Aluminium production rises; research is in full swing for recycling 150 tonnes of red mud

Many experiments with red mud have been performed till date all around the globe for its reuse in a more efficient and sustainable way. Red mud is a toxic by-product generated in the industrial production of alumina. It is rich in iron and considered as a treasure trove of elements.

With an annual generation of about 150 tonnes of red mud during bauxite to alumina production, more and more scientists are getting involved in examinations for its reuse in metal industry. In the recent time, some scientists at an experimental metallurgy plant in Aachen in Germany are also pursuing an experiment on the same. Mixed with carbon and then melted at high temperatures, the scientists are striving to prepare the red mud for reusing it in the steel industry.

Bernd Friedrich, a metal recycling expert at the IME-institute for process metallurgy and metal recycling said, "Of course we are interested in the value of these metals inside the Red mud. Firstly, there is a bit of aluminium, iron, scandium - a high technology metal - maybe titanium, and also other metals which are rare earth minerals."

He at the same time added that this is just a beginning of the challenge - "In order to recover the iron, we must use very high temperatures, so that the metal melts. We must work with the waste in many different states, dry, hot, acid, alcaline. Our research aims to optimise techniques in order to find the right way to recycle Red mud."

Many other scientists around the world are inventing more innovative ways to recycle this waste product. Such as, in Leuven in Belgium, red mud is heated at a slightly lower temperature of around 1300 degree centigrade.

Scientists from one European research project have also come up with some creative solutions. "At this lab furnace we melt the waste. Once that metal waste has melted, we cool it down in a bucket. The final product we recover is similar to glass, and it can eventually be used as a reactive substance for making construction materials, for instance," said mineralogist Tobias Hertel.

He further said that at first they closely analyse the resulting material to accurately determine its internal composition. "We can have an exact quantification of which elements are in it, and also at which concentration," explained metallurgical engineer Annelies Malflict, adding: "We can go up to really low concentrations of elements like silicon, aluminium, calcium, sodium, oxygen that are in it.''

Followed by the above process, they grind the red mud glass and then mix it with sand and graphite to produce construction materials like bricks, light weight aggregates, or even roof or floor tiles.

Ioannis Pontikis, a chemical engineer at the Catholic University of Leuven who is also the institution’s red mud project coordinator also opined in respect to the experiment, "For us it is important that we minimise the global carbon dioxide production. And not only that. We also have an eye at the global, wider environmental footprint (of the process). These products are more green in the sense that we have been using only residues and we want to do it without compromising properties, both mechanical and physical properties.''

With the incessant progress of the experimental project, researchers are in hope that their joint efforts will increase red mud recycling five-fold in the upcoming decade.