1. Introduction

• 1.1 Sector Description
• 1.2 Scope of the Code
• 1.3 Code Development
• 1.4 Code Structure

Primary aluminum production is a major industry in Canada, ranking third worldwide with an annual production capacity of approximately 3 million tonnes (2.96 Mt in 2010),¹ 90% of which is produced in Quebec. Aluminum metal is extracted from alumina (aluminum oxide, Al₂O₃·xH₂O), which itself comes from bauxite deposits, through electrolytic reduction in a molten bath consisting of aluminum fluoride and cryolite at a temperature of approximately 960°C. Between 0.2–0.25 tonnes of aluminum is generally produced for each tonne of bauxite. Aside from the electrolytic reduction process, the primary aluminum sector includes many related activities, such as the production of metallurgical grade alumina, the manufacture of carbon anodes and the calcining of petroleum coke. All these activities require the use of electricity, fuel and raw materials (petroleum coke, aluminum fluoride, bauxite, cryolite, tar pitch, etc.) that lead to emissions of air pollutants including: sulphur dioxide (SO₂), total particulate matter (TPM), polycyclic aromatic hydrocarbons (PAH), total fluorides and nitrogen oxides (NO_X).

Federal, provincial and territorial environment ministers are taking action to better protect human health and the environment by endorsing and implementing the new Air Quality Management System (AQMS). The AQMS includes Canadian Ambient Air Quality Standards for fine particulate matter and ground-level ozone, Base Level Industrial Emissions Requirements (BLIERs) and local Air Zone Management by the provincial/territorial jurisdictions. For the Aluminium Sector, BLIERs were developed for TPM, PAH and SO₂ and it was recommended that a code of practice (Code) be developed to help reduce emissions of PM_2.5.

As far as emissions of particulate matter are concerned, fine particulate matter with an aerodynamic diameter of less than 2.5 microns (PM_2.5) is the most dangerous, as it may lead to serious health problems when it reaches the lungs. In Canada, roughly 45% of PM_2.5 emissions are derived from stationary combustion sources of firewood and other fuels, whereas 20% comes from transport activities (road, off-road, rail, sea, etc.). The remainder (35%) results from industrial activities. According to data from Environment Canada’s National Pollutant Release Inventory (NPRI), a large proportion of particulate matter emissions reported by the Canadian primary aluminum sector is PM_2.5 (51% of TPM emissions in 2009).

The primary aluminum sector encompasses many production activities that yield a finished product at a competitive cost (Figure 1-1). There are four key activities associated with aluminum production, namely:

• bauxite-based metallurgical grade alumina production facilities;
• petroleum coke calcining units;
• prebaked anode production facilities; and
• alumina reduction (electrolysis) facilities.

A Canadian aluminum smelter typically consists of the electrolysis plant and the prebaked anode plant, whereas other activities can be independent of the smelter. There are two Canadian smelters that include only the electrolysis plant and buy their raw materials (sealed prebaked anodes) instead of manufacturing them on-site or obtain them from another facility owned by the same company.

Primary activities are supported by secondary activities, such as port and/or rail services for transporting raw materials to various plants and regional hydroelectric stations, which reduce production costs. The aluminum produced is then taken over by a sales operation or value-added product facilities.

Figure 1-1: Overview of the Various Activities Associated with the Primary Aluminum Sector

In 2010, Canada’s primary aluminum production sector comprised 10 smelters operated by 3 companies: Rio Tinto Alcan (RTA) with 46% of production capacity, Alcoa with 36% and Aluminerie Alouette (AA) with 18% (see Table 1-1). Canadian aluminum production at slightly less than 3.0 Mt in 2011 represented approximately 12% of the world’s production. Of the 10 smelters currently in operation, 8 use prebaked anode technology, which represents roughly 85% of Canadian production. The remainder comes from smelters that use Söderberg technology, the effectiveness and environmental performance of which are far inferior to prebaked anode technology.² It is expected that all Söderberg plants will be closed or modernized by 2015, meaning that aluminum will be produced exclusively with prebaked anodes in Canada. Despite these anticipated closures, Canada’s aluminum production is expected to rise in the medium term in response to a growing market for aluminum. In fact, a number of investment projects are currently under way (e.g., Kitimat and Jonquière) or under review (e.g., Baie-Comeau and Sept-Îles) that would increase Canada’s aluminum production capacity to approximately 4 Mt, if the market is favourable.

Six of the eight Canadian smelters using prebaked anode technology manufacture their own anodes in a facility adjacent to the alumina reduction plant (Table 1-1). Only the Laterrière and Baie-Comeau smelters obtain their prebaked anodes from an outside plant. The six prebaked anode plants have a production capacity of roughly 1300 kt/y, for a potential 2.3 Mt of aluminum. This production capacity could increase in the future with the various modernization projects under review.

RTA operates three petroleum coke (green coke) calciners for the production of calcined coke (Kitimat, Arvida and Strathcona), a component of green anode paste (Alcoa also owns 31% of the Strathcona plant). The three calcination plants have a combined calcined coke production capacity of more than 500 kt/y (Table 1-1). This provides enough coke for the production of 1.4 Mt of aluminum, given a net anode consumption of 420 kg/t of aluminum and prebaked anode coke content of 85%.³ These plants fulfill more than 75% of the calcined coke needs of RTA smelters (including ABI Alcoa and excluding Alouette) in Canada.⁴

In Canada, only RTA operates a bauxite refining plant, namely the Vaudreuil plant in Jonquière, which annually produces approximately 1.5 Mt of metallurgical grade alumina and speciality chemicals (e.g., commercial alumina, aluminum fluoride and commercial hydrates), thus supplying a large share of the network of RTA electrolysis plants in the Saguenay region. The additional alumina is imported from major producing countries (Australia, Brazil and Guinea), which also supply the Vaudreuil plant with bauxite.

^a 25% held by RTA.
^b 39% held by Alcoa.
^c Belongs to a consortium (RTA, Austria Metall AG, Hydro Aluminium, SGF, Marubeni), 40% of which is held by RTA.
^d Over 70% of aluminum production comes from electrolytic cells with prebaked anodes.
^e Plant production has recently decreased (251 kt in 2008, 224 kt in 2009, 184 kt in 2010) due to the smelter modernization project that will gradually be replacing Söderberg cells, increasing capacity to 400 kt of aluminum per year.
^f Plant that does not manufacture prebaked anodes, but rather briquettes to supply the Söderberg electrolysis plant.
^g Values obtained from the NPRI for 2010.

The Code applies to primary aluminum sector facilities, namely alumina reduction plants, prebaked anode plants, green coke calcining plants and bauxite refining plants. Secondary activities, including port and/or rail services for transporting raw materials, regional hydroelectric plants, pot relining centres, and value-added product facilities, are not covered by the Code, nor are activities associated with the alumina reduction process using Söderberg technology.

The Code was developed as part of the qualitative BLIERs of Environment Canada’s AQMS policy aimed at facilitating and encouraging the continuous improvement of the environmental performance of Canada’s aluminum facilities. The Code outlines the concerns associated with emissions of fine particulate matter (PM_2.5) for each of the primary activities and makes recommendations to reduce these types of emissions. Due to inherent technological constraints, the overall objective of the Code is not to completely eliminate PM_2.5 emissions, but rather to control them using effective measures and work practices. Moreover, the Code does not take into consideration practices that would require an existing facility to make major technological changes. In designing a new facility, other technologies can be taken into consideration to further minimize emissions. These technologies include high draft ventilation of pots activated when opening the hoods, or a regenerative oxidation system to eliminate pitch emissions.

Although the recommendations are clear and precise as to the expected results, they should be applied where and when appropriate based on the particular circumstances of each facility. Consequently, the Code does not aim to quantify the effect that each recommendation would have on PM_2.5 emissions. Rather, it should be considered a basic tool for developing a program of good practices by the facilities without posing regulatory constraints. However, the recommendations made here in no way reduce the scope or application of the legal requirements of municipal, provincial and federal governments.

The Code was developed by Environment Canada in consultation with aluminum industry representatives and other stakeholders. Information on operating procedures and best practices is taken from various sources, including technical and scientific journals, as well as environmental codes of practice published by Environment Canada, the European Commission, the World Bank and the Light Metals Research Centre (LMRC) at the University of Auckland in New Zealand.

The LMRC recently published a guide on gaseous and particulate fluoride for the Chinese primary aluminum industry, explaining the factors affecting fluoride emissions and establishing best practices designed to control them.⁵ Many of the solutions proposed in the LMRC guide can also help control the release of fine particulate matter and were therefore used to develop the recommendations proposed in the Code. The recommendations were also developed based on the situation of Canada’s primary aluminum sector in 2012, particularly with regard to existing air emission control technologies.

The Code describes the operational activities (Section 2) and the concerns associated with particulate matter emissions as a result of these activities (Section 3). The recommended work practices intended to control fine particulate matter emissions are set out in Section 4. Lastly, Section 5 provides a general approach to the implementation and monitoring of the Code by the institutions concerned.

¹ The Aluminum Association, Canadian Primary Aluminum Production.
² European Commission, Integrated Pollution Prevention and Control – Draft Reference Document on Best Available Techniques for the Non-Ferrous Metals Industries, July 2009.
³ Mirchi, A. A. et al., Alcan Characterisation of Pitch Performance for Pitch Binder Evaluation and Process Changes in an Aluminium Smelter, Light Metals 2002.
⁴ Rio Tinto Alcan Inc., Anode Grade Coke & Coke Calcination, presentation to Environment Canada, August 2011.
⁵ Light Metals Research Centre, Fluoride Emissions Management Guide (FEMG), Version 4, February 2011.