Applications to Waste and Recycling
Applications of Thermo-Calc to waste and recycling include predicting the following:
Application Examples
Reducing Fe Content in Al Scrap through the Addition of Mn
Scrap melters have to deal with ever-increasing levels of undesirable elements and impurities. An important issue in recycling Al scrap is to control such impurities, especially Fe, which may lead to the formation of detrimental phases, such as β-Al9Fe2Si2. One approach is to add Mn (sometimes with Cr) to form Fe-containing α-Al15Si2Mn4, which suppresses the formation of the detrimental phases and can be separated from the melt.
Thermo-Calc can be used to understand the chemical reactions and predict the Mn addition and processing temperature. The figure shows that adding Mn to scrap reduces the Fe content but increases the Mn content. The optimal Mn addition can be determined based on a compromise, which depends on the desired alloy composition.
Optimizing Flux Composition for Efficient Aluminum Recycling
In recycling operations, impurities such as Na and Ca are frequently introduced through scrap, dross, or contaminated charge materials. Thermo-Calc can be used to study how the flux composition influences element reduction.
In this example, the Ca and Na reduction in an Al-4.5% Mg melt with an initial amount of 200ppm Ca and 200ppm Na for a KCl-MgCl2 flux is presented. By increasing the MgCl2 content in the flux, you can remove the Ca and Na from the Al melt (top figure) and simultaneously maintain the Mg content (bottom figure). The calculations were performed by combining the TCSALT: Molten Salts Database with the TCAL: Aluminium-based Alloys Database.
With such an approach, users can simulate different recycling scenarios and design fluxes that enhance recovery rates, reduce flux consumption, and lower the amount of salt slag waste generated.
