By Michael Taylor and Melanie Burton

Newmont Mining Corp sent out its first copper concentrate shipment from Indonesia this week that ended a nine-month hiatus, highlighting a ramp up in copper mine supply that is expected to tip the market into surplus this year.

U.S.-based miners Newmont and Freeport-McMoRan Inc halted exports in January after Indonesia imposed a hefty export tax that the miners said violated their mining contracts.

The export tax was part of moves to force all miners to develop local mineral processing facilities, which would bring bigger returns for the government from Indonesia's mineral resources.

Newmont signed a key deal to resolve the export dispute with the Indonesian government early in September and expects to be fully operational at its Batu Hijau mine within six to eight weeks. It had halted production in June.

"We've exported 30,000 tonnes," Newmont Indonesia spokesman Rubi Purnomo told Reuters in a text message, adding that the shipment was made late on Monday.

The country's largest producer, Freeport, resumed shipments in early August after it agreed with the government on an initial road map for building processing capability in the country.

Freeport's open-pit mining was facing a week-long suspension as an investigation takes place into a fatal mining accident at the weekend. But traders said they expected Freeport to continue shipping concentrate from its stockpiles.

"A one week stoppage isn't going to make too much of a dent - they've got some pretty huge port stocks," one Singapore-based concentrate trader said.

Freeport said in mid-August it had built up a 140,000-tonne stockpile and that it expects total copper concentrate production to reach 1.8 million tonnes this year, down from an expected 2.2 million tonnes, with exports of about 700,000 tonnes.

As a result of boom time investment, new mine supply from around the world is feeding into the market and is expected to result in a surplus, weighted towards the end of the year.

Goldman Sachs said this month it expects copper to fall to $6,600/t on a three- and six-month horizon, and $6,200/t on a 12-month horizon.

Benchmark copper on the London Metal Exchange traded at around $6,743 a tonne on Tuesday and was facing its steepest monthly loss since March. It is down 8.4 percent year to date.

Cashing in on improving mine supply, Pan Pacific Copper, Japan's biggest copper smelter, aims to raise by more than 9 percent the processing fees it charges sellers of raw material concentrate in 2015, a senior executive said on Monday.

Higher charges are typically seen when concentrate supply rises or when smelter capacity thins. Last year the fees were at $92 per tonne and 9.2 cents per pound.

For the first six months of the year, the global refined copper market was in a 526,000 tonnes deficit compared with a 139,000 tonnes surplus in the same period a year earlier, the International Copper Study Group said.

Analysts polled by Reuters expect a 226,000 tonne surplus this year.