How are tin cans made?

Question

From raw material to finished product, where do the minerals for the can come from

Answer 1

Must be from the car junk yard.

Answer 2

Nearly all cans nowadays are made of steel, not tin, since steel is cheaper and much stronger. They may also be made of aluminum, since it is lighter and easier to recycle. Steel cans are usually tin plated to protect against rust.

Steel of course comes from iron ore, there are many iron containing minerals used to make iron and steel. Tin almost always comes from cassiterite, (SnO2), a somewhat rare mineral.

Smelting and refining iron and tin are somewhat complicated processes, and I don't want to take the time to go into them here.

To make a can, steel is rolled into very thin sheets, and then crimped to add the ribs or pleats on the side of the can. This makes the can stronger and helps it resist denting and crushing. The "wavy" sheets are then cut into long strips, and rolled and cut into the sides of the can. A special welding machine joins the the cut ends into a continuous cylinder. If you take off the label, most cans will have a visible seam on one side. The tops and bottoms are "stamped" out of another sheet of steel, just like a cookie cutter. the bottoms are then "crimped" onto the cans by another specialized machine.

In order to add the tin plating, the topless cans and lids are coated with a small amount of "flux." This is a substance that makes the steel "compatible", or able to stick to the tin, so the cans will get a thin, even coating. The cans and lids are then dipped into a bath of molten tin, which has a relatively low melting point.

At this point the cans and lids are usually sent to the food manufacturer. Here they are sterilized, filled with their intended contents, and heated almost to boiling. The Lids are attached by another specialized machine the same way as the bottoms, they are crimped and the combined edge of the can and lid is bent through a total of 270 degrees.

This combination of a very close fitting seam, and the forces involved in bending, make the can completely airtight, and no further welding or sealing is necessary. The fact that the contents are near boiling when the can is sealed, means that the food is cooked, sterilized, and any air is displaced from the can by steam. This means that food sealed in cans will not decompose or become rotten, unless the can is pierced or damaged, and food can be stored in cans for many years.

The process of sealing food in metal cans was originally invented by the British merchant Peter Durand around 1810. Durand was looking for a way to replace the heavy glass bottles originally used for sealing food. Glass bottles where expensive and of course much less durable than steel cans.

Answer 3

..out of tin...?