gas is to prevent contact between the gas phase in particular its content of co 2 and the green liquor which has been formed in the embodiment shown in fig2 any cooling liquid bath or similar device not shown for washing cooling moisture saturating the gas phase and any space not shown for weak green liquor are arranged outside the vessel for the reactor part 1 the separating part 3 and the green liquor space 4 fig3 shows a device according to a third embodiment of the invention in this embodiment the reactor part has been given a shape which tapers in the downwards direction like an upside down truncated lopped core an arrangement which amplifies the cyclone effect and improves the separation of the gas phase from the smelt phase the construction is also advantageous since the ceramic lining 2 becomes in the main self supporting the green liquor space 4 is preferably accommodated n a separate vessel which is connected to the reactor part 1 at the outlet 10 for the smelt phase the outer walls 12 of the device are cooled protected in the separating part by a cooling flow 14 which is supplied at the support.