New recycling method is worth its salt

A new method to recycle the salty water produced by coal mining could benefit both the mining industry and the environment, according to an award-winning paper by Professor Alison Lewis, head of UCT's Crystallisation and Precipitation Unit in the Department of Chemical Engineering, and recent recipient of the NRF's Champion of Research Capacity Development award.

Lewis was awarded the Best-Paper prize at the Water in Mining Conference held in Perth, Australia by the Australasian Institute of Mining and Metallurgy and the Sustainable Minerals Institute.

Co-authored by PhD researchers Dyllon Randall and Sarashree Reddy, master's student Rinesh Jivanji and research officer Jeeten Nathoo, the paper proposes a protocol methodology for testing the technical and economic feasibility of eutectic freeze crystallisation (EFC) for South African coal mines.

Nathoo explains that briny water produced in mining is often dumped into drainage areas, where the water evaporates, leaving its minerals behind. The EFC method retains the water and recycles the extracted salts.

The result is not only pure, drinkable water, but also pure salts that can be resold rather than dumped.

And the process consumes about one sixth of the energy of the current process.