Охотиться

Description

Huntite is a natural double carbonate of calcium and magnesium with the composition CaMg3(CO3)4. The name of the mineral is given in honor of geologist Walter F. Hunt; The Russian name “Hunt” in the product card was obtained by machine translation of the English Huntite and has nothing to do with the substance. In nature, the mineral occurs intergrown with hydromagnesite Mg5(CO3)4(OH)2·4H2O, and the commercial product is a enriched ore containing both minerals.

Basic Attributes

• CAS No.: 19569-21-2
• Formula according to the product card: CH2O3 1/4 Ca 3/4 Mg
• Mineralogical formula: CaMg3(CO3)4
• Molecular Weight: 353.03
• Exact weight: 359.919
• EU number: 606-340-1
• PSA Specifications: 230
• Density: 2.696 g/cm³

Trade designations

Card synonyms - Neracarb HH and Ultracarb 1250 - are brands of mineral fire retardants based on a mixture of huntite and hydromagnesite (Nearcarb, UltraCarb). The product is supplied in the form of a fine white powder, the granulometry and degree of enrichment vary by brand.

Mechanism of fire retardant action

The two minerals in the composition decompose at different temperatures, and the protection works in stages:

• hydromagnesite begins to decompose in the range from 220 °C in open air to 250 °C under pressure in an extruder, releasing water and carbon dioxide
• huntite decomposes above 400 °C, absorbing heat and releasing carbon dioxide

The released water and CO2 dilute the flammable gases at the surface of the material, the decomposition of both minerals occurs with the absorption of heat, and a stable mineral residue of calcium and magnesium oxides remains on the surface. The first stage at 220–250 °C is high enough for the filler to withstand the polymer being processed in the extruder.

Scope of application

• halogen-free fire retardant filler for polyethylene, polypropylene and polyvinyl chloride
• fire retardant compositions for rubber compounds, including cable
• paints and varnishes with increased fire resistance
• white mineral filler in polymer and building compositions

Advantage over halogen-containing flame retardants: there are no halogens in the composition, during combustion no toxic halogen-containing smoke is formed, and decomposition products are water and carbon dioxide.

Storage and handling

The powder is stored in a closed container in a dry room: the hydromagnesite component contains water of crystallization, and the powder itself is hygroscopic on the surface and prone to clumping. When working, use respiratory protection against mineral dust. The material is non-flammable and is not a dangerous cargo.