Every mineral we produce is refined through decades of expertise to meet modern industrial demands. From construction and agriculture to advanced manufacturing, our materials help industries build stronger, cleaner, and longer-lasting solutions.
Engineered to perform reliably under demanding conditions, UltraCarb supports applications in both construction and manufacturing, meeting the needs of industries where protection against fire hazards is essential.
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Discover why your industry would benefit from our flame retardant mineral UltraCarb.
UltraCarb acts as both a flame retardant and smoke suppressant, making it a vital component for industries focused on safety and compliance. Suitable for use in a range of applications, including polymers, cables, and building materials, UltraCarb is a preferred mineral choice for sectors where high levels of fire resistance are critical.
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Ensure flame resistance with UltraCarb
UltraCarb, the halogen-free flame-retardant mineral from LKAB Minerals, excels in fire resistance and smoke suppression.
UltraCarb is a cost-effective mixture of minerals, which is also known as HMH. It is a proven fire-retardant filler, used in a wide range of polymers and rubbers such as polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), ethylene-propylene diene monomer (EPDM) and nitrile rubber (NBR).
The combination gives a unique product in which specific properties can be optimised by selected mining and processing to fit a variety of applications.
Unique fire retardant properties
UltraCarb has a unique 3-stage fire-retardant mechanism. Whereas the classical endothermic flame retardant fillers act by releasing water in a single action process, our product works as follows:
Water is released at temperatures of ~220°C (thermal decomposition)
CO2 release at temperatures of ~330°C
At around 560°C, particles gather on the surface of the burning polymer, forming a stable, cement-like char – this char slows down the fire and prevents it from spreading through burning droplets
The platy, high surface area particles of our halogen-free mineral provide excellent properties when you use these as a functional filler in polymers. The products’ high heat absorption protects polymers from rapid thermal degradation and the formation of combustible products.
UltraCarb standard grades
Primary Hydromagnesite
Primary Huntite
LH3
1250
LH15
1251 (stearate surface treated)
LH15C (stearate surface treated)
1253 (proprietary surface treated)
LH15X (proprietary surface treated)
1290
1291 (proprietary surface treated)
UltraCarb packaging
Our UltraCarb product range is available in 25kg paper bags, 1000kg bulk bags or in bulk within a tanker.
Stearate surface treatment improves wetting and reduces the agglomeration in the compound. Proprietary surface treatments are beneficial as an external lubricant, act as a processing aid for extrusion and improve the LOI in EVA.
Applications of our flame retardant mineral UltraCarb
UltraCarb is a natural mineral composed of huntite and hydromagnesite, primarily used as a halogen-free flame retardant and smoke suppressant in various industries. Some key applications include:
Plastics & polymers
Used in cable sheathing, coatings, and polymer compounds to enhance fire resistance.
Common in polyolefins (PE, PP), PVC, and rubber-based materials.
Reduces heat release, smoke production, and toxic gas emissions during combustion.
Construction & building materials
Added to insulation materials, sealants, and adhesives for flame-retardant properties.
Enhances fire safety in cladding, roofing membranes, and composites.
Coatings & paints
Improves fire resistance in industrial and decorative paints.
Provides low-smoke properties in protective coatings for public spaces.
Textiles & fabrics
Applied to furniture, upholstery, and automotive textiles to meet fire safety standards.
Used in technical textiles and protective clothing for improved flame resistance.
Wire & cable industry
Incorporated into low-smoke, halogen-free flame-retardant (LSHFFR) cables for electrical applications.
Common in power cables, communication cables, and automotive wiring.
Sportswear & equipment
Integrated into performance sportswear and protective gear to improve flame resistance and meet safety standards.
Used in padding, protective layers, and technical textiles for sports equipment to reduce flammability and smoke emissions.
Helps manufacturers develop safer, halogen-free sports clothing and also helps enhance the performance of the equipment.
Mineral information
Physical properties of UltraCarb
Specific gravity [g/cm3]
2.4
Refractive index
1.56
Hardness (Mohs)
2.5
Surface area [m2/g]
11 – 17
Loose bulk density [kg/l]
0.4
Chemical properties of UltraCarb
MgO [%]
36 – 39
CaO [%]
6 – 9
SiO2 [%]
0.2 – 1
Loss on ignition at 1,000°C
51 – 54
UltraCarb origin
The naturally occurring mixtures of Hydromagnesite and Huntite mineral deposits are formed by near surface geochemical processes. The formation of our own Turkish deposits is the result of three specific conditions:
A depositional area of magnesium-rich ultramafic basement rocks.
A lake environment which evolved into a basin.
Tectonic activity – this allows magnesium-rich groundwater to reach the surface.
The precipitation of HMH is related to the mixing of ground water with fresh water from the lake environment.
HMH toxicology
UltraCarb is naturally halogen-free, therefore does not emit toxic smoke when burnt.
Enhance the durability and reliability of your materials with our flame retardant mineral UltraCarb.
UltraCarb from LKAB Minerals offers reliable flame retardant solutions tailored to your industry’s needs. Contact our team for detailed information and guidance on integrating UltraCarb into your projects!
Flame retardant UltraCarb FAQs
UltraCarb is a halogen‑free flame‑retardant mineral filler based on a natural mixture of hydromagnesite and huntite (HMH). It is used in polymers, cables, rubbers and coatings where fire performance, smoke reduction and environmental responsibility are critical.
UltraCarb consists of hydromagnesite and huntite, two naturally occurring carbonate minerals that decompose at different temperatures to provide staged flame retardancy.
Hydromagnesite is a hydrated magnesium carbonate mineral with the formula Mg₅(CO₃)₄(OH)₂·4H₂O. It releases water and carbon dioxide when heated, cooling the polymer and diluting flammable gases during a fire.
Huntite is a magnesium calcium carbonate mineral with the formula Mg₃Ca(CO₃)₄. It decomposes at higher temperatures, releasing CO₂ and forming a protective mineral layer that helps block heat and oxygen.
HMH stands for hydromagnesite-huntite mixture. In UltraCarb, the optimised combination of both minerals provides improved flame retardancy compared to single‑mineral fillers.
UltraCarb works through a three‑stage flame‑retardant mechanism: 1. Endothermic cooling via water release 2. CO₂ release to dilute flammable gases 3. Formation of a stable mineral residue that acts as a barrier
This multi‑stage mechanism improves fire performance and smoke suppression.
Compared to aluminium trihydrate (ATH) and magnesium hydroxide (MDH), UltraCarb works over a broader temperature range, can allow lower filler loadings in some systems, and offers a more natural, halogen‑free flame‑retardant solution.
UltraCarb is commonly used in cable and wire insulation, halogen‑free flame‑retardant polymers, rubber compounds, coatings and construction materials.
Yes. UltraCarb is a halogen‑free flame‑retardant solution, suitable for applications requiring low smoke, low toxicity and enhanced fire safety.
UltraCarb is based on naturally occurring minerals and supports the development of more sustainable, halogen‑free fire‑safe materials.
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