SU142634A1 - The method of producing potassium nitrite - Google Patents

Description

A known method for producing potassium nitrite from sodium nitrite in the interaction of the latter with carbonate or oxalate calme, followed by fractional crystallization, the method of interaction with K2CO3 has been developed for the industrial preparation of a product of reactive qualification. Potassium nitrite is also obtained by reducing potassium nitrate with sponge lead. The past method has a number of disadvantages. The content of the main substance (KNOo) in the product obtained by this method does not exceed 80%. The product is contaminated with lead impurities and nitrate salts; for production, scarce, expensive and poisonous spongy lead is consumed.

The described new method for the production of potassium nitrite by the exchange reaction of sodium nitrite with the potassium salt is: in order to obtain a cleaner product, potassium chloride is used as the potassium salt and the third component is added.

This method is based on the coprecipitation of chloride admixture with the 2Ka2CO3 double salt observed by the author.

The study of the coprecipitation of chlorides with the double salt of the above composition was carried out by the method of fractional crystallization of an evaporated solution containing equivalent amounts of K2CO3 and NaNO2 and various amounts of chloride impurities. It is established that the chloride content in the solid phase in this case does not depend on the rate and temperature of crystallization. Therefore, it should be followed up; that co-precipitation is associated with anomalous isomorphism.

Example. In the reactor, equipped with a mechanical stirrer and heated, load 0.7 weight. including sodium nitrite, 0.6 wt. including potassium chloride, 0.14 weight. h of potash and 1.5 wt. H. water:

The reaction mixture is evaporated to a specific gravity of 1.64 at 80. The temperature of the boiling solution at the end of evaporation is 138 °. As

 142634-2 -. by increasing the boiling point, the content of chlorion and carbonation in the solution decreases. Ratior is enriched in potassium nitrite.

A mixture of sulfates is precipitated with a calculated amount of a saturated solution of technical caustic bari.

The solution is filtered, evaporated to a thick slurry to the consistency and cooled, with intensive stirring in the crystallizers, to ambient temperature. The crystals are centrifuged, dried and crushed. Uterine resolver is used in subsequent operations. The nitrate yield is about 45%. The yield can be significantly increased by using sludge, which contains up to 40% potassium nitrite. The slurry is washed on the filter to reduce the content of KN02 to 4-5%. The washings are evaporated to a specific gravity of 1.5, separated from the precipitate consisting predominantly of NaCl and used for loading in subsequent operations. Under these conditions, the yield of potassium nitrite rises to 70-80%.

The product obtained by the described method contains an insignificant amount of chlorides, and other impurities, namely:

Pitrita sodium 98%

Carbonate (in terms of KA2COz) 0.8

Chloride (C1) 0.9

Sulfate (SO /) 0.09

Water Insoluble Substances 0.01

In a series of experiments, it was found that upon receipt of potassium nitrite by reacting NaNOg with KC1 without the participation of potash, the content of chlorides in the product increases 6–7 times.

Subject invention

A method of producing potassium nitrite by the exchange reaction of sodium nitrite with a potassium salt, characterized in that, in order to obtain a more pure product, potassium chloride x is used as the potassium salt and the third component lotash is introduced.