Magnesium Chloride Hexahydrate vs. Anhydrous Magnesium Chloride: What’s the Difference?

Magnesium chloride is an essential magnesium salt widely used across industrial, food, and pharmaceutical applications. It exists in different hydration forms, with the two most common being Magnesium Chloride Hexahydrate (MgCl₂·6H₂O) and Anhydrous Magnesium Chloride (MgCl₂). While they share the same chemical base, their physical properties, applications, and handling requirements are significantly different. Understanding these differences can help you select the right type for your specific needs.

1. Chemical Composition

Magnesium Chloride Hexahydrate (MgCl₂·6H₂O):

Contains six molecules of water of crystallization. This gives it a higher moisture content and lower percentage of active magnesium by weight.

Anhydrous Magnesium Chloride (MgCl₂):

Completely free of water. It is more concentrated in active magnesium content and usually appears as white or off-white flakes or powder.

2. Appearance & Physical Properties

3. Application Differences

Hexahydrate Magnesium Chloride:

Deicing and dust control

Textile and dyeing industry

Construction additives

Aquaculture and agriculture

Food additive (coagulant in tofu making)

Anhydrous Magnesium Chloride:

High-temperature industrial applications

Metallurgy (magnesium metal production)

Catalyst and flame retardant production

Used as a raw material in specialty chemical synthesis

Desiccant or moisture-absorbing agent

4. Storage & Handling

• Hexahydrate: Less sensitive to moisture but may cake if not stored properly.

• Anhydrous: Highly hygroscopic (absorbs moisture quickly), must be stored in airtight, moisture-proof packaging.

5. Cost and Availability

• Hexahydrate is more widely available and cost-effective for bulk, low-temperature applications.

• Anhydrous is typically more expensive due to higher purity and production cost, used when water content must be strictly controlled.

Conclusion

Choosing between Magnesium Chloride Hexahydrate and Anhydrous Magnesium Chloride depends on your application’s purity requirements, moisture sensitivity, and end-use conditions. At Shandong Runfu Ca Mg Chemical Technology Co., Ltd., we supply both forms with consistent quality and customizable specifications.

Whether you need hexahydrate flakes for deicing or high-purity anhydrous MgCl₂ for metallurgy or chemical synthesis, we are here to support your needs with professional service and technical guidance.

Contact us at: sales@runfucamg.com
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