There are two types of coal basins in Tibia. Movable, which are the yellow ones and not movables, which are the green ones. You can find them all over tibia, there are a few places, mostly close to cities, that have movable coal basins, but you can purchase them in furniture shops and lit them with a firebug. You can’t place items on top of them, but you can use the yellow type, while lit, to bake bread and other kinds of dough