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Metso vertical grinding technology reduces energy consumption by 30% in Anglo American's regrinding circuit

The adoption of Metso's Vertimill grinding mills in Anglo American's Minas-Rio System resulted in a 30% reduction in electric power consumed during regrinding operations. The energy gain represents a financial savings of approximately Eur 5,5 million (R$23 million) per year (excluding taxes) – including energy costs, demand and charges related to the use of the regrinding circuit.

For the Anglo American venture, Metso supplied 16 Vertimill VTM-1500-WB model grinding mills. The circuit comprises two regrinding lines, each composed of 8 mills, each with a power of 1.1 megawatts (MW), and four cyclone batteries for grading iron ore. "Minas-Rio uses 17.9 MW of power in its regrinding process while the application with ball mills would be 25.6 MW; this represents a significant reduction of 7.7 MW", says Rodrigo Vilela, Director of Operation of Anglo American's Minas-Rio system, part of Anglo American's Iron Ore Business Unit in Brazil.

According to Vilela, the granulometry of the iron ore in the Minas-Rio System at the end of the regrinding process is 80% less than 36 micrometers. The iron ore from the underflow of the regrinding cyclones feeds the Vertimill grinding mills through the lower part and the resulting product is transported to the top of the mills, towards the concentrate thickener, the last step of the milling process. 

About Metso's Vertimills Line

Metso has over 100 years of experience in designing and building mills and three decades of success with Vertimill grinding mill applications. Since their launch in 1979, more than 440 Vertimills have been sold worldwide.

The Vertimill grinding mill can handle feed sizes up to 6 mm and grinding products smaller than 20 microns, and features standard mill sizes ranging from 15 HP (11 kW) to 4500 HP (3352 kW). 

Among the characteristics of the Vertimill, the reduction in capacity stands out – it can operate with a minimum energy consumption of 20%, making it ideal for regrinding applications and other applications with highly variable flows. The product offers a number of advantages over traditional ball mills, such as lower operating costs and greater energy efficiency (from 25 to 35%). Another benefit that stands out is the low maintenance, since the thread coatings are the only significant components of wear.

Metso's solution brought a number of differentiators to the Anglo American project: the use of the mills reduced the creation of ultrafine particles, noise emissions and the number of peripherals, as well as providing simpler and safer civilian bases due to less exposure to movable parts.

About the Minas-Rio Project

The Minas-Rio Project is considered to be the largest mining venture in the world and comprises four initiatives: the opening of a mine and the installation of an iron ore processing plant, both in Minas Gerais, the construction of a pipeline and the implementation of a terminal in the Açu Port, Rio de Janeiro. Currently, the operation is in the ramp-up phase to reach the nominal production capacity of 26.5 million tons of iron ore per year in the second quarter of 2016. 

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