Vale's dry concentration pilot holds tailings promise

Brazilian mining firm Vale has launched a pilot plant that performs dry magnetic concentration of low-grade ore using rare earth magnets, reducing the need for potentially dangerous wet tailings dams. 
Vale's dry concentration pilot holds tailings promise Vale's dry concentration pilot holds tailings promise Vale's dry concentration pilot holds tailings promise Vale's dry concentration pilot holds tailings promise Vale's dry concentration pilot holds tailings promise

Currently the company produces 60% of iron ore using natural moisture

The Fines Dry Magnetic Separation (FDMS) system to be used at the plant was developed by Brazilian innovator firm New Steel, which Vale acquired for US$500 million in 2018. 

Vale intends for the pilot FDMS plant, which will cost US$3 million and be located in Minas Gerais state, to be developed into an industrial plant by 2022 with a production capacity of 1.5 million tonnes per year. 

A separate pilot FDMS plant already operational at the company's Fábrica's mine, also in Minas Gerais, has been able to concentrate 30 t/hr of ore, also using the dry magnetic separation technology with rare earth magnets. 

Tailings evolution 

Because New Steel's method removes the need for flotation, tailings can be stacked rather than kept behind dams.

"New Steel puts Vale at the forefront of investments in ore processing technology. We will continue to seek solutions that increase the safety of our operations," said Vale executive director of Ferrous, Marcello Spinelli.

With New Steel, Vale estimates that, in 2024, 70% of production will come from dry or natural moisture processing, without adding water to the process and without using tailings dams.

Currently the company produces 60% of iron ore using natural moisture processing. However, by 2024, from the production using wet processing (30%), 16% will have filtered and dry-stacked tailings. Only 14% will continue using the conventional method with wet concentration and tailings disposal in dams or deactivated extraction sites.

Vale said the first units to use the technique will be the Vargem Grande complex in Nova Lima, Pico mine in Itabirito, Cauê and Conceição mines in Itabira, and Brucutu mine in São Gonçalo do Rio Abaixo. 

Overall, Vale will invest US$1.8 billion in filtering and dry stacking in the coming years. 

The investment comes in the wake of the Brumadinho dam disaster on 25 January 2019, when a tailings dam at the Córrego do Feijão iron ore mine failed, killing 259. 

 

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