Feature Articles

IRON ORE February 2017
Vale Carajás S11D

On 16 December 2016 Vale SA officially opened the Carajás S11D Iron Project, the largest project the company has ever undertaken. S11D’s location in the protected Carajás National Forest has heavily influenced the design of the project and adoption of technology to minimise its impact on the environment. The project will deliver 90Mtpa of high grade, low cost, iron ore fines when it ramps up to full production in 2020 and will be very competitive with Australian operations.

Vale’s Northern System includes the iron ore production centres at Carajás Serra Norte, Serra Leste and Serra Sul (S11D). It is in south east Pará State around 550km south west of the provincial capital Belem.

The Carajás iron ore deposits were discovered in 1967 but it was not until 1985 that production commenced at the Serra Norte orebodies with product shipped 590km by a purpose built Carajás Railway (EFC) to Vale’s Ponta de Madeira Maritime terminal on the Atlantic coast at São Luís in Maranhão State.

The Carajás deposits formed by weathering enrichment of jaspilites in the Neoarchean Grão Pará Group. The deposits extend for tens of kilometres on the northern and southern flanks of the north west trending Carajás fold and occur as prominent strike ridges covered by stunted vegetation rising above the surrounding IUCN class VI protected Carajás National Forest.

At Serra Sul detailed geological studies commenced in 2004. These defined a mineralised zone around 25km in extent which includes the 9.5km S11D ore body at its south eastern end. The S11D Ore Reserve (2015) is 4.24Bt at 66.7% Fe. Conceptual designs and economic studies began in 2006 and took into account the environmental constraints of the surrounding forest. From the start, it was proposed to locate the processing plant outside the forest, to reduce the project footprint, and to transport ore from the mine to the wet processing plant by a 9.5km conveyor. The original mining proposal was for conventional open pit operation with truck haulage to a semi mobile in pit crushing plant feeding the long distance conveyor and for waste rock to be dumped adjacent to the pit. To further reduce environmental impact, this plan was revised and two newer technologies, truckless mining and dry processing, were incorporated into the project design.

In the new configuration, mine truck haulage was converted to in pit crushing and conveying. Crushing is completed at mobile crushers at the working face and ore is then transported by link conveyors to the long distance conveyor feeding the processing plant. The waste rock dumps were re-sited on pasture land outside the forest area and linked to the mine by conveyor. Except for loaders, dozers and light vehicles all in pit equipment is powered by electricit from the regional grid. Vale also changed to processing at natural moisture content (“dry processing) which it developed for Serra Norte using innovative elliptical motion polyurethane screens.

Compared to the original plan the new configuration has major environmental benefits:

  • No tailings for disposal

  • Processing water usage is reduced by 93%

  • Process power down by 18,000MWh per year

  • Diesel fuel usage is reduced by 77%

  • Reduced industrial waste from truck tyres, filters, and lubricants

The final configuration of the project was defined in 2010 and in November 2012 Vale received the installation license allowing work to commence on the expansion of capacity of the EFC including a 101km rail spur, track duplication and re-alignment. In July 2013 the installation licence for the mine and plant were issued and construction commenced. The total capex for the project was US$14.4bn consisting of US$6.5bn on the mine and the plant and US$7.9bn on capacity expansion of the EFC and the Ponta da Madeira Maritime Terminal.

At full production in 2020 Carajás S11D will have one of the lowest site operating costs in the world due to, high mechanisation, ore body size and continuity, low stripping ratio and soft ore. However, compared to Australian producers the project suffers from its distance to Chinese ports with freight costs per tonne double those from Australian iron ore ports. The freight cost is offset by the ore grade and associated premiums, making S11D’s ore highly competitive with Australian banded iron ore deposits on a Value Adjusted CFR basis.