Chip-based high-value mineral extraction

November 2017
Researchers at the University of South Australia’s Future Industries Institute (FII) have developed a faster, cheaper, and safer way of refining high-value metals by exploiting microfluidic chip technology.

The approach has been demonstrated for platinum and rare earth elements over the last five years and now the group is scaling up to handle commercial volumes.

Recycling precious metals is often achieved by dissolving valuable waste or ore in highly acidic water, then using a specific chemical to selectively react and extract the valuable metal into an oil.

The oil containing the valuable metal is then separated from the water which carries away everything else, but thiscan be difficult because droplets are formed during mixing and coalescence, which can be slow or completely fail for complex extraction systems.

To speed things up, the team designed a new microfluidic chip which forces many streams of water and oil to flow parallel to one another, achieving rapid extraction without a slow phase separation step.

The valuable metal effectively “changes lanes” from stream to stream like traffic on a microfluidic freeway, usually within just a few seconds of contact. UniSA’s new chips allow 20 times higher throughput than previous chip designs.

“The ANFF SA facilities helped the team transition from an ‘idea’ through ‘proof-of-concept’ and now exploring higher TRL (technology readiness level) testing and manufacturing,” A/Prof Craig Priest, Project leader, Senior Research Fellow at UniSA’s Future Industries Institute, and ANFF SA Director.

Modelling of the microfluidic chip was conducted using ANFF’s Design House suite of software. The chips were fabricated in ANFF SA and Optofab laboratories using photolithography, etching, laser milling and thermal bonding of glass.

“ANFF SA’s micro-injection moulding and micromilling capabilities will be critical in the development of the next generation prototype and developing methods that are suitable for mass manufacturing,” Craig added.