May 2011

Innovation needs no risks

Using tried-and-true technology for a world-class operation

By Heather Ednie

The first metal was produced at Anglo American’s Barro Alto nickel project in March | Photo courtesy of VisMedia


PROJECT AT A GLANCE: BARRO ALTO

Owner: Anglo American
Location: State of Goiás, Brazil
Capital cost (full project): US$1.98 billion
Planned production rate: 36,000 tonnes content in ferronickel annually
Operations startup: March 2011
Expected mine life: 25+ years
• Nearly 30,000 tonnes structural steel used
• More than 10,000 design documents prepared
• Over 33,000 vendor documents received, reviewed, approved


Sometimes the best results come from doing something creative with the tools you know and trust. An illustration of this can be found at Anglo American’s Barro Alto project in Brazil, where engineering, procurement, construction management (EPCM) contractor SNC-Lavalin Minerconsult (SLM) used a sound project management approach and innovative design to optimize the use of proven technology in a conventional pyrometallurgical facility to process saprolite ore to produce ferronickel.

The project was managed by an integrated team in close coordination with Anglo American general project director Euler Piantino and his team of experts. The EPCM phase of the Barro Alto project was begun by SLM personnel in January 2007 and is scheduled to be completed this June. At its peak in late 2008 and early 2009, the company had over 400 employees on the project, providing services from detailed engineering through to completion of the pre-commissioning stage. The EPCM phase, directed by Rene Navarro, SNC-Lavalin’s project manager, is effectively completed and the plant facilities were turned over to the owner for commissioning, with the first metal produced in March, 2011.

Reliable innovation

Throughout the plant, proven technology and equipment were selected, then carefully laid out and arranged to optimize plant performance. The topography of the site allowed the selection of the most advantageous location for the operation. “The way we configured the equipment – the whole layout of the plant – takes advantage of gravity,” says John McCreight, senior project control/risk manager, Barro Alto project, SNC-Lavalin. “The entire operation flows downhill. The crushing station is located at the highest point, and from there, ore moves down to end at the lowest point: the load-out area.”

The deposit is located in very aged, fractured rock, enabling it to be mined using a front-end loader. The fragmented ore enters the mill through roll crushers, or sizers, and from there it is conveyed to a homogenized ore lay-down area and blended. The blended ore is conveyed to the drying station to achieve the minimum humidity to make the calcining process more efficient. The rainy season in the region stretches from October through March, so humidity and moisture in the ore is a concern.

The ore crushing and drying plant will handle 2.4 million tonnes of ore annually. The dry ore is fed into a rotary kiln, where coal is added, both to raise the temperature and as a reducing agent to form calcine. From the kiln, the ore is fed into an electric induction furnace. “We incorporated two rotary kiln electric furnace lines to maintain a continuous feed,” McCreight says.

From the furnace, the slag is tapped off and the ferrous nickel mineral fed to a simple refinery where carbon and impurities are burned off, producing a ferrous nickel liquid that feeds through a tundish. The final product, granulated pellet-like powder, is loaded into large bags for shipment, primarily to producers of stainless steel.

Environmental management at the site is relatively straightforward. “The slag tapped off the furnace is granulated and stockpiled on site – it’s relatively inert,” McCreight says. “We have a detailed water management system, designed so that water will only be pumped from the local river during a short period of the rainy season, when there’s an excess of water in the region, to minimize any impact on the local farming industry and the community.”

A fresh water recirculation pond, containing over 1.85 million cubic metres of water (or up to 10 months of normal operation water needs), was constructed downhill from the plant to collect drainage and run-off water and recirculate it back into the cooling and service water systems.

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