EarthTalk: Most gold mining operations use
cyanide to extract gold from surrounding rock. What are
the environmental implications of this, and are there alternatives?
—J. Pelton, via e-mail
90 percent of gold mines around the world employ
"cyanidation," the use of a sodium cyanide
compound to separate the gold from finely ground
© Kacos2000, courtesy Flickr
“cyanidation”—the use of a sodium cyanide
compound to separate a precious metal from finely ground
rock—has become less common in other forms of mining,
it is still the dominant practice in gold mining. Some 90
percent of gold mines around the world employ cyanidation
to harvest their loot.
gold mining, a diluted cyanide solution is sprayed on crushed
ore that is placed in piles or mixed with ore in enclosed
vats,” reports the State Environmental Resource Center
(SERC), a project of the non-profit Defenders of Wildlife.
“The cyanide attaches to minute particles of gold
to form a water-soluble, gold-cyanide compound from which
the gold can be recovered.”
of course not all the cyanide gets recovered. Some of it
gets spilled, and some is left within mine waste that is
often buried underground woefully close to groundwater,
leaving neighbors and public health officials worried about
its effects on drinking water and on surrounding ecosystems
and local wildlife.
and regulatory documents often state that cyanide in water
rapidly breaks down in the presence of sunlight into largely
harmless substances, such as carbon dioxide and nitrate
or ammonia,” reports Earthworks, a Washington, DC-based
non-profit. “However, cyanide also tends to react
readily with many other chemical elements and is known to
form, at a minimum, hundreds of different compounds.”
While many of these compounds are less toxic than the original
cyanide, says Earthworks, they can still persist in the
environment and accumulate in fish and plant tissues, wreaking
havoc on up the food chain.
2000, a breach in a tailings (mining waste) dam at a gold
mine in Baia Mare, Romania resulted in the release of 100,000
cubic meters of cyanide-rich waste into the surrounding
watershed. Nearly all aquatic life in nearby waters died,
while drinking water supplies were cut off for some 2.5
the wake of this accident, gold miners around the world
have been taking steps to deal with tailings in a safer
manner, through the use of special systems designed to prevent
cyanide or its breakdown compounds from escaping into the
environment. But such precautions at present are only voluntary.
Regulators in the U.S.—the third largest gold producer
after South Africa and Australia—don’t require
mine operators to monitor cyanide and its breakdown compounds
in nearby groundwater and water bodies, so no one knows
just how big a problem might be.
promising alternative to using cyanide in gold mines is
the Haber Gold Process, a non-toxic extraction system that
tests have shown can result in more gold recovery over a
shorter period than cyanidation. Another alternative is
YES Technologies’ biocatalyzed leaching process which
proponents say is 200 times less toxic than cyanide. But
with cyanidation well-entrenched in the industry and regulators
looking the other way, these alternatives face an uphill
battle in gaining widespread adoption.
Environmental Resource Center (SERC); Earthworks;
EarthTalk: Why don’t more states mandate
deposits on beverage bottles as incentives for people to
return them? Most bottles I’ve seen only list a few
states on them.
—Alan Wu, Cary, NC
10 U.S. states have "bottle bills" requiring
deposits on some beverage containers so consumers
will return them.
© Mr. T. in DC, courtesy Flickr
bills, otherwise known as container recycling laws, mandate
that certain types of beverage containers require a small
deposit (usually five or ten cents) at checkout beyond the
price of the beverage itself. Customers can return the empty
containers later and reclaim their nickels and dimes. The
idea is to provide a financial incentive for consumers to
recycle and to force industry
to re-use the raw materials.
the Container Recycling Institute (CRI), a California-based
non-profit which encourages the collection and recycling
of packaging materials (and runs the website BottleBill.org),
the benefits of bottle bills include: supplying recyclable
materials for a high-demand market; conserving energy, natural
resources and landfill space; creating new businesses and
green jobs; and reducing waste disposal costs and litter.
The 10 U.S. states that currently have container recycling
laws recycle at least 70 percent of their bottles and cans;
this amounts to a recycling rate 2.5 times higher than in
states without bottle bills.
make up a whopping 5.6 percent of the overall U.S. waste
stream, so every bottle and can that gets recycled counts
toward freeing up landfill space. And CRI reports that beverage
containers account for some 20 percent of the greenhouse
gas emissions resulting from landfilling municipal solid
waste and replacing the wasted products with new ones made
from virgin feedstock. So by promoting more recycling, bottle
bills indirectly reduce our carbon footprints.
The 10 U.S. states
with bottle bills are California, Connecticut, Hawaii, Iowa,
Maine, Massachusetts, Michigan, New York, Oregon and Vermont.
Delaware’s legislature repealed its bottle bill after
almost three decades on the books last year as the state’s
bottle recycling rate had dropped to just 12 percent due
to more and more retailers refusing to deal with the hassle
of accepting returned containers. In place of its bottle
bill, Delaware enacted a $0.04/bottle recycling fee that
will help defray the costs of starting up a curbside recycling
pickup system to service the entire state.
extremely disappointed they chose to repeal their law, rather
than enforce it,” reported CRI’s Susan Collins,
adding that the new fee places a burden on consumers only.
“Consumers will be subsidizing the producers and that
is unfair.” CRI supports “extended producer
responsibility” where producers and consumers together
pay for the life cycle costs of product packaging.
the main reason bottle bills haven’t caught on is
because of opposition to them by the beverage industry,
which doesn’t want to bear the costs of recycling
and claims that the extra nickel or dime on the initial
cost of the beverage is enough to turn potential customers
away. The U.S. Public Interest Research Group (USPIRG) found
that the beverage industry and its representatives spent
about $14 million in campaign contributions aimed at defeating
a national bottle bill between 1989 and 1994. Meanwhile,
members of a Senate committee who voted against national
bottle bill legislation in 1992 received some 75 times more
in beverage-industry PAC money than those who voted in favor
of the bill.
Recycling Institute; USPIRG.