How Aluminium Is Produced:
The pure form of aluminium does not naturally occur in nature, so remained largely unknown until as recently as 200 years ago. Creating aluminium using electricity was first developed in 1886 and is still used to this day.
BAUXITE MINING:
The aluminium production process starts with the mining of bauxites, an aluminium rich mineral in in the form of aluminium hydroxide. About 90% of global bauxite supply is found in tropical areas.ALUMINA PRODUCTION:
1.Crushing:
Bauxite is crushed, dried and ground in special mills where it is mixed with a small amount of water.
This process produces a thick paste that is collected in special containers and heated with steam to remove most of
the silicon present in bauxites.
2.Digestion:
REDUCTION PROCESS:
Electrolyitc Reduction
At an aluminium smelter, alumina is poured into special reduction cells with molten cryolite at 950℃. Electric currents are then induced in the mixture at 400 kA or above; this current breaks the bond between the aluminium and oxygen atoms resulting in liquid aluminium settling at the bottom of the reduction cell.PRIMARY ALUMINIUM:
Casting:
Primary aluminium is cast into ingots and shipped to customers or used in the production of aluminium alloys for various purposes.ALUMINIUM ALLOYS:
Extrusion:
The process where the aluminium is shaped to its required form. This process is used for making the
vast majority of aluminium products from spectacle frames, telephone bodies, aeroplane fuselages or spaceship
bodies.
Rolling
RECYCLING:
Unlike iron, aluminium is corrosion resistant so it can be remelted and reused an infinite number of
times. The added benefit is that recycling aluminium requires only 5% of the energy needed to make the same
amount of primary aluminium.
PROPERTIES, ADVANTAGES, DISADVANTAGES AND APPLICATIONS
3.1 Properties
1. Durability:
Aluminium building products are made from alloys, which are weather-proof, corrosion-resistant and immune to the harmful effects of UV rays, ensuring optimal performance over a very long serviceable lifetime.
3.1 Properties
1. Durability:
Aluminium building products are made from alloys, which are weather-proof, corrosion-resistant and immune to the harmful effects of UV rays, ensuring optimal performance over a very long serviceable lifetime.
2. Design flexibility:
The extrusion process offers an almost infinite range of forms and sections, allowing designers to integrate numerous functions into one profile. Rolled products may be manufactured flat, curved, shaped into cassettes, or sandwiched with other materials. In addition, aluminium can be sawed, drilled, riveted, screwed, bent, welded and soldered in the workshop or on the building site.
The extrusion process offers an almost infinite range of forms and sections, allowing designers to integrate numerous functions into one profile. Rolled products may be manufactured flat, curved, shaped into cassettes, or sandwiched with other materials. In addition, aluminium can be sawed, drilled, riveted, screwed, bent, welded and soldered in the workshop or on the building site.
3. Hundreds of surface finishes:
Aluminium can be anodized or painted in any colour, to any optical effect, using any number of surface touches, in order to meet a designer’s decorative needs. Such processes also serve to enhance the material’s durability and corrosion resistance, as well as providing an easy-to-clean surface.
Aluminium can be anodized or painted in any colour, to any optical effect, using any number of surface touches, in order to meet a designer’s decorative needs. Such processes also serve to enhance the material’s durability and corrosion resistance, as well as providing an easy-to-clean surface.
4. High reflectivity:
This characteristic feature makes aluminium a very efficient material for light management. Aluminium solar collectors can be installed to lower energy consumption for artificial lighting and heating in winter, while aluminium shading devices can be used to reduce the need for air conditioning in summer.
This characteristic feature makes aluminium a very efficient material for light management. Aluminium solar collectors can be installed to lower energy consumption for artificial lighting and heating in winter, while aluminium shading devices can be used to reduce the need for air conditioning in summer.
5. Fire safety:
Aluminium does not burn and is therefore classed as a non-combustible construction material. Aluminium alloys will nevertheless melt at around 650°C, but without releasing harmful gases. Industrial roofs and external walls are increasingly made of thin aluminium cladding panels, intended to melt during a major fire, allowing heat and smoke to escape and thereby minimizing damage.
Aluminium does not burn and is therefore classed as a non-combustible construction material. Aluminium alloys will nevertheless melt at around 650°C, but without releasing harmful gases. Industrial roofs and external walls are increasingly made of thin aluminium cladding panels, intended to melt during a major fire, allowing heat and smoke to escape and thereby minimizing damage.
6. Optimal security:
Where high security is required, specially designed, strengthened aluminium frames can be used. While the glass for such applications may well be heavy, the overall weight of the structure remains manageable thanks to the light weight of the aluminium frame.
Where high security is required, specially designed, strengthened aluminium frames can be used. While the glass for such applications may well be heavy, the overall weight of the structure remains manageable thanks to the light weight of the aluminium frame.
3.2 Advantages
1. Lightweight
Aluminium is one of the lightest available commercial metals with a density approximately one third that of steel or copper.
1. Lightweight
Aluminium is one of the lightest available commercial metals with a density approximately one third that of steel or copper.
2. Excellent Corrosion Resistance
Aluminium has excellent resistance to corrosion due to the thin layer of aluminium oxide that forms on the surface of aluminium when it is exposed to air
Aluminium has excellent resistance to corrosion due to the thin layer of aluminium oxide that forms on the surface of aluminium when it is exposed to air
3. Strong at Low Temperatures
Where as steel becomes brittle at low temperatures, aluminium increases in tensile strength and retains excellent toughness.
Where as steel becomes brittle at low temperatures, aluminium increases in tensile strength and retains excellent toughness.
4. Easy to Work
Aluminium can be easily fabricated into various forms such as foil, sheets, geometric shapes, rod, tube and wire.
Aluminium can be easily fabricated into various forms such as foil, sheets, geometric shapes, rod, tube and wire.
5. Easy Surface Treatment
For many applications, aluminium requires no protective or decorative coating; the surface supplied is entirely adequate without further finishing
For many applications, aluminium requires no protective or decorative coating; the surface supplied is entirely adequate without further finishing
3.3 Disadvantages:
1. Thermal insulation was almost definitely insufficient: aluminium being a good thermal conductor.
2. Poor water proofing due to the inadequately designed/executed joints between the roof aluminium sheets
3. General noise caused by rain or hail falling on aluminium roof and wall sheets.
1. Thermal insulation was almost definitely insufficient: aluminium being a good thermal conductor.
2. Poor water proofing due to the inadequately designed/executed joints between the roof aluminium sheets
3. General noise caused by rain or hail falling on aluminium roof and wall sheets.
3.4 Applications
The best application can be obtained in some typical cases, which are characterised in getting profit at least of one of the main basic properties: lightness, corrosion resistance and functionality. The structural applications which best fit these properties in the field of civil engineering are the following:
The best application can be obtained in some typical cases, which are characterised in getting profit at least of one of the main basic properties: lightness, corrosion resistance and functionality. The structural applications which best fit these properties in the field of civil engineering are the following:
1. Long-span roof systems in which live loads are small compared with dead loads, as in the case of reticular space structures and geodetic domes covering large span areas, like halls and auditoriums.
2. Structures located in inaccessible places far from the fabrication shop, for which transport economy and ease of erection are of extreme importance, like for instance electrical transmission towers, which can be carried by helicopter.
3. Structures situated in corrosive or humid environments such as swimming pool roofs, river bridges, hydraulic structures and offshore super-structures.
4. Structures having moving parts, such as sewage plant crane bridges and moving bridges, where lightness means economy of power under service.
5. Structures for special purposes, for which maintenance operations are particularly difficult and must be limited, as in case of masts, lighting towers, antennas towers, sign motorway portals, and so on.
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