Hydro Paragominas' innovation in bauxite waste management

Hydro Paragominas has come up with a smart solution for managing waste. 

The company is the country's second-largest bauxite producer and mines in Paragominas, Pará. They have found an innovative way to handle tailings (waste material from mining), which doesn't involve the risky use of tailings dams. This new approach is called the TDB (Tailings Dry Backfill) method. Here's how it works:

• Instead of traditional tailings dams, Hydro Paragominas now lets the tailings naturally dry in designated areas. 
• Once dried, they use this material to fill in the pits from where they extracted the bauxite. 

This approach is the first of its kind in Brazil's bauxite industry and earned Hydro Paragominas the title of Company of the Year in the Mineral Sector's Environmental Governance category.

Anderson Martins, the Industrial Director at Hydro Paragominas, hatched the idea for TDB in 2020, and they quickly put the plan into action after obtaining the necessary permits. The key is to allow the waste material to dry naturally in dedicated areas through evaporation. Then, they recover and reuse it to fill in the open pits from the bauxite extraction process.

Their system, Plateau, consists of four reservoirs where the tailings are arranged in layers to dry and become more stable. This Plateau System, RP1, is built on an old bauxite mining site and can hold around 11 million cubic meters of waste. It's divided into four tailings reservoirs and eight water reservoirs for recycling water in their production process.

The great thing is that these tailings are purely physical waste since no chemicals are involved in processing bauxite. So they can be safely disposed of without any risk of contamination. The material dries year-round, and every 60 days, the dried material is loaded into trucks and transported to the mine area to fill the pits. They use trucks, tractors, and excavators for this operation.

In the mining process, Hydro Paragominas follows these steps: 

• They remove the plant layer, store it for future use, remove waste rock with no economic value (it stays in the mine area), and finally, extract bauxite for processing. 
• During processing, bauxite is separated from other materials, which go to the tailings disposal area to dry before being transported to fill the pits. 
• After filling the pits, they put the waste rock (clay) back and then the organic soil layer, which kickstarts the area's regrowth. 
• They currently generate around 4.5 million tonnes of dry waste annually, which they return to nature. 
• They also recycle the water from the tailings and have two water storage basins. 
• The distance from the waste disposal plateau to the pit is approximately 5 km.

According to Martins, one significant advantage of TDB is that they no longer need to build or raise tailings dams, eliminating the associated risks.

If you want to know more about the South American aluminium industry, read AL Circle's latest e-Magazine.