The flying giant

Compañía Minera Doña Inés de Collahuasi SCM, one of the largest copper producers in Chile, has improved the reliability and throughput of its mine in Northern Chile with new drive systems in four of its ore mills. Getting the required equipment to the site was a challenge in planning and logistics.

by Felipe Contreras, Werner Kitz

Compañía Minera Doña Inés de Collahuasi SCM (Collahuasi) was looking to boost the reliability and throughput of its copper ore operations in northern Chile. The mine’s operators, therefore, commissioned Siemens to modernize the drive system of four ore mills at the site – two 8 MW semi-autogenous (SAG) mills and two 9.7 MW ball mills. In addition to delivering four complete state-of-the-art dual-pinion drive systems for the mills, Siemens also provided six 4,000 kW and six 4,850 kW synchronous motors, Flender couplings with torque limiting, Sinamics SL150 converters with thyristor columns, and a transformer. In addition, the Siemens team upgraded all software and hardware systems and was responsible for the installation.

A large, delicate undertaking

This project wasn’t without its challenges. Everything had to be online within nine months – a relatively short time period for a project of this dimension. Furthermore, a window of just 13 days had been reserved for installation. If that wasn’t enough, Collahuasi’s open-pit mine is remote, located 180 kilometers southeast the port of Iquique at an altitude of 4,200 meters. Because of the high altitude, parts and components required special electrical and thermal dimensioning – per se not a problem for Siemens, as the company has equipped many mines in remote locations like this. The bigger problem was getting the four dual-pinion drives to site quickly for installation.

 

Transporting the first four giant machines – each weighing 42 tons – from the factory in Berlin, Germany, to the high-altitude site in northern Chile, normally takes time. And time was the one thing the team didn’t have. The only viable solution for was to forgo sea transport and use airfreight instead. But which machine can handle such loads? One freight plane – the Antonov An-225 – was built especially to handle giant cargo. At 84 meters long, with a wingspan of 88 meters, the An-225 itself weighs 285 tons. It needs 32 wheels to handle its own weight as well as that of its cargo. In fact, the An-225 is not only the largest cargo plane, it is the biggest airplane in the world.

 

Once completed, the dual-pinion drives made their way from Siemens’ Dynamowerk motor factory in Berlin to the nearby Leipzig/Halle Airport, where they were then loaded onto an An-225 and flown to an airport near Iquique. Back on the ground, the drives continued on by special transport up the Chilean mountains to the mine and arrived on time for the installation phase. The remaining components embarked on their journey to Chile by ship.

Online within nine months

Part of this project’s challenge was for the Siemens engineers to design the new systems to fit the existing foundations, which were used by the predecessor equipment from a different manufacturer. Doing so prevented costly downtimes. Also, to minimize any risks associated with the conversion, Siemens replaced the entire mill automation system with modern technology rather than take the laborious task of adapting the hardware and software.

 

Installing the new automation systems and the direct converter in new, pre-assembled E-Houses was also crucial to keeping within the deadline. The E-Houses were fully developed, produced and pre-tested in the Siemens plant in Santiago, Chile. This simplified the process of connecting and commissioning on site and made it possible for the system to be installed within an extremely short standstill period of just 13 days – and for everything to be online within nine months.

 

The first six operational months of the four motors already proved the increase in reliability and consequently the step up in mill throughput. And that means a significantly higher availability of Chilean copper in the market – and higher profits for Collahuasi.

2017-07-11
Felipe Contreras, Werner Kitz

Picture credits: Siemens AG

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