BAUSEP - separating ash and slag to manufacture resource-efficient building products

Slag discharge
© Shutterstock / PhotoChur
In the BAUSEP project, research is being conducted into how ash and slag can be separated so that it can be used to manufacture resource-efficient building products.

When it comes to resource-efficient recycling, the aim is to recover equivalent or better-quality base materials from the residues. The construction industry has a high demand for raw materials. At the same time, it produces large quantities of mineral waste in the form of leftover building materials, meaning that there is still potential for development in this regard. The use of construction waste, slag, dust and ash as sources of raw materials can make a significant contribution to conserving natural resources and ensuring the continued supply of mineral-based raw materials.

The German Federal Ministry of Education and Research (BMBF) has recognized this potential and wants to further advance closed-loop recycling in Germany. The BAUSEP project is also being funded as part of the measure “Resource-efficient circular economy - Building and mineral cycles (ReMin)”. The aim of this project is to recover secondary mineral raw materials from waste incineration ash and slag produced by the iron and steel industry and to use them to manufacture resource-efficient building products.

Project goals

In a first step, appropriate investigations in both the technical and legal fields need to be carried out to assess the potential of using processed secondary raw materials recovered from waste incineration ash and slag to make building products. Methods will initially be developed in the laboratory and then implemented in an industrial environment. The focus in BAUSEP is on paving stones and drainage segments. In addition to their manufacture, the durability of these building products will also be evaluated.

In order to establish a sustainable resource-efficient material cycle, the ability to recycle the manufactured products will then be assessed. To measure the sustainability of the new building products, all processes implemented in the project will be subjected to a life cycle assessment combined with a techno-economic analysis.

Current project status

The BAUSEP project can be divided into several work steps:

To start with, the incoming waste incineration ash and slag will be inspected, and representative samples taken.  Apart from removing coarse scrap, the chemical and mineralogical composition of the materials will also be analyzed.

Once the materials have been appropriately processed (washed, crushed, screened), they will be used to manufacture building products on a laboratory scale.

If production and durability tests are successful at this stage, the knowledge gained will be scaled up to industrial level.

The ability to recycle the manufactured building products will then be evaluated.  To do this, they will be crushed using conventional and innovative techniques and utilized to make new building materials.

The project will be accompanied by a life cycle assessment coupled with a techno-economic analysis.

Project partners

  • Fraunhofer Institute for Building Physics IBP (project coordinator)
  • bvw Steinwerk Hamminkeln GmbH & Co. KG
  • Clausthaler Umwelttechnik Forschungszentrum (CUTEC-Institut)
  • KM GmbH für Straßenbau und Umwelttechnik
  • Department for Earth and Environmental Sciences, Section for Mineralogy, Petrology & Geochemistry, Ludwig Maximilians University Munich
  • Stadtreinigung Hamburg AöR
  • thyssenkrupp MillServices & Systems GmbH