Skip to main content

The Truth About Dams in Minas Gerais, Brazil


There are multiple kind of dams in Brazil. Some are used to hold water, some to generate energy and some to hold industrial and mining waste. The variety of dams reflect their conditions: many dams are in poor shape while some maintain low risk to the environment and the people living near it.

The mining waste dams are notorious for their relevant environmental impact. Even though technology has progressed, it is known that companies in the states of Minas Gerais in Brazil prefer not to employ the new findings. The reason is the same of always: to keep their profits as high as possible.

Brazil itself lacks a system that has deep information on these dams. When a catastrophe happens, like the ones in Brumadinho and Mariana, the government officials feel unprepared and have to collect information on the spot to help the people affected by the spilling.

The state of Minas Gerais does have a system for the registration of dams and their conditions. When the requirements are not met in the reports, the officials communicate the dam owners what they need to do in order to keep their dams safe to the environment. 

The following study from 2008 uses a methodology proposed by Menescal et al in 2001 which was adapted for mining waste dams. The results are as follows:


  • ·       Most of the dams with high hazard potentials were the ones with the lowest retention volumes of waste;

  • ·       The most common method for the growth of the dams is the upstream one, which is also the cheapest of all of them;

  • ·       Most of the dams presented adequate (yet still dangerous given their volumes of retention and locations in the region) results of percolation, deformation and deterioration;

  • ·    Over 60% of the dams hold high volumes of waste;

  • ·    About 76% of the dams have population spots downstream;

  • ·    About 30% of the dams need extra examination and attention from the owners and authorities;
  •     About 48% of the dams in working conditions showed a high hazard potential and 51% had worse results;
Labels:

Comments

Post a Comment

Popular posts from this blog

Photovoltaics: Band Diagram

In the previous post we discussed silicon, which is the most used material in photovoltaics. In this post, we introduce the band diagram, for which we will use silicon as an example. We will start our discussion of the band diagram with the Bohr model of the silicon atom. In semiconductor materials the outer shell of the atom, which is called the valence shell, is not completely filled. The outer shell of silicon contains 4 out of the possible 8 electrons, which we call valence electrons. As we discussed in the previous post, each silicon atom in a crystalline structure is bonded to four other silicon atoms. The bonds between the silicon atoms are called covalent bonds. These bonds actually consist of two valence electrons that are shared by two silicon atoms. All valence electrons are fixed in the lattice, forming covalent bonds, and are therefore immobile. However, at a temperature above absolute zero, thermal energy is supplied to these miconductor and some of the vale...
Post a Comment
Read more

Heat Management in Fuel Cells

For a fuel cell to run efficiently, there needs to be proper control of its temperature and heat generation. Some fuel cells work well in room temperature, but others require temperatures as high as 1000 ºC, and any value outside of the accepted range results in lowered efficiency of the device. Higher temperatures lead to faster kinetics and voltage, and lower temperatures cause shorter warm-up times, lower thermodynamical stresses and retardation of corrosion and other temperature-dependent processes. For fuel cells, higher temperatures also mean greater vaporization of the liquid water and, as a result, more of the waste heat becomes the latent vaporization heat.  The temperature profile in a fuel cell is ever-changing, even when the flow rate of the gases is constant. That happens because of the transfer of heat and phase change of some reactants. The accurate prediction of the temperature and heat distribution is essential to determine temperature-dependent parameters a...
Post a Comment
Read more

Fuel Cell Charge Transport

Conduction is the process which dictates the transport of charges through the fuel cell layers, except for the membrane. That means that the lack of adequate contact between the diffusion layer, bipolar plates and cooling plates is the cause of most of the ohmic losses outside of the membrane. There is where most of the overall ohmic loss occur. To help solving that problem, either the membrane needs to be made thinner, or its material needs to be more conductive. History and tests given that, have told us that making the membrane thinner is easier than the alternative. The challenge with making the membrane material more conductive balancing that property with its thermal and chemical stability.  The image below describes the relationship between membrane thickness and local conductivity: Source: SPIEGEL, Colleen.  PEM Fuel Cell Modeling and Simulation Using MATLAB ® .  Burlington, MA, USA: Academic Press, 2008. 440 p.
Post a Comment
Read more