Method for preparing fertilizer grade monoammonium phosphate from sulfurous gases by ammonia-process desulfurization

Abstract

The invention discloses a method for preparing fertilizer grade monoammonium phosphate from sulfurous gases by ammonia-process desulfurization, which comprises the following steps: (1) adopting four stages to absorb SO2 from gases; at the first stage, washing smoke by water, removing dust slag and reducing the temperature of smoke; at the second stage, absorbing SO2 by ammonia or ammonium sulfiterepeatedly to obtain ammonium bisulfite; at the third stage, absorbing SO2 by an absorption liquid with high alkalinity continuously; and at the fourth stage, washing by clean water to recycle residual ammonia and SO2; (2) generating a monoammonium phosphate solution after acidolysis: carrying out acidolysis on the obtained ammonium bisulfite solution in the last step by phosphoric acid in an acidolysis device, producing the monoammonium phosphate solution and giving out gas SO2; (3) producing the product monoammonium phosphate: carrying out conventional dehydration, crystallization and drying processes on the monoammonium phosphate solution to obtain the monoammonium phosphate fertilizer; and (4) producing sulfuric acid with the recycled SO2. By using the method of the invention, SO2 in the sulfurous gases can be fully recycled, and meanwhile, the monoammonium phosphate fertilizer with large consumption in the market is produced. The method is applicable to the thermoelectricity enterprises, the enterprises manufacturing sulphuric acid or the enterprises sintering sulfur-containing raw ores.

Description

technical field [0001] The invention relates to the chemical purification of gas, in particular to the desulfurization of sulfur-containing gas, and also to the method for producing fertilizer-grade ammonium phosphate from the desulfurized product. Background technique [0002] As we all know, the tail gas emitted by coal-fired boilers (referred to as flue gas) contains sulfur dioxide, the tail gas produced by sulfuric acid and the waste gas from the sintering of sulfur-containing raw ore also contain sulfur dioxide, and they are collectively referred to as "sulfur-containing gases". These sulfur-containing gases need to remove the sulfur from them before they can be discharged. The commonly used desulfurization methods are limestone-gypsum method, magnesium oxide method and ammonia method. There is already a scheme for ammonia flue gas desulfurization in the Chinese patent application, such as No. CN101053743 "wet type ammonia flue gas desulfurization process and its devic...

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Problems solved by technology

[0004] The purpose of the present invention is to provide a method for preparing fertilizer-grade ammonium phosphate by ammonia desulfurization of sulfur-containing gas, so as to solve the problem of the outlet of flue gas desulfurization products, fully recycle and utilize sulfur resources, reduce the consumption of sulfur resources and reduce the impact of sulfuric acid production on the environment. destroy

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