Dunite is an igneous, plutonic rock, of ultramafic composition, with coarse-grained or phaneritic texture. The mineral assemblage is greater than 90% olivine, with minor amounts of other minerals such as pyroxene, chromite and pyrope. Dunite is the olivine-rich end-member of the peridotite group of mantle-derived rocks. It repalces the usage of DBM in many applications.

In general, our dunite is a natural refractory material over 1350°C with high MgO content up to 48% also has a high melting point and refractoriness up to 1760°C, It has high thermal shock resistance and low thermal expansion High mechanical and thermal performance, Most importantly Low impurities and LOI below 2%,Low moisture and water absorption below 1%.

The main characteristics make olivine sand ideal for the production of austenitic manganese steels. Olivine sand is also used for facing moulding mixtures in the manufacture of large steel and iron castings, which allows them to be obtained with a cleaner surface than using quartz sand. The special advantage of olivine sand is manifested in the production of heavy castings, when resistance to high ferro static pressure is required; due to the slow and linear nature of volumetric changes (in contrast to quartz sand, which has a structural transformation at 575 °C). Olivine has no allotropic transformations, resistant to slagging with iron oxides. The sintering temperature of 1450 °C, begins to fuse at temperatures above 1760 °C and the melting point between 1800 and 1850 °C.

Fine-grained olivine sand is not wetted with liquid metal and has angular grains that provide a dense surface with low permeability. This makes it possible to use olivine sand in the manufacture of moulds, rods and castings of non-ferrous alloys.

Olivine sandis one of the most widely used Refractory Mineral. Its low free-silica content and strong resistance to metal attack along with the refractory properties caused that Olivine Sand to be used as Eccentric Bottom Taphole (EBT) Filler in Electric Arc Furnace (EAF), popularly known as EBT Filler.

Characteristics

It contains 40-48% of MgO and 38-44% of SiO2
It is the parent rock of Magnesite
It is dark Grey to Olive Green in colour.

Attributes

High purity
Reliable
Well packed

Specification

Important Properties

Melting Point (°C) ~ 1800
Bulk Density, Loose (g/cm3) 1.8-2.0
Thermal Expansion (in./in.) 0.0083
pH Slightly Basic
Free Silica Content (%) < 0.1
Mohs Hardness @20°C 7.0 (Scale 7-8000)
Thermal Conductivity @1000°C (cal/s-cm -°C) 0.0025
Fusion Temperature of Olivine Sand is 1600 °C to 1750 °C

Standard Sizes from our Plant

Application

Dunite is used as a raw material for basic refractories along with Dead Burnt Magnesite in manufacturing of Magnesia Bricks and Monolithic Refractories such as Ramming Mixes, Gunning Mixes, Tundish Spray Mixes and Fluxes. It has the advantage of excellent resistance against metals and slag penetration (due to high forsterite content), thermal shock, wear attack.

In Refractory Industries to manufacture Dunite Refractory Bricks.
As flux material in Steel Plants replacing limestone.
In forging industries abroad in powder form to replace silica sand.

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Important Properties​

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