Granted Patent B2

US 7,264,729 · App. 11/143,914 · Granted Sep 4, 2007

Abstract

Claims (13)

1. A process for reducing contaminants in contaminated condensate resulting from the refining of aluminum, which comprises:

(a) adding from 1 ppm to 1,000 ppm of a cationic melamine formaldehyde coagulant having a having a mean diameter of from about 1 micron to about 25 microns to the condensate to be treated;

(b) then adding from 1 ppm to 1,000 ppm of a cationic mannich-tannin coagulant having a mean diameter of from about 40 microns to about 200 microns;

(c) filtering said condensate with a continuous-backwash, fluidized bed upflow filter

wherein the media of the fluidized bed develops a negative charge, and the temperature of the treated condensate is from 80° C. to 100° C., to reduce said contaminants in said condensate.

2. The process of claim 1 wherein the condensate is generated in production of alumina from bauxite ore.

3. The process of claim 2 wherein the production alumina from bauxite ore is the Bayer process.

4. The process of claim 3 wherein the condensate is selected from the group consisting of digestion condensate, evaporator condensate, and clean condensate from surface condensers.

5. The process of claim 4 wherein the condensate is clean condensate from surface condensers.

6. The process of claim 5 wherein the condensate is recycled in the Bayer process for converting bauxite ore to alumina.

7. The process of claim 6 wherein the condensate is further purified by demineralization with ion exchange, reverse osmosis, evaporation, partial demineralization, decarbonation, degassification, and/or mixed bed demineralization.

8. The process of claim 7 wherein the condensate is clarified after coagulation and prior to filtering.

9. The process of claim 1 , 2 , 3 , 4 , 5 , 6 , 7 , or 8 wherein the condensate is clarified by passing the condensate through a lamella separator.

Assignments (25)