Use of quaternary ammonium compounds as collectors in froth flotation processes

1. A method for froth flotation of a mineral-containing ore, the method comprising contacting the ore with:

a) a product obtainable by the condensation, in one or several steps, of:

i) a compound having the formula

where R 1 is a hydrocarbyl group having 7-24 carbon atoms, which may be branched or linear, saturated or unsaturated, AO is an alkyleneoxy group having 2-4 carbon atoms, n is a number between 0 and 20, and Y is O, C(═O)NH or NZ, where Z is a group R 2 , where R 2 is a C1-C4 alkyl group, or the benzyl group, provided that when Y is NZ or C(═O)NH, then n is ≧1;

ii) a dicarboxylic acid or a derivative thereof having the formula (IIa) or (IIb)

where D is —OH, —Cl, or —OR 4 , where R 4 is a C1-C4 alkyl group; R3 is an alkylene radical of formula —(CH 2 ) z —, in which z is an integer from 0 to 10, and in which the alkylene radical may be substituted by 1 or 2 —OH groups; the group —CH═CH—, a cycloalkylene, a cycloalkenylene, or an arylene group; and

iii) an alkanolamine having the formula (III)

where each x independently is a number between 1 and 5 and Σx on average is a number between 2 and 10, AO is an alkyleneoxy group having 2-4 carbon atoms, R 5 is a C1-C3 alkyl group or a group [AO] x where AO and x have the same meaning as above;

followed by reaction with an alkylating agent R 6 X, where R 6 is a hydrocarbyl group and X − is an anion derived from the alkylating agent R 6 X; or

b) a product obtainable by the condensation of:

i) compound (I), or of a compound obtained by partial or total quaternisation of (I);

ii) (IIa) or (IIb); and

iii) a compound obtained by partial or total quaternisation of the alkanolamine (III).

2. The method according to claim 1 where the condensation product comprises a compound of the formula

where R 1 , Y, AO, n, R3, x and R 5 have the same meaning as in claim 1 ; t is 0 when Y is O or C(═O)NH, and t is 1 when Y is NZ; R 6 is a hydrocarbyl group and X − is an anion derived from the alkylating agent R 6 X; and p is a number within the range 1-15.

3. The method according to claim 2 , where more than 50% by weight of the molecules has a value of p≧3.

4. The method of claim 1 wherein the froth flotation is reverse froth flotation and wherein the ore contains silicates.

5. The method according to claim 4 , where the ore contains calcium carbonate or ferruginous minerals.

6. The method according to claim 1 , where Y is O and n=0.

7. The method according to claim 1 , where Y is NZ and n is 1.

8. The method according to claim 1 , where R3 is arylene.

9. The method according to claim 1 , wherein said dicarboxylic acid or a derivative thereof having the formula (IIa) or (IIb) is selected from the group consisting of tetrahydrophtalic acid, the acid chloride, methyl ester or ethyl ester of tetrahydrophtalic acid, and the cyclic anhydride of tetrahydrophtalic acid.

10. The method according to claim 1 , where R3 is an alkylene radical of formula —(CH 2 ) z — in which z is an integer from 2 to 4.

11. The method according to claim 1 , where R 5 is CH 3 , AO is ethyleneoxy and x=1.

12. The method according to claim 1 where the condensation product comprises a compound of the formula

where R is a linear or branched, saturated or unsaturated acyl group having 8 to 24 carbon atoms, p is on average ≧3, R 5 is a C1-C3 alkyl group, R 6 is a C1-C4 hydrocarbyl group and X=Cl, Br, CH 3 OSO 3 , or CH 3 OCO 2 .

13. The method according to claim 1 where the condensation product comprises a compound of the formula

where R is a linear or branched, saturated or unsaturated hydrocarbyl group having 8 to 24 carbon atoms, p is on average ≧3, R 5 is a C1-C3 alkyl group, R 6 is a C1-C4 hydrocarbyl group, and X=Cl, Br, CH 3 OSO 3 , or CH 3 OCO 2 .

14. The method according to claim 1 where the condensation product comprises a compound of the formula

where R is a linear or branched, saturated or unsaturated hydrocarbyl group having 8 to 24 carbon atoms, AO is an alkyleneoxy group having 2-4, carbon atoms, n is a number between 1 and 20, Z is a group R 2 , where R 2 is a C1-C4 alkyl group, or the benzyl group, p is on average ≧3, R 5 is a C1-C3 alkyl group, R 6 is a C1-C4 hydrocarbyl group and X=Cl, Br, CH 3 OSO 3 , or CH 3 OCO 2 .