March 2019

One day, Billy was in his room listening to his favourite song when all of a sudden, a thought struck him.

Huh. I love my earbuds so much. I wonder what they're made of.

So Billy decided to hunt for the answer:

How are earbuds made?

Billy went on his computer and searched: "How are earbuds made." He watched this video:

How Earbuds Are Made - With Jennie the Scientist

Earbuds are made of three components: the plug, the wire, and the actual earbuds.

Wire

Plug

Earbuds

The plug is made of plastic, steel, and aluminum.

The wire is made of copper with a plastic sheath surrounding it.

The earbuds themselves are mainly made of 3 components: foam, plastic, and copper wires.

The two major ingredients in earbuds are thermoplastics and copper, so those are the two materials we will be focusing on.

Let's start off with plastic.

Plastics are predominately derived from fossil fuels as coal, natural gas, and crude oil. However, bioplastics are manufactured from plant sources.

Canada has the third largest oil reserves in the world after Venezuela and Saudi Arabia.

Most of the time, these natural ingredients are extracted from the ground using a process called OPEN-PIT MINING.

Open-pit mining is when a big pit is dug into the earth and materials are extracted from that pit and sent to a refinery for processing.

First, a process called FRACTIONAL DISTILLATION is used to separate the crude oil into groups that are made of different parts.

Next, a process called POLYMERIZATION is used to make thermoplastics. Polymerization is a chemical reaction that uses special chemicals called CATALYSTS to make plastic. Catalysts break the double bonds in the starting monomer (e.g, ethylene) and connect the carbon atoms into a chain.

After polymerization, we are left with something called RESIN, a plastic polymer. A polymer is a material that is made up of a long chain of repeating monomers.

Next, the resin is heated up, then shaped to create the plastic that is used in everyday materials, like the plastic sheath used to make earbuds.

Catalyst

The polymerization process

Now let's move on to copper.

Copper is a reddish-brown metal that is mined in British Columbia, Ontario, and Manitoba. Canada is the world's ninth largest producer of copper.

Like plastics, the most common way of retrieving copper from the ground is open-pit mining. However, sometimes, surface mining is also used. SURFACE MINING is when the soil and rock on top of the desired minerals is removed. It is used when the mineral is close to the ground surface.

Surface Mining

After mining, it is crushed into powder and concentrated using froth flotation to get rid of any unnecessary materials. This happens in a copper processing plant.

600 degrees!

Then it is roasted at around 600 degrees to remove sulphur and dry ore.

First, copper ore is extracted from the Earth.

Next, it is smelted at 1200 degrees to remove any leftover unwanted ores.

Air is then blown onto the resulting item to make partly purified blistered copper.

Then using, electrolysis, it is purified, then shipped to other factories where the copper gets made into different products, such as wires that are used in earbuds.

HOW DOES ELECTROLYSIS PURIFY COPPER?

In copper electrolysis, impure copper is made the anode and a previously purified copper sheet is used as the cathode. Both these sheets are placed in an electrolyte solution. When the current is passed through this system, copper ions (Cu+2) are pulled out of the anode and are attracted to the negatively charged cathode, where they are deposited as pure neutral copper atoms. As a result, the cathode sheet grows and the anode erodes away. The remaining sludge may contain other valuable metals such as silver and gold.

Cathode (-)

Anode (+)

Electrolyte (Copper sulfate and sulfuric acid solution)

Sludge