Engineering Ethics Blog: The Brumadinho Dam Disaster

On Friday, Jan. 25, a dam holding back millions of gallons
of toxic mining tailings broke at the Brumadinho iron mine outside the city of
Belo Horizonte in Brazil.  The resulting
floodwaters engulfed a cafeteria owned by the Vale mining company where hundreds
of workers were having lunch.  As of
today (Sunday Jan. 27), forty bodies have been recovered and about 250 more
people are missing.  The president of
Vale, Fabio Schvartsman, expressed his grief and surprise in a statement that
was reported by the website Buzzfeednews. 
This accident comes a little more than three years after another dam
holding mining tailings collapsed at a different Brazilian Vale facility in
Bento Rodrigues, killing nineteen and leading to what many sources call
Brazil’s worst environmental disaster as brownish waste filled a river and ran
all the way to the Atlantic, despoiling water supplies and beaches along the

Mining is a dangerous business, and most miners know
this.  But that does not absolve mining
companies of the responsibility to ensure that avoidable disasters don’t
happen.  Twice now, Vale has allowed
tailing dams to fail, leading to consequences that in the United States would
probably put a firm out of business.  But
the company failed to learn enough from its 2015 disaster to keep this latest
one from happening.

What is a mining company doing with lakes full of toxic
waste anyway?  It has to do with the way
that lower-grade iron ore is processed in a system called
“beneficiation.”  To be smelted
(turned into pure iron) efficiently, ore must have a minimum iron content of
about 60%.  Lower-quality ore can still
be used, but it has to be concentrated with a variety of techniques such as
gravity separation and magnetic separation. 
Another technique is flotation, in which the ore is ground to a powder
and then has water added to make it into a slurry with special chemicals that
separate the desirable iron-bearing part from the waste with air bubbles. 

Once the good stuff is taken out, you are left with tons of
basically useless rock powder, and if the last step was flotation, the stuff is
in slurry form rather than dry.  It would
take a huge amount of power to dry it, so the least expensive alternative is to
pipe it into a man-made reservoir and hope it will eventually settle enough to
where the water can be recovered. 
Evidently this is often more of a hope than a reality, so the near-term
solution is simply to put more and more liquid waste into the reservoir and
hope the dam holds. 

Judging when one reservoir is full and another one should be
built, at much trouble and expense, is a difficult call—a little like preparing
for a war.  The only way you know you
didn’t prepare adequately is if you lose, and by then it’s too late.  If the company shuts down one reservoir and
builds another one before the first one is full, they’re wasting reservoir
capacity.  But if they keep putting stuff
in till the dam bursts, well, you get disasters like Bento Rodrigues and

The best way to keep these things from happening is to build
dams that don’t fail.  Good dams are
expensive, but there are less expensive things one can do to minimize the
damage if a dam does fail.  Alarm and
alert systems and evacuation plans are useful in this regard, but hardly
anything along these lines was done before the earlier dam failure in Bento
Rodrigues, which became completely inaccessible by road once the resulting flood
washed the access road away.  Having a
major disaster is bad enough, but having one that rescue teams can’t get access
to except by helicopter is a nightmare.

There are technical reasons, I’m sure, for the dam collapse
at Brumadinho, but the record of the Vale firm shows that technology, or lack
thereof, is not the only problem.  Civil
engineers have known how to build dams that don’t fail for more than a
century.  What is lacking here is a
commitment to safety of employees, as well as a sense of stewardship of
investors’ capital and the environment. 

Large companies such as Vale operate in a legal and
governmental environment that plays a huge role in determining their
behavior.  The Wikipedia page on the 2015
Bento Rodrigues disaster indicates that the joint venture firm that owned the
Brumadinho dam commissioned an inspection by a dam engineer in 2014.  He found serious deficiencies and warned of
possible failure.  But clearly, whatever
the company did to prevent it wasn’t enough. 
And now something similar has happened again.

Such an egregious case of negligence calls for major changes
in the relationships and power structures of private firms and the
government.  Without a collective voice
such as a union, the miners are at the mercy of their employers.  Without the threat of severe and long-lasting
negative consequences for endangering their employees, the mining company is
simply going to go on doing what it’s been doing:  making money while spending as little as
possible on things that don’t lead directly to profits—things such as better
dams and evacuation plans.  Logically,
then, it will take a force greater than the company’s own willingness to make
sure that another disaster like the two we’ve seen won’t happen again.  And in the absence of powerful moral centers
of authority such as churches, the government is the only place where such a
force can come from. 

Unfortunately, in some countries the government and large
companies are on the same side of most disputes, and that may be the case
here.  Words are cheap, and while the
expressions of sympathy and offers of help on the parts of the Vale’s
Schvartsman and the President of Brazil are no doubt sincere, words alone will
not keep another disaster from happening. 
Resources—money—will have to be redirected out of the pockets of the
owners toward safer dams, more reservoirs when old ones get to capacity, and
intelligent safety plans that give the workers a chance to survive if disaster
does strike. 

Mining will always be dangerous, but a miner shouldn’t have
to take his life into his hands every day. 
Let’s hope that this second major catastrophe at Brumadinho will lead to
reforms that make mining in Brazil a lot safer.

Sources:  I learned about this disaster from the
website Buzzfeednews, which I found out recently gets more traffic than the
website of the New York Times.  The story on the Brumadinho disaster is at  I also referred to information about
beneficiation from the website
and referred to the Wikipedia articles on the Brumadinho and Bento Rodrigues
mining disasters. 

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