From Brines: Brines contain between 30 and several hundred ppm of (as iodide). The deposits in the USA are mainly in Michigan and Oklahoma. Extraction is similar to that of bromine. Brines are mixed with hydrochloric or sulfuric acid and oxidized with excess chlorine. The elemental iodine formed is blown out with air and absorbed in a sulfuric acid-hydroiodic acid-water mixture in an absorber. Reduction with sulfur dioxide converts the iodine into hydroiodic acid. Part of this is taken off and the hydroiodic acid oxidized with chlorine to iodine. The iodine is filtered off and dried and any organic impurities oxidized by melting under sulfuric acid.

The following equations give the individual steps:

In Japan another process is used in which the iodine formed by chlorine oxidation is absorbed as polyiodide on an anionic ion exchanger. Desorption with alkali yields concentrated iodide- and iodate-containing solutions which are worked up to elemental iodine.

From Waste Solutions in Niter Production: The Chilean niter deposits contain up to 0.3% iodine in the form of calcium iodate. After dissolution and recrystallization of the niter, the supernatant liquor contains up to 9 g/L of sodium iodate. Iodine is liberated by reduction with sulfur dioxide (in the form of sodium bisulfite), further reduction to iodide being avoided by maintaining stoichiometry:

The iodine is filtered off and purified by sublimation. The now iodide-free solution is then neutralized and reutilized for dissolving fresh niter.