Use for ore beneficiation, of at least one compound of general formula: wherein: - R 2 is chosen from the group consisting of: - a direct bond, - a C 1 -C 20, linear or branched, saturated or unsaturated hydrocarbon chain optionally substituted by one or more -OH group(s), preferably an alkylene radical of formula - (CH 2) z -, in which z is an integer from 1 to 20, preferably from 1 to 10, preferably from 2 to 6, and most preferably 4, a substituted alkylene radical wherein said alkylene radical is substituted by 1 or 2 -OH groups, an alkenylene radical having from 1 to 20, preferably from 1 to 10 carbon atoms, a substituted alkenylene radical, wherein said alkenylene radical is substituted by 1 or 2 methyl and/or methylene groups, - a cycloalkylene, - a cycloalkenylene and - an arylene group, - R 4 is chosen from among a hydrocarbyl group having 8-24 carbon atoms, preferably 12 to 24 carbon atoms and a group of formula R 6 -O-(A'O) w -T-, wherein R 6 is a hydrocarbyl group having 8-24 carbon atoms, preferably 12 to 24 carbon atoms, w represents an integer ranging from 0 to 20, preferably from 0 to 10 and more preferably from 0 to 3, A'O is an alkyleneoxy group containing 2-4 carbon atoms; T is alkylene with 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms, most preferably 2 or 3 carbon atoms, - R 5 is a hydrocarbyl group, preferably a C 1 -C 4 alkyl group, or the benzyl group, - X is any leaving group known in the art using alkylating agents, and preferably X is generally chosen from among halogens, sulphates, carbonates, - AO is an alkyleneoxy group containing 2-4 carbon atoms, preferably 2 carbon atoms, - n represents an integer of between 1 and 20, more preferably between 1 and 10, even more preferably between 1 and 6, limits inclusive, - t is 0 or 1, - y is 0 or 1, - p ranges from 1 to 15, preferably from 1 to 10, more preferably from 1 to 5, - G represents a group of formula in which B is chosen from alkyl having 1-4 carbon atoms and benzyl, s is 1, 2 or 3, preferably 2 or 3, and R 5, X, and t are as defined above, and wherein the group - (CH 2) s - is a spacer between the two nitrogen atoms to which it is linked. - R 2 is chosen from the group consisting of: - a direct bond, - a C 1 -C 20, linear or branched, saturated or unsaturated hydrocarbon chain optionally substituted by one or more -OH group(s), preferably an alkylene radical of formula - (CH 2) z -, in which z is an integer from 1 to 20, preferably from 1 to 10, preferably from 2 to 6, and most preferably 4, a substituted alkylene radical wherein said alkylene radical is substituted by 1 or 2 -OH groups, an alkenylene radical having from 1 to 20, preferably from 1 to 10 carbon atoms, a substituted alkenylene radical, wherein said alkenylene radical is substituted by 1 or 2 methyl and/or methylene groups, - a cycloalkylene, - a cycloalkenylene and - an arylene group, - a direct bond, - a C 1 -C 20, linear or branched, saturated or unsaturated hydrocarbon chain optionally substituted by one or more -OH group(s), preferably an alkylene radical of formula - (CH 2) z -, in which z is an integer from 1 to 20, preferably from 1 to 10, preferably from 2 to 6, and most preferably 4, a substituted alkylene radical wherein said alkylene radical is substituted by 1 or 2 -OH groups, an alkenylene radical having from 1 to 20, preferably from 1 to 10 carbon atoms, a substituted alkenylene radical, wherein said alkenylene radical is substituted by 1 or 2 methyl and/or methylene groups, - a cycloalkylene, - a cycloalkenylene and - an arylene group, - R 4 is chosen from among a hydrocarbyl group having 8-24 carbon atoms, preferably 12 to 24 carbon atoms and a group of formula R 6 -O-(A'O) w -T-, wherein R 6 is a hydrocarbyl group having 8-24 carbon atoms, preferably 12 to 24 carbon atoms, w represents an integer ranging from 0 to 20, preferably from 0 to 10 and more preferably from 0 to 3, A'O is an alkyleneoxy group containing 2-4 carbon atoms; T is alkylene with 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms, most preferably 2 or 3 carbon atoms, - R 5 is a hydrocarbyl group, preferably a C 1 -C 4 alkyl group, or the benzyl group, - X is any leaving group known in the art using alkylating agents, and preferably X is generally chosen from among halogens, sulphates, carbonates, - AO is an alkyleneoxy group containing 2-4 carbon atoms, preferably 2 carbon atoms, - n represents an integer of between 1 and 20, more preferably between 1 and 10, even more preferably between 1 and 6, limits inclusive, - t is 0 or 1, - y is 0 or 1, - p ranges from 1 to 15, preferably from 1 to 10, more preferably from 1 to 5, - G represents a group of formula in which B is chosen from alkyl having 1-4 carbon atoms and benzyl, s is 1, 2 or 3, preferably 2 or 3, and R 5, X, and t are as defined above, and wherein the group - (CH 2) s - is a spacer between the two nitrogen atoms to which it is linked.