Gas-liquid mixed extraction iodine recovery technology

Abstract

The invention discloses a gas-liquid mixed extraction iodine recovery technology. According to the invention, phosphate rock is soaked in sulfuric acid, and iodine-containing dilute phosphoric acid is obtained; an oxidizing agent is added into the dilute phosphoric acid, such that gas-phase iodine is obtained; the gas-phase iodine is subjected to a reaction with a reducing agent, such that iodine is precipitated. The invention is characterized in that: iodine-containing dilute phosphoric acid obtained by the reaction of phosphate rock and sulfuric acid and iodine-containing exhaust gas are simultaneously delivered into and sufficiently mixed in a gas-liquid mixed extraction integral iodine recovery apparatus; the oxidizing agent is added and a reaction is carried out, such that iodine molecules are obtained; the reducing agent is added under a condition of a controlled temperature, such that a concentrated iodine liquid is obtained; two-stage clarification, precipitation, filtration, and rectification purification are carried out, such that finished product iodine is obtained. The technology provided by the invention makes up for the defects of a method for extracting iodine from wastes produced in the process for producing phosphorus products from iodine-containing phosphorite. With the technology, iodine in iodine-containing dilute phosphoric acid and iodine-containing exhaust gas can be recovered simultaneously. Through two-stage clarification, defluoridation is realized, and floccule and impurities are removed, such that the purity of iodine is improved. The technology is also advantaged in simple technology, high recovery rate, and low economic cost. With the technology, iodine-containing exhaust gas can be fully utilized, and the pollution of tail-gas discharging to the environment can be reduced.

Description

technical field

[0001] The invention relates to a gas-liquid mixed extraction iodine recovery process, which belongs to the technical field of chemical industry. Background technique

[0002] Iodine is one of the scarce resources. Most of the phosphate rocks are associated with iodine oxides, the content is generally about 30ppm, and the iodine grade is low and the reserves are large. In long-term production, when the iodine-containing phosphate rock reacts with sulfuric acid, the iodine in the phosphate rock enters the liquid acid and gas produced by the reaction respectively. When the production is carried out by the dihydrate wet phosphoric acid process, 50% of the iodine in the phosphate rock enters the liquid acid, 30% of the iodine enters the reaction gas, and the rest enters the phosphogypsum (slag). When the semi-aqueous wet-process phosphoric acid process is used for production, 20% of the iodine in the phosphate rock enters the liquid acid, 70% of the iodine ente...

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