METHOD OF PREPARING NITRITE-NITRATE SALTS Russian patent published in 2008 - IPC C01D9/06 C01B21/50 

FIELD: inorganic compounds synthesis.

SUBSTANCE: essence of the method consists in that condensate of liquor-tanned vapor formed in the step of concentration of nitrite-nitrate lies in evaporation apparatuses is purified through membranes of reverse-osmosis installation with pore size 0.0001-0.001 μm at pressure 2.5 MPa. Obtained permeate is directed to feed steam-generation boilers operated at pressure 1.3 MPa. In concentrate stream leaving reverse-osmosis installation, salt concentration is checked: at concentration of salts below 6 g/L concentrate is recycled to the inlet of reverse-osmosis installation and, at concentration of salts 6-20 g/L, concentrate is returned to nitrite-nitrate lye concentration step. Before being passed to reverse-osmosis installation, condensate of liquor-tanned vapor leaving evaporation apparatus is additionally cooled in two stepped coolers operated both in consecutive and parallel regimes and recovered heat is reused in heat circuit of steam-generation boilers.

EFFECT: reduced process expenses, increased production of nitrite-nitrate salts due to recycling salts carried away by condensate of liquor-tanned vapor into process cycle, and excluded discharge of salts into closed water industry system.

3 cl, 1 dwg, 2 tbl, 2 ex