Pure Aluminum is a suitable material that is commonly used in different industrial fields. The growth of technology helps manufacturers create various products to help the modern era in architecture and designs. Aluminum has physical specifications that make it suitable for construction products. This material’s most essential characteristics include versatility, strength, low weight, durability, and corrosion resistance.
Although the material is one of the most found substances in the mother earth, producing pure Aluminum suitable for industrial projects is not a simple procedure. The production includes many stages, starting with obtaining and mining bauxite and then more specific processes. Bauxite is a mineral containing 50% aluminum and is used as a primary material. The second stage is creating alumina from the mineral obtained with different methods such as the Bayer process. Another vital component in the production process is cryolite made from hydrofluoric acid and aluminum hydroxide and soda mixture. More details are introduced in How is The Pure Aluminum Produced part 1 article about the stages above. This article is about other steps, including production, cast house, new technologies, and recycling.
Pure Aluminum Production
After mining bauxite, making alumina from the mineral and stockpiled cryolite, it is time for the procedure’s most crucial stage, the electrolytic reduction, to make Aluminum. The reduction zone is considered the heart of a smelter. This area does not look similar to the production shops in typical steel workshops that create steel or iron. This area consists of several rectangular buildings while having a length that sometimes can exceed 1 kilometer. Hundreds of reduction cells or posts are arranged in rows and hooked up to power sources with massive and huge cables inside these facilities. Each reduction cell has a different constant voltage at the electrodes having a range between 4 and 6 volts, while the amperage of each can reach 400 KA and even more. The main production force is the electric current. It is good to mention that there are only a handful of people in a standard reduction zone, as all the main processes are fully automatic.
The electrolytic reduction process is used in each cell to produce Aluminum from alumina. For creating a conducive environment at a temperature of 950 centigrade degrees, the entire cell is filled up with molten cryolite. The bottom section of the cell works as a cathode, while cryolite-carbon blocks play the cathode. These blocks have a 1.5-meter length and 0.5-meter width that are lowered into the cell and look like giant hammers. An automatic alumina feeding machine dumps a new portion of material into the cell with every thirty minutes sequence. The electric current breaks down the bond between oxygen and Aluminum, causing the metal to settle to the bottom of the processing area and form a 10-15 cm depth layer. In contrast, the oxygen binds with the carbon in the anode sections to create carbon dioxide.
The Aluminum gets extracted from the cell with special equipment and vacuuming systems about two to four times per day. A hole is punched in the cryolite coat that forms on the surface of the cell. After this, a pipe is lowered and fixed on the spot. The liquid metal gets sucked into the bucket through the line from which all air is pumped out. One ton of metal is obtained from every reduction cell, while one bucket can hold 4 tons of molten metal. Once the bucket is complete, it is taken to the cast house for creating other products such as aluminum composite panels. One of the essential things about this procedure is that it consumes a considerable amount of electric power. Thus, it is crucial to use renewable energy sources such as hydroelectric power plants that don’t spoil the environment.
Cast House
Molten Aluminum is transported in buckets to the cast house of the smelter. At this step, the metal still contains a lot of silicon, copper, iron and other elements. However, even the smallest number of extra admixtures can have a drastic impact on metal properties; thus, in the cast house, all admixtures are omitted by remelting the meal in a particular heater at 800 centigrade degrees. The resultant pure Aluminum is cast into special molds where it is allowed to become solid. The smallest aluminum ingots are known as pigs, weighing between 6 and 22.5 kg. The manufacturers should remelt pigs after receiving and then recast them in the shape of any industrial materials such as Aluminum sidings. The most significant ingots are 30-tonne slabs and have 11.5-meter length. Hot Aluminum needs to be poured into a mold like this over two hours only from the bottom up. After casting the slab, it is cooled down with water, and as soon the process is completed, the slab is ready for shipment. Slabs are usually rolled into thin sheets that are then used in the manufacture of different products.
Cast house is an area in which Aluminum is given the required shape and chemical composition. The crucial thing is that pure metal is used less than alloys. These alloys are made by mixing Aluminum with various other metals to increase its strength or make it denser or even change its heat transmission properties. Common alloying elements include iron, silicon, magnesium, manganese, copper, lithium, zirconium, etc.
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