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Mercury Excess

Congress and EPA probe possibility of long-term storage of liquid metal

by Cheryl Hogue
July 2, 2007 | A version of this story appeared in Volume 85, Issue 27

Credit: Nick Koudis/Getty Images
Congress and EPA weigh options for long-term storage of the toxic metal.
Credit: Nick Koudis/Getty Images
Congress and EPA weigh options for long-term storage of the toxic metal.

AS CONGRESS begins considering a ban on the export of elemental mercury, lawmakers now must address a looming issue: What will happen to tons of U.S. industrial quicksilver if overseas sales are halted?

With the U.S. facing international pressure to ban exports of mercury, Congress and the Environmental Protection Agency are independently exploring options for permanent storage of the neurotoxic metal.

The origin of the problem is basic: Domestic supply outpaces demand. Thousands of tons of mercury are now used at eight U.S. chemical plants that eventually will shut down, and the mercury at these sites will be recovered. Hazardous waste handlers keep mercury from polluting the environment by reclaiming the liquid metal from scrap electrical switches, thermometers, and fluorescent light bulbs. Meanwhile, the gold-mining industry continues to extract mercury from the earth as a by-product. Currently, excess U.S. supplies of mercury from these sources are sold internationally.

Legislation before the House and Senate would outlaw these overseas sales. The proposed export ban is aimed at decreasing the supply of quicksilver on the world market because the mercury increasingly finds its way to small-scale gold miners in developing countries (C&EN, May 28, page 26). Millions of these miners around the world are suffering from poisoning from mercury, which is relatively inexpensive and easy to obtain.

To separate small bits of gold from rock and sand, the miners pour mercury into pans to form an easily separable amalgam. Gold buyers heat the miners' amalgam in an open pan, releasing mercury into the air. Some of the mercury pollutes surrounding communities while the rest is carried by the atmosphere and eventually deposits far away, including in the U.S. Between 650 and 1,000 metric tons of mercury are released by small-scale gold mining every year, according to estimates by the United Nations Environment Program (UNEP).

Storing Mercury The Military Way

The U.S. military is leading the way in demonstrating how commodity mercury can be stored safely over the long term. The Defense Department has good reason to do so: It has a mercury stockpile of 4,436 metric tons that it doesn't intend to sell, at least not for the next 40 years.

DOD has determined that its mercury is no longer needed for national defense reasons.

The Defense National Stockpile Center (DNSC) is in the process of consolidating its mercury holdings from facilities in New Jersey, Indiana, and Ohio at the Hawthorne Army Depot in Nevada (C&EN, May 28, page 26). The mercury is in steel flasks each about the size of a 3-L bottle of soda and holding 76 lb of quicksilver.

To prepare its inventory of mercury for long-term storage, DNSC "overpackaged" the flasks, explains Dennis M. Lynch, environmental protection specialist with the center. Six flasks were placed in a 30-gal steel drum with absorbent on the bottom and lined with a thick plastic bag. Cardboard inserts keep the flasks separated. The drums are closed with a rubber gasket and a bolt, providing a water- and air-tight seal. Arrayed in a warehouse, the 30-gal drums are on pallets with pans beneath them to catch any mercury that might leak from the drums.

This overpacking cost about $20 per flask, Lynch said. The center looked into consolidating the metal into containers holding 1 metric ton of mercury. But DNSC did not pursue this option because it would have cost about $100 per flask and posed a greater risk of releasing mercury than did leaving it in the smaller containers, he said. Less than 0.01% of the overpacked flasks—an estimated 120 flasks—are projected to leak over the course of 40 years, Lynch added.

DNSC estimates that storage of mercury at Hawthorne will cost $.0515 per lb per year, for a total of a little more than $500,000 per year for the military's entire stockpile of mercury, Lynch said. A contractor will operate the storage facility, he added.

A House bill (H.R. 1534), introduced by Rep. Thomas H. Allen (D-Maine), and a virtually identical Senate measure (S. 906), introduced by Sen. Barack Obama (D-Ill.), are designed to help protect small-scale gold miners and the environment by putting a dent in the world's supply of mercury. A smaller supply, in turn, is expected to encourage these miners to move to mercury-free technologies, which are already available, for winnowing gold.

The legislation would establish a committee to advise the government on storing excess elemental mercury from the private sector. Establishing a storage location would provide a place for the tons of the mercury now used at eight U.S. chlor-alkali plants as cathodes in the electrolysis of a sodium chloride solution to produce chlorine gas and sodium hydroxide. Such a site also would be a repository for mercury produced in gold mining or recovered from waste.

At a June 22 hearing, the House Energy & Commerce Subcommittee on Environment & Hazardous Materials explored storage concerns as well as pros and cons of an export ban, which would heighten the need for domestic mercury storage.

The Bush Administration opposes a ban on mercury exports, James B. Gulliford, EPA assistant administrator for prevention, pesticides, and toxic substances, told the subcommittee. "The Administration believes that the first priority should be given to pursuing demand management strategies," he said.

Under the aegis of UNEP, the U.S. government is involved in several projects worldwide to help stem the demand for mercury, Gulliford said. For instance, EPA is helping to cut demand in Russia's chlor-alkali sector by reducing the amount of mercury that escapes from these plants and by encouraging these factories to convert to technologies that do not use mercury. The agency is also working with hospitals in China to eliminate the use of thermometers and blood pressure measuring devices that use mercury, Gulliford said.

REDUCTIONS in both supply and demand are necessary worldwide to encourage developing countries to shift away from technologies using mercury, said Linda Greer, senior scientist with the Natural Resources Defense Council. If demand goes down without decreasing availability of the metal, supplies will go up, and the price will fall, making the use of mercury more attractive, she told the subcommittee.

"The single most important thing that the U.S. and other developed nations must do to reduce pollution from the use of mercury in commerce is to stockpile the surplus mercury we are accumulating," Greer said, endorsing H.R. 1534. "This will stem the tide of mercury flow into the developing world." Greer noted that the European Union is moving legislation to ban its exports of mercury.

U.S. chlor-alkali manufacturers say the government needs to settle issues about mercury storage before it halts international sales of the metal.

"It is premature to establish a ban on mercury exports until the U.S. has a program established and in place for the permanent storage of mercury," said Arthur E. Dungan, president of the Chlorine Institute. This chemical industry trade group, which represents chlor-alkali makers, backs the creation of a federal stockpile for mercury, he said at the hearing.

Rep. John Shimkus (R-Ill.), ranking minority member of the subcommittee, expressed doubts about the practicality of creating a federal storage facility for mercury. Such a strategy is likely to wind up in endless debate, he said, comparing it with the nuclear waste storage facility at Yucca Mountain in Nevada.

"Long-term storage of mercury is relatively easy and cheap, compared to storage and disposal of other hazardous materials," commented H.R. 1534 sponsor Allen, who is a member of the subcommittee.

"Mercury is a dream chemical for storage compared with other toxics," Greer said, noting that elemental mercury is neither explosive nor reactive.

Dungan pointed out that the Departments of Defense and Energy currently warehouse thousands of tons of mercury. The two departments have plans to store their stockpiles for the next 40 years. Unlike nuclear waste, mercury can easily and safely be stored in a warehouse, he added.

At the hearing, Bruce Lawrence, president and owner of Bethlehem Apparatus of Hellertown, Pa., spoke out against the export ban and the creation of a federal storage facility for excess U.S. mercury stocks. Lawrence's firm recovers mercury from scrap and closed chlor-alkali plants and is working to develop a proprietary technology to treat mercury so it can be disposed of in a hazardous waste landfill.

A U.S. export ban, Lawrence argued, would encourage mining of mercury elsewhere in the world, especially in small-scale efforts using crude equipment that loses a large percentage of mercury to the air when ore is processed. Lawrence also called for DOE and DOD to resume sales of mercury onto the world market.

Credit: Defense National Stockpile Center
The Defense National Stockpile Center stores mercury in 30-gal drums, each containing six steel flasks that individually hold 76 lb of the liquid metal.
Credit: Defense National Stockpile Center
The Defense National Stockpile Center stores mercury in 30-gal drums, each containing six steel flasks that individually hold 76 lb of the liquid metal.

MEANWHILE, EPA is delving into possible storage options for private-sector mercury. The agency convened a meeting of stakeholders on June 14 to discuss the matter.

The possibility of storing mercury in perpetuity raises a thorny regulatory issue for EPA. As long as stored mercury might possibly be sold, facilities holding it are exempt from abiding by complicated and expensive hazardous waste disposal regulations. But if the mercury is stored without the possibility of future sales—a situation that a blanket export ban would create—the status of the material changes, and the storage facilities would have to meet stringent hazardous waste requirements.

This is because EPA views commodity-grade mercury as a product, not a waste, explained James Berlow, director of the agency's Hazardous Waste Minimization & Management Division. As long as there is a market for this material and the potential for future sale or use, stocks of mercury will be considered a product and not a hazardous waste, he said at the meeting.

In contrast, the act of safekeeping mercury in perpetuity would likely qualify as disposal of a hazardous waste and thus would require storage facilities to get a permit under the federal Resource Conservation & Recovery Act (RCRA), Berlow said. He cautioned that this view is his own and not that of EPA. Currently, DOD's and DOE's mercury warehouses do not require a RCRA hazardous waste storage permit because the two departments have not disavowed all intentions of selling the metal in the future, Berlow said.

Under EPA regulations, commodity-grade mercury can't be disposed of in landfills nor can it be mixed with other materials to make it suitable for landfills, Berlow said. Only waste containing less than 260 parts per million of mercury can legally be buried in U.S. landfills.

Many of the stakeholders convened by EPA said if Congress outlaws exports of mercury, the federal government will need to be involved with long-term storage of the metal. Several suggested that the military's new mercury-storage facility at the Hawthorne Army Depot in Nevada could be expanded to accept mercury from businesses. The Defense National Stockpile Center is consolidating the military's holdings of mercury at the Nevada facility.

By law, however, DOD can accept hazardous waste only from defense agencies, said Dennis M. Lynch, environmental protection specialist at the stockpile center.

At the stakeholder meeting, Lawrence said his company is working on a method to amalgamate mercury so it ultimately could be stored in a landfill. Bethlehem Apparatus hopes to develop a technology that will render a material that could be disposed of in a landfill in Canada that accepts hazardous waste with a concentration of mercury higher than 260 ppm, he said.

But Lawrence's plan could not be executed unless EPA changes its hazardous waste regulations, Berlow said. Under those rules, liquid mercury may not be treated so it can be buried in a landfill, he explained.

Congress could create a public-private entity to manage all U.S. mercury stocks, suggested Bradley J. Buscher, chairman and chief executive officer of Mercury Waste Solutions, a reclamation facility in Wisconsin. At the EPA stakeholders' meeting, Buscher proposed such a public-private organization, similar to the U.S. Enrichment Corp., which took over DOE's uranium-enrichment operations. Under Buscher's proposal, all domestic mercury would be sold to the new entity at market price.

EPA's stakeholder group will continue its discussions on mercury storage issues later this month. Rep. Albert R. Wynn (D-Md.), chairman of the Environment & Hazardous Materials Subcommittee, has not yet decided when he might call for a vote on H.R. 1534, a spokesman for the panel told C&EN.


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