Investigation of ferrous conglomerate particles found in carwash slurry and their environmental implications

Ferrous particles are usually found in atmospheric particulate matters due to the cars chassis oxidation. These particles are able forming conglomerates with the other mineral particles. Thus, the investigated carwash slurry (CS) reveals a high mineralized composition dominated by Quartz, Calcite and clay minerals with significant amount of iron hydroxides. We found some unusual bigger particles of ferrous conglomerate (FC) into the CS sample. XRD and mineralogical microscopy (MOM) reveal that FC sample is formed by a nanostructured mixture of 56 wt.% Calcite and 44 wt.% Goethite. SEM images and EDS spectra reveal submicron particles within the FC structure with a dense mixture of Ca and Fe. FTIR investigation reveal strong absorption bands for goethite and very weak ones for Lepidocrocite within the FC sample. The results indicates that the conglomerate weas formed on the car chassis rust by wet partial dissolution of calcite that locally forms Ca(OH)2 which further is re-crystallized as calcite due to the CO2 from the combustion gases. Fine crystallites of iron hydroxides are embedded into the re- crystallized calcite. In conclusion, the magnetic selection is recommended for the ferrous conglomerate particles removal from CS to be used as natural coverage for of urban dump sites rehabilitation. Keywords: Particulate Matters, ferrous conglomerate, environment