Method for preparing dihydric phosphate

Abstract

The invention discloses a method of producing dihydric phosphate, which essentially comprises steps as follows: firstly, chloride is mixed with excessive phosphoric acid in order to obtain material liquid; secondly, the material liquid is added into the spray dryer to atomize into tiny droplets; thirdly, the droplets are instantaneously contacted and heated with as much hot air as is sufficient to enable double decomposition reaction between chloride and phosphoric acid to happen, so that hydrogen chloride gas escapes through the double decomposition reaction between chloride and phosphoric acid, and the remaining reaction products are hydrolyzed, the pH value thereof is regulated, and a dihydric phosphate product is obtained after cooling and crystallization. The production method has technical advantages that the shortcomings of prior art can be overcome, the spray dryer is adopted as a core reactor to atomize the material liquid into small droplets to be contacted with the high-temperature hot air, the specific surface area of evaporation is maximum, so that the escaping time of HCl and the water vapor is 3 to 8 seconds only, the reaction conversion rate reaches up to 97 percent, the cost of raw materials can be significantly reduced, the material liquid continues to be in and out, the reaction device is simple and practical, so that large-scale industrialization production can be achieved.

Description

Technical field: [0001] The invention relates to the field of production of dihydrogen phosphate, in particular to a method for producing dihydrogen phosphate by atomizing phosphoric acid and chloride at high temperature for metathesis reaction. Background technique: [0002] At present, the traditional production method of dihydrogen phosphate mainly uses hydroxide and phosphoric acid to carry out acid-base neutralization reaction, such as: the production of potassium dihydrogen phosphate is to select potassium hydroxide and phosphoric acid as raw materials, and directly produce Make potassium dihydrogen phosphate, although this method is simple, potassium hydroxide raw material is expensive, and production cost is high, and product added value is low. Other methods such as: Potassium chloride and phosphoric acid metathesis low-temperature extraction method, the loss of extractant is serious, the price is high, and the environmental pollution is heavy; Phosphate metathesis ...

AI Technical Summary

Problems solved by technology

In order to solve the strong corrosion problem of phosphoric acid and hydrochloric acid mixed acid, the core reactor adopts a graphite reactor impregnated with polytetrafluoroethylene, which effectively solves the problem of corrosion of the equipment by the strong corrosive medium in the reaction system, but the system has the following disadvantages: 1. 1. The core reactor adopts graphite reactor. In order to strengthen the sealing of the reactor, the processing technology of graphite material is adopted as a whole. The length-to-diameter ratio is large and the effective volume is small, so it is difficult for the device to achieve large-scale production; 2. The reaction adopts intermittent operation , the hydrogen chloride generated under high temperature reaction naturally escapes from the liquid phase by stirring, the hydrogen chloride escape efficiency is low, and the conversion time of potassium chloride is as long as 1.5 to 4 hours, which seriously restricts the reaction rate and is difficult to adapt to large-scale industrial production

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