EU project explores recovering ultrafine particles of raw materials

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The FineFuture project, a consortium of 16 partners from industry and science, is to look at the flotation phenomena used to separate out vital raw materials and to research and develop new technological solutions.

Critical raw materials such as copper, cobalt, and rare earths are of strategic importance to the European economy, but the ore grain size of many of these metals are too small to be separated using the standard process of flotation.

The FineFuture project will look to develop new technological solutions for this process. The three-year project has received over €6.2million in funding from the EU and will be coordinated by Helmholtz-Zentrum Dresden-Rossendorf (HZDR).

Europe currently accounts for just three percent of global mine production but with rising prices and the growing global demand for strategically important, technologically interesting metals deposits, previously considered uneconomic to mine, are now becoming the focus of the mining industry: these low concentrated ores are finely dispersed in the rock, meaning that tremendous technological effort is required to recover them.

“The issue of raw materials can only be addressed at the European level,” emphasised Professor Kerstin Eckert from the Institute of Fluid Dynamics at HZDR, which is coordinating the whole project: “With the consortium’s combined expertise, we have the chance to make substantial improvements in the yield and recovery rate.”

The FineFuture project involves cooperation between partners from a total of eleven countries; their aim is to combine progressive facility design and process innovations to achieve a 30 percent higher recovery rate in the future. In addition, more efficient techniques involving fewer process steps should reduce water and energy consumption and minimize the discharge of chemicals to the environment.

“In the metals and minerals industry, froth flotation is the most important way of recovering valuable raw materials from ores,” explained Dr. Martin Rudolph from the Helmholtz Institute Freiberg for Resource Technology (HIF), which belongs to the HZDR. “However, recovery of particles below 20 micrometers in size – which is less than half the thickness of a human hair – is beyond the capabilities of current flotation technologies.” Froth flotation exploits the differences in the surface properties of mineral particles. If gas bubbles are added to a liquid with finely ground particles, the bubbles adhere to particles with a hydrophobic (i.e. water-repellent) surface. These particles, with air bubbles attached, then rise to the surface and form a froth layer, which can be skimmed off. Reagents tailored to the relevant recoverable material ensure that the “right” particles find their way into the froth.

Many fundamental questions have yet to be answered before mineral particles in the range of 0.1 to 20 micrometers can be separated on an industrial scale in the future. Such a technology would also be of major importance for recycling or for recovering raw materials from old heaps.

Research undertaken by the nine academic project partners mainly focuses on developing a better understanding of the mechanisms and microprocesses involved in fine particle flotation: two of the nine work packages concentrate on the physico-chemical and hydrodynamic aspects of processing. These include the binding mechanisms and frothing characteristics of the valuable particles, and turbulent flows in the flotation tank. The latter influence the collision frequency of particles and bubbles: adhesion is only possible when air bubbles come into contact with hydrophobized mineral particles.

The partners hope that their research results will enable them to derive approaches, such as innovative hydrodynamic concepts, that can be used to increase the probability of bubbles colliding with fine particles. This is where the know-how and technology of flotation cell manufacturers comes in. The researchers want to exploit insights into interface interactions to improve the adhesion of ultrafine valuable particles to the gas bubbles by optimizing reagents. The newly developed technologies will then be tested and optimized in simulated environments, in the laboratory, and in pilot plants.

In addition to leading European research institutions, seven companies from the areas of mining, the materials processing industry, and machinery and plant engineering are involved in FineFuture, including the Polish corporation KGHM – one of the world’s largest mining groups and copper mine operators – and three other raw materials companies.

FineFuture partners: