Solidification/stabilization of an extremely heavy metals rich industrial side stream with ettringite-rich solid binders

The correct treatment is important when disposing of industrial waste that contains heavy metals. Otherwise, the harmful components can escape and pollute the environment. One common way to prevent this is mixing harmful solid waste with cement, which is then made solid with water to trap the harmful components within. In this PhD thesis study cement was replaced with substituting materials such as ladle slag from steelmaking. Finding replacements for cement is a current research topic due to the large carbon footprint of cement production. The replacing materials chosen for this study have smaller carbon footprints, and they offer the possibility to utilize industrial side products as raw materials instead of using natural resources for waste management.

The materials were tested by mixing them with a solid waste material that contains several heavy metals in high concentrations. The leaching of the heavy metals from the final product was measured and compared to the limit values defined for landfilled waste in the Finnish legislation (331/2013). The results show that the studied materials are suitable for treating harmful solid industrial waste. The provides new options for both management of harmful solid industrial waste and commercial utilization of industrial side products.