RAW MATERIAL OF COMPOSITE PELLETS USED IN KILN PROCESS FOR PRODUCTION OF PHOSPHORIC ACID, AND SHAPING METHOD THEREFOR

摘要

Disclosed is a composite pellet used as a raw material in a kiln process for the production of phosphoric acid, which is of a core-shell structure in which the shell clads the core, wherein the core consists of a core material and a binder, and the shell consists of a cladding material and a binder; the core material mainly consists of a carbonaceous reductant powder, a phosphate ore powder and a silica powder, the cladding material mainly consists of a carbonaceous reductant powder and a silica powder, and the core and the shell are composited by a binder to form the shell-core structure. The preparation of the composite pellets comprises the steps of preparing the cores, preparing the cladding material, shaping, drying and solidifying composite green pellets etc., specifically comprising subjecting the obtained cores to a double-layer roll sieving treatment, then sending same into a pelletiser, introducing the cladding material, adding the binder during the cladding treatment, and obtaining the composite green pellets after the cladding treatment; then sending the composite green pellets to a drier for drying and solidifying, and finally shaping to obtain the composite pellets. The composite pellets prepared by the present invention have a smaller range of formulation fluctuation, more stable quality, higher strength and better performance.