| abstract |
Sand or rock masses containing mineral oil are deoiled with a deoiling agent containing an aqueous solution of a water-soluble copolymer which is a random distribution of 5 to 60% of weight of units of the formula <IMAGE> 2 to 40% by weight of units of the formula <IMAGE> 38 to 93% by weight of units of the formula <IMAGE> and partial hydrolysates thereof, wherein when R1 is hydrogen, R2 is hydrogen, methyl or ethyl, Y is -CO-NH-C(CH3)2-CH2- or a direct bond, and X(+) is a cation; when R1 and R2 are identical or different, each is hydrogen, methyl, ethyl or, together are trimethylene, Y is -CO-NH-C(CH3)2-CH2- and X(+) is a cation. |