The present invention relates to a process for enriching an iron mineral from a silicate-containing iron ore by reverse froth flotation of the ore using a collecting composition comprising: a) a compound of formula R1O-A-NH(CH2)nNH2 (I), wherein R1 is a straight or branched hydrocarbyl group with 12-15 carbon atoms, A is a group —CH2CHXCH2—, wherein X is hydrogen or a hydroxyl group, and n is a number 2-6; b) a compound of formula R2NH2 (II), where R2 is a hydrocarbyl group having 12-14 carbon atoms; c) a compound of formula R3NH2 (III), wherein R3 is a straight or branched, saturated or unsaturated hydrocarbyl group having 16-22 carbon atoms; and d) optionally a depressing agent for the iron mineral, wherein the amount of a) is at least 65% by weight, based on the total weight of a), b) and c), and at most 90% by weight, based on the total weight of a), b) and c), and wherein the weight ratio between c) and b) is 4:1 to 1:1.