01 July 2022
In the last decade, PT Freeport Indonesia has applied the machine operation technology remotely in mining underground minerals. The safety of mining workers from various threats is the main consideration in using technology as well as to maintain productivity.
Aprilia Ayomi (25) hands move nimbly. She pushed forward the levers in both hands, then pulled them back. A moment later, she shifted the lever left and right. While continuing to play the two levers that are placed at knee level while sitting, her eyes do not turn away from the screen in front of her.
Lia, who was born in Serui Regency, Papua, sits nicely in the second floor of the building operating the levers and buttons. She works with four monitors. Two monitors on the front are placed in a row with a distance of about 1.5 meters from the seat in a straight line of sight.
One other screen is still on the front of Lia which is placed about 50 centimeters from her seat in a lower position than the first two screens. One more screen is placed on the left of the seat.
The four screens have different functions. Two screens in front of the eye, showing the real condition of the heavy equipment operated by Lia from her seat in the building, about 7 kilometers from the position of the heavy equipment in the tunnel.
The screen in front of Lia, which is closer and lower than the two screens in front of her, shows the condition of the tunnel in a moving yellow graph. Meanwhile, the screen on the left, which is a touchscreen, displays features for starting work and selecting available machines.
From the four screens, Lia ensures that her work runs smoothly, namely extracting mining materials in underground tunnels. The material is then transported to be fed into a funnel for further processing in the tunnel below. The material is in the form of chunks of grey stone containing gold, silver, and copper.
On Tuesday (31/5/2022), the extraction of mining material from the tunnel which was already available went quite smoothly, although the operating system that drives the loader type of heavy equipment had been disconnected several times.
Lia is a remote-controlled heavy equipment operator at the underground mine of Grasberg Block Cave (GBC) owned by PT Freeport Indonesia (PTFI) in Tembagapura, Mimika Regency, Papua. Not in the tunnel, she operates the heavy equipment from the control room in the ground office.
Lia, who has been working since February 2021, operates a loader from a soft chair. From a console called minegem, she controls the machine to pick up material, transport it, and load it into funnels for further processing. "Every day I transport mining materials 150 times. If there is a system problem, it can be less than that," said the the woman who is an accounting graduate from Gadjah Mada University, Yogyakarta,
Lia is one of dozens of operators who just from a chair in a refrigerated room press buttons, push and pull levers, shift left and right, while in a tunnel 7 km from their position the machine and train roaring in operation. The sound of heavy machinery engines, friction with mining materials, the breaking of boulder in the 45 meter x 20 meter workspace. Instructions from the system traffic controller also added to the crowd. It wasn't in a tunnel, just in a room on the ground.
Aside from the loader, from the control room on the second floor of one of the buildings at Mile Post (MP) 72 Tembagapura, the officers operate heavy equipment such as rock breakers and trains transporting mining materials. They press buttons and pull levers while keeping their gaze fixed on the screen, causing the machine to move in accordance with the command.
For the time being, heavy equipment and remote trains are used in the mining industry to extract previously detonated mining materials from tunnels and cut chunks of material longer than 80 centimeters. Furthermore, remote operations are used on the material transporting carts so that they can be forwarded to the splitting section and broken down into small pieces before being transported to the processing plant to concentrate on land.
Heavy equipment and long-distance underground mining material are not yet fully operational. Operations are used at production points where there is a high threat level, such as taking material at wet points where there is a possibility of wet mud.
At GBC, for example, of the 32 loaders in operation, 16 are operator controlled from buildings on the ground. The same happened in another underground mining area, the Deep Mile Level Zone (DMLZ), where 9 of the 32 loaders were remotely controlled.
The material crushing machine unit is making progress. Since its implementation in 2015, coverage has been 100% in both the DMZL and the GBC. The same applies to the material transporting trains at GBC which are already covered 100 percent with the remote system. While in the DMZL, the train has not been used. Mining materials are still being transported by trucks.
The company, in which Indonesia owns 51 percent of the shares through PT Inalum (Persero), uses a fiber-optic network to operate long-distance heavy equipment. The network connects underground mining equipment, heavy machinery, and trains to ground control centers. The communications system is managed by Midroc, a Swedish company, which implements the remote technology at the Kiruna underground mine, Sweden.
Safety of Workers
Currently, PTFI manages three underground mines, namely Deep Mile Zone Level (DMZL), Grasberg Block Cave (GBC), and Big Gossan. All three are 1,200-1,500 meters underground from the Grasberg open pit's surface, with a circular mine opening tapering downwards. The Grasberg mine finished production in 2019 so the company is currently focusing on three mining areas. From the remote machine control room, the three underground mining points are 7 km away.
For the operator, working in a room away from the tunnel ensures safety and comfort. "Working from a building far away from underground mines is unquestionably more comfortable, but you must be serious. The danger is almost non-existent " said Yosias Pekei (29) who operates a long-distance stone crusher. He used to work as a heavy equipment operator in the tunnel.
Remote machine operation for underground mines is used to address the issue of safety. The threat of any fatal risks is low because the operator is far from the tunnel.
Underground mining operations are fraught with risks, including earthquakes that can result in rock eruptions and wet mud trapped with mining material in rock crevices. Other risks include tunnel collapse, toxic gas, and dust exposure, and fire. In the 15 years since the underground mining operation began, 11 incidents have resulted in worker deaths, including two deaths in 2013 due to wet mudflow in a tunnel in the DMZL.
With these risks, PTFI's Senior Vice President Underground Mine Henky Rumbino suggested that heavy equipment be operated from a safe location. The concept takes the operator out of it, but the tool continues to function. "The main and foremost consideration for this remote production operation is worker safety," said the man from Wamena, Jayawija Regency, Papua.
According to Henky, there are a number of vulnerable points in the retrieval of material collection to storage, particularly the risk of wet mud. If done manually, this condition can endanger worker safety and production. Converting to a remote production operating system is one way to avoid hazards while production is ongoing.
The scope of remote production operations was then expanded, though initially, it was still limited. The system began to stabilize after various evaluations, and there was a wider range of production levels, namely mining material extraction, stone crushing, and train transport of mining materials.
The innovation that converts some production to remote operations, according to Henky, stems from risk assessment in underground mines (wet mud, earthquake, exposure to gas or dust). Based on these discoveries, mapping is created to solve problems, including remote operation solutions.
In response to these circumstances, the company contacted underground mining companies in other countries, including Kiruna, Sweden. Following that, PTFI implemented a number of good and safe practices, including the use of remote technology for heavy equipment operations.
The remote operation of heavy equipment for underground mining production begins in the Deep Ore Zone (DOZ) area, where production has ended. The technology used at the time was still simple. Heavy equipment operations, specifically loaders, continue to take place in the tunnel from a distance of 100 meters. This does not address the danger of a wet mud flow, which can strike up to 150 meters from the point of emergence. The development will continue until the technology is ready for use.
So far, the use of heavy equipment and mining material transportation equipment has met production targets. Loader-type heavy equipment, for example, has hourly productivity of 270 tons of mining material. This figure is not much different from the manual operation of 280 tons per hour. Productivity can continue to rise with continuously improved systems and work effectiveness.
The underground mine operated by PTFI currently produces 5.52 million tonnes of ore per month or 183,000 tonnes per day. GBC is the largest producer, producing 3 million tonnes of ore per month.
One of the current issues is the controller's frequent loss of connection. When Kompas was in the control room on Tuesday (31/5/2022), loss of control often occurred in the loader operator console called minegem. While the system was being repaired, operators were forced to switch to another console.
Of course, innovation will continue; it may even reach other levels of underground mining operations, such as drilling and blasting mining materials, which are currently done by hand. The 55-year-old mine's high-tech application space is still wide open, with innovation opportunities from 5G technology currently being tested on loaders.
“With mining becoming more massive and risky, we are definitely open to developing technology,” said PTFI Mining Engineering Head, Carl Tauran.
With a business license valid until 2041, we can expect many technological advances in PTFI's underground mines. Technology must be used to improve the safety and convenience of human labor.
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