But this is rarely the case, a large proportion of the mined gold is so-called "invisible gold” enclosed in sulphide minerals which may contain arsenic, copper and other heavy metals. Extracting gold in these cases, cyanide leaching is used to dissolve minerals that enclose the gold. This could mean that high levels of arsenic and heavy metals are being contained in the residue (tailings) from the gold extracting process. Oxidation of sulfide minerals in contact with water could form an acidic leachate (called Acid mine drainage) containing high levels of heavy metals. A major environmental challenge concerning gold extraction processes from sulphide mine ores is therefore, to prevent the spread of cyanide, arsenic and heavy metals into the surrounding environment.
The SUSMIN-project identifies and evaluates environmental impacts and economical challenges of gold mining in EU. The objective of the SUSMIN-project is to increase the transnational cooperation and to support environmentally, socially and economically sustainable gold production within EU to decrease import dependency.
Roger Hamberg, a PhD student in Applied Geology at Luleå University of Technology, is working with other researchers in the EU to reduce the environmental impact of gold mining processes.
– My research concerns the remediation of tailings from gold mining processes, where cyanide has been used. In my project we mix tailings with cement by using a method called "Cemented paste backfill" (CPB). In CPB, mixtures of tailings and cement form a solid mass, and focuses on being a geotechnical support to underground mine cavities increasing operational benefits for the mining industry. The environmental effect of CPB, in particular effects on the mobility of arsenic has not been subject to extensive research. This is what my research more specifically targeting, says Roger Hamberg.
The project is funded by the Ramboll Foundation, SUSMIN -Tools for sustainable gold mining in the EU, Norrbotten Research Council and the Centre of advanced mining and metallurgy (CAMM). Scientists from Finland, Ireland, Portugal, Poland, Romania and Sweden are included in the cooperation.
– Gold will always be a desirable and valuable material, therefore, more sustainable mining practices will be required in the future, says Roger Hamberg.