Aluminium – The Youngest Metal :
Although Aluminium is the third most abundant element on earth following oxygen and silicon, its production in an industrial scale has taken place in 1886 with the employment of the electrolysis method.
Just like the other much used metals such as iron, lead and tin, aluminium too is found in form of its compounds in the nature. The first person, who extracted the metal from its compound aluminium oxide in 1807 was Sir Humphrey Davy, Thereafter, Hans Christian Oersted, Frederick Wöhler and Henri Sainte-Clairre Deville have introduced innovations in aluminium extraction.
The production of aluminium in an industrial scale was carried out by Charles Martin Hall of USA and Paul T. Heroult of France in 1886 using the electrolysis method at the same time independent of each other. Since this is the method still used in our day, 1886 is accepted as the starting year of the aluminium industry.
With the invention of dynamo by Werner Von Siemens in 1886 and discovery of the Bayer Process, which allows obtaining aluminium from bauxite, by K.J.Bayer in 1892, the production of aluminium on an industrial scale has become greatly simplified and this young metal has become the second most used metal after iron and steel in the world.
Aluminium Extraction :
Aluminium is extracted using the same method world-wide since a century. Aluminium is extracted in two stages. At the first stage, “alumina“ is obtained from the bauxite ore using the Bayer process. At the second stage, aluminium is obtained from alumina through electrolysis. The alumina facilities are constructed next to the bauxite ore locations generally. The bauxite ore taken from the mine is processed with caustic soda solution to obtain aluminium hydroxide. The insoluble remains resulting from this process (red sludge) is separated and the “alumina” (aluminium oxide) is obtained through the calcination of the aluminium hydroxide.
The subsequent step is the conversion of “alumina” in to aluminium. Alumina, with a white powder-like appearance, is taken in to the special enclosure called a “cell”, where the electrolysis process takes place.
The purpose here is separating the aluminium from oxygen. A direct current at 4-5 volts is applied for the electrolysis process. The process is completed by collecting the aluminium accumulated at the bottom.
In general, 4 units of bauxite by weight yields 2 units of alumina and 2 units of alumina yields 1 unit of aluminium.
The energy consumption of 42.000 kWh required for producing each ton of primary aluminium in the past has been reduced to an average of 16.500 kWh today. This value is further reduced to 13.000 kWh/t if the state of the art technologies are employed.
The aluminuim obtained by means of the processes explained above is described as “primary aluminium’’.
Classification of the Aluminum Products According to the Types of Aluminum Production Methods :
Aluminium is converted in to a variety of semi-finished and finished products using the extrusion, rolling and casting processes.
Flat Rolled Products
Flat rolled products such as plates, sheets and foils are obtained from aluminium through the hot and cold rolling methods.
Extrusion Products
Aluminium profiles, rods, pipes, sheets and rods of various cross-sections are obtained using the extrusion process.
Aluminium is an eminently suitable metal for the extrusion process, whereby many products of different shapes and sizes can be produced economically according to the area of utilization without requiring any other shaping process.
Cast Products
Parts of various sizes and shapes are produced out of aluminium using the die-casting, high-pressure or chill-casting methods used by various aluminium suppliers.
Aluminium Conductors
Being lighter than copper, aluminium provides a great advantage in transmitting electrical power. Therefore, the power transmission lines are made out of aluminium today. The aluminium conductors are produced with a three step process as obtaining rods by continuous casting, converting the rods in to wires by rolling and braiding the wires.
Categorization of Aluminium Use by the Industries :
Aluminium and Construction
The construction sector is using 1.2 million tons of aluminium per annum in Europe, 1.05 tons of aluminium in the USA and 915.000 tons of aluminium in Japan (utilization of aluminium for architectural purposes world-wide in 2000).
Aluminium is used in large quantities for cladding the roofs and facades of the buildings and for manufacturing the doors and windows, stairs, roof frames, scaffolding and hot houses.
In addition to its toughness, aluminium becomes imperishable in a sense with the anodizing(eloxal) process. With either the natural or color eloxal coating or the lacquer coating (electrostatic powder or liquid coating), aluminium provides a rich variety of choices for the architects and engineers in the construction sector. Aluminium extrusion, flat products and cast products are used for manufacturing door/window profiles, exterior /roof cladding and accessories in the construction sector.
Aluminium and Packaging
Aluminium is one of the most versatile packaging materials. Aluminium responds eminently to many packaging applications from container production to the medicinal drug packaging sector. From the toothpaste tube in the bathroom to an endless number of products in the super market (i.e. chocolates etc.) to foil-wrapped oven-ready foods in the kitchen to the cold beverages, aluminium wraps and protects many products. The homogenous structure of aluminium, the capability of producing thin foils (aluminium paper), air-tightness and ease of shaping make the aluminium an ideal packaging material.
Because aluminium is impermeable to the air and ultraviolet radiation, it protects the foods with the natural colors and aromas. In the foil form, aluminium is the most preferred material for vacuum packaging and heat-sealed packaging (yoghurt, medicinal drugs etc.) in the metalized film form (aluminium-coated plastic).
One of the most wide-spread utilization areas of aluminium is the beverage and bear cans. 80% of all the beverage cans used in the world are made of aluminium. The reason is the lightness, ease of opening, impact resistance, robustness, fast cooling and recyclability properties of aluminium.
The high scrap value of the used aluminium beverage cans facilitates the collection of the cans for recycling purposes.
New cans are produced as a result of the recycling process, which starts with the purchase of the used aluminium cans from the consumers.
Aluminium and Transportation Vehicles
Aluminium is one of the most important materials used in the production of the transportation vehicles in the transportation sector. Almost 20% of the Aluminium consumption goes to the production of the transportation vehicles.
The lighter a transportation vehicle is the less energy is required to make them move. 150 kg of Aluminium is used in a car today. Thus approximately 300 kg of iron, steel and copper materials are saved. According to the results of the calculations and experiments conducted, it has been found out that 1500 liters of fuel is saved in the life cycle of a car as compared to a car, in which aluminium was not used.
This fact provides a great benefit in terms of the savings in the fuel expenses for the drivers as well as environmental health by reducing the waste exhaust gases emitted to the atmosphere.
Lightness becomes even more important for the vehicles that have to move and stop frequently such as buses and trains. Important savings in fuel is realized by using aluminium in the large land vehicles today such as the buses, trains, trucks etc.
Furthermore, utilization of aluminium is increasing in the highway traffic and direction signalization systems as well as expressway parapet walls and bridges. In the marine craft, especially in the boats, the center of gravity of the aluminium superstructures are reduces, thus the balance if the hull is improved, allowing for a larger usable volume. The sail masts of the smaller boats and yachts are made of aluminium. 70% of the weight of an airplane is aluminium. Aluminium has provided the largest contribution to the development of the airplanes, hence the aviation sector, due to its lightness along with its durability. After the dur-aluminium (aluminium-copper), the most important aircraft building materials will be the aluminium-lithium alloys. The airplanes can be made 15% lighter with the aluminium-lithium alloys.
Aluminium and Conductors
Aluminium is an excellent conducting metal. Therefore, out of the entire aluminium utilization in the world, 10% is used in the electrical and electronics sector in Europe, 9% in the USA and 7% in Japan. The largest utilization area of the aluminium in this field is the power transmission lines. The steel-core aluminium conductors have become the only material preferred for the high voltage power transmission lines. Aluminium is widely used in the underground cables, electrical cable ducts and motor coil windings as well. In electronics, the frames, chips, transistor heat sinks, data recording systems and the electronic equipment cases are included in the utilization areas of aluminium.
Aluminium and the Other Engineering Applications :
In the machine component applications, the high strength/weight ratio, corrosion resistance and ease of tooling are the superior characteristics of aluminium. Carrying large individual parts is possible due to its lightness. Thanks to its ability of tooling with tight tolerances, manufacturing large components in standard units is possible. Aluminium extrusion provides large benefits in manufacturing the parts with complex cross-sections.
Gear boxes, engine blocks and cylinder heads are made easily with aluminium casting. Utilization of aluminium in the crank shaft bearings in the latest applications has imparted a long life to such parts.
The sleek and shiny light alloy hub caps, which do not required any paint of maintenance and referred to as “steel hubs” erroneously in the automotive sector recently, are in fact made of aluminium.
Aluminium and Energy Saving :
During the technological developments introduced between 1950 and 1986, the amount of the energy required for producing aluminium was reduced by 30%. In the Western World, 61% of the electrical power used for aluminium production is obtained from the hydro power plants. Because the aluminium allows saving more energy in its fields of utilization than the amount of energy consumed for production due to the unlimited ability of recycling, its becomes an “energy bank”.
For example, if the bed of a damper truck would have been made of aluminium instead of steel, 70.000 kWh of energy would be consumed for producing the aluminium to be used for that purpose.
However, as the weight of the truck is reduced with the utilization of aluminium, the fuel saving at the end of a 5-year period would be 250.000 kWh. In the meantime, it should be remembered that the energy saved by the truck is obtained from the expensive fossil fuels, while the energy used for producing aluminum is obtained from the inexpensive hydro power sources.
The railway and airway transportation can be shown as an example to the savings obtained from aluminium. If the airplanes of today were not made of aluminium, the operating expenses would rise to very high uneconomical levels, even if the plane could fly.
Aluminium and Recycling :
Aluminium is 100% and infinitely recyclable. Therefore, the high value of the aluminium scrap encourages the recycling of all of the aluminium consumed, including used aluminium beverage cans. Thus, becoming a new beverage can take only a few weeks. Aluminium never becomes a “waste” and harms the environment. 30% of the aluminium used is obtained by recycling the used aluminium. This ratio is as high as 70% in the electrical, construction and transportation vehicle sectors.
According to a release by the Aluminium Can Recycling Organization of Europe (ACRE), 70 cans out of 100 is recovered by recycling. This rate is expected to rise further in the near future.
Various smelting furnaces are used for recycling the aluminium scrap in many forms (casting scrap, profile scrap, plate scrap, used aluminium goods etc.) and slag. Among those, a new concept furnace with high yield and low energy consumption has become prominent: the Convector Furnace. The Convector Furnaces can melt down the metal 2 to 3 times faster than the other types of furnace and the fuel convection is lowered accordingly. Furthermore, this is preferred for melting the dirty, mixed, iron-containing scrap and slag as it does not require the use of any flux.
Aluminium and Environment :
All industrial applications make an impact on the environment. The Aluminium Sector is one of the industries that affect the environment least. The Aluminium production methods do not harm the environment.
In the primary Aluminium production facilities, the fluorine gas emissions have been reduced by 50% and powder wastes by 75%. The wastes generated in such facilities are at a level, which is not harmful for the environment.
Aluminum and its Sources :
Aluminium is the third most abundant element found in the earth’s crust. This means that sufficient Aluminium will be available as long as the human kind exists.
The reserves of bauxite, which is the most efficient raw material of Aluminium today, are sufficient to last for 3000 years at the present rate of consumption. New bauxite reserves equaling to twice the consumption rate are available. In parallel thereof, studies are continuing for extracting Aluminium from the new kaolin-based ores.
Bauxite is obtained from the open pit mines, whereafter the excavated areas are refilled and replanted to restore the previous appearance of the nature.
Aluminium and Future :
As the industry and technology develops further, the use of aluminium also increases. Aluminium is preferred for the products that are lighter, stronger, more efficient, longer-lasting and, as a result, more economical.
Aluminium is the indispensable material for the aircraft, including the space ships, better buildings and bridges, power transmission lines and the other engineering applications.
The Aluminium industry is continuing with the research and development efforts aimed at new alloys, technological developments, production methods, product design and quality control.
Aluminium and Quality :
The quality of the primary Aluminium is closely related to the quality of the ore it is extracted from and the operational conditions of the electrolysis process.
As the raw materials for the extrusion and flat products, the Aluminium ingots are recommended to be 99.5%-99.7% pure. The desired alloy is prepared by adding the required elements (silicone, magnesium, copper, zinc etc.) into this material. Obtaining the desired mechanical characteristics in all the Aluminium products is only possible by satisfying the proper alloy and heat treatment conditions.
Leaving maximum 0.25% of iron in the Aluminium used for the extrusion products of architectural purposes is recommended in connection with the decorative appearance of the profile after the anodizing process and the quality of the anodizing process.
Attention should be paid to ensure that the profile sizes and tolerances remain within the values stipulated in the standards as well as the surface quality. The compliance of anodizing and electrostatic coating, which are the principal surface treatment operations for Aluminium, with the relevant standards should be sought. Regarding the anodizing quality, the anodizing thickness and adherence quality, and for the coating job, the surface treatment before painting, the quality of the dye used, thickness of the paint film and adhesion quality are important factors.
For the coated Aluminium products, any one of the polyester, pvdf or plastisol-based paints should be selected and used depending on the weather conditions and the effects of the sun.
The suggestions given above are also applicable for the flat products to be used for architectural purposes..
Since the Aluminium conductors are used for power transmission, their quality is exceptionally important. The conductivity value of the conductors has to be minimum 61% IACS at 200C. Otherwise the line losses caused by the conversion of the electrical energy in to heat increase.
Therefore, standards specifying the values regarding the purity and mechanical properties of the Aluminium conductors, which have to be complied with, have been issued.
In the cast products, absence of cracks and gas pockets in the product’s structure is required along with the desired alloy and tempering.
The Turkish Standards Institute (TSE) has prepared the standards of the Aluminium products. Using the products that comply with those standards is an important duty on the part of the users. By doing these two very important issues, unfair competition and wasting the national wealth, can be prevented. Purchasing the products with the TSE mark/certification in the public tenders has been stipulated.
Aluminium prices are based on supply and demand drivers. Today, aluminium has become a tradable commodity, being exchanged on various mediums, such as London Metal Exchange (LME), Shanghai Metal Exhange (SHMET), etc.
Source: www.aluminyumsanayi.com
Alu Foil Key Assets
Net Saver of Resources
Thanks to aluminium’s high resource efficiency, Aluminium foil in food and drink packaging applications saves more resources than what may alternatively be needed in its production. Various Life Cycle Assessments (LCAs) show that aluminium foil packaging and household foil contribute less than 10% of the environmental impact in a product‘s lifecycle – production, preparation and consumption.
Barrier Protection
Alufoil’s total barrier to light, gases and moisture is the principal reason for its use in fl exible laminates for food, drink and technical applications. Even when very thin, it provides perfect protection and preservation of aroma and product characteristics. It can help to extend the viable life of sensitive products for many months, even years, fully retaining valuable aromas. By enabling products to be preserved for long periods without the need for refrigeration, alufoil packaging helps to prevent spoilage and can provide large energy savings.
Mechanical Properties
Light yet strong, alufoil has unique deadfold characteristics which make it ideal for wrapping and re-wrapping many different products and product shapes, while minimising the need for sealants. Because it is very malleable it can be easily deformed without losing its barrier integrity, making it an ideal material for use in combination with other fl exible substrates to create very thin laminates for a variety of markets, and consequently once again saving resources.
Formability and Strength
When pressed into a shaped dish, the aluminium foil memorises its shape, particularly where the folds and rims occur. Shape, thickness, alloy and temper can be selected to create exactly the
performance characteristics required.
Lightweight and Space Efficient
Economies in both transport and storage result from lightness, fl at or reeled format of empty packs and, in the case of alufoil containers, their nesting shapes which are particularly suited to
fi lling-machine magazines. Alufoil helps saving resources during packaging, product and waste transportation. By enabling products to be preserved for long periods without the need for refrigeration, alufoil packaging provides large energy savings – their shape can make them very ‘space effi cient’ in storage and display, enabling further energy and cost savings. Alufoil is
weight saving, effective and minimises the amount of packaging material needed.
Structural Stability
In light honeycomb structures, aluminium foil introduces the necessary stiffness and stability enabling architects to lighten building structures and foundations, and engineers to save weight in all types of transport – ships, planes, trucks and cars.
Recycling
Aluminium is 100 % recyclable, endlessly, without any loss of quality. The recycling process for aluminium requires 95 % less energy compared to the primary production, which corresponds
to enormous emission savings. Modern separation techniques allow aluminium foil in household waste to be extracted and recycled at a fraction of its original energy cost.
Recovery
If aluminium foil is not collected for recycling but processed in incinerators mostly the thin, laminated foil material is oxidised and releases energy, which can be recovered. What’s more,
the remaining non-oxidised aluminium can be extracted from the bottom ashes of the incinerator and subsequently used for recycling purposes.
Heat Performance
Alufoil is very conductive to heat. It stands up to all temperature variations encountered in the processing and use of packaging – from well below blast-freezing to the extremes of baking and grilling without distorting, melting or the risk of sudden cracking. Alufoil also dissipates heat quickly – ideal for autoclaving and heat-sealing processes. It can help minimise sealing times and evens out the temperature gradient, both within containers and fl exible packaging, helping to protect product quality and energy economy. Its heat conductivity can help minimise processing, chilling and reheating times. Vital to the effi cient operation of a vehicle’s power plant, and to the
comfort of driver and passengers, alufoil-fi nned heat exchangers provide both cooling and heating as required. Thanks to its light weight, alufoil has become the automatic choice.
Multi-mode Heating or Cooking
Food in alufoil dishes can be cooked, re-heated or heated by convection, microwave or fan oven or in ‘bain-marie’ systems. Alufoil packaging helps to save time and resources during preparation.
Hygiene
Once produced, alufoil is completely sterile thanks to the high temperature annealing process. It is safe for use in contact with foodstuffs and it doesn’t harbour or promote the growth of bacteria.
Safety and Product Security
Alufoil is safe for use in contact with foodstuffs. Uncoated aluminium foil will not react with the vast majority of foods. In many applications, alufoil is not in contact with the product as it is used in association with other materials within a laminate. In addition it is an ideal protection against product tampering and can support anti-counterfeiting features.
Decorative Potential
Alufoil’s bright or matt metallic finish plus its compatibility with all printing technologies provides designers with enormous scope to create packs with stunning graphic design, shelf presence and brand identity.
Reflectivity
Aluminium foil refl ects up to 98% of light and infrared heat. The bright surface also has low heat emissivity. This helps to save energy in insulation. Its insulation role extends into fire protection. In ‘fi re walls’ for vehicles and ships, for fi re-resistant doors and building panels, aluminium foil dissipates heat and stops access to the oxygen required to support flames.
Electrical Conductivity
Alufoil shields against magnetic and radio frequency emissions. Used in fibre-optic cables, alufoil acts as a ‘tracer’ to enable testing of the integrity of cable links. In cable wrap, electrical conductivity enables the integrity of the cable circuit to be verified.
Aluminium and Our Health
An average human body contains approximately 35 g of Aluminium. Almost 50% of that quantity is located in the lungs, 25% in the soft tissues and 25% in the bones. The amounts of Aluminium that can be absorbed from the kitchen utensils, kitchen foils and beverage cans is a very small portion of the Aluminium that can be absorbed from the daily food intake.
Although articles have been published in some sources concerning the effects of Aluminium on the human health, Aluminium does not have any effects that threaten the human health directly.
The conclusions and recommendations set out in the European Union guidelines concerning the metals that come in contact with foodstuff are as follows:
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User information stating; “Do not allow these products to contact the food with high acid content or moist-salty food before cooking” or “to be used for storing foods in the refrigerator” shall be provided by the manufacturers on the un-coated Aluminium products that contact the foods.
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The informational explanations should be provided by the un-coated Aluminium utensil manufacturers to be used in the acidic or salty environments.
Aluminium and the Alzheimer Disease
The Alzheimer disease is one of the most common brain diseases. There is a false conviction that Aluminium causes Alzheimer disease in the society. The research for finding the causes of the Alzheimer disease is still continuing today. In these studies, the genetic factors, metabolic variables, abnormal proteins and the environmental factors associated with Aluminium, solvents and other metals are evaluated. Since 2- to 30 times more Aluminium is found in the brain cells of the Alzheimer patients, it is considered as a possible cause of the disease. However, there is no definitive evidence that the accumulation of Aluminium in the brain is a cause or a result of the said disease. The most important parameter in the development of this disease is the genetic traits and the interaction of the environmental factors with each other and therefore, Aluminium alone is not a reason for developing the disease.
According to the World Health Organization (WHO):
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No evidence has been found suggesting that Aluminium is the primary cause of the Alzheimer disease,
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It has been demonstrated that Aluminium does not lead to any pathology, including the humans.
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No acceleration in the development of the Alzheimer disease has been observed in the patients, who use drinking water with high Aluminium content.
References:
Compiled from the works of the:
WHO – World Health Organization
Ministry of Health, Canada
Dr. Peter Baum – Council of Europe
German Risk Assessment Institute
W.Ted Brown M.D. Ph.D – New York State Inst. Research Dept.