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%.

Blast Furnace (Iron & Steel Industries)

Oliven Dunite is rich in MgO (40-45%) and ideal for use as a fluxing agent in blast furnace in place of dolomite. Using Oliven Dunite in the flux protects the furnace’s refractory lining by improving the alkali removal, controls the sulphur content in pig iron and offers operational and economic advantages.

Oliven Dunite as a magnesium source is preferred due to its advantageous properties:

Improved sintering capacity and product quality
Reduced energy consumption
Reduced slag volume
Oliven Dunite makes the slag viscosity less dependent on variations in the slag composition.

Advantages

Reduced energy consumption (does not require energy for decomposition as dolomite).
Reduces slag volume and production cost
Improves alkalinity and fluidity, applicability in high temperature processes, sintering capacity and gas flow permeability
Safeguards the environment. Oliven Dunite is as green as it gets!
Ensures control of the sulphur content in pig iron, protection of any refractory lining, applicability with out preliminary heat treatment, stable slag viscosity, high abrasion resistance, easy and safe storage
Almost zero CO2 emissions (< 2% compared to dolomite’s 40%).
Rich in MgO:

Very fast saturation of the slag in MgO and protection of the refractory lining.
Less consumption comparing to dolomite.

Better control of the Sulphur and Phosphorous in Pig iron.
Better thermal equilibrium.

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.

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

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.

➢Slag conditioning in Blast Furnaces

➢ EBT filler

➢ Refractory bricks and mortars

➢ Mineral wool

➢ Foundry sand

➢ Sandblasting

➢ Fertilizers

➢ CO2 sequestration

➢ Cement industry

Electric Furnace (EBT)

Oliven Dunite sand’s refractory properties in association with its well-defined granulometry ensure an easy tap hole opening for fast free flowing of molten metal.

Oliven Dunite EBT is a high refractory Dunite-based granular material, used as filler in the Eccentric Bottom Tap hole (EBT).
Oliven Dunit EBT filler’s refractory properties (refractoriness around 1.450°C) along with its well-defined & consistent grain size distribution & shape, ensure an easy tap hole opening (over 98% success rate) for fast free flowing of molten metal.
Relatively low-cost product with a low environmental footprint.
No sintering under liquid steel temperatures and no steel leakage from the tap hole.

Refractories

Due to its insulating, heat storing and refractory properties (high thermal shock resistance, low thermal expansion, high mechanical and thermal performance),Oliven Dunite is successfully used in forsterite bricks, storage heaters and refractory monolithics and mortars.

Ceramic bonded forsterite (Dunite-Magnesia) bricks with high refractoriness and a long list of benefits, for use in cement, glass and lime kilns, in rotary kilns, EAFs, Ladles & blast furnaces.
Refractory monolithics like spraying, ramming, vibrating and gunning mixes as well as various types of mortars are used as the protective surface in furnaces, ladles and tundishes while also facilitating deskulling. Partial replacement of DBM by Oliven Dunite offers significant techno-economical advantages.

Foundry Sand

Oliven Dunite is ideal for high temperature castings such as manganese steel to to avoid the high thermal expansion and the reactivity of traditional silica sand. Due to its properties (high thermal shock resistance, low thermal expansion and angular grain structure which facilitates gas permeability and vapor outlet) it produces a high quality clean and smooth surface, which requires a minimum amount of finishing, educes the surface grinding costs and has a high reusage ratio. Its high thermal conductivity facilitates the cooling process and reduces waste metal. Oliven Dunite sand is environmentally friendly and an economical solution in comparison with zircon and chromite sand.

Sand Blast

Dunite is an ideal abrasive due to its hardness (6,5-7.0 Mohs), high relative density and angular grain structure. It is not classified as a hazardous material or waste (when in need to be disposed), it is environmentally friendly and can be recycled and re-used. smooth surface, which requires a minimum amount of finishing,

Mineral Wool

Due to its high MgO content, dunite is used as a cost-effective raw material to add MgO in mineral wool in order to improve its thermal and mechanical properties and low environmental footprint compared to dolomite, limestone or lime.

Oliven Dunite is especially suitable as a raw material for mineral wool:

It can be used as a source of both SiO2 and MgO in the formulation.
Depending on the formulation, it can form low melting point phases with other components in the wool.
It is a relative low cost MgO source with a low environmental footprint compared to dolomite, limestone or lime.

Fertilizers

Dunite can be used in the production of magnesium sulphate for fertilizers and for ammendement of magnesium and iron deficient soils

Micro Silica

Dunite can be used as an alternative raw material for microsilica production through acid dissolution co-producing useful magnesium salts such as magnesium sulfate and magnesium chloride.

Fluidised Bed Combustion

Dunite can be used as bed material in fluidized bed type combustion (FBC) especially in biomass gasification applications in power stations. The main advantage of using dunite as bed material instead of the traditional silica sand is that the former helps prevent bed agglomeration due to its higher refractoriness and its significantly lower tendency to react with biomass ash to form low melting alkali silicates.

CO2 Seqestration

Olivine containing minerals, such as dunite are receiving much attention recently for their inherent CO2 sequestration properties. While reaction of olivine with atmospheric CO2 to form stable mineral structures is a very slow natural process, enhanced weathering projects (e.g. use of carbon negative sand for coastal or farming soil enhanced weathering) could prove valuable in global mitigation efforts for climate change. Grecian Magnesite is already involved in such international projects.

Chemical Composition

Standard Size From Our Plant

Important Properties​

​

​​Application ​

​

Important Properties

Application