Gearless mill drive system in iron ore processing
ABB was recently contracted to supply gearless mill drive (GMD) systems for two 38 foot semiautogenous grinding (SAG) mills at the Serra Azul iron ore mine in Brazil. The Serra Azul mine unit, owned by MMX Mineração e Metálicos, an EBX Group company, is located in the iron quadrangle of Minas Gerais, next to Belo Horizonte – the heart of the Brazilian mining state. The Tico-Tico and Ipê mines form this unit with a current production capacity of 8.7 million t of iron ore per year.
ABB’s scope of supply includes two GMD systems for 38 foot 23 mw SAG mills (Fig.) comprising transformers, ring motors and complete containerized electrical houses (e-houses). The variable speed drive solution allows for optimization of the grinding processes for ores with varying properties and different mill loads. The GMD eliminates the need of critical high maintenance mechanical equipment such as gearbox, ring gear and pinion. It enables operational optimization, energy and costs savings, high system efficiency and availability while reducing maintenance needs at the same time. This order is ABB’s first GMD reference in iron ore processing. ABB’s strong presence in Latin America and its state-of-the-art grinding solutions helped to secure the contract. The Serra Azul order will be ABB’s seventh installed unit in Brazil and the 48th in Latin America. The order was part of a multi billion US$ mine expansion, projected to increase annual iron-ore processing capacity to over 24 million t/a by 2015, allowing MMX to triple its output at Serra Azul. The expansion involves construction of an iron ore enriching plant and a railroad terminal.