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On a list of 717 tailings dams in Brazil, at least 88 dams have a construction method "in unknown or unknown upheaval," according to a list released Thursday (31) by the National Mining Agency (National Mine Agency ). ANM). Of these, 43 are clbadified as mothers of potential high badociated damage.
The upstream method is the same as the Vale dams that broke out in Mariana in 2015 and Brumadinho in 2019 and are considered less safe by specialists. Other types of construction, considered safer, are upstream, in the center and on one floor.
Type of Mining Dams Construction in Brazil
in Units
Source: AMN
Dams clbadified as dams with a high potential level of damage are structures considered to be risky with respect to failure or malfunction of a dam. This clbadification takes into account loss of life and social, economic and environmental impacts. In total, Brazil has about 200 dams in these conditions.
In addition to clbadifying potential damage, the ANM also clbadifies roadblocks according to the risk of accident. Of the 88 dams that have a construction method "upwelling upstream or unknown", 12 are considered medium risk.
The majority (72) is clbadified as a low-risk structure – the same clbadification as the Córrego do Feijão Dam 1 in Brumadinho (MG), which broke out last Friday (25), killing hundreds and missing.
Although it is quite common and less expensive, the method of damping Upstream – the same as that used in the dams responsible for the tragedies of Brumadinho and Mariana – is considered obsolete and the least safe for specialists In upheaval upheaval, the dam grows in stages in the reservoir, using the rejection of the ore beneficiation process on the initial lift.
- Understanding the operation of dams due to upstream depreciation
- Dismantling: discover the process or to finish with dams similar to those of Mariana and Brumadinho
Minas Gerais calls for the elimination of 50 dams
Government investigation in the state of Minas Gerais, identified the existence of 50 dams upstream. Of these, 27 are active, 22 are paralyzed, in addition to the B1 of Mina do Feijão, Vale, which broke out in Brumadinho.
However, in the list of the ANM published Thursday, the number of dams with the method "upstream or unknown" is 41.
In a resolution released on Wednesday (30), the Secretariat to the mine environment The General determined that all such dams would be phased out in 3 years and gave companies 360 days to present the technology to be adopted and the schedule work plan.
A 2016 decree, issued after the disaster of Mariana, already banned in the state the licensing of new dams and the extension of structures using or having used the method of 39; elevation. But there was still no defined policy on dams in operation or already deactivated.
Vale announced Tuesday that it would eliminate the 10 upstream dams still maintained by the company. According to the company, they are located in the cities of Ouro Preto, Belo Vale, Congonhas, Brumadinho and Nova Lima, all located in Minas Gerais, in units of Abóboras, Vargem Grande, from Capão do Mato and Tamanduá, in the complex of Vargem Grande and Jangada, Fábrica, Segredo, João Pereira and Alto Bandeira, in the Paraopeba complex.
Vale said it would take three years and $ 5 billion to "leverage structures such as tailings dams in order to re-integrate them into the environment", which we calls the decommissioning. To speed up the process, the company announced that it would stop the production of iron ore in neighboring areas, impacting 40 million tons of iron ore and 11 million tons of pellets a year.
Describing dams is not simple and also involves risks
Proceeding to what is called the dismantling and reintegration of dams in the environment There are two main routes: emptying or landing the area, or reprocessing materials deposited in dams, separating mineral waste and directing dry solid waste to another location.
The specialists heard by G1 explain that the process of characterization of a dam is not simple, that it usually has a high cost and that it is not immune to new accidents.
For example, the dam that collapsed in Brumadinho, although it had been authorized to expand its activities last December, had not received residues since 2016 and had become the muddy sea where hundreds of people had disappeared. According to informed Vale, the structure was inactive, had no lake and "was under development the project to decommission it."
"The decommissioning of this type of dams is necessary, it reduces the risks for the population, but does not solve the problem", warns Bruno Milanez, expert in environmental policy and researcher at the. Federal University of Juiz de Fora.
"As the elevation of a dam is risky, decommissioning also carries a risk.It is a very delicate process as it involves emptying the dam or transferring the material to another one. sites will require even more rigorous monitoring, "he adds.
In addition to the project to open a mine or a dam, the deactivation, rehabilitation of the area and the recovery of vegetation also depend on environmental licenses.
If, on the one hand, the process of shutting down the production and use of dams represents an economic impact for mining companies, part of the decommissioning process may also generate income.
The Vale decommissioning project, which collapsed in Brumadinho, provided for a new treatment to remove the ore from the accumulated discharges in the dam. Vale obtained the environmental license for these activities at the end of 2018, but the company denied the start of work on the site.
Vale has not yet specified how decommissioning will be done in these 10 dams that will be deactivated. According to the company, the processes of interruption and deactivation must be subject to an environmental agency license "Until then, it was believed that with proper monitoring, these dams were safe, it would be necessary -be reviewing these concepts, "said the company's executive director of finance and investor relations. Luciano Siani "Even these old and disabled dams, like this one, will be undergoing major investments to eliminate any risk," he added.
BREAKAGE OF MOISTURE IN BRUMADINHO
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