| 摘要 |
A process for continuous crystallization from a solution of at least one crystallizable material in a series of crystallization stages with partial crystallization in each stage, and classifying of partially crystallized suspension between each stage, wherein suspension from the last stage is passed to a separator which separates and returns a stream of remaining crystals to the last stage, and remaining solution from the separator is discharged and product crystals are taken from the first stage, the improvement constituting the invention is that partially grown crystals are circulated in circuits constituted by two or more subsequent crystallization stages in the series and by their connection conduits thereby that a stream of partially crystallized suspension after separation of a coarse fraction by classification is passed from a stage to the next stage in the series, whereas a stream of return suspension is passed in countercurrent in the series from a stage to the preceding stage without classification and that the suspension of product crystals is taken from the first stage through an elutriation column (hydraulic classification tube) in counter-current with the incoming feed which takes crystals which are only partially grown back to the first stage.
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