A methanol/water scrubbing solution containing colloidal metal sulfides formed from metal carbonyls and resulting from the scrubbing of industrial gases, such as synthesis gas, is subjected to agglomeration of the metal sulfides before the scrubbing solution to be separated enters the separating column which separates the methanol from the water containing precipitated metal sulfides. The agglomeration is carried out in a precipitation vessel and the scrubbing liquid is diluted before it enters the precipitation vessel. The result is minimal encrustation of the trays or other parts of the cleaning plant for the scrubbing solution.