Production method of urea-based composite fertilizer

Abstract

The invention relates to a production method of a urea-based nitrogen-phosphorus-potassium composite fertilizer. The production method comprises the following steps: carrying out a reaction among urea and sulfuric acid and water according to a certain ratio so as to generate a urea sulfate solution; sending the urea sulfate solution into a pelletizer, and carrying out a neutralization reaction between the urea sulfate solution and ammonia introduced into the pelletizer, pelletizing the reaction product and other basal fertilizers containing nitrogen, phosphorus and potassium in the pelletizer, drying, screening, cooling and packaging to obtain the final qualified product. By reasonable utilization of various kinds of reaction heat, energy consumption of production is greatly reduced. As the reaction for generation of urea sulfate is carried out at low temperature (60-80 DEG C), hydrolysis and condensation reaction of urea are less. Then, content of biuret of the final product is very low. Product quality can be fundamentally guaranteed. The technology is simple, and production cost is lower. The production method is easy to apply to existing composite fertilizer production equipment.

Description

technical field [0001] The present invention relates to a kind of production method of compound fertilizer, relate to a kind of production method of urea-based compound fertilizer more precisely. Background technique [0002] As the solid fertilizer with the highest nitrogen content, urea has been used in crops for a long time, but for a long time, due to the special properties of urea, when it is co-granulated with other basic fertilizers to produce compound fertilizer, the product is easy to absorb moisture, which is difficult for granulation and post-treatment. Especially in summer production, due to high temperature and high humidity, the granulation loop is easy to get humidified, scarred and blocked, resulting in poor production. [0003] The traditional production process of urea-based compound fertilizer is to crush urea and other basic fertilizers separately and add them to the granulation system to agglomerate them into granules. Although this process is simple, du...

AI Technical Summary

Problems solved by technology

A method for directly producing nitrogen, phosphorus and potassium compound fertilizers by using urea solution. The process uses urea solution with a concentration of 65.0-99.7% and a temperature of 80-140°C from the urea manufacturer, and sprays it into a granulator to reunite with other basic fertilizers. Granulation, this process makes reasonable use of the urea solution produced by the urea plant and increases the granulation temperature, but this process is more suitable for manufacturers with urea plants, so it has certain limitations

In addition, there is also a urea melting process, that is, solid urea is made into ~95% urea melt at 110-120°C, and the urea melt is sprayed into a granulator to reunite with other basic fertilizers to form granules. This process uses urea The thermal energy of the molten liquid increases the granulation temperature and improves the performance of the granules, but the energy consumption of the steam increases due to the melting of urea, and urea is easily hydrolyzed at a higher temperature, especially easy to form condensation that is harmful to the growth of crops. Diurea impurities, so that the quality of compound fertilizer products cannot be completely guaranteed