Patent ID: 7311206

Claim:
A process for enriching an iron mineral from a silicate-rich iron ore by performing a reversed froth flotation of an aqueous suspension of the iron ore at a pH of 7-11 in the presence of a collector comprising at least one quaternary ammonium compound and a depressing agent for the iron mineral, wherein the collector comprises at least one quaternary ammonium compound having the formula R 1 R 1 N + R 3 R 4 1/z X z− (I), in which the groups R 1 can be the same or different and are independently selected from aliphatic groups containing 6-14 carbon atoms, or the group R 2 —(OR 7 ) m —OR 8 —, where the groups R 2 independently are acyl groups containing 6-14 carbon atoms, the groups R 7 independently are alkylene groups containing 2-4 carbon atoms, the groups R 8 independently are alkylene groups containing 2-3 carbon atoms and m is a number from 0-5, R 3 and R 4 independently are alkyl groups containing 1-4 carbon atoms, X is an anionic group, and z is the charge of the anion X, the amount of the quaternary ammonium compounds being 10-500 milligram per kg iron ore.