What is the purity of mirabilite obtained using the CIM method? How many other substances are there?

This needs to be determined based on your specifications for lightly salted water. Mirabilite produced by the CIM method needs to have its 10-water mirabilite precipitated through a freezing system. However, downstream, Glauber’s salt with 10 water molecules is not used directly; these 10 water molecules need to be removed. Given the situation at our factory, no one will take it even for free. It’s too late today; I’ll explain in detail tomorrow

It’s not clear to which stage the purity of mirabilite referred to by the original poster applies – before freezing or after freezing. In fact, the principle of the CIM method is that only monovalent ions can pass through, while divalent and higher-valent ions cannot cross the membrane; by looking at the specifications for low-salt water in your company, it is possible to determine the impurities present in mirabilite. Glauber’s salt can be sold directly, but as far as I know, there is no place where 10-water Glauber’s salt is used; in industry, anhydrous Glauber’s salt, also known as mirabilite, is generally used as a raw material. Calcium sulfate can be used as a dyeing aid in the printing and dyeing industry, as a laxative in the pharmaceutical industry, and as a filler in the dye industry. It is also utilized as a raw material in glass manufacturing, papermaking, detergents, and other applications

If one wants to remove the crystal water, it’s obvious to everyone that it’s very difficult, and energy consumption will be higher as a result. Currently, the price of mirabilite in the market is around 200 yuan per ton. A simple cost-benefit analysis shows that it is not economical to use it. Domestic manufacturers of mirabilite source their raw materials locally, building factories near salt lakes; they can extract the material, perform minor processing, and then sell it with almost no costs involved. Therefore, I suggest that everyone avoid post-treatment and simply discharge it directly

The solid content of the centrifuged wet material is not fixed; it depends on how the centrifuge is operated. Generally, over 50% is no problem; aside from water, there is only a very small amount of sodium chloride, meaning the dry basis can reach over 98%. The concentration of the membrane unit should be kept around 30 g/L; if it is too high, crystallization is likely to occur before the brine is added, while if it is too low, energy consumption increases.

Glauber’s salt is very cheap; it is obtained directly from salt lakes here. The price of sodium sulfate produced from Glauber’s salt is just over 600 yuan per ton when it contains 99% or more purity, while it costs around 300 yuan per ton for sodium sulfate with a purity of about 90%. It seems that such a small amount of mirabilite is like useless stuff – it provides no real value when used, but still has some flavor if discarded