Usiminas

“Mineração Usiminas” adopts new technology for waste disposal

29-06-2018


The company is requesting a license to implement a stacking filtration system,
anticipating a trend that should prevail in the mining industry

 

“Mineração Usiminas” (Musa) has filed a request for environmental licensing in the Regional Superintendence of Environment and Sustainable Development (Supram) to implement a new Waste Disposal System at its “Itatiaiuçu” (Minas Gerais) unit. The Filtered Waste Disposal project should consume an investment of approximately R$ 140 million and its purpose is to technically and environmentally improve the disposal of tailings from the iron ore production process. Once licensed, it will be one of the first major ventures of its kind in the country to use this technology.

Although with higher deployment and operating costs than conventional tailings dams, according to director Wilfred Theodoor Bruijn, “Musa” has made an option for the new method. “We are anticipating what we believe to be a trend for the future in the mining industry. Wastewater filtration has been used successfully in operations located in regions with restricted access to water and we have now been able to successfully adapt the technology to our reality, bringing environmental gains and keeping the high safety standard that already features our operation. “Wilfred also recalls the more restrictive environment in the licensing process of traditional dams”. “For all this, we weighed up that investing in the new technology would be more advantageous and in line with the yearnings of society” says the director.

The stacking filtrate tailing process also requires less disposal area, allows even more process safety, and enables immediate impact control actions. As it is being formed, the pile will simultaneously be regenerated for environmental and geotechnical purposes. The new methodology presents an even longer life span of the structure, raises water recovery levels, as well as provides greater control and stability of the layout structures.

The employment impact estimate is that about 300 jobs will be generated during the construction works as well as another 50 permanent jobs. Once the environmental license is obtained, the expectation is to immediately start the project implementation works. The deadline for completion of the works is estimated at 12 months.

“Mineração Usiminas” Musa expects the licensing process to be completed by next December, as agreed at meetings held between the company and the environmental agency.

Regarding Musa's decision to invest in the new system, Secretary Germano Vieira, from the State Secretary for Environment and Sustainable Development (Semad), says: “We have worked hard to promote new technologies for tailings disposal, as well as alternatives for the construction of dams. The government of Minas Gerais, following legal guidelines, seeks the convergence between economic development and the preservation of environmental quality and praises all projects that comply with this premise, considering that the largest beneficiary of this process is the citizen of Minas Gerais”.

How does it work?

Musa Tailings Disposal System, in the process of environmental licensing, aims to improve tailings disposal from its operations. The materials will be sent to a Filtration Plant, basically composed of the thickening process and the filtration itself. The water from the process will be recirculated, returning to Flotation as process water, while the filtered tailings mass will be transferred by means of a conveyor belt which will form the intermediate stack. From this pile, the filtered tailings will be transported by trucks to the dry stacking area where tractors and rollers will be used to spread and compact the material

MUSA's expectation with the new system is to increase the level of water recirculation in the production process, since there will be no infiltration and evaporation loss of the input, which is usually observed in the conventional tailings disposal system.

In addition, part of the water that is retained along with the tailings in the dam´s reservoir, will recirculate directly to the plant, as the filtration system will increase solids concentration in the final tailings from the current 45% to approximately 88%.


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