Questions regarding the solid-liquid ratio in the crystallizer

According to the book, the solid-liquid ratio in crystallization should be between 20% and 40%. In the crystallizer, it takes a certain crystallization surface area for the supersaturation of the mother liquor to be eliminated. A high solid-liquid ratio in the slurry results in a larger crystallization surface area, which facilitates the elimination of supersaturation, promotes crystal growth, and reduces scaling in the equipment and pipelines. However, an excessively high slurry solid-liquid ratio will result in more crystals being carried away by the overflow ； It can easily cause accidents that result in the crystallizer being stuck in place. I believe that small factories can keep this parameter at its upper limit, as the residence time of the crystal within the crystallizer is short; setting it too low may result in fine crystals. Large plants can keep it at a slightly lower level to prevent mold accidents.

Some factories keep it at 45%, and it must not exceed 55%. For agricultural use, ammonium chloride does not require high levels of salt.

The solid content or suspension density during the crystallization process is an important factor affecting the control of particle size and crystal morphology, but it is not necessarily the decisive factor. For a specific crystalline system, the level of solid content influences secondary nucleation and growth; therefore, controlling the solid content is a factor in regulating particle size, though it may not always be effective. Since there are many factors that affect the crystallization process, each specific system must be examined individually. Detailed discussions can be held if necessary

What was said on the 2nd floor is very accurate. Additionally, if the solid-liquid ratio is too high during continuous operation, it will lead to difficulties in discharging the material, an excessively high viscosity of the system, and poor mixing efficiency.

I’m facing a very tricky problem: the crystals don’t grow larger; there are always many small crystals. How can I increase the size of the crystal particles?

This post was last edited by PORTER on 2009-11-27 09:17. Regarding the question mentioned above, it is necessary to check whether the load on the crystallizer is too high, or whether the capacity of the axial flow pump designed is insufficient, as well as whether issues such as the impeller angle or wear are preventing it from functioning at its designed capacity.

There are many reasons for the phenomenon you mentioned; only by detailing the relevant characteristics of the system can an appropriate solution be found. What kind of material system, operation method, type of crystallizer, etc. 6# huahua521

A higher slurry solid-liquid ratio results in a larger crystallization surface area, allowing the solution’s supersaturation to be eliminated more completely, which can reduce the formation of fine crystals. Therefore, an appropriately high solid-liquid ratio must be maintained.

I have also encountered the problem of small crystal particles. I hope to find more relevant information on this topic.