Phosphorus and flourine absorbing and separating method in preparing kiln process phosphoric acid

Abstract

The phosphoric acid and fluorine absorbing and separating process in preparing kiln process phosphoric acid includes cooling phosphoric acid from the hydration tower in the separating tank, treating in the phosphoric acid circulating tank, pumping with one phosphoric acid pump to the hydration tower for re-spraying, gas-liquid separation of the tower top gas containing fluorine and phosphoric acid fog in the heat exchanger, re-absorbing fluorine containing gas and phosphoric acid fog from the tail gas before the tail gas is exhausted, and recovering fluorine from the separating tank and preparing fluosilic acid in the fluorine recovering system. Compared with available similar technological process, the process of the present invention has low power consumption, high phosphoric acid and fluorine separating effect, capacity of obtaining high concentration low fluorine phosphoric acid and other advantages.

Description

technical field [0001] The invention relates to a method for absorption and separation of tail gas, in particular to a method for absorption and separation of phosphorous and fluorine in kiln process phosphoric acid. Background technique [0002] Fluorine is inevitably contained in phosphate rock, which is essential for the manufacture of phosphoric acid. The fluorine gas in an inorganic state is highly toxic and poses a huge threat to the human body and the environment. In the process of thermal phosphoric acid and kiln phosphoric acid, fluorine element will escape together with the reduced phosphorus from phosphate rock, and in the process of hydration of phosphorus pentoxide, fluorine-containing gas will also dissolve in water and hydrolyze to form Fluorosilicate (H 2 SiF 6 ), coexist in phosphoric acid, which is detrimental to the quality of phosphoric acid. As the concentration of phosphoric acid increases, fluosilicic acid decomposes into hydrogen fluoride and silic...

AI Technical Summary

Problems solved by technology

The existing phosphorus-fluorine absorption process requires additional energy consumption, the separation rate of phosphorus and fluorine is not high, and high-concentration and low-fluorine phosphoric acid cannot be obtained, and P in fluorosilicic acid 2 o 5 The content of the fluorine absorption system is relatively high, and the workload of the fluorine absorption system is relatively large

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