초록 ▼

In one aspect, the invention includes a method of purifying phosphoric acid comprising filtering a feed solution of phosphoric acid through a membrane, wherein the feed solution is maintained at a temperature of from about 30.degree. F. to about 90.degree. F. during the filtering. In another aspect,

In one aspect, the invention includes a method of purifying phosphoric acid comprising filtering a feed solution of phosphoric acid through a membrane, wherein the feed solution is maintained at a temperature of from about 30.degree. F. to about 90.degree. F. during the filtering. In another aspect, the invention includes a method of purifying phosphoric acid comprising: a) providing a feed solution of phosphoric acid, said feed solution comprising greater than 17,000 ppm on a 100% P.sub.2 O.sub.5 basis of each of Al, Fe and Mg; and b) filtering the feed solution through a polyamide filter configured for nanofiltration, the filtering comprising a temperature of from about 30.degree. F. to 90.degree. F., and a pressure of from about 600 psig to about 1000 psig to form a purified phosphoric acid solution, the purified phosphoric acid solution comprising less than 1700 ppm on a 100% P.sub.2 O.sub.5 basis of each of Al, Fe and Mg.

대표청구항 ▼

[ New claims:] [1.] A method of purifying phosphoric acid by nanofiltration while prolonging the life of a nanofiltration membrane comprising passing a solution which contains the phosphoric acid through the nanofiltration membrane at a temperature of from about 30.degree. F. to about 90.degree. F.;

[ New claims:] [1.] A method of purifying phosphoric acid by nanofiltration while prolonging the life of a nanofiltration membrane comprising passing a solution which contains the phosphoric acid through the nanofiltration membrane at a temperature of from about 30.degree. F. to about 90.degree. F.; the nanofiltration membrane having a longer useful life than it would if the temperature of the solution was greater than or equal to 110.degree. F.