Magnesium Oxide (MgO) Storage & Tank Compatibility

Storing Magnesium Oxide (MgO)? Start Here

Magnesium oxide, MgO, is a white, odorless mineral oxide produced by calcining magnesium carbonate or magnesium hydroxide, or by recovering magnesia from seawater and brines. It is one of the most versatile industrial inorganics: a refractory with an extremely high melting point, a basic (alkaline) reagent, and a source of supplemental magnesium. Grades range from light, reactive “caustic-calcined” magnesia used in animal feed, fertilizer, flue-gas scrubbing, wastewater pH adjustment, and acid neutralization, to dead-burned and fused grades used in refractory brick and furnace linings. Because MgO is practically insoluble in water and hydrates slowly to magnesium hydroxide, it is commonly stored as a dry powder or granular solid and dosed as an aqueous slurry. The chemistry that matters for storage is its mild alkalinity, its abrasive particulate nature, and its tendency to absorb moisture and carbon dioxide from air — not aggressive chemical attack on tank materials.

Is Polyethylene (HDPE / XLPE) Safe for Magnesium Oxide (MgO)?

Yes — polyethylene is a sound choice for magnesium oxide. MgO is a basic, non-oxidizing inorganic solid, and the alkaline species it forms in water — magnesium hydroxide — is rated Satisfactory (“S”) on HDPE and crosslinked polyethylene chemical-resistance charts at both ambient (~70°F) and elevated (~140°F) service temperatures. The powder, its saturated solution, and its slurries contain no oxidizers, solvents, hydrocarbons, or strong acids that would degrade polyethylene, so chemical attack is not the limiting factor. The real design considerations for a poly tank are physical: the mineral is abrasive and its slurries settle, so size agitation or recirculation to keep solids suspended, and select a tank with an adequate specific-gravity (fluid-weight) rating for your solids loading. For these reasons a properly rated HDPE or XLPE tank is a durable, cost-effective option for storing magnesium oxide as a dry powder or as a slurry. Always confirm against the product SDS and the tank manufacturer’s chemical-resistance and fluid-weight ratings for your concentration and temperature.

Material compatibility at a glance

Magnesium oxide is a non-oxidizing, non-flammable basic mineral oxide, so the dominant storage drivers are physical — dust control, abrasion, and the mild alkalinity that develops as the powder hydrates — rather than chemical attack. HDPE and XLPE polyethylene are an economical, durable fit for both dry storage and aqueous slurries; bare aluminum is the material to watch in wet, high-pH service.

Ratings: S suitable · C conditional / limited · U unsuitable. Verify against the cited resistance charts and your concentration/temperature before specifying.

The safety that actually matters

• Causes serious eye irritation (H319) — wear chemical splash goggles; the fine alkaline powder is abrasive and drying to the eyes.
• May cause respiratory irritation (H335) — control dust, provide local exhaust ventilation, and wear an appropriate respirator when generating airborne powder.
• Non-flammable and non-reactive under normal conditions (NFPA Flammability 0, Instability 0) — no fire or explosion hazard.
• Reacts exothermically (hydrates) with water and is slowly attacked by acids — add to water carefully and avoid contact with strong acids that can liberate heat.
• Absorbs moisture and carbon dioxide from air — keep containers and tanks sealed to preserve reactivity and prevent caking.
• Follow the specific product SDS for exposure limits, first aid, and disposal; grade, particle size, and impurity content vary by source.

Common questions

What is magnesium oxide used for?

Magnesium oxide (MgO, also called magnesia) is used as a basic reagent for wastewater and process pH adjustment and acid neutralization, as a magnesium source in animal feed and fertilizer, in flue-gas desulfurization, and — in dead-burned and fused grades — as a high-temperature refractory for furnace linings and brick. It is handled as a dry powder, as granules, or dosed as an aqueous slurry.

Can I store magnesium oxide in a polyethylene tank?

Yes. HDPE and XLPE are well suited to magnesium oxide powder and its slurries. The alkaline form it produces in water (magnesium hydroxide) is rated Satisfactory on polyethylene resistance charts at normal and elevated temperatures, and MgO contains nothing that chemically attacks polyethylene. The key design factors are keeping solids suspended and choosing a tank rated for the fluid weight and for abrasion, not chemical compatibility.

Is magnesium oxide corrosive or hazardous?

Magnesium oxide is not classified as corrosive. It is a mild irritant — it causes serious eye irritation (H319) and may cause respiratory irritation (H335), chiefly as airborne dust. It is non-flammable and non-reactive under normal handling. It is mildly alkaline once hydrated, so high-pH effects (such as slow attack on aluminum in wet service) are the main material concern.

Does magnesium oxide dissolve in water?

Only very slightly. MgO is practically insoluble in water (about 0.0086 g per 100 mL) and slowly hydrates to magnesium hydroxide, which is itself only slightly soluble. As a result it is stored and shipped as a dry solid or as a pourable slurry rather than as a clear solution, and it dissolves readily only in dilute acids.