Every little bit counts

With the rise of coal mining in Indonesia, mining companies and contractors are looking for any edge in a hypercompetitive race to remain productive and efficient.

Eagles soar above the green canopy of the Macaranga treetops, circling and searching for the day’s prey. From their view, the Mahakam River, particularly where it passes through the Indonesian city of Samarinda, looks like an ancient drawing of a mythical snake: slithering through the jungle, turning often, sometimes at almost 180 degrees. Samarinda, the provincial capital of East Kalimantan on the island of Borneo, sits beside the river, around 50 kilometres west of the Mahakam’s mouth. Nearly 1,000 kilometres long, it is the longest river in East Kalimantan, stretching from the mountains inland to the delta on the coast, and it acts as a seaway for the island’s coal transport.

Coal mining is booming in East Kalimantan and elsewhere in Indonesia. While the country is the world’s largest exporter of coal for power stations, the province is home to more than a quarter of Indonesia’s total coal reserves. Approximately 6.6 million hectares – roughly the size of Switzerland – have been allocated for mining here. Samarinda has seen the most expansion in the region, with the local government earmarking more than 70 percent of the municipality’s land for mining. To say coal mining in East Kalimantan is competitive is an exercise in understatement.

Tenggarong lies about 50 kilometres northwest of Samarinda and is home to the Jembayan Muarabara coal mine. Purchased by Sakari Resources Ltd. in December 2007, the mine has set, and reached, ambitious production targets, growing from 4 million to 10 million tonnes per year since its acquisition.

Covering some 12,000 hectares, Jembayan’s open- and multi-pit coal mine features a private 26-kilometre road, over which a seemingly endless number of trucks transport the washed and treated coal to a private port. From there, barges ship the coal down the Mahakam for loading at sea. The primary markets served include China, India, South Korea, Japan, Taiwan and Surabaya, Indonesia’s second-largest city.

About Jembayan

The Jembayan Muarabara coal mine covers an area of over 12,000 hectares in East Kalimantan, some 150 kilometres north west of Balikpapan and 80 kilometres inland.
The mine was acquired by Sakari in December 2007 and the achievements since then have been remarkable. Production grew from 4 million tonnes to nearly 10 million tonnes. The resource has grown from about 50 million tonnes (non-JORC) to 604 million tonnes (JORC) and reserves have grown to 142 million tonnes (JORC “Marketable” category).
The multi-pit mine has its own barging port, reached by a 26 kilometre road, from where product is shipped some 70 nautical miles down the Mahakam River for loading at sea.

The drilling and blasting work at the mine is contracted out to PT Pamapersada Nusantara (PAMA), a wholly owned subsidiary of PT United Tractors Tbk. Nurhadi Mansur, the head of drilling and blasting for PAMA at Jembayan, is keenly aware of the pressures of staying efficient in order to meet ever-rising productivity targets.

Fierce competition

“There are so many mines in Kalimantan, and so many competitors, we have to be able to differentiate ourselves from other suppliers,” he says. “We do that by meeting, and when possible surpassing, our targets and the demands of our customers.

“At Jembayan, the ground is unique and can be very different from one area to the next, even in the same pit. Clay, mudstone and sandstone are all there in different amounts and abrasiveness. Staying efficient means knowing that ground like your own family.”

Mansur explains that, using geological data gleaned from exploration, PAMA can differentiate operational drilling methods, including which geometry to use in a particular area to maximize efficiency.

“Our biggest challenge right now is to meet new targets for drill bit life, which is now at 15,000 metres, up from 6,000,” Mansur says. “Cone erosion is a serious issue here as we subsequently deal with lost inserts, so upping our bit life is the best way for us to increase productivity and remain competitive. Sandvik Mining equipment and expertise really help in this regard.”

The two Sandvik D245S blasthole drill rigs at Jembayan are always on the move, drilling the 8.5-metre-deep holes that the blasting team fills with explosives several times a day. And they have to be busy if PAMA is to meet its productivity targets every month. But while these gigantic drill rigs are models of efficiency, Simon Tambunan, PAMA drilling and blasting supervisor, says it’s the Sandvik RR220 X05 drill bits that are stealing the show on the ground.

Surpassing targets

“When drill bits go down for any reason before meeting our depth targets, we lose time, which affects productivity,” Tambunan says. “Sandvik RR220 X05 bits are not only reaching our targets, they’re surpassing them.”

Sandvik engineered the durable RR220 X05 drill bit specifically for customers in these coalfields to satisfy their needs for increased bit life and higher penetration rates in soft and variable ground formations. An upgrade of the range, Sandvik RR221, is slated for release in late 2015.

“Sandvik employees also offer ideas on how to increase productivity and penetration rate, and provide suggestions on how to maintain bit durability and which bit to use in a specific area,” Tambunan says.

Ngadikun Ngadikun, a Sandvik Mining tools sales support representative in Indonesia, is responsible for training PAMA’s Sandvik D245S operators at Jembayan, and he visits the mine frequently.

“For PAMA, it’s vital that Sandvik employees understand the ground at Jembayan,” Ngadikun says. “When it’s clear that we do understand, we establish a trusting relationship and it becomes even easier to make good suggestions because we all want the same thing: peak productivity.”

Tech specs Sandvik RR220 X05 standard air bearing bits

Size 200 mm (7 7/8”)
Type X05 (IADC 412)
Approximate Weight 35 kg (77 lb)

Design specs
Bearing Type Air Bearing
Inner/Gage Rows 6/3
Inner/Gage Inserts 42/31

Operating parameters
Weight on Bit
Lb – Min. to Max. (1,000s) 10.0 – 20.0
Tonnes – Min. to Max. 4.5 – 9.0
Rotation Speed (RPM) – Min. to Max. 80 – 180

Invaluable training

Since PAMA started using Sandvik RR220 X05 drill bits in 2014, the monthly average bit life has already increased by 33 percent (up to over 20,000 metres from 15,000), and the rate of penetration has improved from 61 metres per hour to 69.

“This alone has reduced our drill cost by around 22 percent, from 0.037 USD per cubic metre to 0.029,” Tambunan says. “We always welcome Sandvik to visit and test the bit on site, and the training they provide is invaluable.”

Targets will probably increase again next year, staying in lockstep with the number of competitive operations extracting coal in the area. But Mansur remains confident thanks to his partnership with Sandvik.

“If our targets do increase again next year, we know Sandvik will be there to support us with know-how, service and innovative new products,” he says.