Method and apparatus for preparation of nitrogen and phosphorus composite fertilizer by mixing nitric acid and phosphoric acid

Abstract

The present invention relates to the technical field of nitrogen and phosphorus composite fertilizer production, and in particular relates to a method and an apparatus for preparation of a nitrogen and phosphorus composite fertilizer by mixing nitric acid and phosphoric acid, by arrangement of a reactor, a dilute slurry tank, an evaporator, a concentrated slurry tank and a spray granulation column, and combination of arrangement of a mixer in the spray granulation column and a material collection hopper and a sifter on the bottom, the composite fertilizer production process is shortened, energy consumption and cost are reduced; in the production process, first phosphoric acid and nitric acid are mixed in the reactor, and neutralized with ammonia, pH is controlled, and nitrogen and phosphorus ratio is limited, so that nitrogen and phosphorus content and the dispersion degree in the composite fertilizer are restricted from macroscopic level to microcosmic level, by use of molecular mutual motion and collision energy, uniform dispersion effect can be achieved; after evaporation melting processing, an additive is added for mixing processing, the composite fertilizer is diversified in nutrition, uniform dispersed nutrition can be ensured, the composite fertilizer quality is improved, and the production cost is reduced.

Description

technical field [0001] The invention relates to the technical field of nitrogen-phosphorus compound fertilizer production, in particular to a method and a device for preparing nitrogen-phosphorus compound fertilizer by mixing nitric acid and phosphoric acid. Background technique [0002] At present, the production of nitro-compound fertilizers is mainly based on the molten ammonium nitrate slurry as the mother liquor, and according to the ratio of nitrogen, phosphorus and potassium, powdered phosphate fertilizer and / or potassium fertilizer is added to it after stirring and mixing, and then sprayed and granulated. obtain; before adding the mother liquor to the phosphate fertilizer, it needs to carry out the process steps such as packaging, transshipment, unpacking, and metering of the phosphate fertilizer, and the phosphate fertilizer is very easy to interact with the air in the environment to deteriorate, so that in the process of packaging, transshipment, and metering The r...

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Problems solved by technology

[0002] At present, the production of nitro-compound fertilizers is mainly based on the molten ammonium nitrate slurry as the mother liquor, and according to the ratio of nitrogen, phosphorus and potassium, powdered phosphate fertilizer and / or potassium fertilizer is added to it after stirring and mixing, and then sprayed and granulated. obtain; before adding the mother liquor to the phosphate fertilizer, it needs to carry out the process steps such as packaging, transshipment, unpacking, and metering of the phosphate fertilizer, and the phosphate fertilizer is very easy to interact with the air in the environment to deteriorate, so that in the process of packaging, transshipment, and metering The requirements are relatively strict, especially the addition of phosphorus fertilizer is difficult to control, which leads to the poor quality of the produced nitro compound fertilizer, and after it is fertilized into the soil, it will cause unevenness in the local nutrient structure of the soil, making the fertilization effect Obviousness has hindered the further application of nitro compound fertilizers in the agricultural field and reduced the market share of nitro compound fertilizers

In addition, during the production and processing of nitro-compound fertilizers using existing settings and devices, phosphate fertilizers and potassium fertilizers are added in solid form during the addition process, and are mixed with molten ammonium nitrate slurry. Simple mixing makes it very easy to precipitate in the local position of the molten slurry or the state of local nutrient dispersion is uneven, causing equipment blockage, and even causing the supply of raw materials to be interrupted, making the process an intermittent operation and reducing the production of nitrate. The quality of nitro-based compound fertilizers, especially the phenomenon of partial nutrient excess and local nutrient deficiency in nitro-based compound fertilizers, hinders the further expansion of nitro-based compound fertilizers in the market, and reduces the quality of nitro-based compound fertilizers. market share

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