how and why iron and aluminium are recycle

About Recycling Iron and Aluminium:
All Metals are recyclable.The method is to melt the metal into liquid form and then mold it to the new shape you want.
Problems associated with recycling:
1)The cost of the recycling factory and the technologies is high.
2)difficult to seperate metals by simple method.-->so the cost is high
3)Those Factories will act as a competitor with refinery
The social and economic benifits:
Metal can be recycled so that the cost of metal will be a constant, metals are not infinite source so that the recycle of metals is important to the social, even the earth