Hydromagnesite / Huntite

Introduction:

Sibelco’s Huntite and Hydromagnesite its anatural occurring fine platy sedimentary mineral consisting of a mixture of Huntite (magnesium calcium carbonate, (Mg3Ca(CO₃)₄)) and
Hydromagnesite (hydrated magnesium carbonate, (Mg5(CO3)4(OH)2·4H2O)) produced in our owned quarry in Greece. 

It is characterized by:

• High surface area
• High finess
• High whiteness
• Relatively low density of 2.5 g/cm³ compared to other mineral fillers, which are typically at 2.7 g/cm³
• Medium Mohs Hardness of 2-3
• Three-stage endothermic decomposition, releasing water and CO₂ .

Basic product (mineral blend) properties

Securoc products (mixture of huntite and hydromagnesite) are mostly used as a flame retardant or fire retardant additive in polymers. SECUROC C,D  are the product names for Sibelco’s classified huntite/hydromagnesite products. SECUROC C,D are used as a flame retardant mineral in a wide variety of applications often used as a synergist in combination with ATH. Moreover, SECUROC C,D products show exceptional rheological performance in sealant formulations. In addition these products work as an effective acid scavenger in halogen containing polymers.

Surface treated SECUROC C,D versions are available which exhibit improved dispersability, flowability and hydrophobicity.

Additional benefits when using Securoc C,D:

• Low abrasion due to its low hardnesss of 2-3 on the scale of Mohs

Securoc products overview

Huntite particles have a platy morphology and the particles are usually about 1 μm or less in diameter, much smaller than hydromagnesite particles. It has the following chemical formula and thermally decomposes between about 450°C and 750°C in two stages, releasing only carbon dioxide, leaving a solid residue of magnesium oxide and calcium oxide:  Mg₃Ca(CO₃)₄ → 3MgO + CaO + 4CO₂

The solid residue is called “char” and is critical to obtain smoke suppression. Huntite acts as a char strengthener in combination with other inorganic flame retardants. 

Natural hydromagnesite particles have a “blocky” morphology and once processed the majority of the particles are usually between 1 and 10 μm in diameter depending on the processing. 

It thermally decomposes between about 220°C and 550°C in two stages, initially releasing water then carbon dioxide, leaving a solid residue of magnesium oxide:  Mg₅(CO₃)₄(OH)₂·4H2O → 5MgO + 4CO₂ + 5H₂O