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Brazilian expert study shows no overflow from Alunorte’s residue deposits during February rainfall

Computer simulations carried out by professors from the Federal University of Campina Grande show that there was no overflow from Alunorte’s residue deposit areas in February 2018. The independent study also concludes that Alunorte, from a water management perspective, can produce safely at 100% capacity.

In the study, the researchers simulated scenarios of water storage, pumping and treatment given different levels of alumina production and rainfall using internationally recognized modelling and simulation platforms. The Federal University of Campina Grande (UFCG) is widely recognized as experts within the field of chemical engineering in Brazil. The 14-person strong research team was coordinated by Dr. Romildo Pereira Brito and Dr. Gilmar Trindade de Araújo, both professors at the UFCG. The study was published on November 26. 

Main conclusions of the study: 

  • Computer simulations show that Alunorte’s residue deposit areas DRS1 and DRS2 did not overflow in February 2018.
  • The release of excess rainwater to the Pará river through the water channel “Canal Velho” was the most appropriate decision during the extreme rainfall.
  • Alunorte can, from a water management perspective, safely produce at its nominal capacity of 6.3 million metric tons of alumina a year.
  • With the improvement projects that are being implemented at Alunorte, the alumina refinery is prepared for possible future climate changes that could lead to more frequent extreme rainfalls.

“It is reassuring that we now have a third-party study that states that Alunorte can safely produce at full capacity and that our ongoing improvement projects will make us well-prepared for even heavier rainfalls than what we experienced in February. Together with the reports and confirmations from the Brazilian authorities that we did not have any overflow from the residue deposits, this study is an important confirmation that Alunorte is able to produce safely,” says John Thuestad, Head of the Bauxite & Alumina business area in Hydro.

Strengthening Alunorte’s water treatment capacity

Hydro has ongoing projects to strengthen Alunorte’s water management capacity, which will bring the alumina refinery up to a new environmental standard. The water basin capacity is to be increased by 350% (to be completed by the end of 2018) and the capacity of the water treatment facility will be increased by 50% (to be completed in the second quarter 2019).

The independent study states that the improvement projects related to the storage, pumping and treatment, are correctly designed and ensure the safety of Alunorte’s operations. In the study, the improvements were tested to sustain extreme levels of rain that are probable to occur only once in 10,000 or 5,000 years. The simulations were done for continuous rainfall over 12 and 24 hour- periods. The results show that Alunorte would safely manage both these levels of extreme rainfall, without the need to use the water channel ‘Canal Velho’ to release excess rainwater.

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