Aluminum Foil-The Making Process


The ever-amazing aluminum foil actually contains between 92-99 percent aluminum and is made from an alloy of the metal. Depending upon its usage, this product is manufactured in varying thickness that can range from 0.00017 to 0.2 inches.

Some of aluminum foil’s many uses include air conditioner fin stocks, television and radio capacitors, thermal insulation, transformer electrical coils, decorative items, packaging and containers, and storage tank insulations.

What makes aluminum foil so popular and its uses so widespread is that the raw materials required to manufacture it are present in abundance.

Another advantage is its relative inexpensive nature that makes it affordable to almost everyone. Other qualities, such as its durability, non-toxicity, and being greaseproof also add to its charm.

Aluminum foil is often used in science labs because it is resistant to many chemicals and can be used to shield apparatus and appliances from both electrical and magnetic interference.

To extracting pure aluminum, the bauxite ore is used. The extraction is essentially a two-step process.

In the first step, bauxite is separated from the impurities that it may contain. These include silica, iron oxide, and titanium. When purified aluminum oxide is produced, it is then smelted so that only aluminum is left behind. Then, the aluminum will be rolled and the result is the foil that you purchase from the market.

This procedure is completed in four steps, which are digestion, clarification, precipitation, and calcination.

In the first stage or digestion, the bauxite ore is first ground to a powder. It is then mixed with sodium hydroxide. After that, this mixture is pumped into huge tanks, called digesters, which are pressurized. In the digesters, the combined mixture of bauxite and sodium hydroxide is broken down by the action of heat and pressure. The ore transforms into its next state, say, the sodium aluminate saturated solution. Any contaminants that are insoluble will settle down at the bottom.

Now, start the next phase of clarification. In this process, the saturated solution of sodium aluminate, as well as, the contaminants are both sent through a set of presses and tanks. The filters that are present in those tanks will trap the contaminants. The contaminants will then be disposed off, leaving behind a clean solution of sodium aluminate. This solution is filtered once again before it is sent to a cooling tower.

The third stage entails that the aluminum oxide solution be sent to a large silo. When that happens, aluminum oxide is then seeded with hydrated aluminum crystals. This leads to the formation of aluminum particles. Soon, the seeding crystals will attract the other crystals and soon they will join. These huge aggregates are actually made of aluminum hydrate. The aluminum hydrate clumps will first be filtered out of the solution before being rinsed.

The previous step leads to Calcination, which is the final step of the refinement process. In this phase, the aluminum hydrate is exposed to heat. The extreme temperature will result in dehydration of the material until all the water is dried. The residue will consist of aluminum oxide, a fine white powder.