I like this question very much because it has a lot of chemistry
I willl give you a real example in life
firstly, this happen when you leave the food (most likely soap) in an aluminium container for a while, aluminium ions dissolves and goes to the soap (food) and your body digest it and send the Aluminium ions into your blood ( your body treat Aluminium as Ferric as they have the same chemical properties) . then aluminium try to do like Ferric in the blood to transfer the oxygen to the muscles. the problem after three months, when the marrow build up new red blood cell by using ferric ions and haemoglobin , then the marrow prevent Aluminium to enter into it then Aluminium goes back to precipitate in the brain cause Al zahimar disease.
this is why you can’t inject Aluminium