The invention relates to a method for preparing
ammonium sulfate by continuous conversion of phosphogyspum with a polycrystalline method, belonging to the technical fields of resource comprehensive utilization and
chemical industry, and relates to a method for producing
ammonium sulfate by conversion of phosphogyspum with a polycrystalline method based on a byproduct phosphogyspum in a (
sulfuric acid) wet
phosphoric acid industry as a main
raw material. The production process comprises the following steps: (1) pretreating the
raw material of phosphogyspum discharged in the wet phosphoric acidindustry so as to obtain purified phosphogyspum; (2) absorbing
ammonia and
carbon dioxide with a
ammonia-
sulfate-containing primary
lotion which is produced by washing a
calcium carbonate filter cakewith water in a
filtration process in a
carbonation tower so as to produce an
ammonia sulfate and
carbonate solution; (3) connecting a
calcium carbonate polycrystalline
nucleus generator with a multiple-tank or multiple-partition groove type reactor with a stirrer in series to constitute a conversion crystallizer; (4) filtering a reaction material
slurry discharged from the conversion crystallizer so as to obtain a
filter cake and filtrate containing 38-40% by weight of
ammonium sulfate; (5) carrying out secondary countercurrent washing on the
filter cake obtained in the step (4) with clear water, and feeding the ammonia-sulfate-containing primary
lotion to the
carbonation tower for absorbing gas ammonia and
carbon dioxide so as to produce an ammonia sulfate and carbonate liquid; and (6) neutralizing and decarburizing the filtrate containing
ammonium sulfate from the step (4) with
sulfuric acid, then centrifugally separating so as to obtain a
crystal containing wet
ammonium sulfate, separating out a mother liquid, carrying out cycle concentration on the mother liquid, and
drying the
crystal containing wet
ammonium sulfate so as to obtain a finished product ammonium sulfate.