Raw material processing--ashing--limeing--enrichment--distillation--purification--finished product
(b) Operational points
1 Kelp, Sargassum, and other brown algae can all be used as raw materials for iodine extraction. It is more economical to use Sargassum and kelp roots as raw materials. When the raw materials are dried in the sun, the sediment is removed to prevent raining or washing, because the iodine granules become smaller after the algae die, and are easily dissolved in water or an acidic solution, thereby reducing the yield.
2 Ash the dried raw materials, destroy the organic structure of the raw materials, and facilitate the dissolution of inorganic iodide components. The ashing uses an ashing kiln. The ashing kiln saves more effort than the open ash, and the loss of iodine is less. When ashing, strictly control the temperature, such as the temperature of the iodide melting point, will sublime iodine and reduce production.
3 Put the ash into the liming tank and soak it with 1:1 water. Pass the steam in the lixiviation tank to maintain 70--80°C, soak for a few days, so that the concentration of the soaking liquid reaches 19 Baume, so that the gray The iodide dissolves as much as possible and is concentrated.
4 The soaking solution is heated and concentrated to 25 Baume to increase the iodide concentration. During the heating and cooling process, a large amount of inorganic salt precipitates. When the iodine content is about 4%, distillation can be carried out to iodine.
5 The concentrate is charged into the distiller and the pH is adjusted with industrial sulfuric acid 1-2. After boiling, manganese dioxide is added to continue distillation until all the purple vapors evaporate. The vaporized purple vapor crystallizes in the condenser and is iodine.
6 The crude iodine is sublimated in a sublimator at 60--70°C, and the iodine condensed on the sublimator wall is taken as a purified iodine.
(I) Process flow