Method for recycling iodine from diluted phosphoric acid for phosphoric acid manufacture with wet-process

Abstract

The invention discloses a method for recovering iodine from dilute phosphoric acid in phosphoric acid production with a wet method; iodine is extracted from the dilute phosphoric acid generated in the iodine-containing phosphorus ore production process, wherein, the content of iodine in the dilute phosphoric acid is 50-110mg/L, the concentration of P2O5 in the dilute phosphoric is 25-30%, compound oxidant is added into the phosphoric acid for oxidation reaction, air is used for blowing molecular iodine out, then SO2-containing acidic solution is used for absorbing, the pH value of absorption liquid is between 1-6, then hydrogen peroxide is added to separate iodine out and filtration and separation are carried out to obtain finished iodine. The compound oxidant obtained from the tests conducted by the applicant can improve the efficiency of oxidant and reduce the dosage of oxidant. Proved by the tests performed by the applicant, after the hydrogen peroxide is added with vanadic oxide, the dosage of oxidant can be reduced by 30%; at present, the actual amount of the hydrogen peroxide used for producing 1 ton iodine is 20 tons.

Description

Technical field: [0001] The invention relates to a method for recovering iodine from dilute phosphoric acid produced by wet-process phosphoric acid, in particular to a method for extracting iodine from dilute phosphoric acid with a concentration of 26-30% used in the process of producing phosphorus products from iodine-containing phosphate ore; It belongs to the technical field of environmental protection and chemical industry. Background technique: [0002] At present, most industrial iodine manufacturers in my country use high-grade iodide-containing brine, brine, or kelp soaking solution (iodine content: 200-300mg / L) as raw materials to produce industrial iodine. Most of the processes used are ion exchange resin methods. That is to say, the high-grade iodide-containing bittern, brine, or kelp soaking liquid is acidified with acid, and chlorine gas is introduced to make iodine free and precipitate, and then adsorbed by polystyrene ion exchange resin. There are two methods ...

AI Technical Summary

Problems solved by technology

There are two major problems in this method: the one is that the production operation cost is high, and the 2nd, the production process requires high iodine content to raw materials (brine containing iodide, brine, or kelp soaking liquid)

The inventor has applied for an invention patent application entitled "Method for Extracting Iodine from Dilute Phosphoric Acid Produced in the Production Process of Iodine-Containing Phosphorus", and the patent application number is: 2005100030582. This method can be used to extract iodine from iodine-containing phosphorus Iodine is extracted from dilute phosphoric acid produced during the production of phosphorus products from ores; however, it was found in industrial experiments that using ordinary hydrogen peroxide as an oxidant, the actual amount used is much larger than the theoretical value. In the experiment, 1000 kg of iodine was prepared. Only 600 kg of hydrogen peroxide is needed, but the actual consumption has reached 30 tons

Therefore, the consumption of raw materials is large. In addition, hypochlorous acid is used as an oxidant, and the production cost is high. Moreover, hypochlorous acid will cause corrosion to equipment and affect normal production.