West Angelas

Overview

West Angelas is an open pit operation with site-based processing facilities, started production in 2002.

Rio Tinto's iron ore operations in the Pilbara include a 53 per cent interest in Robe River Iron Associates' three mines: Mesa J, Mesa A / Warramboo and West Angelas. West Angelas has a capacity of 29.5 million tonnes per year and commenced production in 2002. Its mining fleet consists of 38 trucks and 10 loading units. Products are Lump and Fines contributions to Pilbara Blend.

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 owns 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). 

Location

West Angelas iron ore mine is located 110 km west of Newman in Western Australia.

The town was built as a company town and has its own airport that facilitates the transfer of its personnel (FIFO). It is also linked by railway to Port Hedland. The world's largest freighttrains are making the journey to the port for shipping the iron ore to international markets. 

Climate is arid with very hot summers and mild winters. Precipitation  is sparse, but the influx of monsoonal moisture in the summer, which generally begins in December and lasts until March, raises humidity levels and can cause heavy precipitation.

Geology & Mineralization

The Pilbara region is located in the northwest of Western Australia, approximately 1,100km north of Perth. The region contains the 80,000 square km Hamersley Iron Province. The geology of the Province is characterized 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.

The Hamersley Group is approximately 2.5km thick. It contains several large units of Banded Iron Formation (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.

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

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

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.

Mining & Operation

Rio Tinto is a world-class asset manager, operating and maintaining all mining, rail, power and port facilities in the Pilbara on behalf of asset owners Hamersley Iron (Rio Tinto: 100 per cent) and Robe River (Rio Tinto: 53 per cent).

West Angelas is an open pit operation with site-based processing facilities.

The mine's mobile fleet consists of 10 x 730E Komatsu (190t) haul trucks; 28 x 830E Komatsu (220t) haul trucks; 10 x loading units (3 excavators, 2 shovels, 5 front end loaders); 5 x track dozers (3 x D11, 2 x D10); 2 x wheel dozers;  4 x motor graders (3 x 16M, 1 x 24H);  4 x dump trucks; water carts; 5 x large dia blast hole rigs; and, 1 smaller specialist wall control drill rig; 2 x MMU explosive pump trucks.

West Angelas is the site of Rio Tinto's "Mine of the future" project. The mine operates automated trucks, automated rockbreakers, automated drills and blasts, which are controlled from a Perth operations centre rather than local operators on site. An Autonomous Haulage System was tested and found to be viable after a two-year trial period. The autonomous haul system fleet is comprised of 5 x Komatsu 930E haul trucks; 1 x Komatsu 5500 excavator; 1 x Komatsu track dozer; 1 x Komatsu wheel dozer; 1 x Komatsu motor grader; 1 x water cart.

The mining process consists of 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.  

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. The railway and port are owned by Robe River but they are operated by Pilbara Iron.

Environment & Community

Rio Tinto's Iron Ore group seeks to balance economic, social and environmental considerations across all parts of their 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 they 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 the company plans 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.