Abstract: Flocculating agents for the selective flocculation of ultrafine granulometry titanium and iron ores suspended in water, said agents being made up of polymeric or copolymeric compounds containing as the monomeric units the monomers of formula I ##STR1## wherein R.sup.1 and R.sup.2, which can be the same or different, represent a --O--CHR.sup.5 --O--bridge, or two hydroxyl groups which can also be in the form of their ether or ester derivatives, and in which formula one of the symbols R.sup.3, R.sup.4 or R.sup.5 corresponds to an atomic group containing, at a position variously spaced from the substitution site, a polymerizable system which is preferably an olefinic system activated with respect to polymerization reactions, whereas the other symbols, which can be the same or different, can be hydrogen atoms or alkyl, aryl, hydroxyl, alkoxyl, hydroxyalkyl, alkoxyalkyl, haloakyl, carbonyl, carboxyl, ester, amido, nitrilo, or sulfonic groups, or halogen atoms or nitro groups.