Aluminum is classified into unwrought aluminum and wrought aluminum according to components and production process.

　　Unwrought aluminum: Being crisp and hard with aluminum content being less than 98%, used for manufacturing products only through sand casting.

　　Wrought aluminum: Being soft with aluminum content exceeding 98%, used for manufacturing various kinds of utensils through calendaring or impact rolling.

　　According to content of main component, aluminum ingot can be classified into three types: High-grade pure aluminum (with aluminum content being 99.93% ~ 99.999%), industrially high-purity aluminum (with aluminum content being 99.85% ~ 99.90%) and commercially pure aluminum (with aluminum content being 98.0% ~ 99.7%).

　　According to application, aluminum can be classified into: Aluminum ingot for remelting: aluminum content 95% ~ 99.7% and sold as raw materials after further processing.

　　Refined aluminum: With premium aluminum as raw material and three-layer electrolytic refining process, aluminum produced has an aluminum content of 99.93% ~ 99.996%. Due to its high resistance to corrosion, high electric conductivity and high plasticity, refined aluminum has been widely used in electric industry, chemical industry and food industry.

　　High-purity aluminum: With high-quality aluminum as raw material and directional solidification, aluminum obtained has an aluminum content of 99.999%. This kind of aluminum can be used to manufacture high-purity materials and reflecting materials.

　　Aluminum wire bar: Aluminum content 99.5% ~ 99.6%, used for rolling aluminum wires in cable factory.

　　Slab ingot: Aluminum content 98% ~ 99%, used for manufacturing sheet materials in aluminum processing plant.

　　Round ingot: Semi-finished products manufactured in aluminum smelter and offered as ingot blank for extruding machine in aluminum processing plant.

　　Cast aluminum bus: Aluminum content >99.5%, used as conductive busbars with large section.

　　Aluminum rod: aluminum content: About 99.7%; diameter: about 9.5mm; used for drawing electric wires in cable factory.

　　Electrical aluminum: Aluminum ingot with Si content being 0.06% ~ 0.10% and Fe content being 0.13% ~ 0.25%, offered to manufacture aluminum conductor with resistivity being less than 0.028264 Ω in cable factory.

　　Sheet material: Used as raw materials after further processing.

　　Aluminum profile: Used to manufacture structural framework of aluminum doors and windows.

　　Aluminum wire rod: Aluminum of relatively low grade can be used to manufacture low-resistivity and high-strength aluminum conductor.

　　Category of aluminum alloy

　　The number in the first place of four-digit system and four-character designation indicates category of aluminum and aluminum alloy. Specific information is as follows:

　　1 1XXX series: Commercially pure aluminum;

　　2 2XXX series: Al-Cu alloy and Al-Cu-Mn alloy;

　　3 3XXX series: Al-Mn alloy;

　　4 4XXX series: Al-Si alloy;

　　5 5XXX series: Al-Mg alloy;

　　6 6XXX series: Al-Mg-Si alloy;

　　7 7XXX series: Al-Mg-Si-Cu alloy:

　　8 8XXX series: Others.

　　1XXX series: Characteristics: Aluminum content >99.00%, high conductivity, high resistance to corrosion, high welding performance, low strength, no heat-treatment strengthening. Application scope: High-purity aluminum (aluminum content >99.9%) is mainly used for scientific experiments and special purposes and in chemical industry.

　　2XXX series: Characteristics: Aluminum-containing alloy with copper as the main alloy element. Manganese, magnesium, lead and bismuth can also be added for cutability. For example, attention should be paid to safety protection during smelting of 2011 alloy (harmful gas will be generated), 2014 alloy, high-strength, is applied to aviation industry and can be strengthened by heat treatment. 2017 alloy has a lower strength than 2014 alloy but is easy to be processed. Disadvantage: high possibility for intergranular corrosion. Application scope: Aviation industry (2014 alloy), screw (2011 alloy), industries requiring high processing temperature (2017 alloy).

　　3XXX series: Characteristics: Aluminum alloy with manganese as the main alloy element, high resistance to corrosion, high welding performance and high plasticity (close to super-plastic aluminum alloy). Heat-treatment strengthening is not allowed. Disadvantages: Low-strength, but can be strengthened through cold hardening; easy to generate coarse grain during annealing. Application scope: Seamless oil conduit on airplane (3003 alloy); ring-pull can (3004 alloy).

　　4XXX series: With silicon as the main component, not commonly used. Some of 4XXX series alloys can be strengthened by heat treatment, but some of 4XXX series alloys are not allowed to receive heat-treatment strengthening.

　　5XXX series: Characteristics: With magnesium as the main component, high resistance to corrosion, high welding performance, high fatigue strength. Heat-treatment strengthening is not allowed but such series can be strengthened through cold hardening. Application scope: Handle of hay mower, conduit of oil tank on airplane, and body armor.

　　6XXX series: Characteristics: With magnesium and silicon as main components. Mg2Si is the main strengthening phase and such series of alloys are the ones most widely used. 6063 alloy and 6061 alloy are most often used compared with 6082, 6160, 6125, 6262, 6060, 6005 and 6463. Among 6XXX series alloys, the strengths of 6063, 6060 and 6463 are relatively lower, while the strengths of 6262, 6005, 6082 and 6061 are relatively higher. Characteristics: Moderate strength, high resistance to corrosion, high welding performance, favorable processing property (easy to be extruded for moulding) and high performance in heat tinting. Application scope: Such vehicle parts as roof rack, door, window, vehicle body, cooling fin and case.

　　7XXX series: Characteristics: With zinc as the main component and sometimes with a few amount of magnesium and copper. Super-hard aluminum alloy is an alloy containing zinc, lead, magnesium and copper, with its hardness being close to steel. This series of alloys have a lower extrusion velocity than 6XXX series alloys but have a high welding performance. 7005 alloy and 7075 alloy rank the first among 7XXX series and can receive heat-treatment strengthening. Application scope: Aviation industry (force bearing components and landing gear of airplanes), rockets, propellers and spacecraft.

　　Classification of aluminum scrap

　　At present, classifications of scrap aluminum in China are basically the same. Wrought aluminum scrap, unwrought aluminum scrap and alloyed aluminum scrap are classified. Aluminum scrap is identified mainly according to physical and chemical properties of aluminum and aluminum alloy.

　　I Wrought aluminum scrap

　　1 Source

　　Wrought aluminum scrap refers to pure aluminum with a high aluminum content (>98%) and mainly in forms of plate, strip (sheet), wire, tube, residual materials, such domestically discarded utensils as pot and kettle, and discarded equipment, containers, parts and , components to be replaced in factories and enterprises.

　　2 Characteristics

　　Characteristics of wrought aluminum scrap are as follows: Both the surface and the section of wrought aluminum scrap are in silvery white. Such scraps are pliable but strong. Sharp ironware can make deep scars on the surface of such scraps, which are easy to bend with hand and not elastic. Generally, breakage of such scraps requires successively three times of bending. The cross section is higher in the middle and lower on both sides. There are multiple pull racks on the edges of the cross section where the texture is fine. Aluminum is characterized by light weight and is more than two times lighter than such nonferrous metals as copper, lead and zinc. In case of knocking, the sound generated is loud but not sharp, with short aftersound.

　　3 Detailed Classification

　　Wrought aluminum scrap has three types: offcut of Wrought aluminum, industrially wrought aluminum scrap and wrought aluminum scrap for civil use.

　　II Unwrought aluminum scrap

　　1 Source

　　Most of unwrought aluminum scraps come from cast parts and components, like mechanical parts and unwrought aluminum for civil use.

　　2 Characteristics

　　Most of common unwrought aluminum scraps are aluminum-silicon alloys, with silicon content ranging from 4.5% to 13.9%. Some aluminum scraps also contain certain amount of steel and a little iron. Unwrought aluminum scraps are greyish white in color and hard but can be stricken off. Aluminum-silicon alloys, such as mechanical parts and unwrought aluminum for civil use, have a cross section, which is tinged with blue gray and easy to be stricken off and has a coarse-grained texture. Aluminum-copper alloy is hard and has a tenacity better than that of aluminum-silicon alloy. Aluminum-copper alloys, such as cylinder piston and parts that is resistant to impact, high temperature and corrosion, have a white cross section with a fine-grained or fine texture.

　　III Alloyed aluminum scrap

　　1 Source

　　Alloyed aluminum scraps have an appearance similar to that of pure aluminum and are such profiles as aluminum plate, strip (sheet), tube, wire, channel and angle, residual offcuts of profiles, and discarded or replaced structural members, equipment and the like.

　　2 Characteristics

　　Alloyed aluminum scraps generally have an aluminum content of 90% ~ 98.9%. In addition to aluminum, steel, iron, silver, etc. are also contained. In most cases, alloyed aluminum scrap is composed of more than two elements. Such scraps are white in color and hard and have elasticity and poor tenacity. In general, sharp ironware will not leave deep scars on the surface of such aluminum craps. They are difficult to be bent with hands, but just two or three times of bending can break them. The fracture surface is relatively flat and tinged with gray and has a fine texture. There are no (or a few) pull cracks on the edges of the fracture surface. In case of knocking, the sound generated is loud and sharp, with long aftersound (compared with pure aluminum).

　　IV Other aluminum scraps

　　In addition to the above-mentioned three kinds of aluminum scraps, there are waste aluminum wire, waste aluminum case, aluminum toothpaste tube, ointment tube, aluminum skimming, aluminum dross, etc.