Buyer takeaway: Magnesium oxide is MgO (CAS 1309-48-4). Caustic-calcined/light-burned, dead-burned and fused magnesia are selected by reactivity and duty, not just MgO percentage. Confirm calcination family, LOI, activity, particle size and impurities before comparing price.
1. Fix identity and calcination family
Magnesium oxide is different from magnesium hydroxide, magnesium carbonate, magnesium chloride and magnesium sulfate. Commercial magnesia changes as calcination becomes more severe: caustic-calcined material is more reactive, while dead-burned and fused material serve refractory duties.
| Family | Main buying checks |
|---|---|
| Caustic-calcined / light-burned | Activity, LOI, MgO, mesh and chemical/agricultural/environmental duty |
| Dead-burned | MgO, bulk density, CaO/SiO2, grain size and refractory duty |
| Fused | High-temperature refractory properties and grain specification |
2. Write the COA fields that control performance
- MgO content and reporting basis
- Loss on ignition
- Activity, citric-acid solubility or agreed reactivity method
- Mesh/particle distribution and bulk density where needed
- CaO, SiO2, Fe2O3 and other process-sensitive oxides
- Moisture protection, packing and lot traceability
A single MgO assay cannot describe both a reactive neutralizing grade and a refractory grade.
3. Match grade to the application
USGS information distinguishes caustic-calcined magnesia for agricultural, chemical and industrial applications from dead-burned/fused magnesia for refractories. The buyer should state whether the duty is refractory, environmental treatment, fertilizer, feed-related, rubber, construction or another process.
4. Control activity and fineness
More surface area or a finer mesh can change reaction rate, dusting and handling. Activity methods are not interchangeable unless the specification defines the method and acceptance range. Use the activity and fineness page for this intent.
5. Packing and receiving
Specify bag, liner, pallet and moisture protection. For fine reactive grades, include dust controls and a sealed sampling method. Match lot, COA, bag condition and quantity before release.
6. Compare offers
Normalize calcination family, MgO/LOI, activity method, particle size, impurities, packing, quantity and destination. A low price for the wrong calcination family is not a substitute.
RFQ checklist
- Duty and calcination family
- MgO, LOI, activity/solubility method and PSD
- Critical oxides and moisture
- Quantity, packing, port, Incoterm, COA and sample
Frequently asked questions
CAS? 1309-48-4.
Can light-burned replace dead-burned? No, not by name; their reactivity and duty differ.
Is industrial MgO automatically feed grade? No.
Core resources
Product/RFQ · COA/specification · Activity/fineness · Packing · Applications