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A GIFT TO A TRUE FOUNDRYMAN, WHO IS ENTHUSUASTIC TO SUBSTITUTE ZIRCON SAND
General Description--Chrome Spinel Sand
Appearance and odour
Chromite is a black sandy odourless material, which is free flowing when dry. It is insoluble in water and any common organic solvents
Typical Specification
Chromium as Cr2O3 = 45% min. Typical 46%
Fe2O3 = 25% max. Typical 24%
Al2O3 = 12% max.
SiO2 < 1% max., Typical = 0.8%
MgO = 10% - 12%, Typical 10%
TiO2 = 0.60.
Cr : Fe Ratio : 1:55:1.
Origin
South Africa, India
Applications
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used to harden steel, to manufacture stainless steel, and to form alloys
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the refractory industry uses chromite for forming bricks and shapes, as it has a high melting point, moderate thermal expansion, and stable crystalline structure.
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temperature-loadable moulding sand in foundry
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used in plating to produce a hard, beautiful surface and to prevent corrosion.
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used to give glass an emerald green colour. It is responsible for the green colour of emeralds and the red colour of rubies
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wide use as a catalyst
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dichromates such as K2Cr2O7 are oxidising agents and are used in quantitative analysis and also in tanning leather
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lead chromate as chrome yellow is a pigment
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compounds are used in the textile industry as mordant
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used by the aircraft and other industries for anodizing aluminum
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tanning leather
Toxicology--N/A
Important Properties
Size = AFS 45-55. AFS Typical = 50.
Distribution on sieves shall be 70% on ASTM sieve no.50, 70 & 100 corresponding to 300,212 and 150 microns.
Fines limited to 6% max. on 106 micron pan.
Ph value of sand shall be in between 6.5 to 8.
Acid Demand:
Ph--- 4.6
Ph--- 3.0
Ph--- 2.0
Turbidity (ppm)--- 170
Moisture--- 0.2% max
Specific Gravity : 2.65 g/cc
Fusion temperature of Chromite Sand 1600 oC – 1800 oC
Grades
Foundry Grade, Refractory Grade.
Chromite Sand for Cast Iron and Steel Foundries
Chromite sand has established mounting awareness for several years, as a very effective moulding material for a multiplicity of different reasons:
- Low thermal expansion.
- High thermal conductivity.
- Good refractoriness.
Chromite is FeCr2O4, a natural oxide of ferrous iron and chromium, usually with magnesium and aluminium present. It usually occurs in magnesium and iron-rich igneous rocks. Commercial qualities and quantities are available in the Kazakhstan, South Africa, Zimbabwe, Cuba, Turkey, and Finland. When Chromite and finely divided aluminium and carbon are heated, chromium is reduced. All our Chromite is mined in South Africa.
Chromite spinel sand is the sand size fraction removed from the Chrome ore and because of its grain size is not commercially practical for reducing Ferro-chrome alloys.
Ideally for foundry use the chromium (Cr2O3) content should exceed 45% and iron (Fe2O3) no more than 33% of the percentage of chromium to make smelting attractive.
This is the material commonly used in Cast Iron and Steel foundries. It is a boon to Cast Iron and Steel Foundries.
With help of an expert foundryman, Zircon Sand can be replaced by South African Chromite Sand.
Turbidity (impurities)
Turbidity is a measure of the colloidal particles within the raw Chromite sand. It is measured in ppm and is a reflection of the amount of tramp material present. The lower the turbidity, the cleaner the sand. When turbidity is high (i.e. > 150 ppm) then more fayelite can be formed at the mould-metal interface, giving rise to double skinning or Chromite frit.
Our low turbidity is due to excellent washing techniques on site in South Africa.
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