UL has joined Aughinish Alumina in a €5.2m effort to study alumina production using advanced equipment in Britain and Germany, writes Anna Nolan
Kettle fuzz and aluminium production have a lot in common. It all has to do with crystals forming in the wrong place at the wrong time. The University of Limerick is aiming to develop world-class expertise in this area with the opening of a new centre devoted to research on the production of alumina.
Fifteen post-graduate and post-doctoral researchers are already working full-time on alumina-related matters. Over the next few years the numbers should rise to 25 or more, says UL's Prof Kieran Hodnett.
The centre is backed by funding from Aughinish Alumina Ltd which is to invest €5.2 million over five years. The new support builds on an existing investment of €15 million by the Higher Education Authority at UL under the Programme for Research in Third-Level Institutions.
"We are just in the initial phase," says Hodnett, who is professor of chemical and environmental sciences in the Materials & Surface Science Institute (MSSI) at UL. "It is an ambitious programme and we are not afraid to think big."
Hodnett, an expert in crystal research, was the founding director of MSSI. He recently handed over this directorship in order to concentrate on other aspects of his work.
Based in Limerick, the Aughinish refinery extracts about 1.5 million tonnes of alumina from imported bauxite each year. The alumina is then exported to aluminium smelters to be converted into aluminium.
Gibbsite, the form of alumina extracted, is a crystalline substance, and this is where Hodnett's expertise comes into play. The research he is leading involves improvements in the processes used to produce alumina.
"Bauxite contains 50 per cent alumina, and it is important to extract every bit in order to minimise waste," he explains. "And scale formation, similar to that inside a domestic kettle, is a big problem, particularly in crucial places such as plant pipework." The scientific challenge is that the crystallisation process that produces the welcome bauxite also produces the unwelcome scale.
The first stage in crystallisation is called nucleation, and this is followed by rapid growth. "It is relatively easy to disrupt nucleation, but difficult to disrupt growth," says Hodnett.
An important part of the Aughinish process is subjecting a mixture of bauxite and lime to high temperatures and pressures inside a large container known as a reactor or digester. "The kinetics of reaction inside the reactor are not known, and we can't put probes in to find out because the environment inside is corrosive," he said.
The X-ray synchrotron facilities at Daresbury in the UK are to be used to get round this problem. Hodnett's group has been allocated time there in July and again in September. And in October, they have time at a synchrotron in Berlin.
One of the main advantages of using X-ray synchrotron facilities is chemical reactions can be monitored very quickly. In the plant, the chemical process takes about 20 minutes inside a 15 metre-high reactor. This 20 minutes is not long enough to study the process using conventional means.
Instead, a miniature mock-up with walls that are strong but thin enough to allow the X-rays to penetrate is being prepared by UL for use at the synchrotrons. It will hold just 50 millilitres of fluid, but the work is expected to produce very large amounts of research data.
Hodnett's work on crystallisation is proceeding alongside computer simulations led by Dr Patrick Frawley and Dr Andrew Niven, both of the John Holland Research Centre at UL. Their sophisticated computer-based modelling of fluid flows within the plant has already led to maintenance improvements at Aughinish.
The researchers plan to marry the crystal work and the fluid dynamics work. "This is a completely new development in the field," says Hodnett.