High molecular weight polymers containing pendant salicylic acid groups for clarifying bayer process liquors
View Patent ↗A high molecular weight, water-soluble polymer comprising pendant salicylic acid groups and having a weight average molecular weight of at least about 2,000,000 daltons and use of the polymer for clarifying red mud-containing liquors generated in the Bayer process for the recovery of alumina from bauxite.
1. A high molecular weight, water-soluble polymer with an amide linkage to the pendant salicylic acid groups and having a weight average molecular weight of at least about 2,000,000 daltons, the polymer prepared by functionalizing a natural polymer with salicylic acid groups wherein the natural polymer is a protein or carbohydrate.
2. The polymer of claim 1 wherein the polymer was prepared by reacting a natural polymer with chloromethyl salicylic acid under Mannich conditions.
3. A method of flocculating suspended solids in a Bayer process liquor comprising adding to the liquor an effective amount of one or more high molecular weight, water-soluble polymers comprising pendant salicylic acid groups according to claim 1 .
4. The method of claim 3 further comprising hydrolyzing the polymer comprising pendant salicylic acid groups prior to addition to the Bayer process liquor.
5. The method of claim 3 , further comprising adding one or more anionic or nonionic flocculant(s) to the process stream.
6. The method of claim 5 wherein the nonionic flocculant is starch, dextran or flour.
7. The method of claim 5 wherein the anionic flocculant comprises poly (meth)acrylic acid.
8. The method of claim 7 wherein the poly (meth)acrylic acid is selected from the group consisting of poly(meth)acrylic acid, poly(meth)acrylic acid containing pendant hydroxamic acid groups, poly (alkyl (meth)acrylate), (meth)acrylic acid/alkyl (meth)acrylate copolymers, (meth)acrylic acid/acrylamide copolymers, (meth)acrylic acid/acrylamide copolymers containing pendant hydroxamic acid groups, (meth)acrylic acid/acrylamide/alkyl (meth)acrylate terpolymers, and (meth)acrylic acid/acrylamide/AMPS terpolymers.
9. The method of claim 7 wherein the anionic flocculant is added prior to the polymer comprising pendant salicylic acid groups.
10. The method of claim 7 wherein the anionic flocculant is added after the polymer comprising pendant salicylic acid groups.
11. The method of claim 7 wherein the anionic flocculant is added together with the polymer comprising pendant salicylic acid groups.
12. The method of claim 7 wherein the polymer comprising pendant salicylic acid groups has an RSV of at least about 14 dL/g and the anionic flocculant has an RSV of at least about 21 dL/g.
13. The method of claim 1 wherein the Bayer process liquor is selected from settler feed, settler overflow, digestion blow-off, mud washer in the washer train, feed to the primary polishing filters, feed to a mud settler, feed to the primary alumina crystallization tanks, feed to the secondary and tertiary alumina classifers or trays, feed to hydrate filters or feed to a centrifuge.