The simple can you drink Sprite, Coca-Cola or Fanta from is an underappreciated source of aluminum. The fact is that they are made from high-quality aluminum with a small admixture of tin, which is indispensable in the food industry.
Source practicalsurvivalist.com
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How to melt aluminum cans - Metalist's Guide
Recycling scrap aluminum cans into new cans is considered a great example of a nearly waste-free production process. It is the recycling of scrap aluminum cans that has played a major role in the rapid growth of the market for aluminum cans for beer and carbonated drinks.
Remelting scrap aluminum cans
More than 350 billion aluminum cans are sold worldwide. However, not all banks are scrapped. The share of scrap in the total volume of aluminum cans is:
- in Sweden - 90% aluminum cans,
- in the USA - up to 70%,
- in Australia, Canada, Japan and China - about 80%,
- in the world as a whole – a little more than 50%.
Some scrap aluminum cans are melted down in conventional or rotary melting furnaces and are used mainly for the production of foundry alloys. A simple remelting of waste aluminum cans gives approximately the following composition of aluminum: Si – 0.19%; Fe – 0.57%; Cu – 0.29%; Mn – 0.72%; Mg – 0.83%; Zn – 0.07%; Li – 0.01%; Cr – 0.014%; Pb – 0.01%; Ti – 0.01%, the rest – Al.
However, the vast majority of metal from scrap aluminum cans—about 80%—is returned to the manufacturers of new cans. Below are general approaches to recycling aluminum can scrap when it is used again to make cans. Similar, sometimes very complex, technologies are used in many factories in the USA and Western Europe.
Aluminum Can Alloys
It is useful to know that aluminum cans are made from several different aluminum alloys and only from them.
In the body of the can, aluminum alloy 3004 or aluminum alloy 3104 is used, which are very similar in chemical composition: manganese and magnesium on average 1%, copper - up to 0.25% and iron - up to 0.7-0.8%. The lid of the jar is made of 5182 alloy.
This alloy already contains 4-5% magnesium, and 0.20-0.50% manganese. The key for opening the can makes the smallest contribution to the total mass of the can. It is made from alloy 5042 with a magnesium content of 3-4% and manganese - 0.20-0.50%.
Shredding aluminum can scrap
Typically, aluminum cans are sent for remelting in the form of briquettes weighing up to 400 kg and with a density of no more than 500 kg/m3. These briquettes are convenient for transportation, but are not suitable for direct loading into an oven for melting into materials that will be used to make new cans.
Therefore, these briquettes are crushed and sorted to ensure that they do not contain liquids or explosive materials. This is very important to ensure the safety of foundry workers and the safety of foundry equipment.
For this purpose, a special grinding machine is used - a shredder.
Sorting of aluminum scrap
From this shredder, the shredded scrap passes through a magnetic separator, which removes magnetic steel impurities.
After the magnetic separator, the scrap passes through an air knife, which separates materials that are heavier than aluminum: lead, zinc and stainless steel.
After the shredding and sorting operation, the crushed and sorted aluminum cans (or what is left of them) are sent to the devarnish removal equipment.
"Declaring" scrap aluminum cans
Two approaches to continuous thermal varnish removal are used. One is based on holding shredded aluminum scrap for relatively long periods at a specific temperature, and the other is based on short heating cycles, gradually raising the temperature to just below the melting point.
In the first case, a conveyor oven is used, in which crushed aluminum cans pass through a chamber at a temperature of about 520 ° C. This chamber contains varnish combustion products, which are diluted with air to create an atmosphere favorable for varnish removal.
The second approach uses a rotary furnace with a complex system for recirculating combustion products. The final stage temperature is about 615°C, which is very close to the temperature at which melting begins in aluminum-magnesium alloys, which are commonly used to make lids (alloy 5182) and openers (alloy 5054) of beer cans.
Both systems can have problems that result in incomplete varnish removal. If the temperature is too low or the processing time is too short, a black resinous coating remains on the surface of the aluminum.
This leads to the ignition of scrap during its melting and excessive loss of metal due to waste.
If the temperature is too high or the processing time is too long, this leads to significant oxidation of the scrap and also leads to increased metal losses.
Separation of aluminum alloys
The hot, “delaminated” aluminum scrap then enters a thermomechanical separator chamber. This chamber maintains a predetermined temperature and a non-oxidizing atmosphere.
In it, the lids of cans made of alloy 5182, as well as keys made of alloy 5054, are subjected to light mechanical stress, as a result of which they are broken into small fragments along the grain boundaries. The whole process is based on the fact that under the influence of a narrow temperature range, only the grain boundaries are softened.
These small fragments of 5181 and 5054 alloys are continuously screened out and sent to the lid melting furnace, and the remaining aluminum scrap is sent to the can body melting furnace.
Melting aluminum scrap
Special furnaces are usually used to melt aluminum cans. When melting, a significant amount of slag is formed - a mixture of metal, oxides and other contaminants. This slag contains a lot of gases, so it floats well on top of the melt. It is removed and sent for metal recovery.
Melting aluminum in a bucket with plaster
There is another simple and inexpensive option for melting aluminum, which can be done at home.
To work you will need the following set of materials, consumables and tools:
- 9-liter metal bucket;
- 4-liter plastic bucket;
- plastic basin;
- crucible;
- sand, gypsum, water for solution;
- a piece of steel pipe;
Bucket melting furnace
- deep iron plate;
- a pair of metal hooks;
- vice and workbench;
- drill with drills;
- pliers;
- roulette;
- hammer, dowel;
- rubber gloves;
- napkins or rags.
How to make a furnace for melting aluminum
First, prepare a solution - combine gypsum and sand in equal parts, mix the mass thoroughly, pour it into a metal bucket and dilute it with water. Knead the mixture until it is completely homogeneous, without lumps.
Advice! To measure exactly the same amount of gypsum and sand, use a plastic bucket. But they always leave both components in reserve (if there is not enough solution, all efforts to create a furnace will be in vain).
Afterwards, the plastic bucket is pressed directly into the solution, rotating it in different directions and screwing it in. To prevent the container from being squeezed back, it is made heavier: water is poured in or stones and fragments of bricks are placed inside. Leave the bucket until the plaster sets, but first remove all irregularities, bumps, excess mass, and smooth the edges.
Molding plaster using a plastic bucket
After about an hour, moisten a rag with water and wipe the outer surface of the metal bucket and the edges of both containers. After some more time, carefully remove the plastic bucket from the plaster until it has completely hardened.
Important! If the bucket is split, remove its parts with pliers and carefully inspect the plaster surface for small particles and crumbs. All defects are smoothed out and the future stove is left to dry.
How to finish a furnace and melt metal
A device for supplying energy inside the stove is prepared from the pipe. To do this, place a suitable drill on a drill and drill a hole in the side of the smelter, having previously outlined its boundaries.
First, punch a hole using a hammer and dowel, and then use a drill to give the desired shape. Then a pipe with a welded pipe bend is inserted into the hole.
The oven lid is made like this:
- The metal hooks are bent with a hammer to make handles (they are first clamped in a vice).
- Sand and gypsum are poured into a basin in equal parts, mixed until smooth and diluted with water to a thick mass.
- A metal plate is pressed into the center of the solution and hook-handles are installed.
- After the plaster has cured for some time, the dishes are removed and the edges and defects are smoothed out.
- After the lid hardens, a crucible (for example, a large tin can) is placed in the melting pot and the entire structure is assembled together.
The oven is ready. It can be immediately used for melting aluminum and making any objects, parts and accessories.
Characteristics
The purity of materials determines their melting point. Aluminum is suitable for various technological procedures due to its low weight and good ductility. At high temperatures, interaction with oxygen occurs. An oxide film appears on the surface of the metal, which protects it from corrosion and oxidation. Melting aluminum helps to change the structure of the substance, so the protective coating is beneficial for it. Shrinkage and additional internal stress appear during sudden cooling.
Procedure
In any furnace for melting metal (even in a factory one), an important role is played by the lining - lining the inside of the furnace itself with refractory heat-insulating material. Through this process, thermal energy is trapped within the device and helps melt the aluminum or other material.
Important! At home, the role of a lining can be played by a flower pot made of durable ceramics or clay, which reduces thermal conductivity and reduces energy losses.
The first step is to prepare the pot: on one side, a hole is drilled in the lower part to supply energy to the crucible located inside. The lid in this case will be the tray for the pot, which is sold complete with it.
Before making a hole, markings are applied and only then a drill is used. Initially, they work with a thin drill, then with a medium-sized one, and finally with the largest one.
To make a hole ideal for a gas burner, use a Dremel with a cutter. With its help, you can easily give the hole the desired shape.
Once the holes are ready, remove the resulting dust with a vacuum cleaner and try on the burner head. It is important to make sure that it fits exactly into the resulting slot. Also, as preparatory measures before assembling the furnace, make a crucible from a tin can.
A cutting disc is attached to the Dremel, and the collar is cut off, which will prevent the metal from pouring into the mold. Clean the jar of labels and dirt.
Furnace manufacturing and aluminum smelting
Scrap metal is placed inside the jar and placed directly in the center of the flower pot. The latter is first placed on bricks located on any flat surface.
The burner head is connected to the hole in the pot, which is also placed on a brick for ease of operation. The head itself must be securely connected to the gas cylinder.
Then proceed like this:
- Turn the burner tap and ignite the gas.
- The head is placed in a hole cut in the pot and the exact direction and strength of the flame is adjusted.
- Close the pot with the crucible with a lid.
- The condition of the metal is periodically checked - it must completely melt and become liquid.
- When ready, remove the lid and use a screwdriver to remove all dirt and slag from the molten aluminum.
- Turn off the burner and remove it from the pot.
How to use aluminum
Towards the end of the melting process, prepare a mold for pouring the metal and place it in close proximity to the mini-furnace on a brick or other refractory material. Using pliers, grab the edge of the crucible and carefully pour the aluminum directly into the mold.
Casting aluminum into silicone molds
After some time, when the metal has cooled and set, use the same pliers to shake the workpiece into any metal container. Then they inspect it for integrity, absence of defects and foreign inclusions.
