Method for dewatering starch slurries containing swollen starch granules

Claim 2

In a process for the washing of starch conversion products containing swollen starch granules in a continuous centrifugal device, the improvement which comprises adding to the starch slurry 0.1 to 1%, based on weight of starch solids, of a cationic polymer which is a water-soluble acid salt of an aminoalkyl ester of a carboxylic acid polymer thereby increasing the production rate and yield while reducing suspended solids in the effluent.

Claim 3

The process of claim 1 wherein the carboxylic acid is selected from the group consisting of aminoalkyl esters of (a) a homopolymer of a homopolymerizable unsaturated carboxylic acid having 3 to 5 carbon atoms, (b) a copolymer of a copolymerizable mixture of unsaturated carboxylic acids having 3 to 5 carbon atoms, and (c) a copolymer of at least one of said acids having 3 to 5 carbon atoms and at least one copolymerizable ethylenically unsaturated comonomer selected from the group consisting of vinyl acetate, vinyl propionate, vinyl methyl ether, vinyl ethyl ether, the C 1 -C 18 alkyl half esters of maleic and fumaric acids, amides of acrylic and methacrylic acids and the C 1 -C 18 alkyl and C 2 -C 4 hydroxyalkyl esters of acrylic and methacrylic acids, wherein the copolymers of group (c) are prepared with at least 50 mole percent of the unsaturated carboxylic acid component.

Claim 4

The process of claim 1 wherein the water-soluble acid salt of a carboxylic acid polymer is the nitrate salt of the aminoethyl ester of a terpolymer of acrylic acid, hydroxypropyl acrylate, and acrylamide.

Claim 5

The process of claim 1 wherein the water-soluble acid salt of a carboxylic acid is the nitrate salt of poly(aminoethyl acrylate-hydroxypropyl acrylate).

Claim 6

The process of claim 1 wherein the water-soluble acid salt of a carboxylic acid polymer is added in an amount of 0.2 to 0.6%.