A method for reducing viscosity of nitrophosphate fertilizer neutralized slurry by freezing method

Abstract

The invention discloses a viscosity reducing method for freezing method nitrophosphate neutralized slurry. According to the viscosity reducing method, on the basis of the freezing method nitrophosphate technological process, a resin exchange procedure is added for removing metal ions of calcium, magnesium, aluminum and iron in defluorinated mother liquor, and the purpose of reducing the viscosity of the neutralized mother liquor slurry is achieved. Through the method, the viscosity of the neutralized slurry is reduced, the cost is low, operation is simple, secondary pollution is avoided, obtained products are good in physical and chemical property, high in water solubility and wide in application range and meet the integration demand of water and fertilizer.

Description

technical field [0001] The invention relates to a production method of high-concentration water-soluble nitrophosphate fertilizer, in particular to a viscosity-reducing method for neutralizing slurry of high-concentration water-soluble nitrophosphate fertilizer produced by using low-grade phosphate rock. [0002] technical background [0003] Freezing nitrophosphate fertilizer production technology is a production process of nitric acid, phosphate rock and ammonia gas as raw materials, which are frozen and crystallized to produce nitrophosphate fertilizer, such as Jing Hongjian, Chen Mingliang, Chen Jingyu, etc. Freezing method nitrophosphate fertilizer production technology[M] . Beijing: Chemical Industry Press, 2002. Its production process includes acid hydrolysis of phosphate rock, precipitation and separation of acid insoluble matter, freezing crystallization, filtration of calcium nitrate, neutralization of mother liquor ammonia, evaporation of neutralization slurry, biax...

AI Technical Summary

Problems solved by technology

However, in recent years, with the continuous decline of the grade of phosphate rock, the content of metals such as calcium, iron, magnesium, and aluminum in the phosphate rock has continued to rise, making the slurry undergo a series of gas-liquid phase chemical reactions with ammonia during the neutralization process. A large amount of gelatinous substances are generated, which leads to a sharp increase in the viscosity of the neutralization slurry, which brings great difficulties to the neutralization operation, and may even reach the point where it cannot be operated, causing the system to be forced to stop, let alone high-tower granulation requirements

This will not only bring great economic losses, consume a lot of manpower and material resources for cleaning equipment, but also directly affect the normal production and product quality of nitrophosphate fertilizer

Therefore, more and more people began to pay attention to the change and influencing factors of the viscosity of the neutralization slurry, such as the existing report [Pan Peihua. Analysis on the Reasons Affecting the Viscosity of the Neutralization Slurry [J]. Fertilizer Industry, 1999, 6( 26):43-45] and [Campbell G R, Leong Y K, Berndt C C, et al. Ammonium phosphateslurry rheology and particle properties—the influence of Fe (III) and Al(III) impurities, solid concentration and degree of neutralization[J ].Chemical engineering science, 2006, 61(17): 5856-5866.], both reported the influence of metal ions such as calcium, magnesium, iron and aluminum in phosphate rock on the viscosity of the neutralized slurry, and the viscosity of the slurry after removal degree of improvement, but so far there is no public literature report on removing metal ions such as calcium, magnesium, iron and aluminum and reducing slurry viscosity

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