Method for reclaiming iodine from concentrated phosphoric acid from wet method phosphoric acid production

Abstract

The invention discloses a method for recovering iodine from concentrated phosphoric acid which is produced by wet-process phosphoric acid; the method comprises the following steps of: extracting the iodine from the concentrated phosphoric acid produced in the production process of phosphorous ore which contains iodine, wherein, the concentrated phosphoric acid contains 50 to 110 mg / L of the iodine and 40 percent to 52 percent of P2O5; adding 27 percent to 35 percent of hydrogen peroxide water solution into the phosphoric acid as an oxidizing agent for reaction; using air to blow out the molecular iodine of the phosphoric acid; then absorbing the molecular iodine by acid solution containing liquid SO2 with the PH value of the absorbing solution ranging from 1 to 6; adding hydrogen peroxide and leading the iodine to be precipitated; carrying out filtering and separation and obtaining the finished iodine. The applicant finds that the iodine is extracted from the concentrated phosphoric acid after the diluted phosphoric acid is concentrated into the concentrated phosphoric acid; as the material liquid is concentrated, the concentration of the material iodine is high, the solution impurity is little and the content of the reducible matter and the organic matter is low, therefore, the usage of the oxidizing agent can be reduced; the method of the invention has the advantages of high concentration of the material iodine, little usage of the oxidizing agent, easy extraction, high recovery rate and low production cost.

Description

Technical field: [0001] The invention relates to a method for extracting iodine from concentrated phosphoric acid produced by wet-process phosphoric acid, in particular to iodine-containing phosphorus ore as raw material in the process of producing phosphorus products. 2 o 5 The invention discloses a method for extracting iodine from concentrated phosphoric acid with a concentration of 40-52%, belonging to the fields of environmental protection and chemical technology. 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 ...

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 titled "Method for Extracting Iodine from Dilute Phosphoric Acid Produced in the Production Process of Iodine-Containing Phosphorus", and the patent number is: 2005100030582. Iodine is extracted from the dilute phosphoric acid produced during the production of phosphorus products from rocks; however, it has been found in industrial experiments that using ordinary hydrogen peroxide as an oxidant, the actual amount used is much larger than the theoretical value. 600 kg is required, but the actual consumption has reached 30 tons

Therefore, the consumption of raw materials is large and the production cost is high