The Barro Alto mineral resource is primarily saprolite overlain by laterites and extends for 35 km in an arc from southwest to northeast. The deposit is in the Barro Alto mafic-ultramafic complex, which is part of the Pre-Cambrian shield in the state of Goiás. The complex is composed of a sequence of serpentinised dunites and pyroxenites, enveloped by gabbros.

The mineralisation corresponds to the surficial weathered portions of the serpentinites. There are three types of saprolitic ore. The West type ore tends to have higher nickel grades and silica/magnesia ratios than the East type and Plain type ores.

No blasting is required to access the relatively soft laterite/saprolite ore, which is loaded by a fleet of eight 365CL and four 330CL Caterpillar backhoe hydraulic excavators with a maximum working bench height of 2.5 m. These load a fleet of 44 Scania 35 t trucks with Rossetti bodies, which transport the material to a ROM stockpile.

First metal from the Barro Alto ferronickel operation was produced on schedule in March 2011.

Conventional smelter-refinery technology is used to process the saprolite ore to produce ferro-nickel, which is a technology already used by Anglo American at its existing nickel operations.

At Barro Alto, ore is heated at very high temperatures in these two 185 metre rotary kilns in a process known as calcining, which removes moisture and water crystals from the nickel bearing ore and starts the 01 metallurgical process.

The project consists of an open pit mine and a ferronickel plant. The shallow pits forming the mine extend over an area 35 km long with a width of no more than 2 km. The plant uses a classical RKEF process to produce ferronickel by processing a nominal 2.4 Mt/y (dry basis) of ore.

The ore is dumped into a horizontal grizzly after which it goes through a three stage (primary, secondary, tertiary) process using two roll crushers fo ........