NEW DELHI: National Mineral Development Corporation (NMDC) and Steel Authority of India Limited (SAIL) on Monday signed a memorandum of understanding (MoU) to form a joint venture for the development of limestone mines in the sensitive hill region of Arki in Himachal Pradesh. The MoU for the 50:50 joint venture was signed in the presence of Union Minister for Steel Virbhadra Singh, Union Minister of State for Steel A. Sai Prathap, Steel Secretary Atul Chaturvedi, SAIL Chairman S. K. Roongta and NMDC Chairman-cum-Managing Director Rana Som. The Arki mine has deposits of about 100 million tonnes of quality limestone. The SAIL-NMDC joint venture will develop the mine to produce three million tonnes of limestone annually. While the low-silica limestone lumps will be used by SAIL and NMDC as flux for steel making, the fines would be sold in the market. The cement industry has a huge demand for limestone fines.