Processes enabling metal and phosphorus recovery from steelmaking slag

Purpose and goal

The overall goal of the project is to expand the value chain for steelmaking slag used for water filtration. In this project, we will investigate the feasibility of combined processes such as leaching and nano-filtration to recycle phosphorus and selected metals by conducting experiments on a smaller scale and assessing whether the methods can be scaled up. The feasibility study aims to provide data on the extraction potential for metals, primarily zinc and copper but also earth metals and phosphorus, which were removed during water filtration in steel slag.

Expected results and effects

The significance of the developed processes can be great when the value chain is complete, i.e. the investigated steel slag can show the way how they can not only be reused in water purification but also serve as matrices for fixing metals and critical substances which can then be refined. The result of the project is expected to be that two recycling processes have been tested on a laboratory scale and based on real purification problems in society where steel slag produced for water purification purposes has been used.

Planned approach and implementation

The project is implemented in four mini-work packages. 1. Collection of filter materials used in real plants or field trials 2. Production of improved slag pellets and magnetic microparticles in aim to increase the binding of intended elements 3. Processing of sludge / sediment with pyrolysis to produce biogeochar that can either be used directly as phosphorus fertilizer or processed in a further step via leaching and concentration in the osmosis process, 4. Coupling to the previous point where membrane processes nanofiltration and reverse osmosis are used, among other things.