Holistic Recovery of Recyclable Materials from Rolling Slags

Time span

From 01.01.2023 to 31.12.2025



Project type

Holistic Recovery of Recyclable Materials from Rolling Slags

In the Waelue project, the potential for recyclable materials from a rolling slag is to be fully exploited. Rolling slag is a product that accumulates during the recycling of galvanized steel scrap, especially from the automotive industry. During recycling, fly ash containing heavy metals (Zn and Fe, but also Pb) is produced, which is reprocessed using the rolling process. In this process, approx. 90% of the zinc contained can be recovered. Iron and other minor constituents are transferred to the so-called rolling slag. For each ton of flue dust, the rolling process produces approx. 650 kg of a rolling slag (approx. 2 million t/year worldwide). Further utilization of the very iron-rich rolling slag is problematic due to the remaining heavy metal content, which is why it is currently landfilled.

Due to the complex chemical and mineralogical composition, it is not possible to purify the rolling slag using metallurgical processes at moderate temperatures. For this reason, the Waelue project will use smelting reduction in a high-temperature furnace (e.g. plasma furnace) as a recycling method for a rolling slag. The resulting products are pig iron, a residual slag and a zinc-rich flue dust. In the sense of the circular economy, all resulting products are to be reused. The energy costs incurred during the remelting process are offset by the production of marketable products. The resulting pig iron can be used in the steel industry and zinc is recovered as a product from the flue dust. An alkali-activated binder (AAB), for the production of chemically resistant manhole bases, is to be produced from the residual slag. The use of AABs opens up new fields of application and at the same time can make a significant contribution to reducing CO2 emissions.


Helmholtz Institute Freiberg for Resource Technology

Prof. Dr. Ajay Patil

+49 351 2604411






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