Process for producing chlorine dioxide

The invention concerns a process and an apparatus for continuously producing chlorine dioxide, the process comprising the steps of: feeding chlorate ions, acid and hydrogen peroxide as aqueous solutions to a reactor; reducing chlorate ions in the reector to chlorine dioxide, thereby forming a product stream in the reactor containing chlorine dioxide; feeding motive water to an eductor comprising a nozzle; bringing the motive water to flow through the nozzle and causing it to flow further through the eductor in an at least partially spiral or helical manner, transferring the product stream from the reactor to the eductor and mixing it with the motive water and thereby forming a diluted aqueous solution containing chlorine dioxide, and; withdrawing the diluted aqueous solution containing chlorine dioxide from the eductor.