Method for producing potassium nitrate by sodium nitrate and potassium chloride double decomposition reaction

Abstract

The invention discloses a method for producing potassium nitrate through metathesis reaction of sodium nitrate and potassium chloride, which is characterized in that the ratio of potassium chloride and sodium nitrate in the reaction tank is: 1:1.3-1.6, and the amount of water added is 30% of the weight of the reactant %, the temperature in the reaction tank is raised to 65°C-95°C, the feed liquid in the reaction tank is sent to the thickener for treatment, the temperature is kept at 65°C-85°C, and then enters the centrifuge for solid-liquid separation. The feed liquid is adjusted to make the sodium chloride in the feed liquid in an unsaturated state, and the feed liquid is subjected to three-stage flash evaporation, and the feed liquid from the third-stage flash tank is sent to another centrifuge, and the solid-liquid Separation, drying and granulation to obtain the finished potassium nitrate solid, and the separated mother liquor and lotion are recycled for use. The invention has low energy consumption, less water use, simple operation, mild production conditions and easy realization of continuous, automatic and large-scale production.

Description

1. Technical field [0001] The invention relates to a production method of potassium nitrate, in particular to a method for producing potassium nitrate through the metathesis reaction of sodium nitrate and potassium chloride. 2. Background technology [0002] Potassium nitrate is a chemical raw material. Sodium nitrate and potassium chloride are usually converted into potassium nitrate by metathesis reaction. The method is: the main raw materials potassium chloride and sodium nitrate by NaNO 3 : KCl=100:85 ratio into the reaction tank, then add an appropriate amount of water, use steam to heat to 110 ° C - 119 ° C, stirring constantly, when the heating evaporation concentration reaches 45 ° Be / --48°Be / Sodium chloride precipitates out first. After solid-liquid separation, wash the sodium chloride crystals with a small amount of hot water to reduce the loss of potassium nitrate, send the filtrate to the crystallizer, dilute it with 10-15% of the filtrate, and cool it wh...

AI Technical Summary

Problems solved by technology

In order to shorten the production time, some manufacturers adopt heat exchange and forced cooling on the filtrate, but they cannot overcome the fouling, which causes the heat transfer efficiency of the heat exchanger to drop greatly, and they have to stop production and clean the heat exchanger before using it.

Due to the deficiencies and defects in the above-mentioned process technology, the existing production method can only produce intermittently, and cannot realize continuous and automatic production.

On the other hand, the energy consumption is high, the washing water consumption is large, and the potassium yield is low