PRODUCTION PROCESS OF IODINE PRODUCT
Product Description
The production method of iodine is greatly affected by the raw materials. Using seaweed as raw material, there are leaching method, ashing method, dry distillation method, and fermentation method. Except for the leaching method, many other methods have been eliminated. Iodine is extracted from the seaweed extract, and ion exchange method is used now. Extraction of iodine from petroleum well water and underground brine includes ion exchange method, air blowing method, activated carbon method, precipitation method (copper method and silver method), starch method and organic solvent extraction method. At present, industrial production mainly adopts ion exchange method and air blowing method.
(1) The ion exchange method is to soak the material liquid (using kelp as the raw material), add acid to the soaking solution, oxidize with chlorine, adsorb in the ion exchange column, then desorb, iodine, and refine to obtain the finished iodine.
(2) The air blowing method is to acidify the material liquid and pass in chlorine gas to oxidize the iodized salt and blow in air at the same time. Blow out free iodine. The blown-out iodine is absorbed by sulfur dioxide, and then chlorine is passed to free the iodine, and then it is obtained by refining.
Crude iodine can be refined by sublimation method, melting method and steam distillation method. The sublimation method is to heat the crude iodine to condense the iodine vapor at no higher than 113.6°C to obtain larger crystalline iodine. In the steam distillation method, superheated water vapor passes through the crude iodine layer to sublime the iodine, condensate and collect it in water below 50°C, then cool and crystallize, and filter to obtain pure iodine. The melting method is to melt crude iodine in concentrated sulfuric acid, cool and crystallize to obtain refined iodine. This method consumes more acid, but is simple and easy to implement.
Product Method
The production method of iodine is greatly affected by the raw materials. Using seaweed as raw material, there are leaching method, ashing method, dry distillation method, and fermentation method. Except for the leaching method, many other methods have been eliminated. Iodine is extracted from the seaweed extract, and ion exchange method is used now. Extraction of iodine from petroleum well water and underground brine includes ion exchange method, air blowing method, activated carbon method, precipitation method (copper method and silver method), starch method and organic solvent extraction method. At present, industrial production mainly adopts ion exchange method and air blowing method.
(1) The ion exchange method is to soak the material liquid (using kelp as the raw material), add acid to the soaking solution, oxidize with chlorine, adsorb in the ion exchange column, then desorb, iodine, and refine to obtain the finished iodine.
(2) The air blowing method is to acidify the material liquid and pass in chlorine gas to oxidize the iodized salt and blow in air at the same time. Blow out free iodine. The blown-out iodine is absorbed by sulfur dioxide, and then chlorine is passed to free the iodine, and then it is obtained by refining.
Crude iodine can be refined by sublimation method, melting method and steam distillation method. The sublimation method is to heat the crude iodine to condense the iodine vapor at no higher than 113.6°C to obtain larger crystalline iodine. In the steam distillation method, superheated water vapor passes through the crude iodine layer to sublime the iodine, condensate and collect it in water below 50°C, then cool and crystallize, and filter to obtain pure iodine. The melting method is to melt crude iodine in concentrated sulfuric acid, cool and crystallize to obtain refined iodine. This method consumes more acid, but is simple and easy to implement.
Process Flow
(1) Ion exchange method
(2）Ion exchange method
Technical Formula
(1)Ion exchange method
(2)Air blowing method
Product Process
(1) Ion exchange method: Soak kelp with 13-15 times the amount of water, and the iodine content in the water should be more than 0.3g/L once soaked. If soaked twice, it can reach 0.5-0.55g/L. The soaking water contains a lot of fucoidan and other impurities, which affects the extraction of related product mannitol, so it needs to be removed by adding alkali. The content of lye is 36%-40%. Stir thoroughly after adding alkali to make the pH 12 and clear for more than 8 hours. The upper clear liquid is pumped into the acidification tank with acid, and the pH is controlled to 1.5-2. After the sediment is heated and clarified again, the upper clear liquid is still pumped into the acidification tank, and the waste residue can be oxidized by adding acid and oxidant, and then passed into a special column to absorb iodine. After the supernatant is acidified, it is sent to an oxidation tank, where chlorine or sodium hypochlorite is introduced to free the iodine by oxidation. After acidification of the sodium chlorate treatment solution, an oxidizing agent is added to precipitate the iodine contained therein and then recovered. The waste iodine water passing through the exchange column is used to extract mannitol.
(2) The air blowing method is acidified by adding hydrochloric acid to the iodine-containing material liquid, and the pH is controlled at 1-2. Then it is sent to the preheater, preheated to about 40°C, and then enters the oxidizer through the high-level tank, and at the same time passes in an appropriate amount of chlorine gas to oxidize the iodide ions in the feed liquid into iodine molecules. When the oxidation potential reaches 520-530mV (saturated calomel electrode), the oxidation rate is 95%. Send the oxidizing solution into the blow-out tower and evenly drench it from the upper part. Blow in air that has been preheated to 40°C from the lower part of the blow-out tower to blow out the iodine. The iodine-containing air enters the packed absorption tower from the lower part, and the iodine in the air is The sulfur dioxide aqueous solution sprayed from the upper part of the tower is absorbed and reduced to produce a hydroiodic acid solution (absorption liquid). The absorption liquid is pumped into the absorption tower, and cyclically absorbed many times to increase the concentration of hydrogen iodide. When the absorption liquid contains about 150g/L of iodine, it is sent to the iodine analyzer. Under constant agitation, chlorine gas was slowly introduced to free the iodine to precipitate. Then it is filtered through a filter with a vacuum pump, and the obtained crude iodine is melted and refined by adding concentrated sulfuric acid, and cooled and crystallized to obtain the finished iodine. After crushing, it is packed in brown glass bottles or wooden barrels lined with plastic bags, and sealed in storage.
Product Standards
Product Usage
Used as a photographic emulsion, and also used in the manufacture of single crystal prisms for electronic instruments, polarizers for optical instruments, and infrared-transmitting glass. Iodine is the basic raw material for the production of inorganic and organic iodides. It is mainly used in medicine and health. It is used to produce various iodine preparations, fungicides, disinfectants, deodorants, analgesics, and antidote for radioactive substances; iodides are also used Used as drinking water purifier and swimming pool disinfectant. In agriculture, iodine is a raw material for the manufacture of pesticides, and it is also a livestock feed additive. In industry, it is used to produce synthetic dyes, smoke extinguishing agents, and antibacterial agents for cutting oil emulsions.
[Keywords] iodine, liquid chlorine, sodium metabisulfite, sodium nitrite, sulfuric acid
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