THE National Metallurgical Laboratory (NML) and Tata Korf have jointly developed a clean technology blast furnace at Agra that would lower the sulphur dioxide (so2) emissions and fine dust from the hundreds of foundries around the Taj Mahal. The laboratory has developed the technology and transferred to Tata Korf, which is commercialising the furnace among these foundries at Agra.

The so2 and suspended particulate matter (SPM) emissions from foudries had been yellowing the surface of the Taj. However, the new furnace does not use coke, the main source of the sulphur and SPM, but light diesel oil and natural gas. The NML cupola has been found to meet emission norms set by the Central Pollution Control Board. The cokeless cupola is a typical vertical shaft-type blast furnace. The coke produced in India contains high levels of sulphur.

A high-level committee appointed by the Union ministry of environment and forests had found that so2 and spm from the foundaries were yellowing the white marble.