[metallurgy]

If an industrial filter waste dust (https://www.researchgate.net/publication/351770119_MEROS_Dust_Quality_of_Different_Plants_and_Its_Potential_Further_Uses)  contains mainly Na2SO4, Na2CO3, NaCl, NaF and Hg, Pb, Cr, Cd, DOC, T-N, solid residues, organic pollutants, PCDD/F etc. and if we wash this dust with distilled water and then how can we mix the eluate with a compound (iron-steel slag or mill scale contains mostly FeO, Fe2O3, or Fe3O4) which contains mainly iron oxides, or how to enrich iron oxide ratio in the mix?
Should we use solid-state chemistry?