NEW DELHI, April 29 (Reuters) - Sesa Sterlite Ltd SESA.NS , India's largest copper refiner, said on Tuesday it expects charges to treat and refine copper concentrates to remain robust on rising extraction of the metal from existing and upcoming mines.

The company's copper treatment and refining charges (TC/RC) in the three months ended March 31 rose a quarter to 18.5 cents per pound, it said in its results statement on Tuesday.

ID:nWNBS00FV3 ( http://r.reuters.com/kym88v )

Global miners or trading houses pay TC/RC to smelters to convert concentrate into refined metal, with the charges deducted from the sale price, based on London Metal Exchange copper prices CMCU3 CMCU0 .

Sesa Sterlite, a unit of billionaire Anil Agarwal-controlled Vedanta Resources Plc VED.L , also said its smelter that produces 30,000 tonnes of refined copper per month went on a 22-day maintenance shutdown on April 26.

Reuters reported about the shutdown on March 18. Half of the output from the plant in southern India's Tuticorin goes to China. ID:nL3N0MF13V

The company, also the largest private iron ore miner in India, said it produced 1.5 million tonnes of the steelmaking raw material in the last fiscal year from the state of Karnataka against an allowed limit of 2.29 million, as mining was delayed due to the lack of some approvals.

It could however sell only 27,000 tonnes in 2013/14 from the southern state. Sesa Sterlite did not cite any reason for the weak sale volume.

(Reporting by Krishna N Das; Editing by Anand Basu)

((Krishna.Das@thomsonreuters.com; +91-11-4178-1023, +91-98711-18314; Reuters Messaging: Krishna.Das.thomsonreuters.com@reuters.net, Twitter handle: @Krishnadas56))

Keywords: SESA STERLITE COPPER/CHARGES