SODIUM DIFORMATE SYNTHESIS METHOD

FIELD: chemistry. ^ SUBSTANCE: invention relates to a method of preparing a sodium formate-containing composition with formic acid content of not less than 35 % of the total weight of the said composition, in which a) a stream of formic acid with formic acid content of not less than 74 wt % is provided; b) a stream of formic acid from step a) together with sodium formate-containing streams from step f) and step h) are taken to the crystallisation step where an aqueous solution is obtained at high temperature, where the said solution has molar ratio HCOOH:Na[HCOO] greater than 1.5:1 and molar ratio HCOOH: H2O equal to at least 1.1:1; c) at the crystallisation step the aqueous solution from step b) is crystallised to obtain a stream which contains a solid phase and a mother solution; d) the stream obtained from step c) is taken to a separation step on which the solid phase is separated from the mother solution to obtain a stream which contains sodium diformate and a stream which contains a mother solution; e) the stream which contains the mother solution from step d) is divided into two parts; f) one part of the stream from step c) in form of a portion (A) is returned to step b); g) the other part of the stream from step e) in form of a portion (B) together with the stream, including a base, which contains sodium is taken to a neutralisation step to obtain a mixture which contains sodium formate, and where portions of the mother solution (A) and (B) complement each other to 100 wt %, and the weight ratio of portion (A) of the mother solution to portion (B) lies between 20:1 and 1:10; and b) the sodium formate-containing mixture from step g) and optionally from step h), if necessary after its withdrawal, is taken to the concentration step in form of a stream where a portion of water contained in that stream is released, where after separation of the portion of water a stream which contains sodium formate is obtained, which is directly returned to step b) or crystallised at the second crystallisation and separation step, and the obtained liquid phase is taken to the concentration step h) in form of a stream, and the solid phase is taken in form of a stream to step b). The obtained product can be used in industrial production, especially at relatively low temperatures. ^ EFFECT: improved method of preparing a sodium formate-containing composition with formic acid content of not less than 35% of the total weight of the said composition; obtained product has anti