China has paid a high price for its dominance in rare earths

This has given China’s government near complete control over a critical choke point in global trade.

But for decades in northern China, toxic sludge from rare earth processing has been dumped into a 4-square-mile artificial lake. In south-central China, rare earth mines have poisoned dozens of once-green valleys and left hillsides stripped to barren red clay.

Achieving dominance in rare earths came with a heavy cost for China, which largely tolerated severe environmental damage for many years. The industrialized world, by contrast, had tighter regulations and stopped accepting even limited environmental harm from the industry as far back as the 1990s, when rare earth mines and processing centers closed elsewhere.

In China, the worst damage occurred in and around Baotou, a flat, industrial city of 2 million people in China’s Inner Mongolia, on the southern edge of the Gobi Desert. Baotou calls itself the world capital of the rare earth industry, but the city and its people bear the scars from decades of poorly regulated rare earths production.

The artificial lake of sludge known as the Weikuang Dam holds the waste left over after metals are extracted from mined ore. During the winter and spring, the sludge dries out. The dust that then blows off the lake is contaminated with lead, cadmium and other heavy metals, including traces of radioactive thorium, according to technical papers by Chinese scholars.

During the summer rainy season, the sludge becomes coated with a layer of water that mixes with poisons and thorium. This dangerous mix seeps into the groundwater underneath the lake.

The Weikuang Dam, also known as a tailings lake, is 7 miles north of the Yellow River and was built in the 1950s without the thick, waterproof liner underneath that became standard in the West in the 1970s. Baotou’s lake is so large that it cannot easily be rebuilt with a liner.

Government cleanup efforts have helped mitigate some health and safety risks in the industry. But Chinese academics and other experts have warned that environmental damage remains after years of poor practices and lax oversight.

“The closer to the tailings lake, the more serious the pollution and the higher the environmental and ecological risk,” said scholars at the Inner Mongolia University of Science and Technology in a research paper in January.

Similarly, researchers at the elite Chinese Academy of Sciences in Beijing, which is a government ministry, warned in a technical paper last year about “serious air and tailings pond pollution” in the Baotou area.

The Baotou Radiation Environment Management Office warned in 2009 that at the Bayan Obo iron ore and rare earths mine, 80 miles north of the city in the Gobi Desert, radioactive thorium was being “discharged into the environment in the form of waste slag, wastewater and dust.” In 2003, another paper found intellectual development disorders among children in Baotou affected by rare earths industry pollution, and a paper in 2017 found that children in Baotou still had potentially harmful levels of rare earths in their urine.

The enormous Bayan Obo strip mine produces most of China’s so-called light rare earths, like lanthanum for oil refining, and most of its medium rare earths, like samarium for the magnets in fighter jets and missiles. In trade disputes with the United States and the European Union, China has since April halted exports of samarium to any country and has restricted exports of heavy rare earths, which are mined separately near Longnan in south-central China.

Until a crackdown in 2010 and 2011, many illegal mines in south-central China spilled acid and ammonia into streams, poisoning rice fields.

China’s leaders have been working for over a decade to clean up the country’s rare earth industry, at a cost running into the billions of dollars.

“Excessive rare earth mining has resulted in landslides, clogged rivers, environmental pollution emergencies and even major accidents and disasters, causing great damage to people’s safety and health and the ecological environment,” China’s Cabinet wrote in 2012 in a comprehensive report on the industry’s pollution.

During a visit I made in 2010 to the Baotou tailings lake, a berm, little more than a high pile of earth, lay around its perimeter to contain the sludge. Rare earth refineries, then along the north side of the lake, were crude facilities with workers stirring big vats by hand. A nearby residential community had high rates of pollution-related health problems, according to Chinese experts at the time. Baotou itself was shrouded with smog, and the air had an acrid, faintly metallic taste.

Some progress since then is visible. During a return visit in early June, it was clear that the berm had been reinforced with stones. And outside the berm was a concrete-walled moat that could catch leaks from the berm.

The residential community had been moved to a less polluted area of the city. Replacing it were steel-walled industrial sheds. Few people were around. The smog had disappeared, and the air tasted clean.

Dust from the lake is a more difficult problem to resolve. In processing rare earths, acid is used to pry apart the chemical envelope that contains them in nature. Radioactive thorium is almost always released. In Baotou, it was simply dumped into the lake for decades instead of being stored in special repositories, as required in the West.

The Inner Mongolia government announced in 2015 that refineries had begun treating their waste before discharging it into the lake, but did not specify how the thorium was handled.

In the days of the Soviet Union, thorium dust blew across Scandinavia from a tailings pond at a rare earth processing facility in Estonia. Soon after the disintegration of the Soviet Union in 1991, the European Union spent close to 1 billion euros (nearly $1.2 billion) to build an adjacent pit with 10-foot-thick concrete walls, move the sludge into it and then cover it with 30 feet of dirt.

The Weikuang Dam has vastly more sludge because the effluent from rare earth processing is mixed into an enormous volume of material from iron ore processing. Any effort to move and store the sludge would be a logistical challenge, and no attempt to do so was visible when I visited in June.

But even as other cleanup measures continue, Chinese authorities have increasingly censored discussions of rare earth industry pollution. State media reported a decade ago that thousands of acres of grasslands near Baotou had been closed to livestock grazing after sheep and goats had been fatally poisoned by dust from the rare earth industry. But practically no mention of that incident can be found online now inside China.

Oversight of the rare earth industry in Baotou is complicated. Pollution regulation in China is mainly the responsibility of provincial governments — in this case, the government of Inner Mongolia.

But the same provincial government also owns Baogang Group, a mining and chemicals giant that runs the Bayan Obo mine, the steel mills and most of the rare earth refineries in Baotou. Baogang has been a pillar of China’s military-industrial complex since Mao Zedong. The Baotou Museum celebrates that Baogang made much of the steel for China’s tanks and artillery in the 1950s.

During my trip to Baotou in early June, two colleagues and I were stopped on a public road by eight carloads of police officers and Baogang security guards and questioned. We were put in the back of a police cruiser and later taken to a guardroom at Baogang’s headquarters. With 21 carloads of police officers and local officials outside, we were held for two hours and questioned further before being released and told that the Weikuang Dam was “a business secret of the Baogang Group.”

A woman there who said she was with Baogang’s rare earth subsidiary, but did not provide her name, said that Baogang declined to comment.

There were also modest signs of environmental improvement during a visit in April to the main valley producing heavy rare earths near Longnan.

A small tailings pond next to the largest of the mines had a black liner visibly sticking up around its sides, in an apparent attempt to contain pollution.

But a creek flowing through the valley past several smaller mines was bright orange and bubbling mysteriously.