An Encyclopaedia of Indian Archaeology v1.c21.s7.3

v1.c21.s7.3

While 1200°C is adequate for the smelting of copper it is inadequate for the effective smelting of iron, which requires a temperature of 1535°C and a strong reducing environment. It appears that in ancient Indian metallurgy the same type of furnace that was used for smelting copper was also used for smelting iron in which the slag was tapped. Remains of such type of furnace with evidence of their use for smelting both copper and iron metals have recently been discovered at Kumbhariya, a village near Ambaji in n. Gujarat. This large metalworking site has been dated to the 10th-11th century A.D. These furnaces are all broken at the bottom. They have slag adhering inside them. Analysis of this slag shows that some of them were used for smelting copper and the others for smelting iron. They are small in size, shaped like a crucible and made of clay. They are all forced-draught, slag-tapping furnaces. The diameter near their mouth varies from 15 to 20 cm, the thickness of their clay wall from 3 to 4 cm and the diameter of their tuyere from 4 to 5 cm.