Method for preparing composite phosphate

Abstract

The invention discloses a production method of composite 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, and the remaining things are reacted to obtain a compound phosphate product. 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 material liquid continues to be in and out, and large-scale industrialization production can be achieved.

Description

Technical field: [0001] The invention relates to the production field of composite phosphate, in particular to a method for producing composite phosphate by metathesis reaction of phosphoric acid and chloride under high temperature conditions. Background technique: [0002] At present, the traditional production method of phosphate mainly uses hydroxide and phosphoric acid to carry out acid-base neutralization reaction. For example, the production of potassium dihydrogen phosphate is to select potassium hydroxide and phosphoric acid as raw materials and directly produce it through acid-base neutralization reaction. Potassium dihydrogen phosphate, although the method is simple, the potassium hydroxide raw material is expensive, the production cost is high, and the added value of the product 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 environmen...

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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 tightness 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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