Greg tries to resemble real chemistry as much as possible.
With a centrifuge it is possible to filter materials of different density. So if your tin has some parts of iron and zinc inside you can filter them out with the centrifuge (although you normally would keep the tin, but in that case you need to lose it for balance-reasons). The Electrolyzer totally changes the materials. The simplest example is Pyrite FeS, which is Iron and Sulfur, but they are both ions, but since you want the metal Iron you need add two electrons from the sulfur to get elemental Iron and Sulfur.
