Molten Metal Hybrid Filter System For High-purity Metals

2023 Author: Hannah Pearcy | [email protected]. Last modified: 2023-11-26 11:39

In Collaborative Research Center 920, scientists from the TU Bergakademie Freiberg have developed a new process for the production of molten metal hybrid filters. With the patented technology, different impurities and non-metallic inclusions can be removed from molten metals. Components cast from it become safer and more resistant.

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In the manufacturing process of metallic cast materials, there are many different contaminants in the melt that are difficult to remove metallurgically or not at all. The size, type and distribution of such non-metallic inclusions can significantly influence the mechanical properties of the metals. But how can these inclusions be removed from the molten metal? Intelligent ceramic filter materials or filter systems are one option. The inclusions are retained on the filter surface or separate inside the filter.

The Collaborative Research Center 920

In the Collaborative Research Center 920 "Multifunctional Filters for Metal Melt Filtration - A Contribution to Zero Defect Materials", the scientists at the TU Bergakademie Freiberg are developing new intelligent filter materials and filter systems as well as new model-supported filter designs for cleaner metal melts.

Cleaning efficiency of up to 95 percent

The materials scientists at the TU Bergakademie Freiberg have now developed a hybrid filter system that will increase filtration efficiency and in the future will also remove inclusions with different chemical compositions from molten metals. With the patented process, at least two ceramic, differently coated filter materials filter the molten metal more efficiently. So far, the filtration efficiency has been less than 90 percent for inclusion particles in the size range 1 to 100 µm.

In the hybrid filter system, the molten metal only comes into contact with reactive filters that generate gas bubbles in the molten metal in situ or activate gas bubbles at the inclusions and contribute to a kind of flotation of the inclusions. The high reactivity and the gas bubbles promote the agglomeration of the fine inclusions, so that the larger clusters of inclusions either move towards the slag surface of the melt due to buoyancy forces or on active, non-gas-forming, active filters with functionalized filter surfaces - with a chemistry similar to that that of the inclusions - have them removed by filtration processes.

This enables a high cleaning efficiency of more than 95 percent to be achieved. With the new process, the melt becomes cleaner and the quality and resistance of components cast from it are increased. This reduces the rejection rates on the part of users and processors and also opens up new possibilities for recycling metals.