Process for recovering phosphoric acid in flue gas generated in process of smelting ferro phosphorus in electric furnace

Abstract

The invention relates to a process for recovering phosphoric acid in flue gas generated in the process of smelting ferro phosphorus in an electric furnace, which belongs to the technical field of waste gas treatment and utilization. The process mainly comprises the following steps of: feeding the flue gas generated in the process of smelting the ferro phosphorus in the electric furnace into a single-stage water-spraying tower for absorption; introducing mixed gas into a multi-stage series-parallel combined or series-connected water cooling recoverer, and condensing to obtain liquid phosphoricacid; recovering the liquid phosphoric acid and performing gravity settlement; and merging to obtain a phosphoric acid product. By the process, the process of recovering the phosphoric acid in the prior art is changed, the phosphoric acid is directly recovered by one-time spraying, recovery efficiency is high, water treatment is simple, and environment friendliness is realized.

Description

technical field [0001] The invention relates to a process for recovering phosphoric acid from the flue gas of smelting ferrophosphorus in an electric furnace, and belongs to the technical field of waste gas treatment and utilization. Background technique [0002] Flue gas produced by electric furnace smelting ferrophosphorus is rich in P 2 o 5 , the existing technology for the recovery of this flue gas is to use three-stage water shower tower absorption cooling, so that P 2 o 5 Dissolve in water to generate phosphoric acid; reaction formula P 2 o 5 +3H 2 O=2H 3 PO 4 The phosphoric acid washed down by the washing water is collected by the receiving tank, and the phosphoric acid precipitated in the lower layer is recovered through precipitation, and the upper layer water is pumped out with a water pump. After treatment, the flue gas of the electric furnace is repeatedly washed to further enrich the generated phosphoric acid. Although the existing technology needs to co...

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Problems solved by technology

Although the existing technology needs to continuously replenish cooling fresh water, the replenishment amount of spray water should not be too large; if the replenishment amount of spray water is too large, the phosphoric acid will be diluted excessively, and the recovery difficulty of phosphoric acid will increase; therefore, the replenishment amount of fresh cooling water can only satisfy P 2 o 5 The sum of flue gas absorption water plus cooling water evaporation loss is appropriate

In this way, due to the continuous leaching of limited cooling water to enrich the P 2 o 5 Smoke, on the one hand P 2 o 5 The flue gas itself is a high-temperature gas; on the other hand, P 2 o 5 Dissolving in water to form phosphoric acid is an exothermic reaction, which will generate a lot of heat; the combined effect of the two makes the temperature of cooling water higher and higher, and the cooling effect becomes smaller and smaller, and forms high-temperature phosphoric acid gas and water vapor, which eventually makes P 2 o 5 The flue gas recovery rate is reduced, and part of the phosphoric acid gas is discharged into the air with the steam, which affects environmental protection and causes pollution

[0003] In addition, the prior art spray water and P 2 o 5 The flue gas is in direct contact with the whole process, causing water pollution, and the difficulty of water treatment is also very difficult

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