Method for preparing nitrogen-phosphorus-potassium compound fertilizer from fertilizer-grade phosphoric acid eutectic

Abstract

The invention provides a method for preparing a compound fertilizer with an adjustable nitrogen-phosphorus-potassium ratio from a fertilizer-grade phosphoric acid eutectic. The method comprises the steps of (1) conducting double decomposition reaction; (2) conducting a neutralization reaction; (3) crystallizing and refining; and (4) filtering and drying. The method has the beneficial effects that the cost of raw materials is low, zero emission of the whole process is also realized through reutilization of crystallization mother liquor and recovery of a reaction byproduct hydrogen chloride, and efficient utilization of the raw materials is realized; the reaction is segmented, so that the conversion rate of potassium chloride in the reversible reaction is improved, and the problem of crop leaf burn caused by overhigh chlorine ion content of the fertilizer is solved; and the content of nitrogen, phosphorus and potassium in the product is regulated and controlled by simply regulating and controlling the feeding ratio of the reaction raw materials, the controllable range is large, and different requirements of actual agricultural production on the fertilizer can be met.

Description

technical field [0001] The invention belongs to the field of chemical fertilizer preparation, and in particular relates to a method for preparing compound fertilizer with adjustable ratio of nitrogen, phosphorus and potassium from fertilizer-grade phosphoric acid eutectic. Background technique [0002] Nitrogen, phosphorus and potassium, also known as the three elements of fertilizers, are essential nutrients for plant growth. Nitrogen, potassium and phosphorus fertilizers are the most important chemical fertilizers. my country is a large agricultural country and a big country in the production and use of chemical fertilizers in the world. However, most of the cultivated land in our country contains less than 0.2% nitrogen, 450 million mu of potassium-deficient soil, and more than 1 billion mu of phosphorus-deficient soil. With the further development of agriculture , the demand and demand for fertilizers are increasing day by day, and it is particularly important to develop ...

AI Technical Summary

Problems solved by technology

The neutralization method mainly uses phosphoric acid to react with alkaline substances such as potassium hydroxide and potassium carbonate. This method has simple equipment, mature technology, and high product purity. However, the cost of raw materials is high and it is difficult to apply in agriculture.

In contrast, the reaction conditions of the metathesis reaction are mild, the operation is simple, and there is no pollution, but there is also the problem of high chlorine content in the product

In industry, the production method of ammonium dihydrogen phosphate is generally ammonium phosphate method. This method has a simple process and high production efficiency, but there are problems such as difficult filtration of reaction products and poor crystal morphology, which requires further crystallization optimization.

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