Type: Process Essays
Sample donated: Julie Ellis
Last updated: April 24, 2019
PRIMARY AND SECONDARY PRODUCTION Amongthe primary producers, we can clearlyobserve that Chinese producers outnumbered the producers from other countries.
All the leading aluminum producing companies mentioned in Table 2 are private groups except The AluminumCorporation of China Ltd (Chalco) 17. MAJOR PRODUCING COMPANIES COUNTRY PRODUCTION (2016) Hongqiao (private) China 5.83 UC Rusal (private) Russia 3.74 Rio Tinto Alcan (private) Canada 3.54 Shandong Xinfa (private) China 3.21 Chalco (state) China 2.7 Alcoa (private) The United States 2.6 Tab 2.
The world’s leading primary aluminium producing companies in 2016, based onproduction output (in million metric tons) 18. Secondary Production is the recyclingprocess of aluminium scrap into aluminium that can be used again—anenvironmentally beneficial process that is 92 % more energy efficient thanprimary production. The increased proportion of recycled aluminium in manufacturing has createdsignificant economic and environmental wins for both industry and consumers. Approximately40 percent of the North American aluminiumsupply is now created through secondary production, up around 10 percent sincethe early 1990s.
19 As it is shown infigure 4, Brazil has the highest rate secondary production as 98.2% of its canproduction are recovered by recycling 21. In the figure (above) we canobserve the production capacity of secondary aluminiumproducers. Novelis company’s Brazil branch is leading as they can reach up to600000 tonnes of recycled aluminium peryear. Generally, Chinese aluminiummanufacturers show considerable numbers both in primary and secondaryproduction 22.
Fig 4. The world’s leading secondary aluminium producing companies, with productioncapacity up to 2017 (tonnes per year) 20. Secondary aluminium production accounts for nearly 30% of the global aluminium output and its share keeps growing (Figure5).Fig 5. Comparison of primary and secondary aluminium production by the percentage by the year of 2013 23. In a resource-constrained world, recycling is a critical point to consider in sustainable development.
It reducesthe waste and maintains the saving of the resources. Aluminium in use-recyclablealuminium is an energy and resource bank,but because of the long lifespan of many aluminiumproducts, and due to growing demand, this “bank” can only supply 20-25 % of thecurrent demand. The remainder must be produced through primary aluminium 24. 3.
3. PRODUCTION CHAIN (MINE TO MARKET) Production of Aluminum from ore is mainlydependent on Aluminum oxide (Al2O3), which is extracted from bauxite ore. Normallybauxite contains from 30% to 60% Aluminum oxide (which is called also alumina)and it is easy to be found near the earth’s surface.
The process can be dividedinto two parts; the extraction of alumina from bauxite, and the smelting ofAluminum metal from alumina. Separation of alumina generally is done by theBayer Process. This process involves crushing the bauxite into a powder, makinga slurry by mixing it with water, heatingand adding caustic soda (NaOH). The caustic soda is added to dissolve aluminaand allow it to pass through filters, which leavesimpurities behind.
The solution of aluminate is thendrained into precipitator tanks where particles of Aluminum hydroxide are addedas ‘seed’. Agitation and cooling result in Aluminum hydroxide precipitatingonto the seed material, which is then heated and dried to produce alumina.Electrolytic cells are used to smelt Aluminum from alumina in the process whichis discovered by Charles Martin Hall.
Aluminafed into the cells is dissolved in a fluorinated bath of molten cryolite at1742F° (950C°). A direct current of anywhere from 10,000-300,000A is sent fromthe carbon anodes in the cell through the mixture to a cathode shell. Thiselectrical current break down the alumina intoaluminium and oxygen. The Aluminium isattracted to the carbon cathode cell lining when the oxygen reacts with thecarbon to produce carbon dioxide. Then aluminiumis collected and taken to furnaces where recyclable aluminium materials can be added. About 1/3 of all aluminium produced today comes from recycledmaterial 25.
3.4. ENVIRONMENTAL AND SOCIALIMPACTS OF PRODUCTION There are environmental impacts that associatedwith each stage of Aluminium production fromextraction to processing.
One of the major environmental impacts of refining and smelting is greenhouse gas emissions. Thegreenhouse gases result from both the electrical consumption of smelters andthe by-products of processing. The greenhouse gases resulting from primaryproduction include perfluorocarbons (PFC), Sulphur dioxide (S02), polycyclicaromatic hydrocarbon (PAH), fluoride, and carbon dioxide (CO2). Of these gases,PFC’s resulting from the smelting process are the most effective. In the US, primaryAluminum production is the main source of perfluorocarbon(PFC) emissions.
PAHemissions result from the manufacture of anodes for smelters and during theelectrolytic process. Sulphur dioxide and sodium fluoride are emitted fromsmelters and electrical plants. SO2 is one of the primary reasons of acid rain.CO2 emissions can occur during smelting and result from the consumption ofcarbon anodes and from PFC emissions. Theatmospheric pollutants from primary Aluminum production also produce acid rainwhen they mix with vapor of water. When soil pH remains at or above 5.0,Aluminum poses no danger of toxicity for environmental, however acid rainlowers the pH of soil and forces Aluminum into solution which causes it to leakinto the water supply where it can damage root systems and create acidifiedlakes.
The amount of Aluminum that enters the environment due to regularweather processes far exceeds anthropogenic contributions. A life cycle analysis of Aluminumshows distinct advantages to recycling the material. The primary benefit ofrecycling Aluminum is reduced energy consumption. Aluminum recovery from scraprequires only 5 percent of the energy required to extract it. Therefore, secondaryAluminum production from recycling scrap has the potential to significantlyreduce greenhouse gas emissions. The most common source of Aluminum scrap isAluminum cans, but automobiles, building materials, and appliances are alsoviable sources. Repeated recycling of Aluminum does not affect the quality.
Substantial amounts of Aluminum can be toxic to humans, but high exposurelevels are typically limited to miners, Aluminum production workers, anddialysis patients. While there is some evidence linking Aluminum to Alzheimer’sdisease, increased Aluminum consumption has yet to be a proven cause of theonset of Alzheimer’s. Otherwise, Aluminum is not significantly bioaccumulatedin plants and animals #26. Some groups may be adversely affected by theactivities, such as involuntary resettlement, loss of land for harvesting andimpacts on traditional ways of life. The presence of a production plant or minemay also enlarge the economic gaps between groups of people, and generatesocial tensions 27.3.5.
RED MUD DISPOSAL Red mud is one of the majorenvironmental impacts of Aluminium comesfrom the primary production through the refinery process. It has a high content of alkalinity. In early days thered mud was simply dumped into the rivers or the nearby sea. Because of theinefficient washing of the red mud, itcontained a substantial amount of Na2O. Despite today’s efficientwashing process, red mud is deposited aslandfill.
It shows no severe environmental hazard, but it requires a large area ofthe red mud lake. Also, according to the European List of Waste, the red mudresulting from the alumina refining process is classified as a non-hazardouswaste 28, 29.3.6 SUSTAINABILITY POLICY OF ALUMINUM PRODUCINGCOMPANIES Overall, there isa global trend towards the protection ofthe environment by the industry.
The maindriving force behind the environmentalpolicies is coming from European authorities.Inagreement with the European legislation on industrial emissions, the BREF (BATreference documents) chapter for the aluminiumindustry is describing the Best Available Techniques (BAT), and the relatedperformance, which is base conditions for environmental permits for primary andsecondary (recycling) aluminiumproduction sites. European Aluminium manufacturers are actively participatingin the development of this document, with the objective to combine an ambitiousenvironmental protection with the technical and economic feasibility. 30. Since 1990, the European aluminium industry has reduced its CO2emissions by half and Perfluorocarbon (PFC) emissions by 90%. The target is tofurther reduce industrial energy consumption by 10% per tonne of aluminium produced or transformed.
One of the mainconcerns in the Aluminum industry is energyefficiency, and about 40% of the costs of primary aluminium producers in Europe comes from electricity. As base-loadconsumers, aluminium producers assist thebalancing of the grid and the use of renewable energy sources 31. Aluminumproducing companies such as Hydro (Norway) are committed to reducing the greenhouse gas emission bycreating more “green energy”. About two-thirds of the electricity used inprimary production is already from renewable sources, and it is intended to usethis as a platform for developing more renewable sources around the world. Producing more and emitting lesswill lead to increased production outputwhile reducing energy consumption. Recycling more Aluminum is another solutionas it requires only 5 percent of the energy used for primary production, thus saving both energyand greenhouse gas emissions.
32 Life Cycle Assessment (LCA) providesthe best framework for assessing the potential environmental impacts ofproducts including raw material acquisition, fabrication, transportation, use, and end-of-life. The aluminiumindustry is a dedicated supporter of LCAs and advocates for them to cover thefull lifecycle of products, i.e. including environmental loads and benefits ofend-of-life recycling that reflect the true value of recyclability. To facilitate LCAs, the aluminium industry publishes environmentalimpact indicators for its main processes, from mining, alumina refining andelectrolysis, extrusion, rolling, recycling and developed LCA models for carsand several building products according to European and International standards.
The aluminiumindustry is involved in LCA-based methodologies developed by the EuropeanCommission like the Product Environmental Footprint 33.