Eastern Range

Overview

Rio Tinto iron ore operations in the Pilbara have an annual capacity of 220 million tonnes, with advanced plans to increase capacity to 283 million tonnes by 2013, on a pathway to 333 million tonnes. With a network of 14 mines, three shipping terminals and the largest privately owned heavy freight rail network in Australia, Rio Tinto's Pilbara operations make up a major part of Rio Tinot's iron ore activities globally. Rio Tinto's operations began in 1966 and are well positioned to meet the growing needs of the world's iron and steel industry.

In the Pilbara, Rio Tinto wholly own Hamersley Iron's eight mines and also operate the Hope Downs mine (50:50 joint venture between Rio Tinto and Hancock Prospecting Pty Limited), the Channar mine (Rio Tinto: 60 per cent) and the Eastern Range mine (Rio Tinto: 54 per cent). Rio Tinto's iron ore operations in the Pilbara also include a 53 per cent interest in Robe River Iron Associates' three mines: Mesa J, Mesa A/Warramboo and West Angelas.

Location

The Eastern Range mining operation is located 10km from the Paraburdoo mine in Western Australia.

Western Australia occupies the whole western part of the continent. Its economy is largely driven by extraction and processing of a diverse
range  of mineral and petroleum commodities. The state contributes an estimated 58 percent of Australia's Mineral and Energy Exports.

Geology and Mineralization

"The Pilbara region is located in the northwest ofWestern Australia, approximately 1,100km north ofPerth. The region contains the 80,000km2HamersleyIronProvince. The geology of the Province is characterised by a 2,500 million years old group of late Archaean and early Proterozoic rock formations known as the 'Hamersley Group'.

The Hamersley Group was formed by chemical sedimentation of minerals in a marine (ocean) environment.  The processes which formed the Hamersley Group occurred after volcanic activity introduced basalt rocks in the area. Sedimentary rocks like sandstones also occur in the group due to weathering and transportation of rocks which occurred during the period when the Hamersley Group was formed.

During the period of formation, layers of rock with different chemical composition were deposited.  Iron-rich layers alternate with silica-rich layers in the rock formation.  Occasionally these layers are interspersed with layers of sedimentary rock.  This type of rock formation is called a Banded Iron Formation (BIF).

The Hamersley Group is approximately 2.5km thick. It contains several large units of BIF: rock with bands of iron minerals (magnetite and hematite) and gangue minerals (mostly carbonates, silicates and chert).  Typically, unenriched BIF contains about 30 per cent iron by weight.

Geologists have identified and named distinct units within the BIF of the Hamersley Group. Commercially, the most important BIF units are the Brockman Iron Formation (620m thick) and the Marra Mamba Iron Formation (230m thick). These layers host many of the large iron ore deposits in the Province.  The Marra Mamba Iron Formation is older than the Brockman Iron Formation and is situated below the Brockman unit in the original rock sequence.

The BIF layers have been deformed by geological processes, and eroded by weathering resulting in the geological formations that we see today.

Bedded Iron Deposits

Where Banded Iron Formation (BIF) has been enriched by natural processes, these zones can become Bedded Iron Deposits.  Many of the commercially important iron ore deposits in the Pilbara were formed by natural enrichment of BIF. These enriched deposits include the commercially viable ores in the Brockman and Marra Mamba Iron Formations.

The BIF in the Brockman and Marra Mamba Iron Formations was enriched to a high degree forming ore grade ore with more than 60 per cent iron. The natural processes that accomplished this (hypogene and supergene enrichment) involved circulating ground waters. Non-iron minerals in the BIF were largely replaced by hydrous iron oxides (notably goethite) and partly dissolved out. At the same time, magnetite in the BIF oxidised to hematite. Favourable climate and geological structures (folds and faults) stimulated the process. Sedimentary rocks that were interspersed with the BIF became shales.

In the Pilbara, other types of ore deposit exist, notably channel iron deposits, but these are derived from the original bedded iron formations.

Brockman Iron Deposits

The Brockman Iron Deposits have four parts: the lower most Dales Gorge Member, the Whaleback Shale and Joffre Members, and the uppermost Yandicoogina Shale Member.  Brockman ore is mostly in the Dales Gorge and Joffre Members within the Brockman Iron Deposits.

Brockman Iron Deposits typically have hematite as the dominant iron mineral. Brockman deposits also have goethite in varying amounts and have varying phosphorus content and physical characteristics.

The variation exhibited by Brockman deposits is a result of different degrees of dehydration of goethite to microplaty haematite which also affects the amount of residual phosphorus content.

Brockman deposits range from blue grey in colour for deposits with the greatest degree of dehydration to grey-yellow-brown for deposit with higher amounts of goethite and less dehydration. 

Marra Mamba Iron Deposits

There are numerous high grade Marra Mamba Iron Deposits. Marra Mamba deposits all have goethite hematite mineralogy, with a greater proportion of goethite compared to Brockman ores.  There is also a range of physical properties exhibited within Marra Mamba deposits.

The iron content of most high grade Marra Mamba ores is about 62 per cent but can vary significantly.  Key characteristics of Marra Mamba ores include a lower phosphorus content compared to most Brockman ores and a higher loss on ignition which reflects the different goethite mineralogy exhibited in Marra Mamba deposits compared to Brockman ores.  Phosphorus is usually less than 0.07 per cent. Silica and alumina percentages are moderately low. Marra Mamba ores are typically grey-yellow-brown.

Channel Iron Deposits

The Channel Iron Deposits (CIDs) were formed in ancient meandering river channels. As bedded iron deposits were eroded by weathering, iron particles were concentrated in these river channels.  Over time these particles were rimmed with goethite deposited by percolating iron-enriched ground water approximately 15-30 million years ago, which also fused the particles together.

Channel Iron Deposits appear as low flat-topped hills called mesas and have also been located concealed under the cover of more recent rocks.  These deposits range in thickness between 5m and 40m thick.  This type of deposit is believed to be unique toWestern Australia.

CIDs are quite different from bedded ores. Their chief characteristic is their pisolitic 'texture': rounded hematitic 'pea-stones', 0.1mm to 5mm in diameter, rimmed and cemented by a goethitic matrix. The ore is brown-yellow in colour.  They typically contain minor amounts of clay in discrete lenses.

Detrital Iron Deposits

Detrital Iron Deposits (DIDs) are found where weathering has eroded bedded iron deposits and deposited ore fragments in natural traps formed by topography, usually drainage channels or valleys. Some Detrital Iron Deposits are loose gravels while others are naturally cemented (hematite conglomerate). Both types are often found in the same deposit.

The quality of the iron ore in these deposits is dependant on the bedded iron ore deposit which was the source of the ore particles.  Typically these deposits are valued for the high proportion of high quality lump contained within them, as lump sized particles have a greater tendency to be captured in the trap site.

Mining & Operation

Open pit with site-based processing facilities. Ore from Eastern Range passes through two stages of crushing before being conveyed to the Paraburdoo central plant for further processing.. 

Drill and blast, load and haul, process, stockpile and rail-load out

Areas for open-pit mining are selected using the mine plan. Identified areas are tagged, and then holes are drilled in an appropriate pattern by rigs. The drill holes are filled with an explosive, most often ANFO (Ammonium Nitrate/Fuel Oil) and then charged. The resulting blast breaks the material to a size required for digging.

The broken material is loaded for transport by face shovels, excavators or front-end loaders into haul trucks. Haul trucks at Rio Tinto Iron Ore operations are typically in the 190 tonne and 240 tonne class.

Shared from the Greater Paraburdoo operations pooled fleet:

Terex Unit Rig MT4400
• 06H1 â€¢ 06H2 â€¢ 06H3 â€¢ 06H4 â€¢ 06H5 â€¢ 06H6 â€¢ 06H7 â€¢ 06H8 â€¢ 06H11 â€¢ 06H12 â€¢ 06H13 â€¢ 06H14 â€¢ 06H15 â€¢ 06H16 â€¢ 06H17 â€¢ 06H18 â€¢ 06H19 â€¢ 06H20 â€¢ 06H114 â€¢ 06H115 

Caterpillar 785C Haul Truck:  â€¢ 06H160 â€¢ 06H161 â€¢ 06H162 â€¢ 06H163 

Loading Units:ʉۢ Shovel O&K RH200C, 15H2046ʉۢ Letourneau L180, 07H1496, 07H1697, 07H168ʉۢ Hitachi EX3600, 15H2052, 15H2053, 15R02, 15H901ʉۢ Hitachi EX2500, 15H179

Auxillary Equipment Drill: ʉۢ Reedrill SKS12 21H2101ʉۢ Reedrill SKS15 21H2026ʉۢ Reedrill QXR920 21H109ʉۢ Reedrill QXR920 21H2029ʉۢ Reedrill QXR920 21H2191

Dozer:• Caterpillar D11R 08H1061, 08H1062, 08H1063, 08H397 â€¢ Caterpillar D10T 08H93, 08H94

Grader:ʉۢ Caterpillar 16M, 14H & 24H, 12H200, 12H201, 12H219, 12H204, 12H224

Front End Loader:ʉۢ Caterpillar 992, 07H101ʉۢ Caterpillar 998, 07H103ʉۢ Caterpillar AN Loader, 07H109ʉۢ Komatsu WA250, 07H122, 07H123ʉۢ Komatsu WA900, 07H1486

Articulated Truck:• Moxy 06H185. 

Water Truck:• Caterpillar 777D and Caterpillar 785C, 06H107, 06H108, 06H180, 06H254, 06H257

Float:ʉۢ Terex Unit Rig Float 11H92ʉۢ Caterpillar 793 Float 11H93

Tyre Dozer:• Tiger 855 08H80 â€¢ Komatsu WD900, 08H87, 08H89

Processing

Overland conveyors are used to transport partially crushed feed at sites where there are long distances between the pits and process plants. Processing of the ore ranges from simple crushing and screening to a standard size, through to processes that beneficiate or upgrade the quality of the iron ore products. This is done by physical processes, which remove impurities by differences in particle density or size gravity or size separation. Processing may be wet or dry.

The processed ore is stockpiled and blended to meet product quality requirements, before being reclaimed and conveyed to rail load-out. The ore is loaded into ore for transport to the port facilities.

Environment & Community

Rio Tinto's Iron Ore group seeks to balance economic, social and environmental considerations across all parts of its business. This is achieved by making sustainable development considerations an integral part of our business plans and decision-making processes. 

Rio Tinto's Sustainable Development and Climate Change Panel supports senior leadership to embed sustainable development into the way we work. The group oversees the organisation's identification and management of economic, environmental and social risks, and opportunities. 

In addition to Rio Tinto's statement of business practice, The way we work, Rio Tinto define its commitment to sustainable development with nine principles. Together, these principles guide the way we plan for the future.

Closure

The closure of a mine or other operating sites requires planning beyond simply rehabilitating the site. Rio Tinto consider the management of social issues resulting from closure, especially in remote areas where communities are dependent on the socio-economic benefits of the mine.

Rio Tinto plans for closure from the earliest stages of project development to decommissioning activities and are guided by the Rio Tinto Closure Standard. 

The intent of the standard is to ensure that Rio Tinto managed activities are left in a condition which minimises adverse impacts on the human and natural environment.

Rio Tinto experiences with closure planning have helped the business understand that the environmental and social legacy is possibly the most tangible indicator of an operations contribution to sustainable development in the areas where we operate. Consequently, we have adopted a multi-disciplinary approach to closure planning, requiring a wide range of technical and business disciplines. 

These activities allow Rio Tinto to influence the design, development, operation and closure of all managed operations to ensure post-closure outcomes that meet needs and expectations outside of the business.

Product stewardship

Product stewardship means understanding the life cycle of the metals and minerals we produce, including the safe production, use and disposal of metal and mineral products as the need for them continues in society.

Increasingly, producers have both individual and joint responsibility with other stakeholders to ensure that products are managed safely across their life cycles. Our product stewardship work allows us to improve our understanding of the health, safety and environmental implications of the use of our products. Rio Tinto's product stewardship strategy emphasises the importance of understanding threats and opportunities in the market, and the importance of engagement with key stakeholders including customers, suppliers, regulators and communities. 

Rio Tinto is in the process of implementing a formal material-stewardship programme, as well as completing life cycle assessments on key products. Material stewardship is a collective term for resource, process and product stewardship. It means better understanding and taking responsibility for our iron ore products, from their discovery and mining, production, use and management at end of life