Typical grain size distribution for silica foundry sand

Chromite is a chrome ore, with the theoretieal formula Fe0.Cr203, which contains other components such as magnesium and aluminium oxides. For its use in foundries, its silica content must be lower than 2 % in order to prevent sintering at low temperatures. Its characteristics are as follows  

Chromite sand is more refractory than silica. It is more thermally stable and has a greater chilling power. Chromite sand provides a better surface finish on large castings. It is therefore used for the production of large castings and in areas of the mould where chilling is required. 

Zircon is a zirconium silicate, ZrSi04. Zircon is the most widespread zirconium ore. Its characteristics are as follows. 

The general eharacteristics of zircon sand are similar to that of chromite, but zircon sand produces a better finish as a finer grade is used. These physical and thermal properties account for its use for moulding or core-making in difficult cases, in spite of its very high price. 

Olivine sands are a mineral group which includes forsterite, fayalite and others. The characteristics of olivine sands are as follows  

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Figure 2.25 Typical grain size distribution for silica foundry sand [110, Vito, 2001]...

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