Abstract: In a process for making a prilled product from a molten substance therefor steam or heated gas is intermittently introduced into the prilling apparatus to clean the apparatus. In one embodiment the molten substance is passed through a filter zone prior to introduction to a nozzle provided with orifices to produce the prilled product and the flow of molten substance through the filter zone is periodically interrupted and steam or heated gas is passed through the filter zone in the direction opposite to the flow of molten substance to clean the filter zone. More than one filter zone can be operated in parallel so that while one filter zone is being cleaned, molten substance is passed through another filter zone to provide for continuous operation of the process.

Abstract: A process is provided for making a prilled product from a molten substance wherein steam or heated gas is passed through the nozzle which produces the prilled product prior to the introduction of the molten substance through the nozzle at the beginning of the process.