There's a load of precious minerals lying in a gigantic tailings pond, but straining out the rare earths remains a difficult task

(Beijing) -- One crack in a wall is all it would take for a dark gray oval that sits across 11 square kilometers of land to create a massive disaster.

Situated just to the west of Baotou, a city in the resource-rich region of Inner Mongolia, the mine dump for Baotou Iron and Steel Group (Baosteel) is enclosed by a concrete wall that stands 20 meters high. It is one of China's largest tailings pools, and contains roughly 180 million tons of metal waste powder.

Until recently, few outside the city knew about the mine dump, which was created 60 years ago. The mine has gained attention on reports that the hazardous slurry contains large amounts of rare earths and other minerals, estimated by some to have a total value as high as 80 trillion yuan.
 
But the dump has attracted its share of negative news as well. At least 4,000 hectares of farmland have already been contaminated by seepage.  Over 130 hectares of farmland are unable to support crops or have extremely low output.

A number of villagers living nearby have also cited several health problems which they attribute to poor controls on the hazardous waste.

Market Value of Pollution

From a distance, the dump looks much like a dark, shining lake. Close-up, a network of small pipes leads to one large pipe at the center of the pool, and extrudes a continuous stream of brownish-black tailings water. 

Baosteel Rare Earth Research Institute Director Ma Pengqi said the resource value of the tailings pool is equivalent to the Bayan Obo iron ore mine in Baotou, the world's largest rare earths deposit with approved reserves of 36 million tons, 36 percent of the world's total.

In a study conducted by the company, researchers found that the proportion of rare earths in the 180 million tons of slag was higher than the total estimated reserves of raw ore in Bayan Obo. The average grade of rare earths is much more concentrated at 7 percent in the tailings, compared to 5.5 percent in raw ore.

Ma has conducted research on the pool for decades and estimates that the total commercial value of the tailings pond is over 1 trillion yuan, with 500 billion from rare earths and over 600 billion in other mineral deposits.

Many scholars point out that the Baosteel tailings pool was the result of inefficient mining practices, and the by-product created will make further mineral extraction more difficult. 

When Baosteel was established in the 1950s, the steel mill and ore processing plant had to be put 100 kilometers away from the Bayan Obo mining site on the outskirts of Baotou near the Yellow River as the mining site lacked water resources. The mine dump was built near the steel mill.

Official documents show that currently the Baosteel ore processor discharges between 7 million to 8 million tons of tailings into the pool each year. In addition, Baosteel's rare earth subsidiary and smelter plant also discharges 2.1 million cubic meters of toxic wastewater into the pool each year.

It wasn't until the end of the 1970s that the environmental impact caused by the tailings pool began to show. Inner Mongolia University of Science and Technology Professor Wang Jianying said that due to water pressure and other reasons, a large amount of saline sewage leaked through the soil and into what is known as the phreatic layer, or the first stable layer of water below the earth's surface. Nearby groundwater became heavily contaminated.

The seepage had an immediate effect on the environment. Farm yields declined and today much of the land lies abandoned. Groundwater cannot be used for irrigation or human or animal consumption. More than seven villages with over 3,000 residents and 300 hectares of land have been affected.

Moreover, Wang said, the contamination is expanding underground and approaching to the Yellow River at a speed of 20 to 30 meters annually.

Dalahai Village is 1.5 kilometers to the west of the Baosteel tailings pool. According to data from the Baotou Environmental Monitoring Station for  the years 1995, 2000 and 2006, the sulfate, chloride and fluoride content of well water in the village exceeds national irrigation water quality standards by several dozen times.

Potential Radioactive Harms

Both local governments and environmentalists say that above all else, the largest environmental concern is the radioactive hazard presented by the mine dump.

The results of a survey published by Sun Qinghong, researcher of the China Institute of Radiation Protection, show that that radiation in areas close to the tailings pool is higher than the Baotou urban area by varying degrees. To the south and southeast of the tailings pool, levels are elevated significantly. 

There have been a number of tailings dam breaches in recent years. If such a breach occurred at the Baosteel tailings dam, the consequences for Baotou, the largest city in Inner Mongolia, and the Yellow River would be disastrous. The tailings pool is also in an earthquake-prone area.

Among those in the rare earths industry, there have been calls for the government and Baosteel to use new technologies to extract rare earths while at the same time gradually reducing the possible environmental risks of the tailings pool.

In 2010, Baosteel Technology Center Assistant Engineer Zhang Yong and Baosteel Rare Earth Research Institute Director Ma Pengqi wrote a joint article describing a new tailings utilization process, which, according to the paper, would recycle up to 87 percent of rare earths from the tailings dam.

But Ma said that the new technology hasn't been put into practice. "There isn't any hardware or facilities to support the application of the new technology. Currently it's only a concept."

"The method is good enough, but if no one uses it, what can you do?" Ma said. "There is no sense of urgency."

A former Baosteel Research Institute source who asked not to be named said the iron ore that Baosteel has mined in the past is mainly rare-earth associated ore. The source said that based on an annual production of 10 million tons of steel and a 5 to 6 percent proportion of associated ore, Baosteel could produce approximately 500,000 to 600,000 tons of rare earths annually. But the global demand for rare earths is only several hundred thousand tons.

Since the amount of rare earths recovered with current technology for iron ore extraction is still high, there is no profit motive for Baosteel or the local government to spend huge sums extracting rare earths from the tailings pool.

Professor Zhang Xuefeng of the Inner Mongolia University of Science and Technology, who has researched rare earths pollution and the reuse of metallurgical refuse, said Baosteel should first refine the rare earths in the ore and then refine steel, which would improve the utilization of rare earths at the source. This is the best way to improve smelting efficiency and reduce pollution, according to Zhang.

"The current situation is that (Baosteel) first processes iron and then processes rare earths, while valuable minerals such as niobium get dumped," Zhang said.

But Ma also added that Baosteel should reduce the extraction of raw ore. "The company should supply rare earth according to the market demand. Then safeguard the mine as a national and company reserve."

Publicly available information shows that at Baosteel's current extraction rate, the Bayan Obo mine will be emptied of rare earths in 25 years.

Between 2005 and 2006, Xu Guangxian, an academic at the Chinese Academy of Social Sciences, sent letters to State Council scholars making similar proposals to cut down on mining in Bayan Obo and find a way to process metals in the mine dump. However, so far the local government has not issued any policies to address the dump, he said.