Date post: | 05-Apr-2018 |
Category: |
Documents |
Upload: | ismail-khater |
View: | 219 times |
Download: | 0 times |
of 19
8/2/2019 UMC - REAP - Aluminum_Ismail Khater_Ramon Osorio
1/19
HafenCity UniversityResource Efficiency in Architecture and Planning
Urban Material CyclesProf. Kerstin KuchtaProf. Wolfgang Willkomm
ALUMINIUMMaterial flow analysis of 70kg of a car
By: Ismail Khater
Ramn Osrio
Summer Semester 2011
8/2/2019 UMC - REAP - Aluminum_Ismail Khater_Ramon Osorio
2/19
1
1.Abstract
The economic and environmental reasons for recycling and reusing materials are vital to be able to
effectively and efficiently meet the 21st centurys population demands. Aluminium is the third most
abundant element on the earths crust. Today the use of aluminium is widely spread in countlessindustries. As complex a life cycle assessment could be, this paper describes the material cycle of the
aluminium content of a car, which is estimated at around 70kg, from the early stages of extraction
until the re-melting or recycling of the material.
Table of Contents
1. Abstract ........................................................ 1
2. Introduction and Background ...................... 2
2.1 Life Cycle Assessment ............................. 2
2.2 History of Aluminium ............................. 3
2.3 Physical and chemical properties ........... 5
2.4 Mining and Production worldwide ......... 5
2.5 Applications in the car ............................ 7
3. Material Flow processes .............................. 8
3.1 Mining and production processes .......... 8
3.2 Use and Life span .................................. 10
3.3 Disposal and Recycling ......................... 11
3.4 Material Flow analysis .......................... 13
4. Discussion ................................................... 14
4.1 Additional environmental aspects ....... 14
4.2 Conclusion ............................................ 16
Bibliography ................................................... 17
Listof figures
FIGURE 1: LIFE CYCLE STAGES [5] ................................ ........... 3
FIGURE 2: PHASES OF AN LCA[5] .......................................... 3
FIGURE 3:WORLD PRIMARY ALUMINIUM PRODUCTION [7] ......... 4
FIGURE 6: MINING AND PRODUCTION WORLDWIDE [11] ............. 6
FIGURE 5: PRIMARY PRODUCTION WORLDWIDE [27] .................. 6
FIGURE 4:MAIN END-USE MARKETS FOR ALUMINIUM PRODUCTS IN
EUROPE [7] ................................. ............................. 6
FIGURE 7:ALUMINIUM SHARE OVER TIME AS PERCENTAGE OF CURB
WEIGHT [12] ............................................................ 7
FIGURE 8: BAUXITE MINING [13] ................................ ........... 8
FIGURE 9: ALUMINA TO ALUMINIUM, HALL-HROULT PROCESS [13]............................................................................. 9
FIGURE 10: ALUMINIUM PRODUCTION STEPS [18] ................... 10
FIGURE 11: ALUMINIUM USE AND LIFESPAN [3] ....................... 10
FIGURE 12: END OF LIFE VEHICLE ALUMINIUM RECYCLING [3]...... 11
FIGURE 13: ALUMINIUM FLOW CHART [3] .............................. 12
FIGURE 14: MATERIAL FLOW DIAGRAM, OWN CALCULATION BASED
ON [4] AND [9] ....................................................... 13
FIGURE 15: CO2 EMISSION RELATED TO ALUMINIUM PRODUCTION
WORLDWIDE [19] .................................................... 15
FIGURE 16: ENERGY USE OF PRODUCTION PROCESSES AND
THEORETICAL MINIMUM [18] ................................... .. 16
http://umc%20-%20ikro%20-%20005.docx/#_Toc306480970http://umc%20-%20ikro%20-%20005.docx/#_Toc306480970http://umc%20-%20ikro%20-%20005.docx/#_Toc306480970http://umc%20-%20ikro%20-%20005.docx/#_Toc306480970http://umc%20-%20ikro%20-%20005.docx/#_Toc306480970http://umc%20-%20ikro%20-%20005.docx/#_Toc306480970http://umc%20-%20ikro%20-%20005.docx/#_Toc306480971http://umc%20-%20ikro%20-%20005.docx/#_Toc306480971http://umc%20-%20ikro%20-%20005.docx/#_Toc306480971http://umc%20-%20ikro%20-%20005.docx/#_Toc306480971http://umc%20-%20ikro%20-%20005.docx/#_Toc306480971http://umc%20-%20ikro%20-%20005.docx/#_Toc306480971http://umc%20-%20ikro%20-%20005.docx/#_Toc306480971http://umc%20-%20ikro%20-%20005.docx/#_Toc306480971http://umc%20-%20ikro%20-%20005.docx/#_Toc306480972http://umc%20-%20ikro%20-%20005.docx/#_Toc306480972http://umc%20-%20ikro%20-%20005.docx/#_Toc306480972http://umc%20-%20ikro%20-%20005.docx/#_Toc306480972http://umc%20-%20ikro%20-%20005.docx/#_Toc306480972http://umc%20-%20ikro%20-%20005.docx/#_Toc306480972http://umc%20-%20ikro%20-%20005.docx/#_Toc306480972http://umc%20-%20ikro%20-%20005.docx/#_Toc306480972http://umc%20-%20ikro%20-%20005.docx/#_Toc306480972http://umc%20-%20ikro%20-%20005.docx/#_Toc306480972http://umc%20-%20ikro%20-%20005.docx/#_Toc306480972http://umc%20-%20ikro%20-%20005.docx/#_Toc306480972http://umc%20-%20ikro%20-%20005.docx/#_Toc306480972http://umc%20-%20ikro%20-%20005.docx/#_Toc306480972http://umc%20-%20ikro%20-%20005.docx/#_Toc306480973http://umc%20-%20ikro%20-%20005.docx/#_Toc306480973http://umc%20-%20ikro%20-%20005.docx/#_Toc306480973http://umc%20-%20ikro%20-%20005.docx/#_Toc306480973http://umc%20-%20ikro%20-%20005.docx/#_Toc306480973http://umc%20-%20ikro%20-%20005.docx/#_Toc306480973http://umc%20-%20ikro%20-%20005.docx/#_Toc306480974http://umc%20-%20ikro%20-%20005.docx/#_Toc306480974http://umc%20-%20ikro%20-%20005.docx/#_Toc306480974http://umc%20-%20ikro%20-%20005.docx/#_Toc306480974http://umc%20-%20ikro%20-%20005.docx/#_Toc306480974http://umc%20-%20ikro%20-%20005.docx/#_Toc306480974http://umc%20-%20ikro%20-%20005.docx/#_Toc306480975http://umc%20-%20ikro%20-%20005.docx/#_Toc306480975http://umc%20-%20ikro%20-%20005.docx/#_Toc306480975http://umc%20-%20ikro%20-%20005.docx/#_Toc306480975http://umc%20-%20ikro%20-%20005.docx/#_Toc306480975http://umc%20-%20ikro%20-%20005.docx/#_Toc306480975http://umc%20-%20ikro%20-%20005.docx/#_Toc306480975http://umc%20-%20ikro%20-%20005.docx/#_Toc306480975http://umc%20-%20ikro%20-%20005.docx/#_Toc306480975http://umc%20-%20ikro%20-%20005.docx/#_Toc306480975http://umc%20-%20ikro%20-%20005.docx/#_Toc306480975http://umc%20-%20ikro%20-%20005.docx/#_Toc306480975http://umc%20-%20ikro%20-%20005.docx/#_Toc306480976http://umc%20-%20ikro%20-%20005.docx/#_Toc306480976http://umc%20-%20ikro%20-%20005.docx/#_Toc306480976http://umc%20-%20ikro%20-%20005.docx/#_Toc306480976http://umc%20-%20ikro%20-%20005.docx/#_Toc306480976http://umc%20-%20ikro%20-%20005.docx/#_Toc306480976http://umc%20-%20ikro%20-%20005.docx/#_Toc306480976http://umc%20-%20ikro%20-%20005.docx/#_Toc306480976http://umc%20-%20ikro%20-%20005.docx/#_Toc306480976http://umc%20-%20ikro%20-%20005.docx/#_Toc306480977http://umc%20-%20ikro%20-%20005.docx/#_Toc306480977http://umc%20-%20ikro%20-%20005.docx/#_Toc306480977http://umc%20-%20ikro%20-%20005.docx/#_Toc306480977http://umc%20-%20ikro%20-%20005.docx/#_Toc306480977http://umc%20-%20ikro%20-%20005.docx/#_Toc306480977http://umc%20-%20ikro%20-%20005.docx/#_Toc306480979http://umc%20-%20ikro%20-%20005.docx/#_Toc306480979http://umc%20-%20ikro%20-%20005.docx/#_Toc306480979http://umc%20-%20ikro%20-%20005.docx/#_Toc306480979http://umc%20-%20ikro%20-%20005.docx/#_Toc306480979http://umc%20-%20ikro%20-%20005.docx/#_Toc306480979http://umc%20-%20ikro%20-%20005.docx/#_Toc306480980http://umc%20-%20ikro%20-%20005.docx/#_Toc306480980http://umc%20-%20ikro%20-%20005.docx/#_Toc306480980http://umc%20-%20ikro%20-%20005.docx/#_Toc306480980http://umc%20-%20ikro%20-%20005.docx/#_Toc306480980http://umc%20-%20ikro%20-%20005.docx/#_Toc306480980http://umc%20-%20ikro%20-%20005.docx/#_Toc306480981http://umc%20-%20ikro%20-%20005.docx/#_Toc306480981http://umc%20-%20ikro%20-%20005.docx/#_Toc306480981http://umc%20-%20ikro%20-%20005.docx/#_Toc306480981http://umc%20-%20ikro%20-%20005.docx/#_Toc306480981http://umc%20-%20ikro%20-%20005.docx/#_Toc306480981http://umc%20-%20ikro%20-%20005.docx/#_Toc306480982http://umc%20-%20ikro%20-%20005.docx/#_Toc306480982http://umc%20-%20ikro%20-%20005.docx/#_Toc306480982http://umc%20-%20ikro%20-%20005.docx/#_Toc306480982http://umc%20-%20ikro%20-%20005.docx/#_Toc306480982http://umc%20-%20ikro%20-%20005.docx/#_Toc306480982http://umc%20-%20ikro%20-%20005.docx/#_Toc306480983http://umc%20-%20ikro%20-%20005.docx/#_Toc306480983http://umc%20-%20ikro%20-%20005.docx/#_Toc306480983http://umc%20-%20ikro%20-%20005.docx/#_Toc306480983http://umc%20-%20ikro%20-%20005.docx/#_Toc306480983http://umc%20-%20ikro%20-%20005.docx/#_Toc306480983http://umc%20-%20ikro%20-%20005.docx/#_Toc306480983http://umc%20-%20ikro%20-%20005.docx/#_Toc306480983http://umc%20-%20ikro%20-%20005.docx/#_Toc306480983http://umc%20-%20ikro%20-%20005.docx/#_Toc306480983http://umc%20-%20ikro%20-%20005.docx/#_Toc306480983http://umc%20-%20ikro%20-%20005.docx/#_Toc306480984http://umc%20-%20ikro%20-%20005.docx/#_Toc306480984http://umc%20-%20ikro%20-%20005.docx/#_Toc306480984http://umc%20-%20ikro%20-%20005.docx/#_Toc306480984http://umc%20-%20ikro%20-%20005.docx/#_Toc306480984http://umc%20-%20ikro%20-%20005.docx/#_Toc306480984http://umc%20-%20ikro%20-%20005.docx/#_Toc306480984http://umc%20-%20ikro%20-%20005.docx/#_Toc306480984http://umc%20-%20ikro%20-%20005.docx/#_Toc306480984http://umc%20-%20ikro%20-%20005.docx/#_Toc306480984http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480984http://umc%20-%20ikro%20-%20005.docx/#_Toc306480984http://umc%20-%20ikro%20-%20005.docx/#_Toc306480983http://umc%20-%20ikro%20-%20005.docx/#_Toc306480983http://umc%20-%20ikro%20-%20005.docx/#_Toc306480982http://umc%20-%20ikro%20-%20005.docx/#_Toc306480981http://umc%20-%20ikro%20-%20005.docx/#_Toc306480980http://umc%20-%20ikro%20-%20005.docx/#_Toc306480979http://umc%20-%20ikro%20-%20005.docx/#_Toc306480977http://umc%20-%20ikro%20-%20005.docx/#_Toc306480976http://umc%20-%20ikro%20-%20005.docx/#_Toc306480976http://umc%20-%20ikro%20-%20005.docx/#_Toc306480975http://umc%20-%20ikro%20-%20005.docx/#_Toc306480975http://umc%20-%20ikro%20-%20005.docx/#_Toc306480974http://umc%20-%20ikro%20-%20005.docx/#_Toc306480973http://umc%20-%20ikro%20-%20005.docx/#_Toc306480972http://umc%20-%20ikro%20-%20005.docx/#_Toc306480971http://umc%20-%20ikro%20-%20005.docx/#_Toc3064809708/2/2019 UMC - REAP - Aluminum_Ismail Khater_Ramon Osorio
3/192
2. Introduction and Background
Aluminium is an important material used in a diverse range of products. It is also known for being
easily recycled and has many benefits over other metals, such as being lightweight, high strength,
corrosion resistant and having a high thermal and electrical conductivity. [1] The aluminium industryis an immense part of the global economy of individual nations. Top market industries are
transportation, packaging, building and construction. [2] Transportation accounts for about 30
percent of the total aluminium output with a significant annual increase due to its characteristics.
This paper is focused on the material cycle of the aluminium content of a car, as part of an overall
material cycle study of a whole car, which is divided by materials and conducted by students of the
master course resource efficiency in architecture and planning at the HafenCity University in
Hamburg, as the program work for the course Urban Material Cycles. Through the overall study,
one can have a comprehensive understanding on the materials required to build a car, and specificallyin this paper on the material flow of Aluminium. In order to have an example throughout this paper,
the used weight of the aluminium content in a car is 70kg. [3] To be more specific, it is mostly referred
to a German car, as the European Union is one of the largest aluminium end users worldwide. [4]
As a lot of associations are dealing with material flow analysis in the form of a life cycle assessment, a
short description of the concept of it will be explained. After that we will have a look into the
materials history, physical and chemical properties, as well as its worldwide origins and its
applications in a car. Next, a more in-depth material flow and its processes will be prescribed, from
the early mining stages, use phase, to the disposal and recycling of the material. At the end, some
additional aspects, such as the environmental impact will be discussed, followed by a conclusion.
2.1 Life Cycle Assessment
Industries and businesses have started evaluating their environmental impact as their ecological
consciousness is rising. [4] Current concerns about the natural resource depletion and environmental
degradation have caused a movement towards greener solutions through more efficient processes.
Therefore, the environmental performance of these products and their manufacturing procedures
have become a key issue, and finding ways to better optimize these ways is in focus for many
companies to help minimize their effects on the environment. A currently known tool to do so is
called Life Cycle Assessment (LCA), which comes across the entire life cycle of a product. Life Cycle
Assessment approaches industrial systems to assess its cradle to grave practices. It requires detailed
analyses of each and every step of a product, starting from its raw materials, material processing,
manufacturing, distribution, use, repair, maintenance and disposal or recycling. All these stages are
being evaluated, as they are configured mostly in a linear process and therefore interdependent. By
counting the impacts during the product life cycle, life cycle assessment provides a complete view of
the environmental aspects of the product or process and a more accurate image of the true
environmental tradeoffs in product and process selection. [5]
http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc3064809858/2/2019 UMC - REAP - Aluminum_Ismail Khater_Ramon Osorio
4/193
A Life cycle assessments consist of four components, which are systematic and phased. First comes
the goal definition and scoping, which describes the product and its process and activity. Then comes
the inventory analysis, which identifies and quantifies the physical use of energy, water and materials
and the environmental releases as well, such as air emissions and waste and water discharges. After
that comes the impact assessment. This third phase assesses the environmental effects of the
outcome of the inventory analysis. The fourth and last step is the interpretation. Here, an evaluationis done for the output results. The following figure is a diagram showing the whole process
summarized. [5]
The benefits of conducting a life cycle assessment are plenty. It helps decision makers to be able to
identify and select the weak points of a product or process and use the outcome information to
upgrade their businesses. By looking at the whole process, one can prevent or calculate the
environmental impact transferred through any changes made (e.g., from air emissions to wastewater
effluent). [5] In this paper the focus is only on the materials flow and quantity and it does not
represent a comprehensive life cycle assessment, as such an analysis requires a lot of time and
resources.
2.2 History of Aluminium
Despite being the third most abundant element of the Earths crust, the designation of aluminium and
its identification as a chemical element only dates back to the early nineteenth century. A reason for
its late discovery is the fact that aluminium never occurs naturally in metallic form. However, the
history of use of aluminium compounds goes far back in time. Already around 5300 BC, ancient
Persian potters are thought to have used clay consisting largely of aluminium silicates. Later, other
ancient civilization such as Egypt and Babylon, but also Romans and Greeks used aluminium salts as
mordents in fabric dyeing, as astringents for dressing wounds, as well as for cosmetic purposes. [6]
It was not until 1808 that the metal was given its name by English chemist Sir Humphrey Davy, even
though still describing an unknown metal at that time. First being named alumium, it was respelled by
later scientists as the more pleasant sounding aluminium and later changed again to aluminium in
order conform to the ending of most elements. The first to successfully isolate the metal was Danish
scientist Hans Christian Oersted in 1825 by reacting aluminium chloride (AlCl3) with potassium
amalgam, an alloy of potassium and mercury. A few years before, French scientist P. Berthier
Figure 1: life cycle stages [5] Figure 2: phases of an LCA [5]
http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc3064809858/2/2019 UMC - REAP - Aluminum_Ismail Khater_Ramon Osorio
5/194
discovered a hard, reddish, clay-like material containing 52 percent aluminium oxide near the village
of Les Baux in southern France. After the place of discovery he named it bauxite, todays most
common ore of aluminium. [7]
In 1827 Friedrich Wohler in Germany described a process for producing aluminium as a powder by
reacting potassium with anhydrous aluminium chloride. Later, in 1845, he established many of the
metal's properties, including its specific gravity (density). It was this discovery of its exceptional
lightness that boosted scientific research and paved the way for commercial production. However, at
that time the metals price still exceeds that of gold and platinum, bringing rulers such as Napoleon to
serve their guests with plates made from aluminium rather than gold. Despite dropping by 90 percent
in price over the following 10 years due to improved production processes, it was not until 1886 that
considerable production begins to rise. In this year the two unknown young scientists, Paul Louis
Toussaint Hroult (France) and Charles Martin Hall (USA) simultaneously invent a new electrolytic
process, the Hall-Hroult process, which is the basis for all aluminium production today. Following
that, the first aluminium companies were founded in France, Switzerland and the USA in 1888. In
1889 Austrian scientist Karl Josef Bayer invented the Bayer Process for the large-scale production of
alumina from bauxite, and thereby establishing the metals worldwide and multifarious use. [7]
The real rise however only began after the Second World War. The aluminium industry expanded
rapidly during the war to meet the need for military aircraft. This expanded production capacity made
aluminium available for new and renewed markets, including automobiles.
The use of aluminium in Automotive Industry began nevertheless earlier. Aluminium crankcases were
used in the end of the nineteenth century in some car models. Even car with a full aluminium body
was first developed in 1899. What may have been the first AIV (aluminium-intensive vehicle) was
designed and built in 1923. In 1948, Land Rover started using aluminium outer skin sheets. By the
time the aluminium content in cars increased rapidly, so that in 2005 the average volume of
aluminium used in passenger cars was already 131kg and this trend keeps rising. [8]
Figure 3:World Primary Aluminium Production [7]
http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc3064809858/2/2019 UMC - REAP - Aluminum_Ismail Khater_Ramon Osorio
6/195
2.3 Physical and chemical properties
Aluminium is the most abundant metal in the Earths crust and, after oxygen and silicon, the third
most abundant chemical element [9]. It constitutes about 8 percent by weight of the Earth's solid
surface. However, it never occurs naturally in its pure metallic form, as it is chemically too reactive,
but is found in mineral compounds (silicate and oxide) that are very stable. Aluminium is member of
the boron group of chemical elements and its appearance ranges from silvery to dull gray, depending
on the surface roughness. It is nonmagnetic, does not easily ignite and is not soluble in water under
normal circumstances.
One of the most important characteristics is its low specific density. Aluminium has about one-third
the density and stiffness of steel. Due to its light weight, components made from aluminium and its
alloys are vital to the aerospace industry and are important in other areas of transportation and
lightweight construction. Another attribute constituting its widespread use is the metals ability to
resist corrosion due to the phenomenon of passivation. When the metal is exposed to air, a thin
surface layer of aluminium oxide is formed, effectively preventing further oxidation. The corrosionresistance of Aluminium alloys is however reduced due galvanic reactions with alloyed copper or the
presence of dissimilar metals.
Other industrial advantages are its durability with yield strengths of 711 MPa (aluminium alloys even
range from 200 MPa to 600 MPa) and its softness, which makes it easily machined, cast, drawn and
extruded. Beyond that, aluminium is highly reflective (approximately 92 percent of visible light and
about 98 percent of medium and far infrared radiation), making it an important component of silver-
colored paints and mirror finish. Aluminium is a good thermal and electrical conductor, having 59
percent the conductivity of copper, both thermal and electrical. It is nontoxic, but nevertheless
exposure of higher concentrations may lead to serious health effects, such as damage to the central
nervous system and Dementia. [10]
2.4 Mining and Production worldwide
According to the European Aluminium Association, today more aluminium is produced each year than
all other non-ferrous metals combined. The global production volume of 24,290 million tons of
primary aluminium in 2010, including about 25 percent from recycled material, makes aluminium the
second most used metal in the world and the most recycled material [2]. Global consumption of
aluminium has increased rapidly in the past decades and estimations also predict an upward trend in
the future. The growing demand especially of the emerging markets in countries such as China and
India causes a further rise in production and at the same time leads to a geographical shift. Beyond
that, fuel efficiency and hence lightweight vehicle design becomes an increasingly important factor,
which leads to an increase of aluminium content in vehicles. [2]
http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc3064809858/2/2019 UMC - REAP - Aluminum_Ismail Khater_Ramon Osorio
7/196
How will this development affect the security of supply? Are the global reserves sufficient to meet the
growing demand? As aluminium is among the most abundant elements of the Earths crust, the fear
of supply shortage seems unreasonable. Estimations speak of Bauxite resources of about 55 to 75
billion tons, located in Africa (33%), Oceania (24%), South America and the Caribbean (22%), Asia
(15%), and elsewhere (6%). Reserves (considering also current economic and technical feasibility) are
estimated at about 28mio tons, which would be sufficient to maintain supplies for at least the nexttwo hundred years. [11]
Around 85 percent of all Bauxite mined worldwide goes towards production of aluminium metal. The
remaining 15 percent is used in chemical and refractory products, as well as different aluminium
compounds. The top markets for the aluminium industry include transportation, packaging, building,
and construction. Transportation continues to be the largest market, accounting for 36 percent of the
total aluminium output (see figure 4). [7] The global Bauxite output in 2010 was 211,000 tons [11].
The majority of bauxite mining is done in the southern part of the world, largely in developing
countries, whereas primary production is more focused in Europe and North America (figure 6).
Figure 4: mining and production worldwide [11]
Figure 5: primary production worldwide
[27]
Figure 6: Main end-use markets for
aluminium products in Europe [7]
http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc3064809858/2/2019 UMC - REAP - Aluminum_Ismail Khater_Ramon Osorio
8/197
2.5 Applications in the car
Since the oil crisis in the 1970s fuel-efficiency became an increasingly important factor in automotive
industries. Particularly, the recent rise of energy prices boosts the demand for lightweight design. The
amount of aluminium content in vehicles is steadily growing in order to keep vehicle weight under
control, even though the total weight of passenger cars doubled in the past 30 years due to increased
performance and number of appliances. [2]
According to the Aluminium Association (2001), the use of automotive aluminium almost tripled
between 1976 and 1999. The annual growth is expected to continue at a rate of approximately 3.64.5
kg/vehicle, or about 3 percent, for the near future [12].Today European cars contain on average 130
kilograms of aluminium castings, sheet and profiles and American cars some 150 kilograms.
Aluminium has already been applied in a variety of parts, including the engine, body, hood, and front
end. By far the most aluminium content of passenger cars and light trucks is found in castings for the
components (61.9%), such as engine blocks, cylinder heads, and manifolds. Another 15.7 percent is
used in wheels (mostly castings), followed by aluminium foil (12.9%), largely for heat exchangers suchas the radiator. The remaining aluminium applications include exterior trim and interiors (4.6%),
chassis and suspensions (2.6%), closure panels (1.2%, mostly hoods), body structures (0.7%), and
bumper systems (0.4%). [2]
Figure 7: Aluminium share over time as percentage of curb weight [12]
http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc3064809858/2/2019 UMC - REAP - Aluminum_Ismail Khater_Ramon Osorio
9/198
3. Material Flow processes
This section is about the material flow process from its initial stages of mining and production,
throughout its use and life span, to its disposal and recycling stages. Found in bold letters are the
main ingredient materials and processes in their order of production.
3.1 Mining and production processes
Bauxite As mentioned before, aluminium is the third most abundant metal on the earths crust. It is
mostly mined from what is called bauxite, which is the reddish ore found right after usually a half
meter topsoil layer, ranging from three to five meters deep. Since it is found so close to the ground it
is extracted by a process called open-cast strip mining. [13]By doing this, small red pebbles called
pisolites are mined. Their diameter has an average of about five millimeter.
This process requires a lot of earth moving with heavy equipment, [13] which translates directly into
environmental problems such as erosion and creating dust. Erosion is a major issue because most of
the mining happens near rainforests. [3] How this is solved is mainly by returning the residues to their
places and replanting the mined fields. As for the dust creation during the mining process, usually
water is used on the floor, as well as covers for the transportation vehicles. [13]
Figure 8: bauxite mining [13]
http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc3064809858/2/2019 UMC - REAP - Aluminum_Ismail Khater_Ramon Osorio
10/199
Alumina Through a process called the Bayer, which is a chemical refining process, bauxite is
transformed into alumina or aluminium oxide (Al2O3). This is the feedstock for the aluminium smelting
progression. To reduce the transportation costs usually it is done close to the mines. In this process
caustic soda is used at high temperatures to haul out the alumina, which then is left to settle and
crystallize. The residues of caustic soda is then recycled and reused for efficiency. Extracted alumina
ranges from 31 to 59 percent by weight and has an average of 41 percent. Normally, every five tons ofbauxite yield two tons of alumina or one ton of aluminium. Some of the alumina is used not for
aluminium production, but for other uses such as pharmaceutical, medical or other chemical
industries. [13]
Figure 9: alumina to aluminium, hall-Hroult process [13]
Hall-Hroult Process As for the rest of the alumina, it is converted to aluminium using the Hall-
Hroult electrolytic process. This is done by dissolving the alumina into molten cryolites (sodium
aluminium fluoride) inside a large carbon container. Through the lowering of a carbon anode into a
cryolite and the container lining acting as a cathode, a direct current passes through the electrolyte.
The current has the characteristics of high ampere and low voltage. In this process the oxygen atoms
are removed from the alumina through the electrolytic process, causing a reaction with the carbon
producing carbon dioxide. The molten aluminium is left at the bottom of the container, which is
regularly removed to a holding furnace to allow the repetition of the process. The aluminium is then
cast into ingots, rolling slabs or extrusion billets, which are shipped to be processed into their final
products. [13]
http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc3064809858/2/2019 UMC - REAP - Aluminum_Ismail Khater_Ramon Osorio
11/1910
The following figure is an illustrative diagram, showing the steps of both new and recycled aluminium
production.
3.2 Use and Life span
Every aluminium product purchased by its consumer has a range of life span, depending on the type
of product. This lifetime ranges from a few weeks for packaging products like cans to decades such as
building materials, for example aluminium window frames. Transportation has the most applications
for aluminium, reaching 70 percent for casting alloys as shown in the diagram. [3] In western europealone, 3.6 million tons of wrought and casting alloys of aluminium were used only in transportation in
2003. [3] This figure includes cars, aeroplanes, trains and ships. Since aluminium is continously
replacing steel alloys because of its lighter weight, it is foreseen that the aluminium content in cars is
rising every year.
Figure 10: aluminium production steps [18]
Figure 11: aluminium use and lifespan [3]
http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc3064809858/2/2019 UMC - REAP - Aluminum_Ismail Khater_Ramon Osorio
12/1911
Putting an exact lifetime for the aluminium content in cars is very difficult. To give an example,
German cars have an average lifespan within Germany of about 12 years, which is if they get
dismantled after this use period. Often the case is different, where the cars are being shipped to less
developed countries, where the cars are being used for a much longer period of time.
However, aluminium scrap is of very high value compared to other materials as it doesnt lose any of
its properties by recycling it over and over again. Therefore the incentive for recycling it exists, along
with the much lower energy requirements than from mining it. About 90 to 95 percent of the
aluminium in the cars goes back into the loop. [3]
3.3 Disposal and Recycling
The recycling of aluminium is of high economic, environmental and social importance. More than half
of the aluminium used in the European Union is from recycled contents, and this figure is increasing
constantly [3]. Since bauxite is not mined or easily found a lot in this region, it is of high importance to
continuously try to reach higher levels of recycling, as well as finding better, more resource efficient
scrap treatment and recycling processes. Along with that reason comes the high value of aluminium.
This is not only for environmental and social responsibility reasons, but also for economic reasons,
such as waste handling and energy preservation. As a rule of thumb, the energy required to recycle or
remold the aluminium is about 5 percent of the initial energy demand to deal with mined bauxite.
Collection The first step to be able to recycle aluminium is the collection. The industry tries to
harvest as much as possible from the scrap metal available. However, with the help of the society and
authorities, the amount of aluminium collected could increase further. The amount of aluminium
scrap collected in Europe is 96 percent of the total aluminium used. This high percentage is also due
to the high tech and efficient collection methods available and used. For vehicles, some aluminiumparts are first removed during the dismantling of the vehicle. Then, the car body is fed into a
shredder. This results in having a mix of a lot of materials. The first separation process is removing the
ferrous metals with a magnet, leaving plastics, glass, textiles, rubber and non-ferrous metals. In order
to separate the aluminium a lot of processes are used. These include the sink-float process, as well as
an electromagnetic separation. Other process uses laser and x-rays technology to identify the type of
alloys. [3] Following diagram shows the process of extracting the aluminium content in a car.
Figure 12: end of life vehicle aluminium recycling [3]
http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc3064809858/2/2019 UMC - REAP - Aluminum_Ismail Khater_Ramon Osorio
13/1912
Treatment The quality of the scrap is monitored to be able to reduce the adherent materials as
much as possible. The type of alloys is also of high importance, and therefore there is a separation by
type as well. [3] Because of the types of melted materials and joints there are small aluminium losses
during the separation of about 2 to 10 percent. [3]
Residues There are also some residues from each process of the aluminium production and
recycling phases. These remain are also reused, recycled or put back into the cycle. The aluminium
salt slag, which is about 400 kilograms per ton of aluminium, is processed to reusable salt. The
aluminium oxide is also used for various industries, such as for the production of cement. The filter
dust, of about 25 kg/ton, as well as the skimmings (25 kg/ton) and furnace lining (2 kg/ton) are
recycled within the aluminium recycling industry. [3]
The following diagram shows the overall aluminium material processes.
Figure 13: aluminium flow chart [3]
http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc3064809858/2/2019 UMC - REAP - Aluminum_Ismail Khater_Ramon Osorio
14/1913
3.4 Material Flow analysis
In order to quantify the material flow of aluminium in the automotive industry, a model car
containing 70kg of aluminium was taken as a base. The following simplified diagram (figure 14)
depicts the material cycle from mining to recycling stage, considering the main inputs and outputs of
the different production processes. Although the Anode involved in the production process of primary
aluminium does not directly contribute to the mass flow of the metal, it was still included as it is a
main source of fossil fuel consumption. Other resource flows involved, such as water consumption,
were not considered.
The diagram shows that to produce 70kg of aluminium car parts, about double the mass of alumina is
required and almost five times that much of bauxite. Without recycling these proportions would be
even twice that high, as primary and secondary aluminium production contribute to almost the same
parts of aluminium semis. The recycled fraction itself consists mainly of scrap derived from
reprocessing car parts. The minimal loss of around 2,5kg during scrap melting indicates the high
efficiency of the recycling process.
The total waste output during all production stages is considerably high. Producing 70kg of aluminium
car pieces generates almost 100kg of Bauxite residue, consisting of all the material that is not
dissolved during the alumina extraction (Bayer process). Hereby, a toxic read mud remains that cannot
directly be recycled nor easily be disposed. The environmental implications related to this and possible
ways of treatment will be addressed in the following section.
Furthermore, it is shown that about 37kg of carbon and fossil fuels, mostly derived from coal, is
needed for anode production, representing half of the weight of the aluminium content in the car.
Supplementary use of fossil fuels due to energy consumption during the production processes willalso be discussed in the following.
Figure 14: material flow diagram, own calculation based on [4] and [9]
STOCK
http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc3064809858/2/2019 UMC - REAP - Aluminum_Ismail Khater_Ramon Osorio
15/1914
4. Discussion
In this section the aluminium cycle presented in the previous section is discussed and evaluated. In addition,
other important aspects that contribute to the overall environmental footprint of the metal are addressed.
4.1 Additional environmental aspects
Red mud As described in the previous chapter, by far the largest fraction of solid waste is the
insoluble residue of the bauxite digestion (Bayer process). The resulting red mud is highly caustic and
presents one of the aluminium industry's most important disposal problems. It is a mixture of solid
and metallic oxide-bearing compounds originally present in the parent mineral, bauxite, and of
compounds formed or introduced during the Bayer cycle. The sludge consists to 30 to 60 percent of
oxidized iron, causing its red color. Other components include silica, unleashed residual aluminium,
titanium oxide, as well as different organic compounds. It is a highly saline and alkaline mixture with a
pH value ranging from 10 to 13 and high ionic strength. [14]
Red mud cannot be disposed of easily. In most countries where red mud is produced it is pumped into
open holding ponds, where it is stored for several years until the material is settled and can be
recovered for future refining or be neutralized. This presents a problem as it takes up land area that
can neither be built on nor farmed, even when dry. Another common practice of disposal is piping the
mud into the deep sea, causing pollution of surface and underground water and contributing
significantly to the overall cost of alumina production. [15]. Other reported environmental impacts of
bauxite mining and processing include deforestation, increased erosion and disturbance of hydrology
and natural habitats.
A typical plant produces 0.3 to 2.5 tons of red mud with each ton of alumina, depending strongly onthe type of bauxite ore. [16] Considering the model car, about 100kg of bauxite residue would be
generated from 70kg of aluminium content. It is estimated that around 70 million tons of red mud are
produced worldwide every year [17]. Rapidly increasing aluminium production accentuates the
rigorousness of the problem.
Currently, scientific research is searching for new ways of treatment or industrial application of the
material. Possible fields include metallurgical uses (iron and steel production, titania, alumina and
alkali, minor constituents recovery), production of building materials (constructional brick, light
weight aggregates, bricks roofing and flooring tiles, cements etc), catalysis, ceramics (pottery, sanitary
ware, special tiles and glasses, glazes, ferrites) and other miscellaneous direct uses (in waste water
treatment, as a filler, as a fertilizer, etc). However, practical application of those methods still remains
on a very small scale as technical and economic feasibility are still lagging behind. [14]
Energy consumption A major concern in terms of ecological footprint is the high energy intensity
of Aluminium production.Electricity costs typically constitute about one-third of the total production
costs.The worldwide average specific energy consumption is approximately 15kWh per kilogram of
aluminium produced [18]. In the U.S, the aluminium industry consumes about 5 percent of the total
electricity produced, in Australia with over 25000GWh even almost 15percent [19].
http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://umc%20-%20ikro%20-%20005.docx/#_Toc306480985http://en.wikipedia.org/wiki/Industryhttp://en.wikipedia.org/wiki/Metalhttp://en.wikipedia.org/wiki/Oxidisedhttp://en.wikipedia.org/wiki/Ironhttp://en.wikipedia.org/wiki/Silicahttp://en.wikipedia.org/wiki/Titanium_oxidehttp://en.wikipedia.org/wiki/PHhttp://en.wikipedia.org/wiki/Kilowatt-hourhttp://en.wikipedia.org/wiki/Kilowatt-hourhttp://en.wikipedia.org/wiki/PHhttp://en.wikipedia.org/wiki/Titanium_oxidehttp://en.wikipedia.org/wiki/Silicahttp://en.wikipedia.org/wiki/Ironhttp://en.wikipedia.org/wiki/Oxidisedhttp://en.wikipedia.org/wiki/Metalhttp://en.wikipedia.org/wiki/Industry8/2/2019 UMC - REAP - Aluminum_Ismail Khater_Ramon Osorio
16/1915
The high consumption is primarily related to the smelting process, as it is based on a constant electric
current that is needed to reduce alumina to aluminium metal by electrolysis (Hall-Hroult Process). It
requires 46 percent of the total energy consumed during all production stages. Smelters are therefore
mostly located where electric power is both plentiful and inexpensive, such as the United Arab
Emirates with excess natural gas supplies and Iceland and Norway with energy generated from
renewable sources. In addition to consuming a large amount of electricity, this process directlyproduces carbon dioxide (CO2) and under certain conditions other highly potent greenhouse gases.
Total greenhouse gas emissions can only be estimated considering the sources of energy, which vary
widely on a global scale (figure 15). In Australia, one of the largest producers of alumina, electricity
consumption is mostly covered by coal-fired power plants, causing about 2.5 times as much
greenhouse gas per ton of aluminium as the world average. Internationally, however, coal accounts
only for about 30 percent, whereas hydropower is the predominant energy source for aluminium
production. [19]
However, the potential to reduce the energy consumption is significant. The theoretical minimum
energy required is three times lower than the energy consumed in current practice (figure 16).
Current research states that technological improvements could for example reduce energy use for
smelting by more than 30 percent [18]. Furthermore, it must be pointed out that the recycling process
requires only 5 percent compared to the energy used for primary aluminium production. Therefore,
increasing the collection and recycling rates may considerably contribute to reduce the overall energy
consumption in the aluminium industry.
In order evaluate the absolute energy balance of a material; the energy use during its entire life cycle
needs to be considered. As aluminium is light compared to many other alternative materials, it may
save a lot of energy during its life span. Although a holistic assessment of the total energy / carbon
footprint was not feasible in the scope of this work, the following chapter will provide a conclusion of
the aspects covered in this work, and give some recommendations for the future development.
Figure 15: CO2 emission related to aluminium production worldwide [19]
http://en.wikipedia.org/wiki/United_Arab_Emirateshttp://en.wikipedia.org/wiki/United_Arab_Emirateshttp://en.wikipedia.org/wiki/Icelandhttp://en.wikipedia.org/wiki/Norwayhttp://en.wikipedia.org/wiki/Renewable_resourcehttp://en.wikipedia.org/wiki/Renewable_resourcehttp://en.wikipedia.org/wiki/Norwayhttp://en.wikipedia.org/wiki/Icelandhttp://en.wikipedia.org/wiki/United_Arab_Emirateshttp://en.wikipedia.org/wiki/United_Arab_Emirates8/2/2019 UMC - REAP - Aluminum_Ismail Khater_Ramon Osorio
17/1916
4.2 ConclusionThis paper has highlighted the main features of the aluminium life cycle in relation to ecological and
sustainable developments. It aims to summarize and give a brief understanding about the metal, in
relation to the other studied materials, in an attempt to understand the urban material cycles and
their impacts in a holistic manner, rather than just analyzing separate parts of it.
Aluminum is seen today in almost every product in our lives and is related to what we eat, drink,
consume and travel with. When one kilogram of aluminum is recycled 8 kg of Bauxite, 4 kg of
chemical products and 14 kilowatt-hours of electricity are saved. With the aluminiums characteristics
of not degrading and indefinite recycling capabilities, wasting it should be avoided as it createsunnecessary impact on the environment, the public health and increases production demands, as well
as having an energy intensive production process [20]. Therefore, more effort into the recycling
methodologies should be put more in focus, as well as paying more attention from the public to
reduce and eliminate planned obsolescence, which means planning or designing a product with a
limited useful life span, so it will become obsolete or nonfunctional after a certain period of time.
One could argue that if the market finds better ways of recycling aluminum, certain environmental
problems such as red mud and excessive energy use could be dramatically reduced when the market
finds its equilibrium state. Hence, improvement is vital and only possible with the increase of public
awareness of the realities behind aluminum consumption. This is being done best by the unequivocalmethod of making life cycle assessments, which takes all aspects into consideration, including
environmental, economical, health and social. This method shows that for example replacing iron
alloys with aluminum ones have a positive effect on the fossil fuels reduction through having light
weight goods.
By doing these analyses, regional and international regulations, as well as activists and the public
could affect the current industries (production and recycling) with collective efforts, and change them
into more sustainable operations.
Figure 16: energy use of production processes and theoretical minimum [18]
8/2/2019 UMC - REAP - Aluminum_Ismail Khater_Ramon Osorio
18/1917
Bibliography
[1] U.S. department of energy, Ed., U.S. Energy
requirements for aluminum production.
United States: Energy Efficiency and
Renewable Energy, 2007.
[2] Subodh Das and Weimin Yin, "Trends in the
global aluminum fabrication industry," JOM
Journal of the Minerals, Metals and
Materials Society, pp. 83-87, Feb. 2007.
[3] Marle Bertram et al., Aluminum recycling:
the road to high quality products,
Organisation of European Aluminum
Refiners and Remelters, Ed. Brussels,
Belgium: European Aluminum Association,
2005.
[4] Marlen Bertram, Kenneth J. Martchek, and
Georg Rombach, Material Flow Analysis in
the Aluminum Industry, Journal of Industrial
Ecology, Ed. Connecticut, United States: Yale
University, 2009.
[5] Mary Ann Curran et al., Life cycle
assessment:principles and practice. Virginia,
United States of America: Scientific
Applications International Corporation
(SAIC), 2006.
[6] IAI. (2011) http://www.world-
aluminium.org/About+Aluminium/Story+of/
In+history.
[7] EAA. (2011) http://www.eaa.net/en/about-
aluminium/aluminium-history.
[8] The Aluminum Association, "Aluminum: The
Corrosion Resistant Automotive Material,"
2001.
[9] EAA, "Environmental Profile Report for the
European Aluminium Industry," April 2008.
[10] I. J. Polmear, Light Alloys: Metallurgy of the
Light Metals.: Arnold, 1995.
[11] U.S. Geological Survey, "Mineral Commodity
Summaries," 2011.
[12] Ducker Research Inc., "Aluminum Content
for Light Non Commercial Vehicles to be
Assembled in North," 2005.
[13] Justin Ratcliffe, aluminium & sustainability a
cradle to cradle approach.Gloucestershire, United Kingdom: Council
for Aluminium in Building, 2008.
[14] Y. Pontikes. (2005) Red Mud Project.
[Online].
http://www.redmud.org/Characteristics.ht
ml
[15] Dimitrios Boufounos. (2006) European
Commission - LIFE Programme. [Online].
http://ec.europa.eu/environment/life/proje
ct/Projects/index.cfm?fuseaction=home.sho
wFile&rep=laymanReport&fil=LIFE03_ENV_
GR_000213_LAYMAN.pdf
[16] Dinesh Mohan and Charles U. Pittmann,
"Arsenic removal from water/wastewater
using adsorbentsA critical review,"Journal
of Hazardous Materials, pp. 1-53, April2007.
[17] R. C. Sahu, R. K. Patel, and B. C. Ray,
"Neutralization of red mud using mine
water," Rourkela, 2008. [Online].
http://pubs.acs.org/cen/science/88/8843sci
3.html
http://www.redmud.org/Characteristics.htmlhttp://www.redmud.org/Characteristics.htmlhttp://www.redmud.org/Characteristics.htmlhttp://ec.europa.eu/environment/life/project/Projects/index.cfm?fuseaction=home.showFile&rep=laymanReport&fil=LIFE03_ENV_GR_000213_LAYMAN.pdfhttp://ec.europa.eu/environment/life/project/Projects/index.cfm?fuseaction=home.showFile&rep=laymanReport&fil=LIFE03_ENV_GR_000213_LAYMAN.pdfhttp://ec.europa.eu/environment/life/project/Projects/index.cfm?fuseaction=home.showFile&rep=laymanReport&fil=LIFE03_ENV_GR_000213_LAYMAN.pdfhttp://ec.europa.eu/environment/life/project/Projects/index.cfm?fuseaction=home.showFile&rep=laymanReport&fil=LIFE03_ENV_GR_000213_LAYMAN.pdfhttp://ec.europa.eu/environment/life/project/Projects/index.cfm?fuseaction=home.showFile&rep=laymanReport&fil=LIFE03_ENV_GR_000213_LAYMAN.pdfhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://ec.europa.eu/environment/life/project/Projects/index.cfm?fuseaction=home.showFile&rep=laymanReport&fil=LIFE03_ENV_GR_000213_LAYMAN.pdfhttp://ec.europa.eu/environment/life/project/Projects/index.cfm?fuseaction=home.showFile&rep=laymanReport&fil=LIFE03_ENV_GR_000213_LAYMAN.pdfhttp://ec.europa.eu/environment/life/project/Projects/index.cfm?fuseaction=home.showFile&rep=laymanReport&fil=LIFE03_ENV_GR_000213_LAYMAN.pdfhttp://ec.europa.eu/environment/life/project/Projects/index.cfm?fuseaction=home.showFile&rep=laymanReport&fil=LIFE03_ENV_GR_000213_LAYMAN.pdfhttp://www.redmud.org/Characteristics.htmlhttp://www.redmud.org/Characteristics.html8/2/2019 UMC - REAP - Aluminum_Ismail Khater_Ramon Osorio
19/19
[18] U.S. Department of Energy, "U.S. Energy
Requirements for Aluminum Production -
Historical Perspective, Theoretical Limits
and Current Practices," 2007.
[19] Hal Turton, "The Aluminium Smelting
Industry - Structure, market power,
subsidies and," 2002.
[20] H. Hoberg, S. Wolf, and J. Meier-Kortwig,
"Modelling the material flow of recycling
processes for aluminium," RWTH Aachen,.
[21] Subodh Das et al., Trends in the Global
Aluminum Fabrication Industry. Kentucky,
United States: JOM, 2007.
[22] International Institute for Environment and
Development (IIED), "Breaking New Ground:
Mining, Minerals and Sustainable
Development," 2002.
[23] Malcolm A. Weiss, John B. Heywood,
Elisabeth M. Drake, Andreas Schafer, and
Felix F. AuYeung, "ON THE ROAD IN 2020,"
2000.
[24] F. Stodolsky, A. Vyas, R. Cuenca, and L.
Gaines, "Life-Cycle Energy Savings Potential
from Aluminum-Intensive Vehicles," in Total
Life Cycle Conference & Exposition, Vienna,
1995.
[25] IAI. (2011) https://stats.world-
aluminium.org/iai/stats_new/formServer.asp?form=1.
[26] Sarah Everts. (2010) chemica l&
engeneering news. [Online].
http://pubs.acs.org/cen/science/88/8843sci
3.html
[27] IAI. (2011) https://stats.world-
aluminium.org/iai/stats_new/formServer.as
p?form=1.
[28] Marlen Bertram et al., Material Flow
Analysis in the Aluminum Industry, Journal
of Industrial Ecology, Ed. Connecticut ,
United States: Yale University, 2009.
[29] U.S. Department of Energy.: environmental
department, 2007.
[30] EAA. (2011) http://www.eaa.net/en/about-
aluminium/aluminium-history.
[31] International Aluminium Institute. (2011)https://stats.world-
aluminium.org/iai/stats_new/formServer.as
p?form=1.
http://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.htmlhttp://pubs.acs.org/cen/science/88/8843sci3.html