The Batu Hijau mine as seen from above. Truck and shovel in operation (insert).

The Batu Hijau mine as seen from above. Truck and shovel in operation (insert).

Sumbawa attractions are not only about beautiful beaches, small islands, buffalos, horses and famous natural honey. Now Sumbawa also offers a mine tour. But it is not a tour to a defunct traditional gold mine. Instead it is a tour to an active and operational large scale copper and gold mining operation in Sekongkang area, West Sumbawa.

Since 2000, the Batu Hijau copper/gold mine started operation with about 7,000 employees. This is a big operation. There are hundreds of big trucks and other gigantic equipments operating in this mine. So, a special permit is required before you can visit this mine. The company usually arranges tours for local communities and students on a regular basis.

Check out the company’s contact details at their website at www.ptnnt.co.id. Make an enquiry for a visit. If they grant you one, it will become your rare experience while you are in Sumbawa. Worth giving a try. You will no only see big trucks in action, but also see how a ‘green’ mining is on display with excellent environmental stewardship practices.

About Batu Hijau Mine

This information is summarized from the company’s webiste. Batu Hijau is a large, open-pit mine operation where valuable ore containing copper, gold and silver is mined from the surface using equipment, such as electric shovels, haul trucks. Mining at Batu Hijau begins with drilling and blasting. The blasts loosen and break the rocks into sizes typically less than 25 cm in diameter. Using several giant electric shovels, the ore is loaded and then hauled by 240-tonne capacity haul trucks from the mine to two primary crushers. In the primary crushers, the ore size is reduced to an average diameter of less than 15 cm. The ore is hauled to the mineral recovery process plant while the subgrade is hauled to the sub-grade stockpile areas for possible future processing.

From the crushers, the ore is transported on a six-kilometer conveyor belt to a processing plant known as the concentrator. In the concentrator valuable minerals are separated from rock that has no economical value through grinding and flotation. The rock, after being mixed with water from the sea, is ground using two Semi Autogenous Grinding (SAG) mills and four Ball Mills. The finely ground particles in the slurry leaving the ball mills are pumped to another set of cyclones for final ore-particle size separation.

The fine slurry from the cyclones flows forward to flotation tanks where valuable minerals are recovered. These tanks are called flotation cells. The flotation process is unique because it does not use excessive chemicals so that it is safe and help minimize impacts to the environment. Physically, the process separates valuable minerals from the rocks using froth (bubbles) and reagents in a small amount.

The concentrate after filtering looks like fine powdered rock or sand and is stored in a large, covered building while awaiting shipment. The concentrate is transferred via conveyor belts and loaded on large cargo ships.

The concentrate is finally shipped to a number of smelters in the country, i.e., PT Smelting in Gresik, and overseas (Japan, South Korea, India, Europe) where it is smelted down to separate and recover the valuable metals, mainly copper, gold and silver. (LI/KM)

About Author: Kasan Mulyono
Writer. Lecturer. Ph.D in Economics. Mine worker. PR veteran. Casual cyclist. Father of 4. Husband to Kartina. Moslem. Lives in Lombok & West Sumbawa, West Nusa Tenggara, Indonesia. FB: KasanMulyono2015 Email: k_mulyono@yahoo.com Twitter: KasanMulyono Instagram: KasanMulyono