Processes enabling metal and phosphorus recovery from steelmaking slag

Purpose and goal:

Metals and phosphorus from non-point pollution sources and emission points such as mine ponds were the focus of this project.

The aim was to show the potential of extracting metals and phosphorus from metallurgical slags that were used as filter material/sorbent in water purification through nanofiltration. The goal was also to prepare three ground test slags with magnetite and binder so that granules could be produced. This objective was obtained and the materials could be tested on a lab scale as a feasible way to bind leaching metals and phosphorus from sediments in ponds or lakes.

Expected results and effects:

Contaminated lake sediments also spiked with phosphorus (P) and metals (Me) were incubated with manufactured and modified slag granules (MSG). Pyrolysis to so-called biogeochar was successful, extraction and nanofiltration was performed on granules that had been in contact with P and Me leaking sediments. Magnetite, 10%, was sufficient addition to MSG to be able to separate these from sediment.

We are preparing a publication with an overview of the research area and results from this pre-study. Approach and implementation:

The project was carried out in four work packages, each project partner responsible for his area but in collaboration with the project manager. Pyrolysis furnace and nanofiltration as well as lab equipment for granulation and incubation experiments were available and accounted for most of the own effort. However, we carried out the effort with technical problems during the pyrolysis and the production of granules in two grain sizes between 1-4 mm.

However, the results were good and should be able to be used as a starting point for scaling up to full-scale trials.