In order to reduce or avoid the discharge of gaseous pollutants H.sub.2 S and SO.sub.2 to the environment in a process for the production of slag sand (granules) from blast-furnace slag by granulation of the slag by means of a water jet, the propulsion jet interspersed with water vapor, granules and pollutants is injected directly into a water receiver, the residual vapor still remaining and the pollutants H.sub.2 S and SO.sub.2 not yet washed out are cooled down in a condenser in counter-current with spray water and condensed, and the residual gas remaining after the vapor condensation is taken off from the top end of the condenser and recycled via a recycle line back to the injector.