This article was originally published by Undark.
Thabang Ditibane spread his arms wide to describe the size of the stone that killed a fellow South African miner four years ago.
“I heard the sound and turned around, and the rock had smashed his head,” said Ditibane, a rock drill operator at the Eland mine, north of Johannesburg. Ditibane, a rock drill operator at the Eland mine, north of Johannesburg, stood in a 6-foot tall gulley, illuminated by a string like a snake-like light. There were also thousands of tons of rocks above.
The incident occurred at another mine. A rock had suddenly fallen into the tunnel. Such occurrences, called falls of ground, or FOGs, have long been a leading cause of accidental deaths in South Africa’s mines. The Minerals Council South Africa, which is the main industry group, says that more than 80,000 South African miner workers have died at work since the beginning of industrial-scale extraction in the late 19th Century. More than 1,000,000 have sustained serious injuries. While the country’s record has improved significantly in recent decades, according to the International Council on Mining and Metals, an industry group, its mines are still among the most dangerous in the world.
Representatives of labor unions want the industry and government to invest more in safety. The industry is “not doing enough to invest in health and safety matters. They invest more in making profits,” said Livhuwani Mammburu, spokesperson for South Africa’s National Union of Mineworkers.
Experts say South Africa’s mines are not nearly as dangerous as they once were. Since the early 1990s, increased regulatory scrutiny, labor activism, as well as investor pressure, have led the sector to mine safer. “Zero Harm” is now the stated goal of the industry, labor organizations, and the government.
Statistics show that there has been a marked drop in fatalities from FOGs this year. Industry executives and experts say that in order to reach the goal of zero incidents, new technologies will be required, including sophisticated radars, which can detect ground falling before they actually happen. Some experts believe the new tools can reduce the number of fatalities by drawing on the success stories of radars that were used to warn of impending landslides at surface mines.
It’s unclear how far these tools can go. The mining sector has signaled its readiness to continue investments in research and development, but costs will be a factor in any company’s decision to adopt such technology. The unexpected in geology, especially in South Africa, can lead to devastating surprises underground. Ore is mined at depths of nearly 2.5 miles below the surface.
“We will welcome any kind of technology,” Mammburu said, “that is meant to save lives in the mining industry.”
As the name suggests, a fall of ground is a terrifying prospect: The rock overhead suddenly collapses. Gravity, mining-related disturbances and natural geological weaknesses all can play a part.
The rock mass is “not homogeneous as one would expect,” said Bryan Watson, a rock engineer at Johannesburg’s University of the Witwatersrand. He explained that the mass, which appears solid, is actually riven with gaps and joints. Watson explained that molten magma is pushed up from the Earth’s core and exploits any weakness, causing it to separate. When miners dig underneath those fissures and areas of weakened rock, he added, it creates “a void into which the rock can fall.”
A FOG can also be triggered by natural earthquakes or small shakings due to mining activities close to a fault line. These seismic events can also trigger a rock burst in which pressurized rocks explode and propel shards at speeds of up to 20 miles an hour. Watson stated that mining blasting can sometimes cause unnatural cracks, which can lead to rocks dislodging, possibly crushing workers.
Nearly all rock drill operators, such as Ditibane are BlackThese are the ones who have borne the greatest risks. The miners work in cramped and hot conditions. They use hydropower drills to drill holes into the rock faces. These holes are then drilled by miners, who then add explosives to the mine. Afterward, miners haul the rubble to the surface, where it’s processed to extract gold or platinum.A rock drill operator at Eland mine, South Africa. Netting to prevent injuries from rockfall has been installed on the tunnel’s ceiling. Visual by Ed Stoddard of Undark
During apartheid—which subjected an overwhelmingly Black, migrant labor force to ruthless exploitation—miners often worked with scant safety protections. 800 South African miner died at work in 1986. Since the end of apartheid in 1994, South Africa’s mines have gradually become safer. Fatalities reached a record low of 51 in 2019—still almost one per week on average. During the Covid-19 epidemic, these numbers increased again, but nowhere near their apartheid level. FOGs are the leading cause of death. From 2000 to 2021, rockfalls accounted for 39 percent of mine fatalities, according to Undark’s calculation from industry and government data.
There are many factors that have contributed to this improved safety record. The 1996 regulations forced mines into implementing new safety standards. They also had to undergo more frequent inspections.
Many mining companies have seen their incentive structures shift. Investors are becoming more concerned about safety. In some cases, compensation for CEOs is tied to safety records. Mines may also be shut down due to accidents. “All of those costs now are being viewed as extremely serious, along with implications for the reputation of the company, but also individual reputations and performance of executives,” said May Hermanus, the former chief inspector of mines in South Africa.
Nearly all rock drill operators, such as Ditibane are BlackThey are the ones who have historically borne the greatest risks.
Underground mines have safety netting and bolting installed on their roofs to prevent FOGs. The practice was once used only in select cases, but it has been widely adopted over the last decade. The basic idea is that the mesh captures any rocks that fall.
Recent industry groups have recognized the need for further changes. In July 2021, the Minerals Council unveiled an action plan to eliminate FOG fatalities. Its analysis showed “a steep reduction in FOG fatalities between 2003 and 2011, followed by a plateauing period between 2012 and 2020.”
Paul Dunne CEO Northam Platinum Holdings Limited said that there was a decline in safety. “All the CEOs were unhappy about that,” he said. Dunne’s company operates three platinum mines in South Africa, and he said that falls of ground posed the highest risk. “That’s why we chose to address it.”
Now some experts are looking for an even more effective tool—a way to forecast FOGs before they even happen.
In 2013, a wall gave way at the Bingham Canyon Mine, an open-pit copper mine outside Salt Lake City, Utah. The landslide spewed 165 million tons of rock—enough, according to a team of geologists who analyzed the incident, to cover New York City’s Central Park 65-feet deep in debris. The event, they wrote, was “likely the largest non-volcanic landslide in North American history.”
However, no one was there. Before The slide was a radar developed by IDS GeoRadar that detected increasing instability. “Mining operations were shut down the previous day in anticipation of the slide, and there were no injuries,” wrote Francesca Guerra, the marketing manager for the Italian firm, in an email to Undark.
Now IDS and other companies have been working on bringing such technology—which can detect movement without penetrating the rock—underground. IDS says the technology has been deployed worldwide, and in South Africa is being used in “special projects.”
However, it is difficult to move such radar underground. The radar that is used on the surface can weigh more than two tonnes.
The event, they wrote, was “likely the largest non-volcanic landslide in North American history.”
Anglo American Platinum, South Africa’s technology company, has teamed up with Geobotica to develop a handheld underground radar.
“The idea came from the success achieved in open-pit mines using radar technology.” said Riaan Carstens, lead geotechnical engineer at Anglo. “Where it was deployed, used effectively, they pretty much eliminated fatalities from slope failure. The question was then posed: Can we use this technology in the underground space to warn people working in the vicinity of a potential fall of ground?”
Geobotica reduced this to a rectangular-shaped device weighing in at 7 ounces.
Geobotica CEO Lachie Campbell said that the device emits a signal which travels through air and bounces off rock surfaces. These signals are then picked up by the radar. “We send out a signal from the radar that’s in a very defined wave,” he said, “It comes back at a certain angle, and if the rock doesn’t move, that angle is always the same. But if the rock moves a little bit, it comes back at a slightly different angle.” Those slight movements, undetectable without such specialized equipment, can signal an impending collapse.
This process is known as interferometry. The power intensity is one of the challenges in underground adapting this technology.
“We create our radar signal digitally on a low-power chip, rather than using traditional radar components,” Campbell wrote in an email to Undark. The advances allow them, he wrote, to effectively shrink a 2.2 ton diesel-powered trailer system “right down to something that fits in your pocket and runs for months on a single charge.”
Campbell demonstrated how the radar (resembling a phone) could detect changes in Campbell’s heart rate when he stops breathing. This is similar to an electrocardiogram. Campbell explained that underground, the radar can filter the movement of people so it can focus on the rock.
“This is the only way that you can forecast if a rock is going to collapse,” he said. “You need a precision that is sub-millimeter.”
IDS, an Italian company is trying to reduce the size of a radar for underground use. Their current model, called the HYDRA-U, “is designed for quick and easy transport and deployment in critical areas by one single person,” according to the company. It measures approximately 4 feet high when mounted on a tripod. It can be attached to a suitcase-sized power supply.
However, it is uncertain whether such technology will become widespread. South African mining companies agree that such initiatives should be explored, but it could prove costly. “The costs involved in these advanced new technologies, we have to make sure that it is feasible,” said Jared Coetzer, head of investor relations for Harmony GoldThe company manages eight underground mining operations in the country. “We would certainly be willing to consider all options available to assist with reducing any incidents.”
Italian company IDS GeoRadar’s current model for underground mines is the HYDRA-U.
Visual: IDS GeoRadar/YouTube
This technology has been limited in its real-world application underground. It may not catch all FOGs, but it is not widely believed by everyone. Watson, a rock engineer, stated that radar is not foolproof because geology holds many secrets.
“We don’t yet know what kind of movements are going to take place before there is a fall of ground,” he said. “How long have you got? Do you have two minutes, an hour, or a full day? We’re not sure.”
High-tech radar doesn’t negate the importance of basic tools such as bolting and netting in reducing fatalities. “There has always been a view that these falls of ground are preventable,” South African human rights lawyer Richard Spoor said in an interview. “For years the industry was skimping on roof support because it’s very expensive.”
According to Allan Seccombe (head communications, Minerals Council), four FOG deaths have been reported so far this year. That’s far fewer than the 19 on record this time last year.
FOGs could have still caused unspecified injuries. South African miners are still being injured on the job. 44 people died in accidents last week in 2022, as opposed to 55 deaths in the same period lastyear.
“Our main, important goal is to make sure there is zero harm, there are zero injuries and zero deaths in the mining industry,” said Mammburu of the National Union of Mineworkers.