Anion exchange resins mineral processing

To complete the deionization process, water from the cation unit is passed through a strong base anion exchange resin in the hydroxide form. The resin exchanges hydrogen ions for both highly ionized mineral ions and the more weakly ionized carbonic and silicic acids according to1,2 ... 

Even in this case, the use of a hybrid process combining NF, IE, and ED appears to improve the economics and performance of the tartaric stabilization of wines. For instance, Ferrarini (2001) proposed to split raw wine into a retentate and permeate by NF. The permeate, being richer in minerals, was processed by using in sequence cationic and anionic exchange resins and ED to reduce its potassium, calcium, and tartrate ion contents. By recombining the de-ashed permeate with the NF retentate, Ferrarini (2001) asserted to obtain a stabilized wine retaining almost all the flavor and aroma compounds originally present in raw wine. 

The cation exchange step is exactly as described for the Strong Acid Cation (SAC)-Strong Base Anion (SBA) process but now the acidic cation column effluent passes down a column of weakly basic anion exchange resin. The strong mineral acids are taken up by the anion resin through addition to form the acid salt forms, whilst the too weakly acidic dissolved carbon dioxide and silica pass through unaffected (Chapter 4). 

Naturally occurring minerals called zeolites have long been known to be capable of trading cations in their rather open crystalline lattice for others present in a solution in contact with the zeolite. This is an example of ion exchange, which has become a very popular separation process, particularly since, some 55 years ago, synthetic resins which are capable of exchanging cations or anions were developed. These synthetic resins have considerably more exchange capacity than the zeolites, which they almost totally replaced. 

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