Collaboration between the Coal Authority and the Department of Geography to reduce the cost of mine water treatment

The Coal Authority has joined forces with scientists from the University of Sheffield in an innovative trial geared to saving money in its treatment of mine water.

Each week the authority, which manages Britain’s coal mining legacy, has to use contractors to clean the water cascades and pipework at its 75 sites across the country that treat water pumped from redundant coal mines.  The regular costly ‘wash and brush-ups’ are needed to prevent the build-up of ochre – iron solids - on the infrastructure of the individual treatment schemes.

Now, in a move to reduce those costs, the authority is working with the Dr Maria Romero-Gonzalez and her research group in the Department of Geography at the University of Sheffield in a 6 month trial of new super hydrophobic materials that will hopefully repel the ochre and prevent it sticking and subsequently reducing the effectiveness of the schemes.

Dr Maria Romero-Gonzalez, Director of the Environmental Science Programme at the University of Sheffield, said:

This is a unique opportunity to study the durability and performance of the coatings under a variety of weather conditions. We will use electron microscopy and other surface analysis techniques to investigate the efficiency of the coatings at surface level. This will help us to assess how good the coating is and evaluate its application for treating ochre accumulation. The results will allow us to estimate the technical and economic benefits of using coatings for cleaning mine water, providing the Coal Authority with innovative solutions for treating water.

“Hydrophobic materials are nothing new,” explained Dr Chris Satterley, Technical Research and Development Manager for the Coal Authority. “But the most recent generation of super hydrophobic materials are now available commercially and we want to see whether they will help us to make valuable savings at our schemes.  Currently it costs us a lot of money to regularly clear up the build-up of ochre, which, if left, obstructs the process of the schemes. But if this simple process works, it could be a significant development for our on-going maintenance.”

Various hydrophobic materials were tested in laboratory conditions by Maria and her team; two were selected to be used on site at the mine water treatment scheme at A-Winning in Derbyshire.

“It worked very well in the laboratory but now we need to see if it is just as effective out in the open and on site,” added Chris. “Initial observations show that the coating is working and is repelling large solids and ochre flocs. But it is still early days and we will be working closely with our University of Sheffield colleagues to see how it works over a longer period of time.”

The mine water treatment schemes run by the authority are all individual and depend on the amount of water being pumped out of disused pits and the local geology. Typically, they comprise water cascades, a series of settlement lagoons, and drying and reed beds. They treat some 122 billion litres of water each year and also prevent some 4,000 tonnes of iron solids from entering local water courses and polluting important sources of drinking water for local communities.