Okay, imagine you want to make a toy car out of play-doh, but the play-doh you have is very dirty and has impurities in it. You want to make the toy car strong and clean so you need to clean the play-doh first.
In the same way, to make strong and clean steel, we need to remove the impurities from iron that we get from mines. This is what basic oxygen steelmaking does.
First, we put the iron in a big container and heat it up really hot using fire. Then, we add something called oxygen gas that helps us separate out the impurities from the iron.
The oxygen gas reacts with the impurities and makes them come out of the iron in a form of a gas. This is a bit like when you blow bubbles from soap water, the bubbles come out of water when you blow air into it.
The impurities that come out in the form of gas rise to the top of the container and we remove them using a big spoon. This makes the iron really clean and pure.
Now, we have clean and pure iron that we can use to make strong steel. We add different things to the iron like carbon and other metals to make different types of steel for different uses.
This is how basic oxygen steelmaking works!