What is Magnesium Hydroxide CAS 1309-42-8?

Magnesium hydroxide is a white inorganic powder with low water solubility. It is used as a flame retardant, acid neutralizer, pH buffer and source of magnesium in industrial, environmental and pharmaceutical applications.

How does magnesium hydroxide work as a flame retardant?

It decomposes endothermically at high temperature, releasing water vapor and forming magnesium oxide. This removes heat from the polymer and dilutes flammable gases, while the oxide residue contributes to char formation and smoke suppression.

At what temperature does decomposition begin?

Magnesium hydroxide normally begins significant decomposition around 300-330 degrees Celsius. This thermal stability is higher than many hydrated fillers, making it suitable for polymers processed at elevated temperatures.

Why is it useful in wastewater treatment and acid neutralization?

Its low solubility provides controlled release of hydroxyl ions, buffering pH to a moderate alkaline level and reducing the risk of over-alkalization compared with strong bases. It also produces less sludge in many neutralization applications.

What are the main applications?

Typical uses include halogen-free flame-retardant compounds, wire and cable, plastics and rubber, wastewater neutralization, flue-gas desulfurization, chemical intermediates, pharmaceuticals and mineral-based products.

Which grade and packaging are available?

The listing is industrial/flame-retardant grade with 95-99% magnesium hydroxide, customizable on request. It is supplied in 25 kg woven bags with an inner PE liner or 500-1000 kg jumbo bags on pallets.

What specifications should be checked before ordering?

Confirm magnesium hydroxide content, particle size, surface area, whiteness, moisture, loss on ignition, heavy metals and any surface treatment. Request the batch analysis, technical data and safety information before purchase.

How should magnesium hydroxide be stored and handled?

Store in tightly closed bags in a cool, dry, ventilated area away from acids, moisture and incompatible materials. Use dust-control measures and suitable respiratory protection, and follow the safety information for handling and disposal.

Magnesium Hydroxide CAS 1309-42-8

Magnesium Hydroxide, CAS 1309-42-8, is an inorganic alkaline powder supplied as a halogen-free flame retardant, acid scavenger and smoke suppressant. Confirm the required grade, then request a quotation with COA/TDS/SDS for bulk supply.

CAS: 1309-42-8
Synonyms: Magnesium dihydroxide, Brucite, Milk of magnesia (suspension), Magnesium hydroxide powder, MDH flame retardant
Einecs: 215-170-3
Molecular Formula: Mg(OH)₂
Grade: Industrial / Flame-retardant grade (95–99% Mg(OH)₂, customized on request)
Package: 25 kg woven bag with inner PE liner / 500–1000 kg jumbo bag on pallet, customizable

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Product Description

Magnesium Hydroxide, CAS 1309-42-8, also known as magnesium dihydroxide or brucite, is an inorganic alkaline powder; the EC/EINECS number is 215-170-3.

Synonyms: magnesium dihydroxide; brucite; milk of magnesia (suspension); magnesium hydroxide powder; MDH flame retardant.

CAS: 1309-42-8.

Molecular formula: Mg(OH)₂.

It is a white to off-white fine powder, odorless, with low water solubility.

EC number: 215-170-3.

The assay (Mg(OH)₂) is 95.0–99.0% min depending on grade; magnesium oxide (as MgO) is about 63–65%.

Loss on ignition is 30–34%; bulk density is 0.30–0.60 g/cm³ (tapped, grade dependent).

It decomposes endothermically at high temperature (about 300–330 °C), releasing water vapor and forming magnesium oxide.

It is used in halogen-free flame-retardant compounds, wire and cable, plastics and rubber.

It is used in wastewater neutralization, flue-gas desulfurization and acid neutralization.

It is used in chemical intermediates, pharmaceuticals and mineral-based products.

Its low solubility provides controlled release of hydroxyl ions, buffering pH to a moderate alkaline level.

Confirm magnesium hydroxide content, particle size, surface area, whiteness, moisture, loss on ignition, heavy metals and surface treatment.

Store in tightly closed bags in a cool, dry, ventilated area away from acids, moisture and incompatible materials.

Confirm packaging with the requested quantity and destination requirements.

Document requirements should be confirmed from the current specification, SDS, COA or other product-specific files.

The page is an RFQ entry point and does not state stock, price, MOQ or fixed lead time.

For an RFQ, state the intended use, required grade, particle size, quantity, packaging, destination and document needs.

FAQ - Technical & Supply Chain

Q:
What is Magnesium Hydroxide CAS 1309-42-8?

A: Magnesium hydroxide is a white inorganic powder with low water solubility. It is used as a flame retardant, acid neutralizer, pH buffer and source of magnesium in industrial, environmental and pharmaceutical applications.
Q:
How does magnesium hydroxide work as a flame retardant?

A: It decomposes endothermically at high temperature, releasing water vapor and forming magnesium oxide. This removes heat from the polymer and dilutes flammable gases, while the oxide residue contributes to char formation and smoke suppression.
Q:
At what temperature does decomposition begin?

A: Magnesium hydroxide normally begins significant decomposition around 300-330 degrees Celsius. This thermal stability is higher than many hydrated fillers, making it suitable for polymers processed at elevated temperatures.
Q:
Why is it useful in wastewater treatment and acid neutralization?

A: Its low solubility provides controlled release of hydroxyl ions, buffering pH to a moderate alkaline level and reducing the risk of over-alkalization compared with strong bases. It also produces less sludge in many neutralization applications.
Q:
What are the main applications?

A: Typical uses include halogen-free flame-retardant compounds, wire and cable, plastics and rubber, wastewater neutralization, flue-gas desulfurization, chemical intermediates, pharmaceuticals and mineral-based products.
Q:
Which grade and packaging are available?

A: The listing is industrial/flame-retardant grade with 95-99% magnesium hydroxide, customizable on request. It is supplied in 25 kg woven bags with an inner PE liner or 500-1000 kg jumbo bags on pallets.
Q:
What specifications should be checked before ordering?

A: Confirm magnesium hydroxide content, particle size, surface area, whiteness, moisture, loss on ignition, heavy metals and any surface treatment. Request the batch analysis, technical data and safety information before purchase.
Q:
How should magnesium hydroxide be stored and handled?

A: Store in tightly closed bags in a cool, dry, ventilated area away from acids, moisture and incompatible materials. Use dust-control measures and suitable respiratory protection, and follow the safety information for handling and disposal.

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