In a typical metal charge for the production of metal ore it is, which is mined from the earth. This blend contains minerals - chemical compounds with the metal, which must receive. This blend also comprises chemical compounds, which do not include the metal member. They are called gangue. Also useful metal ore minerals contain these impurity elements. To separate these impurity elements from the wanted metal is the main object of the metallurgical.
When the charge is aluminum remelting scrap consists of, which are likely on the ground, than under the ground. However, an analogy between these two types of charge much more, than it might seem at first glance. Aluminum scrap comes with their "waste rock" in the form mounted thereon various parts of other materials, as well as various coatings. This leads to the presence of aluminum in the charge a large amount of impurities, that have a significant impact on the production of secondary aluminum alloys. To combat these impurities in the production of secondary aluminum alloys have to apply additional technologies and processes.
Various aluminum alloys - wrought and casting - differently affect the range and quality of secondary aluminum alloys. The difficulty of recycling of aluminum alloys is, after remelting to remain within the tolerances for the presence in the alloy of different impurity elements for him.
Automobile aluminum scrap
Доля различных деформируемых алюминиевых сплавов в современном автомобиле в среднем составляет:
- 35 % – 6060 (0,45 % silicon - 0,2 % iron - 0,5 % магния);
- 11 % – 6082 (1,0 % silicon - 0,3 % iron - 0,7 % manganese - 0,9 % магния);
- 10 % – 3003 (0,5 % silicon – 0,5 % iron - 1,3 % марганца);
- 9 % – 5182 (0,1 % silicon - 0,2 % iron - 0,4 % manganese - 4,5 % магния);
- 14 % – 5754 (0,3 % silicon - 0,2 % iron - 0,4 % manganese - 3,2 % магния);
- 15 % – 6016 (1,25 % silicon - 0,3 % iron - 0,5 % магния);
- 6 % – 7020 (0,2 % silicon - 0,3 % iron - 0,3 % manganese - 1,2 % magnesium - 4,5 % цинка).
If this mixture directly, not sorted, melted, we get the "alloy", which will contain 0,57 % silicon – 0,26 % gland – 0,32 % manganese – 1,27 % magnesium – 0,27 % zinc.
zinc content is too high for all alloys except alloys of the 7xxx series. However, the silicon content is too high for 7xxx alloys. Therefore, for the manufacture of any of the remelted scrap alloy it is necessary to dilute the primary aluminum. If the scrap contains aluminum waste and scrap cast aluminum alloys, then the problem becomes even more acute.
Currently casting and wrought alloys of various series have very limited compatibility in chemical composition.
So, 1xxx series alloys, 2xxx and 7xxx alloys are compatible only with their own series.
3xxx series alloys have limited compatibility with a series of casting alloys 5hh.h, which contains a lot of magnesium, and Mn.
5xxx series alloys are highly compatible with alloys casting 5hh.h series.
6xxx alloys have limited compatibility with casting alloys series 3hh.h, 5xx.x and 4hh.h.
Currently in the world are developing aluminum alloys, which had a wide compatibility for future recycling. This will make the aluminum alloys are more environmentally friendly and commercially attractive.
Источник: Mark E. Schlesinger, Aluminum Recycling, 2011