suitable material for use as an additive to making a natural till denser. In a new project, a sample area with a mixture of green liquor dregs and till has been used to cover mining waste.

Mining waste is often sulfidic which oxidizes if it comes into contact with oxygen and water. This can cause harmful metals to be released and transported to surface- and groundwater, which can lead to environmental damage.

"This fall I have installed instruments to evaluate a remidiation of a waste rock dump in a test area at the Näsliden mine in Västerbotten," says Susanne Nigéus.

A common remidiation method is to cover the waste with a compacted layer of clayey till. This prevents water and oxygen from reaching the mining waste, which prevents oxidation. Since 2009, green liquor dregs, a residual product from the pulp industry, have been investigated at Luleå University of Technology as an additive to improve the natural till if the clay content is not sufficient.

"Our installed instruments measure oxygen concentration, soil moisture and temperature. The purpose is to find out how much water and oxygen reaches the waste under the dirt layer and how frost penetrates through the coverage," says Susanne Nigéus.

A desirable result would be if it appears that the sealing layer is near water saturated and that the oxygen concentration is near zero. This would minimize the sulfide oxidation and leaching of metals to the ground and surface water. The first results of the experiment are expected in autumn 2018.

Susanne Nigéus

Nigéus, Susanne - PhD Student

Organisation: Soil Mechanics, Geosciences and Environmental Engineering, Mining and Geotechnical Engineering, Department of Civil, Environmental and Natural Resources Engineering
Phone: +46 (0)920 492838