Abstract: An improved method for spraying molten material in order to obtain solidified grains or prills. Molten material, such as NPK-fertilizer is fed into a symetrical rotating reservoir which rotates about a vertical axis and whose upright walls are provided with apertures for spraying. The interior of the rotating reservoir accommodates a member provided with blades, which member rotates at a speed different from that of the reservoir. The sprayed molten material cools while falling to form solid round prills. The blades inside the reservoir rotate at a speed at least 1.5 times greater than the speed of rotation for the reservoir.