Dirty Metals: Mining, Communities, and the Environment

From EARTHWORKS and Oxfam America.

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The first step in mining is to locate a subterranean ore deposit and bring it to the surface. Increasingly, mining operations find that it’s cheaper to do this by blasting away the soil and surface rock, called “overburden,” rather than by digging underground shafts. The resulting open-pit mines essentially obliter- ate the surrounding landscape and open up vast craters. The world’s largest open pit, the Bingham Canyon mine in Utah, measures 1.5 kilometers (1 mile) deep and 4 kilometers (2.5 miles) wide. Open-pit mines produce 8 to 10 times as much waste rubble as underground mines. This rubble is generally piled into enormous mounds, some of them reaching heights of 100 meters, which is nearly as tall as a 30-story building. In the United States, 97 percent of all metals are now mined in open pits. Globally, that figure is two-thirds and it’s rising.3

Once the ore is brought to the surface it must be processed to extract the mineral. The processing varies depending on the metal being mined, but it too generates immense quan- tities of waste. That’s because the amount of recoverable metal in even high grade ores is generally just a small frac- tion of their total mass. The amount of waste created per unit of recovered metal has tended to increase as more and more high-grade deposits are exhausted and the industry turns increasingly to lower grade ores. In the United States, for example, the copper ore mined at the beginning of the 20th century consisted of about 2.5 percent usable metal by weight; today that proportion has dropped to 0.51 percent. In gold mining, it is estimated that only 0.00001 percent (that’s one-hundred thousandth of 1 percent) of the ore is actually refined into gold. Everything else is waste.4

The cumulative amounts of solid waste produced by these processes are so large as to be almost incomprehensible. As a global average, the production of 1 ton of copper results in 110 tons of waste ore and 200 tons of overburden. Every

year, mines in the United States generate an amount of solid waste equivalent in weight to nearly nine times the trash produced by all US cities and towns combined. The total amount of waste ore (not including overburden) that has been generated to date by the US metals mining indus- try probably exceeds 90 billion tons.5

But to understand why the waste is so dangerous, you have to look at more than just the amount of it. You have to look at what the waste contains—and a lot of the con- tents are toxic. When it comes to toxic emissions, metals mining is one of the leading industries. In the United States, where companies are required to report such emis- sions, the industry’s own data have earned it the dubious distinction of being the country’s top polluter. In 2001, the most recent year for which data were available, metals mines produced 1,300 tons of toxic waste—46 percent of the total for all US industry combined—including 96 per- cent of all reported arsenic emissions, and 76 percent of all lead emissions.6


Ruined Lands, Poisoned Waters

Some of these toxics are contaminants of the ore itself—for example, heavy metals such as mercury, arsenic, selenium, and lead often drain out of the piles of waste rock. But other toxics are introduced intentionally during the extrac- tion process. Gold, for instance, is commonly extracted through a technique called “heap leaching.” The ore con- taining the gold is crushed, piled into heaps, and sprayed with cyanide, which trickles down through the ore, bond- ing with the gold. The resulting gold-cyanide solution is collected at the base of the heap and pumped to a mill, where the gold and cyanide are chemically separated. The cyanide is then stored in artificial ponds for reuse. Each bout of leaching takes a few months, after which the heaps receive a layer of fresh ore. Given the scale and duration of these operations (usually decades), contamination of the surrounding environment with cyanide is almost inevitable. A rice-grain sized dose of cyanide can be fatal to humans; cyanide concentrations of 1 microgram (one-mil- lionth of a gram) per liter of water can be fatal to fish.7

Wasting Rivers and Seas

Toxic emissions can be insidious—largely invisible until their effects are widespread. But there’s another kind of mining pollution that’s impossible to miss: tailings dam fail- ures. A by-product of extraction, tailings are usually a soupy to semi-solid suspension of pulverized rock in water, generally laden with toxics. On-site tailings disposal generally consists of bulldozing some of the dried tailings into a dam which can then retain the more fluid material. The dam is periodi- cally enlarged as the level of the tailings reservoir rises.

Despite its name, a tailings dam bears little structural simi- larity to an ordinary river dam. A conventional dam is gen- erally constructed as a single project, to a single set of pre- determined standards. On the other hand, the “construc- tion” of a tailings dam usually occurs over the life of the mine, which makes it much more difficult to maintain structural integrity. Over the past quarter century or so, tailings dam failures have accounted for three-quarters of all major mining accidents.8

Consider, for example, the failure at the Omai gold mine in Guyana. A project of the Canadian mining corporation Cambior, the Omai is one of the largest open-pit mines in the world. Its tailings dam failed in 1995, releasing some 3 billion cubic liters of cyanide-laden tailings into the Omai River, a tributary of Guyana’s largest river, the Essequibo. Following the spill, the President of Guyana declared all 51 kilometers (32 miles) of river drainage from the mine to the Atlantic Ocean—home to 23,000 people—an official “Environmental Disaster Zone.” Initial government reports estimated the cyanide concentration in the Omai to be 28 parts per million, which is 140 times the level that the US Environmental Protection Agency (EPA) considers lethal.9

To get around the problems of managing tailings on site, some mines pump them directly into nearby bodies of water. “Riverine tailings disposal”—a euphemism for dumping mine waste into rivers—poisons aquatic ecosys- tems, clogs rivers, and can disrupt the hydrology of entire watersheds. Once a common practice around the world, it has now been effectively banned by most developed coun- tries, including the United States and Canada. Elsewhere, the practice is not common, at least officially. Today, only three mines in the world, all located on the giant Pacific island of New Guinea, openly use this disposal method: the Ok Tedi, Grasberg, and Porgera mines. (For more on Ok Tedi, see page 7; for Grasberg, see pages 14, 19, and 24. Porgera is a gold mine run by Placer Dome, a Canadian corporation; it has been dumping all its tailings directly into the Porgera River since 1992.) To date, only three com- panies (the Canadian firm Falconbridge and Australian firms Western Mining Corporation and BHP Billiton) have publicly pledged not to dump waste into rivers.10

Riverine disposal is, however, practiced illegally at many other mines. In Ilo, Peru, for example, two mines and a smelter operated by the Southern Peru Copper Corporation (controlled by the Mexican firm Grupo Mexico) have caused severe environmental degradation through this kind of dumping, which the company prac- ticed for decades, in violation of Peruvian law. Between 1960 and 1992, the company dumped an average of 2,100 tons of smelter slag per day onto beaches north of Ilo; until 1995, it pumped an average of 107,000 tons of tailings per day into nearby Ite Bay. Between 8 and 9 million tons of accumulated slag now form artificial beaches along the coast. The mine tailings are now pumped into inland tail- ings ponds, but these are still contaminating the Locumba River, which flows into the bay.11

Ocean dumping is a form of water disposal that is less con- spicuous than the river option, and the Ilo mines are hard- ly the only coastal mines to have used the sea as a waste disposal site. Coastal dumping is a grave ecological concern because coastal waters are biologically the richest parts of the oceans, and because they support ocean life elsewhere as well: many open-ocean species depend on coastal habitat for part of their life cycle. Coastal dumping is a menace to public health as well. For example, in Northern Sulawesi, Indonesia, the Minahasa Raya gold mine, operated by the US-based Newmont Corporation, dumped over 4 million tons of tailings into Buyat Bay during the mine’s seven-year life, from 1996 to 2003. Local people have reported skin rashes after contact with seawater, and a toxicologist has found heavy metals in fish and plankton.12

It’s especially unfortunate that coastal dumping is practiced in parts of the Pacific that are home to some of the world’s richest coral reef communities—places like the coastal waters of Marinduque island in the Philippines. Those are the waters where the Marcopper copper mine pumped 200 million tons of toxic waste rock over a period of 16 years, carpeting 80 square kilometers of seabed, suffocating coral reefs, and poisoning reef fish. In the island’s fishing com- munities, children have tested dangerously high for lead and cyanide.13

In response to public health and ecological concerns over shallow sea disposal, the industry is turning increasingly to deep-water disposal, a practice in which a pipe conducts the tailings to a depth of at least 100 meters before releasing them into waters considerably deeper than 500 meters. The industry argues that this is a “best practice” because deep seawater has low levels of dissolved oxygen—a necessary ingredient for the chemical reactions that release heavy met- als from the rock. (See page 9.) But deep-water disposal remains highly controversial because so little is known about the ecology of the ocean floors, and because of the possibili- ty that broken pipes, deep-water currents, or geologic activi- ty could disperse the waste into shallower waters.14

A growing awareness of the risks of marine tailings dispos- al has led the United States and Canada to effectively ban the practice. And in December 2003, the World Bank’s Extractive Industries Review recommended that the Bank not finance mines that dump their tailings at sea. But it remains to be seen whether such moves are the beginnings of a broader ban, since other mines that use marine dispos- al continue to be developed. For example, BHP-Billiton has proposed a nickel mine on Indonesia’s Gag Island, which contains the third-largest nickel deposit in the world. If the project is approved in its present form, all waste would be dumped at sea—even though the coral reefs off the island are among the most biologically diverse in the world.15