The invention relates to a production method and apparatus of hollow granular water-soluble
fertilizer. The production method comprises the following steps: adding
phosphoric acid,
urea,
potassium salt and micro
fertilizer into a mixer, and preparing mixed
slurry; then adding the mixed
slurry in a foaming device, reacting and foaming, obtaining viscous
slurry, pumping the viscous slurry into a rotary differential spray head, scattering the slurry into liquid drops by virtue of the spray head, enabling the liquid drops to drop in a solidifying device, thermally polymerizing and solidifying intohollow particles, and subsequently cooling and screening to obtain a final product. The apparatus comprises a
urea transport unit, a
phosphoric acid transport unit and a
potassium salt transport unit, as well as a mixer, a foaming device, a solidifying device, an
exhaust gas treatment unit and an after-
treatment unit which are communicated with the units. By adopting the production method, additional
foaming agent and instant-soluble additives are not needed,
carbon dioxide gas generated during the reaction is fixed inside the granular water-soluble
fertilizer to change the internal physicalstructure of the granular water-soluble fertilizer product so as to achieve an instant soluble effect, the hollow granular
water soluble fertilizer meeting different technological requirements can beacquired, the product is unlikely in
moisture absorption and
caking, and the dissolving rate is increased.