Think video games aren't educational? Think again! Everyday Einstein looks at the science and technology behind mining for metal via a 3D video game called Minecraft.
A few weeks back, my family was introduced to a game called Minecraft. Have you heard of it? It's a virtual game in which players create fantastic structures out of 3D blocks. While it sounds simplistic, the game can be quite addictive. And what's more, it allows for some fruitful discussion about the science and technology behind making real life materials.
This week, I’ll look at just one example: mining for metal.
In order to find the good stuff in Minecraft, you have to create pickaxes and mine deep into the ground where you can find metal ore. The most common metal ore in the game is iron. Interestingly, the most common element forming our real-life Earth is also iron.
What Is Smelting?
However, iron in its metallic form is extremely rare on our planet. Aside from a large deposit in Greenland, most of the metallic iron found on Earth comes from meteorites. So if you want large amounts of iron, the only way to get it is to smelt it from iron ore.
Smelting is the process of removing the impurities from an ore in order to extract the desired metal. In Minecraft, to smelt iron ore you have to first put the ore into a forge (which is built out of rock), add a heat source, and wait.
After a few seconds, out pops an iron ingot. An “ingot” is bar of metal, and is used as a handy way of storing refined metal before it is cast into its final form, such as a pan, fork, or iPhone case. While ingots are typically in the shape of gold bars, they can be cast into other shapes as well. As you might imagine, the real-life process of smelting iron ore into ingots is a bit more complicated.
Gangue + Flux = Slag
There are a lot of different ways to smelt iron, depending on what you plan to do with it (and what technology is available to you). However, all of the processes involve heating the iron ore up to extremely high temperatures and invoking various chemical reactions to help remove the unwanted materials, called gangue, from the ore.
So what’s with all of these funny words? Do metallurgists just like funny sounds? Gangue, flux, slag?
Often, another material is added to the iron to help remove gangue more easily. This material is called a “flux.” Once the flux has bonded to the gangue, it is usually called "slag." Slag separates from the melted metal in much the same way that olive oil poured into a glass of water will float to the top of the mixture. This allows the slag to be easily removed from the molten metal. The flux most often used in iron smelting is limestone.
So what’s with all of these funny words? Do metallurgists just like funny sounds? Gangue, flux, slag? Actually the word "gangue" comes from German, and is related to the modern word gang, as in: a set of things that run together.
Flux gets its name from the fact that after it binds to the gangue, it makes it more viscous, allowing it to flow out of the ore.
Most people believe that "slag" comes from the old German word “slagen,” which means "to strike with a hammer." That’s because one of the early ways of smelting iron ore was to use a bloomery, which was a type of furnace that caused the iron and slag to stick together in a big chunk called a “bloom.” Separating the slag from the iron involved heating the bloom up and striking it with a hammer.
So flux turns the gangue (or impurities) into slag. The slag is removed, leaving the metal behind. Now what?