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The Brumadinho Dam disaster

The Brumadinho Dam disaster

by Karl D. Stephan | February 07, 2019

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Brumadinho Dam. (Video screenshot) By TV NBR, CC BY 3.0, via Wikimedia Commons

Note: This article from Karl Stephan’s Engineering Ethics blog was posted on January 28, so some information may be out of date. However, Professor Stephan’s ethical assessment is not.

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 way. 

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 Brumadinho.

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.

Karl D. Stephan is a professor of electrical engineering at Texas State University in San Marcos, Texas. This article has been republished, with permission, from his blog Engineering Ethics, which is a MercatorNet partner site. His ebook Ethical and Otherwise: Engineering In the Headlines is available in Kindle format and also in the iTunes store.

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 https://www.buzzfeednews.com/article/hazelshearing/brazil-dam-burst-vale-brumadinho.  I also referred to information about beneficiation from the website http://ispatguru.com/beneficiation-of-iron-ores/ and referred to the Wikipedia articles on the Brumadinho and Bento Rodrigues mining disasters. 

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