Stannol has completed an EU-funded project on tin recycling. As part of the project, the company commissioned an external study at the University of Rostock, in which solder samples made from primary and secondary tin were examined comparatively. The aim was to scientifically prove that primary and secondary tin do not differ from each other in terms of purity and quality.
Crystallographic examination under an optical microscope revealed no visible differences between the two variants on the prepared microsections of the samples. An etching process made the individual crystals and grain boundaries in the tin samples clearly visible. No impurities were found along the grain boundaries of either the primary or secondary tin.
The purity of the tin samples was also analyzed qualitatively using a scanning electron microscope and energy-dispersive X-ray spectroscopy by means of a mapping scan and quantitatively using point analysis with stoichiometric evaluation. The results of these analysis methods also show a high purity of the samples of both tin variants.
In the thermal analysis, only slight differences in the order of <0.5 K were found between secondary and primary tin. The slightly higher melting point of the secondary tin is somewhat closer to the theoretical literature value of the melting temperature for the pure tin. Together with a lower standard deviation of the measured melting temperature values for secondary tin compared to primary tin, this proves that secondary tin does not differ qualitatively from primary tin.
