NMDC, the country’s leading iron ore producer has decided to keep the rates of some grades of iron ore unchanged for this month. At its board meeting, the public sector steel major decided to retain the prices of fines and lumps at the April 2013 level. Accordingly, the rates applicable would be Rs 4,600 a tonne for lumps and Rs 2,610 for fines. It had cut prices during February and March on lower demand, but with demand showing signs of picking up it decided to hold prices, sources said.