Process for the preparation of cyclohexanone oxime

The invention relates to a process for the production of cyclohexanone oxime in which a phosphate-containing aqueous reaction medium is cycled from a hydroxylammonium synthesis zone to a cyclohexanone oxime synthesis zone and back to the hydroxylammonium synthesis zone, in which hydroxylammonium synthesis zone hydroxylammonium is formed by catalytic reduction of nitrate with hydrogen, and in which cyclohexanone oxime synthesis zone hydroxylammonium is reacted with cyclohexanone to form cyclohexanone oxime, the cyclohexanone and an organic solvent being fed into the cyclohexanone oxime synthesis zone, an organic medium comprising the organic solvent and cyclohexanone oxime being withdrawn from the cyclohexanone oxime synthesis zone, characterized in that the ratio fh/fc