Bridging the gap between engineering and geology, the aim of minerals engineering is to provide a better recovery in terms of the exploitation of deposits. Mineralogists from Liege and Madrid have specialized in the quantitative analysis of digital microscopic images. The objective is to better understand the intergrowth textures of the different minerals in the same rock. These techniques make it possible not only to understand how to better liberate the minerals captured in the rock for a better recovery, but also to rethink the entire recycling process for used metals.
Worse than a needle in a haystack
The theory of liberation involves the separation of the different molecules in a rock. It literally consists of separating the minerals from each other. Gold serves as a good example. “In the collective imagination we think of a prospector panning for gold fragments in a river, but that was an artisanal activity practiced during the gold rushes of the 19th century”, Eric Pirard reminds us. Most gold-extraction, as is the case with other minerals, takes place in large factories that process hundreds of thousands of tons of material. With a ratio of barely 5 grams of gold to every tonne of rock “you may just as well search for a needle in a haystack. It would be easier to find a needle in fact, as it does not stick to the hay. All you need is a magnet”, the researcher adds, with irony.
(1) Pérez-Barnuevo, L., et al. Automated characterization of intergrowth textures in mineral particles. A case study. Miner. Eng. (2013), http://dx.doi.org/10.1016/j.mineng.2013.05.001