Industrial Chemicals
Magnesium Oxide
Magnesium oxide (caustic magnesia) is produced by calcining magnesite at 700–900 °C into a mineral-sourced caustic magnesia. It is highly reactive and readily absorbs moisture, so it is supplied in sealed packaging. Used as a magnesium raw material for fertilizers, in magnesium-based binder and building materials, for soil amendment and for desulfurization. This is a calcined mineral product, not a chemically synthesised magnesium oxide. The specification table below is for the 90% min grade; the technical data sheet for the 85% min grade is available on request.
Please note: Non-hazardous goods. Industrial and agricultural use — not for food or pharmaceutical use. Hygroscopic: keep sealed and dry; it absorbs moisture and hydrates. Export of this product under HS 2519903000 is not restricted. A routine export filing procedure applies and is completed per shipment.
Quick facts
- CAS number
- 1309-48-4
- Formula
- MgO
- Appearance
- White to pale beige powder
- HS heading
- 2519903000
Customs classification depends on declared use and current regulation. Confirm the applicable code with your customs broker for your shipment.
Specification
Typical technical specification
From the product TDS, issued 2026-09-13, written against YB/T 5206-2023. The batch certificate of analysis issued with your shipment is the controlling record.
| Parameter | Value |
|---|---|
| MgO content | ≥ 90.0% |
| Reactive MgO | ≥ 65% |
| Calcium oxide (CaO) | ≤ 2.5% |
| Silica (SiO₂) | ≤ 4.0% |
| Iron oxide (Fe₂O₃) | ≤ 1.0% |
| Aluminium oxide (Al₂O₃) | ≤ 1.0% |
| Loss on ignition | ≤ 6.0% |
Grades and forms
MgO 85% min
Building materials, soil amendment and fertilizer raw material. Active MgO ≥55% · SiO₂ ≤6% · CaO ≤4% · loss on ignition ≤8%
MgO 90% min
Calcined magnesite, 700–900 °C; reactive MgO ≥ 65%
Applications
- Magnesium-based binder and building materials
- Soil amendment
- Raw material for fertilizer production
- Desulfurization agent
Product
What it looks like
Photographs and video of the material as supplied. Colour and granule size vary within the range stated in the technical data sheet.
FAQ
Questions importers ask about this product
- What packing options are available for Magnesium Oxide?
- 50 kg PP woven bag with PE inner liner; 1000 kg jumbo bag (FIBC) with PE inner liner; Private label and buyer-specific shipping marks available. Private-label printing and buyer-specific shipping marks can be arranged.
- Can you supply Magnesium Oxide to a specific specification?
- Yes. Send the grade, purity and any impurity limits your process requires and we will confirm what we can supply. Indicative specifications for our standard grades are listed on this page; the controlling values are those in the technical data sheet (TDS) issued for your order.
- Which documents are provided with a Magnesium Oxide shipment?
- Commercial invoice, packing list, bill of lading, certificate of analysis for the batch, and the technical data sheet (TDS) and safety data sheet (SDS) for the product. Certificates for specific destinations can be arranged on request.
- What is the minimum order quantity?
- Our standard export minimum is one 20'GP container (approx. 25 MT). For a first order we can discuss a smaller trial quantity.
- What is the difference between your MgO 85% and MgO 90% grades?
- Purity is the wrong way to choose, and a supplier quoting only the percentage has not asked what the oxide is for. The 85% grade is for building materials, soil amendment and fertilizer raw material, with active MgO ≥55%, SiO₂ ≤6%, CaO ≤4% and loss on ignition ≤8%. The 90% grade is caustic magnesia calcined from magnesite at 700–900 °C with reactive MgO ≥65% — that reactivity, not the headline percentage, is what decides how it behaves in your process. Tell us the application and we will point to the grade.
- Can I use magnesium oxide instead of magnesium sulphate for soil magnesium?
- They behave differently. Magnesium oxide is only slightly soluble, so it releases magnesium slowly and nudges pH up — useful as a soil amendment or a raw material in fertilizer manufacture. Magnesium sulphate dissolves readily and delivers magnesium and sulphur immediately, which is what fertigation and foliar programmes need. Which one fits depends on whether you want a slow reserve or an available supply.
- How should magnesium oxide be stored?
- Sealed and dry. Caustic magnesia is hygroscopic: exposed to humid air it absorbs moisture and hydrates, which is why it ships in sealed PE-lined bags and why we offer 50 kg bags and 1000 kg FIBC jumbo bags rather than open handling. Stack off the floor and keep the liner closed between uses.
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Enquire about Magnesium Oxide
Grade, purity, packing, quantity and destination port is all we need to quote.