Chromite Sand Use for Large Steel Castings

 

L  Chrome ore has good resistance to alkaline slag and does not react with iron oxide; therefore, in practical applications, chrome ore can avoid thermal chemical sand sticking on surface of casting. Thus it will save cost on further surface treatment.

L  during the molten metal casting process, the chromium ore itself undergoes solid phase sintering, which prevents the penetration of molten metal, thereby preventing mechanical sand sticking;

L  the thermal conductivity of chromite sand is several times greater than that of silica sand, which can increase the cooling rate of castings. Therefore, chromite sand can act as an external cold iron in practical applications;

L  the harmful impurity in chromium ore is carbonate (CaCO3MgCO3). When it comes into contact with high-temperature metals, it decomposes CO2, which is easy to cause porosity in the casting; usually, the chromite ore containing carbonate is heated to 900°C High temperature roasting at 950°C decomposes the carbonate.

L  the influence of the particle size of chrome ore on its refractoriness the particle size of chrome ore can significantly affect its refractoriness. In the past, it was believed that too coarse particle size would reduce the surface finish of castings. however, the surface of sand molds and cores made of chrome ore are usually sprayed with a certain thickness of paint, so that the surface finish of castings is hardly affected.

 

Application:

Chromite Sand in the foundry industry

L  Chromite sand is an ideal to be used in high duty grey iron and steel foundries as core and mould making sand for lost foam casting, shell molding casting, investment casting, etc.

L  the high thermal conductivity of chromite sand gives it good chilling properties, low thermal expansion gives rise to good dimensional stability.

L  Its basicity being close to neutral allows the use of a wide range of resin bonding systems and inorganic binders, it has a high refractoriness and a broad sieve distribution.

CHEMICAL COMPOSITION
Cr2O3	≥46.0%
SiO2	≤1.0%
FeO	≤26.5%
CaO	≤0.3%
MgO	≤10%
AL2O3	≤15.5%
P	≤0.003%
S	≤0.003%
Cr/Fe	1.55:1
TYPICAL PHYSICAL PROPERTIES
Hardness:	Mohs:5.5-6
Melting Point:	Sublimes at 2180 ℃
Sintering point:	1800℃
Specific Gravity:	4.0-4.8 g/cm3
Bulk density(LPD):	2.5-3 g/cm3
Color:	Black
PH	7-9
Percentage of free acid present in the sand	0%
the amount of the acid	≤2ML
Percentage of soil	≤0.1
Percentage of Moisture	≤0.1

 

AVAILABLE SIZES

AFS25-35,AFS25-30,AFS30-35,AFS35-40,AFS40-45,AFS45-50,AFS40-50,AFS50-55,AFS55-60,AFS60-65

the grit size depends on the casting size as below:

≤500KGS	500-1000KGS	1-10 Tons	10-30 Tons	30-100 Tons
AFS 55-70	AFS 45-50	AFS 45-50	AFS40-45	AFS 35-40