Alumina Limited

Bauxite to aluminium:
the process

01

Aquisition of Bauxite Reserves

Aluminium ore, most commonly bauxite, is plentiful and occurs mainly in tropical and sub-tropical areas - Africa, West Indies, South America and Australia - with some deposits in Europe. Although plentiful, bauxite quality is diminishing, is often not readily accessible and is becoming harder to gain approvals for expansions or new mines. AWAC is the world's largest bauxite miner. AWAC operates mines integrated with alumina refineries in Western Australia and Brazil.

 
 
AWAC Sustainability Approach

AWAC's licence to operate is based on its recognised ability to successfully restore mining sites to their pre-mining condition, re-establishing eco-systems and biodiversity values or, where appropriate, following consultation with local communities and the relevant Government, rehabilitate the land for other productive purposes such as agriculture, commercial, residential or recreational use. Before expanding or commencing a new mine, external consultants are engaged to conduct comprehensive environmental impact assessments to determine the impact the project would have on the environment. The ecosystem and species diversity are thoroughly analysed with special emphasis on threatened species, critical habitats and unique flora and fauna. Engagement with the local communities and stakeholders is also a priority to identify and evaluate specific sustainability issues, environmental, economic and social.

02

Bauxite Mining

AWAC's bauxite deposits are generally extracted by open cut mining from strata, typically some 4-6 metres thick under a shallow covering of topsoil and vegetation. The topsoil is removed and stored for later use in restoration of the forest. Generally there is a layer of capstone that is removed to expose the bauxite ore which is extracted, broken up and transported to refineries for further processing. AWAC is the world's largest bauxite miner and is well positioned with long life mines. AWAC's Huntly mine is the world's largest bauxite mine, supplying bauxite ore to Pinjarra and Kwinana Refineries.

 
 
AWAC Sustainability Approach

Mining is generally limited to relatively small pits and haul roads or infrastructure such as conveyors and railways are constructed to enable transportation of the ore. Particular care is taken in building roads etc to avoid isolation of wildlife, disruption of streams and critical habitats. For example in Australia, haul roads were repositioned to protect nesting areas for threatened bird species. Mining operations can alter rainfall runoff patterns and surface and ground water hydrology which can have impacts on stream ecology and biodiversity. These are monitored and managed to preserve biodiversity.

03

Mine rehabilitation

Rehabilitation is one of the most important parts of the mining process. AWAC supports the objective of returning mined areas to a sustainable future use. In most cases this means returning disturbed land to the pre-existing flora and fauna condition. Preservation of biodiversity of plant species and fauna species is an important focus and is a major consideration for rehabilitation plans or future use decisions. Typically rehabilitation efforts include returning collected and fresh topsoil, spreading collected and treated seeds and planting of nursery established plants.

 
 
AWAC Sustainability Approach

A key objective at AWAC’s mines and bauxite residue areas is to minimise the footprint of disturbed land by implementing a program of progressive land rehabilitation. In the Western Australian mines AWAC has achieved 100 per cent of plant species richness in AWAC's rehabilitated mining areas, the first mining company in the world to achieve that goal.

04

Refining

Aluminium does not occur naturally as a metal, but must first be refined from bauxite in its oxide form. Bauxite is generally washed, ground and dissolved in caustic soda (sodium hydroxide) at high pressure and temperature at an alumina refinery. Approximately two tonnes of alumina are required to produce one tonne of aluminium. AWAC is one of the world’s largest alumina businesses operating six alumina refineries in several countries, Australia, Brazil, Spain, Suriname(closed 2015) and the USA (curtailed in 2016). AWAC is a low cost alumina producer with global alumina production capacity of 14.6 million tonnes per year (including the equity interest in the joint venture in the Ma’aden alumina refinery in Saudi Arabia.

 
 
AWAC Sustainability Approach

Refining alumina is an energy intensive operation therefore key AWAC sustainability targets involve improving energy efficiency and reducing GHG emissions. A strategy is to source operating locations with low carbon based power. In 2015 the San Ciprian refinery was converted from fuel oil as an energy source to natural gas. AWAC’s refineries form part of Alcoa’s Global business. Alcoa has a long-term goal of reducing GHG emission compared to 2005 levels by 30% by 2020 and 35% by 2030. Also, for each tonne of alumina produced approximately 2 tonnes of bauxite residue results. The goal is to reduce bauxite residue land requirements per unit of alumina by 15% by 2020 and 30% by 2030 and recycle or reuse 15% of residue generated by 2020 and 30% by 2030.

05

Smelting

Alumina is converted into aluminium by dissolving it in an electrolytic bath of molten cryolite (sodium aluminium fluoride) within a large carbon or graphite lined steel container known as a "pot". An electric current is passed through the electrolyte at low voltage, but very high current. Molten aluminium is deposited at the bottom of the pot and is siphoned off periodically. It can be blended to an alloy specification, cleaned and then generally cast. AWAC operates one aluminium smelter located at Portland in Australia with an equity capacity of 197,000 tonnes of metal.

 
 
AWAC Sustainability Approach

The process of aluminium smelting requires significant amounts of electricity resulting in GHG emissions. Process efforts have been focussed on reducing direct emissions associated with perflurorcarbons (PFCs) in the smelting process and also opportunities to reduce energy intensity.

06

Recycling

First produced in 1888, aluminium has become the second most-used metal in the world after iron. Nearly three-quarters of all aluminium ever made remains in use today, representing a growing ‘energy and resource bank’, and the metal can be recycled and reused endlessly. While AWAC is not involved in recycling of aluminium, it is important to appreciate that end product from AWAC’s business can be easily recycled. Examples of areas where aluminium helps people and the economy to operate effectively and efficiently include air, road, rail and sea transport; food and medicine; packaging; construction; electronics and electricity transmission.