Did you know that iodine is one of the most scarce elements on Earth? It can be found in small quantities in rocks, soil, plants and the sea. The biggest problem for iodine manufacturing is finding a way to extract this rare element to make a consistent and reliable supply of the raw material. If you’re interested in learning how iodine is found and how it can be extracted, read on or contact us.
Iodine Production From Seaweed
The first successful manufacturing of iodine was from seaweed in 1817. The seaweed was dried, burned and separated to obtain iodine potassium and sodium salts. This method is rarely used today since it is not economically viable. However, some iodine is still produced from seaweed as a co-product during the extraction of sodium alginate and mannitol. In this process, the seaweed is leached, alkalinized and then treated with sulfuric acid to obtain free iodine.
Extraction: From Brines to Iodine
Iodide is present in the salty brines of natural gas fields and is extracted to make iodine by three main processes:
Blow-out – During the blow-out process, oxidized iodine is extracted in a countercurrent air flow process based on the distinct vapor pressure of the iodine. The iodine-filled air is reduced to iodide by the addition of sulfur oxide. In the finishing process, the acidic iodide solution is oxidized by addition of chlorine to form iodine crystals.
Carbon Absorption – Carbon Absorption is most often used when the brine has a low iodine concentration. The free iodine in the acidified brine solution is captured with activated carbon and neutralized with ammonia. The iodine is extracted from the activated carbon using hot caustic soda, which produces an iodate-iodide mixture. This solution is acidified with sulfuric acid and the iodine is separated by filtration.
Ion Exchange – In ion exchange, the free iodine from oxidized brines is flown through resin-packed ion exchange columns. Once the resin is saturated with free iodine, it is transferred to an elution column that is treated with a caustic salt solution. The eluted iodine is recovered by addition of acid and removed by solid/liquid separation.
Production From Caliche Ore
Iodine can be found in caliche ore, and the north of Chile has the largest deposits of caliche ore in the world. Our joint venture partner mines the caliche ore deposits in Chile to produce the world’s largest supply of raw iodine. Production of iodine from caliche ore is a two-step process:
1. Extraction of iodate solutions from the caliche ore
2. Reduction of iodate to iodine
Iodate can be extracted from ore by leaching in one of two ways depending on the ore’s nitrate concentration:
•Heap leaching for low nitrate containing ores
•Vat leaching from high nitrate containing ores
Most of the iodate solution from leaching goes through a sulfur oxide absorption tower. The iodide produced mixes with the rest of the iodate solution, which results in a suspension. The iodine in suspension is reduced to iodide, with the addition of sulfur oxide, and then recovered as a concentrated iodide solution. Most iodine precipitates out of the solution to form crystals, which are captured by flotation.
Let Ajay-SQM Be Your Iodine Derivative Supplier
With three manufacturing facilities worldwide dedicated to the production of iodide compounds, the Ajay-SQM Group has the capacity, reliability and distribution capability to meet the needs of our customers. If you are looking for a reliable and trusted provider of iodine compounds, contact us today.
Additional Iodine Reading
How Iodine is Extracted From Caliche Ore
5 Ways Iodine Derivatives Are Used Everyday
Infographic: Common Iodide Sources and Uses
