The iodine

Iodine is a solid halogen at ordinary temperatures. It occurs in nature as iodide and iodate. Seawater contains only 0.05 ppm iodine, but natural brines from oil and gas deposits have concentrations of around 130 ppm in Japan and 1,300 ppm in the USA, and marine organisms such as brown algae can contain up to 4,500 ppm after drying. In addition to these large iodine reserves, we should also mention Chile's nitrate deposits, known as "caliches", where iodine appears as a co-product of their exploitation, at an average content of around 400 ppm. Iodine is also a co-product of Chinese phosphates.

From the caliche, the iodine is leached and recovered by flotation, extraction in kerosene and blowing out process.

Iodine is recovered from brines by air blowing or resin separation.

For phosphate ores, iodine is volatilized during calcination and recovered by absorption in a sodium solution.

Chile and Japan dominate the world iodine market, although there are a dozen other producing countries.

Iodine has many uses. It is used in medicine, in the pharmaceutical industry, in the food industry, in industrial catalysis, etc.

Throughout the dossier, contents are given on a mass basis.

Remember that 1 ppm = 1 part per million, in this case 1 g/t.