How to shorten the crystallization time and obtain high-quality zinc sulfate heptahydrate crystal products

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In industrial production, zinc sulfate heptahydrate is a crystalline product obtained from concentrated zinc sulfate solutions at temperatures below 39 degrees Celsius. Crystallization is an important process, as well as a purification step. The standard process involves using crystallization to remove the vast majority of anionic impurities as well as some cationic impurities. Larger crystals tend to lose water more easily; since they contain fewer adsorbed impurities, the quality of the product is better. To obtain products with larger crystal grains, it is necessary to extend the crystallization time. In its current production processes, Changsha Ruiqi Chemicals experiences a crystallization time of over ten hours. If this time is insufficient, only products with fine particles are obtained; such particles have a large specific surface area, which allows them to absorb more free water. As a result, it is difficult to remove this water using a centrifuge, leading to insufficient zinc content in the final product and easy caking, thereby resulting in substandard products. Now the question is: how can we significantly reduce the free water content of the product and thereby shorten the crystallization time? Is there a better way to shorten the crystallization time? ?