In the blast furnace hearth the calcium aluminate by-products of coke dissolution can react with the hearth refractories. Reactions between these coke ash minerals and the aluminosilicate and alumina-carbon hearth refractories may result in increased refractory wear reducing the blast furnace campaign life. Hence improved understanding of these interactions may have implications for the campaign life of the blast furnace hearth refractory materials. The interactions between the coke ash minerals and aluminosilicate hearth refractory have been assessed by heating samples of calcium aluminates (CA, CA2 & CA6) coupled with aluminosilicate refractory to temperatures representative of the blast furnace hearth (1450 degrees C to 1550 degrees C) in an inert atmosphere over a range of reaction times (4 - 24 hours). It was found that there was significant reaction between the refractory, CA and CA2 but little reaction with the CA6. The reaction layers formed at the interface between the couples were found to consist of CA2, CA6, corundum, plagioclase and melilite. The formation of a layer with these phases is likely to cause refractory wear due to reduced mechanical strength at highest operating temperatures and by spalling induced by volume changes and changes in thermal expansion characteristics. From assessment of the kinetics of the system it was found that the aluminosilicate refractory followed the linear rate law for reactions with CA and CA2. Given the lack of reaction of the refractory with CA6 little comment can be made on the kinetics other than they are slow.