Patent ID: 7052669

Claim:
A process for continuous production of ammonium thiosulphate, (NH 4 ) 2 S 2 O 3 (ATS) from NH 3 , H 2 S and SO 2 comprising steps of: (a) partial condensation in a partial condenser of a first gaseous or partial liquid feed stream comprising H 2 O, H 2 S and NH 3 with a molar H 2 S:NH 3 ratio <0.4; (b) passing the aqueous condensate comprising NH 4 HS and NH 3 from the partial condenser to a reactor in which said condensate is contacted with a third feed gas stream comprising H 2 S and with an aqueous solution comprising NH 4 HSO 3 and (NH 4 ) 2 SO 3 under formation of an aqueous solution of (NH 4 ) 2 S 2 O 3 ; (c) passing the gas stream comprising NH 3 and H 2 S from the partial condenser to a mixing device in which said gas stream is completely dissolved in the water drained off from an aerosol filter; (d) passing a second feed gas stream comprising approximately ⅔ mole SO 2 per mole of NH 3 contained in the first feed stream to a SO 2 absorber and the aerosol filter; (e) passing the aqueous solution produced in mixing device to the SO 2 absorber; (f) passing the off gas from the absorber to the aerosol filter; and (g) adding to the aerosol filter a balance amount of water required for obtaining approximately 40–65 wt % (NH 4 ) 2 S 2 O 3 in the aqueous solution of (NH 4 ) 2 S 2 O 3 being withdrawn from the reactor.