How to Read a Magnesium Oxide Datasheet: Activity, Purity, Particle Size and Other Key Specifications

2026-09-20 00:20:58

Two Magnesium oxide lots can share the same "98% MgO" headline and behave completely differently in your process. The difference hides in the second-tier numbers - activity value, CaO, LOI, D50 - and in how honestly the datasheet presents them. This guide walks buyers through every standard line on an MgO datasheet, what it actually measures, and why it matters for your application and your cost.

Why Datasheet Literacy Saves Money

MgO is bought by the ton but consumed by the reaction. Overpaying for reactivity you do not need, or under-buying and overdosing to compensate, both come from misreading specifications. Ten minutes of datasheet fluency protects every purchasing decision you make in this category.

The Two Numbers That Matter Most

1. Activity value (iodine adsorption, mg I2/g)

This is *the* reactivity metric for light and active magnesia. It measures how much iodine a gram of MgO adsorbs, which correlates with surface area and lattice reactivity. In practical terms, activity value predicts:

·         How fast MgO hydrates and neutralizes acids (rubber, hydrometallurgy, SMC thickening)

·         How much product you actually consume per ton of throughput

·         Whether your viscosity curve (SMC) or pH response (precipitation) is reproducible

Buyer rule: always specify activity as a guaranteed band, never accept a "typical" value. And remember it is perishable - humidity and CO2 in storage degrade it.

2. MgO content (purity)

The assay defines how much of the powder is actual magnesium oxide versus inert impurities. But context matters:

·         Is the assay on an ignited basis or as-received basis?

·         What is the LOI (loss on ignition)? A high LOI means part of that "98%" is carbonate/hydroxide that will burn off as weight loss in your process.

·         What are the individual impurities? Two 98% grades with different CaO contents can behave very differently.

Specification-by-Specification Reference

Matching Specifications to Applications

Note how different the priorities are: the same "specification sheet" is read through different eyes for a rubber compounder and a cobalt extraction plant. Tell your supplier the application, not just the grade name.

Red Flags on a Datasheet

1. "Typical" values with no guaranteed range - the supplier is promising averages, not deliveries.

2. No activity value at all on a grade sold as "active" - an immediate walk-away.

3. Wide spec windows (for example, activity 100-180) presented as a feature; wide windows mean wide process behavior.

4. No LOI on a purity claim - the assay may be flattering.

5. No batch COA policy - you are buying hope, not chemistry.

6. As-received vs ignited basis confusion - always ask which basis the assay uses.

Questions to Ask Before Ordering

1. What activity band do you guarantee per batch, and what is your last 12-month capability (Cpk) on it?

2. Which impurity limits do you guarantee, and can I see recent COAs?

3. How is the product packaged against moisture for sea freight?

4. Can you support a bench or pilot trial with my process matrix?

5. What happens if a lot misses the band - replacement terms?

A serious manufacturer answers all five with documents, not adjectives. Wanfeng verifies composition, particle size, whiteness, bulk density and activity in its powder technology testing center on every development batch, and supplies per-batch COAs as standard - see the QM-98 light active grade or high purity MgO datasheets for examples.

FAQ

What is a good activity value for magnesium oxide?

There is no universal number - it is application-specific and normally agreed as a guaranteed band. High-activity hydrometallurgical and rubber grades commonly sit in the 100-160 mg I2/g range; food and process grades differ. Match the band to your process, then hold the supplier to it.

Is higher purity always better?

Higher MgO content generally helps, but impurity identity matters more than the headline: a 96% grade with low CaO/Fe can outperform a 98% grade with poor impurity control for your duty.

Why does my MgO activity drop during storage?

Active MgO absorbs moisture and CO2, converting surface layers to hydroxide and carbonate. Sealed, dry storage with FIFO rotation preserves the activity you paid for.

What particle size should I choose?

Fine particles react and disperse faster but can complicate handling and settling; the optimum balances your process. Discuss D50 targets with the supplier's technical team for your specific duty.

Get Datasheets That Hold Up in Your Process

Wanfeng supplies magnesium oxide across nine product series with guaranteed specification bands and per-batch verification. Request datasheets and samples for your application, or read our guide on Magnesium oxide for hydrometallurgy for a worked example.