Preparation method of diammonium phosphate

Abstract

The invention discloses a preparation method of diammonium phosphate. The method comprises the following steps of: (1) adding phosphoric acid accounting for 40-60 weight percent of reaction raw material phosphoric acid and ammonia accounting for 70-90 weight percent of reaction raw material ammonia into a tubular reactor to carry out a neutralization reaction to generate ammonium phosphate slurry; and (2) spraying the ammonium phosphate slurry prepared in the step (1) into a drum ammoniating granulator, then leading the ammonia into a material bed of the drum ammoniating granulator so as toensure that the ammonium phosphate slurry is further ammonified to have a neutralization degree of 1.7-1.9, and granulating while ammoniating to generate solid wet materials and granulating tail gas;and drying the solid wet materials to obtain the diammonium phosphate. In the method, a washing system is used as a primary reactor, thereby greatly improving the production loading capacity of the whole set of devices. The phosphoric acid and the ammonia quickly react, and the reaction time is short, thus less citrate-soluble phosphates are generated, and the content of water-soluble phosphorus in a product is high. All reaction heat enters a granulating working procedure so as to sufficiently utilize the reaction heat to evaporate water, thus the system energy consumption is low, and the utilization of the reaction heat is better.

Description

technical field [0001] The invention relates to a preparation method of diammonium phosphate. Background technique [0002] As a high-concentration and high-efficiency compound fertilizer, ammonium phosphate has gradually become the most important type of fertilizer in the chemical fertilizer industry. In the case of increasingly tight phosphorus resources in the world, the advantages of developing ammonium phosphate preparation technology with low energy consumption and low pollution have become increasingly prominent. At present, the main diammonium phosphate (DAP) production processes at home and abroad include pre-neutralization tank + tubular reactor-drum ammoniation granulation process, double-tube reactor process, pre-neutralization tank-tubular reactor series process, Pre-neutralization-concentration-tubular reactor slurry process, etc. [0003] The NPK plant of Hubei Dayukou Chemical Co., Ltd. was transformed from a 560,000-ton TSP plant designed by Donghua Engine...

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Problems solved by technology

In the transformation of a 560,000-ton TSP plant into a 500,000-ton NPK or 350,000-ton DAP project, according to the comprehensive analysis of the design of the TSP plant, if the pre-neutralization tank + tubular reactor-drum ammoniation granulation process, double Tube reactor process, pre-neutralization tank-tubular reactor series process, the transformation is difficult and the investment cost is high. In addition, there is no mature experience in the production of DAP in Hubei mine; the single-tube reactor process is used to investigate Huangmailing Phosphorus Chemical Group Co., Ltd. Manufacturers who use this kind of reactor have a low success rate and are difficult to reach the design load, resulting in high energy consumption and unsightly product appearance, resulting in high production costs and poor product performance.

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