Scrap Steel Refining: Separating Metals for New Steel

[LAP3141]

A lot of scrap steel is recycled to make new steel. But how is this scrap steel refined?

Recycled scrap must be a mixture of various types of steel with each type containing different amounts of manganese, vanadium, chromium, etc. How are these other metals separated from the scrap melt so that new steels, such as 4140, which have a strict specification, be produced?

The carbon additives can be oxidized out, but I'm not sure how the metallic additives can be separated.

 

[Bystander]

http://www.singletonscrapmetal.co.uk/news-story.asp?NID=28

 

[Frank Peters]

http://www.singletonscrapmetal.co.uk/news-story.asp?NID=28

??

Perhaps you misunderstand the issue.

Steel is an alloy and the different types of steel contain different proportions of added metals such as manganese, molybdenum, vanadium, chromium, silicon, etc. Scrap steel must contain mixtures of different steel alloys and when this scrap steel is melted it will likely not be a match to any commercial alloy.

In order to make a specific steel alloy, such as 4140, a precise amount of added metals must be added to the melt. Thus, any scrap steel that is used to make 4140, or any other steel alloy, must first be purified by separating the alloying agents (molybdenum, vanadium, etc.).

How is this separation accomplished? How is the molybdenum, vanadium, chromium, silicon, etc. separated from the scrap steel melt to leave just pure iron?

 

[jim mcnamara]

Separation or sorting by type of steel = manual. Sometimes impurities (not alloying metals) are removed by electrolysis during the melt.
See: https://www.thermofisher.com/blog/metals/why-scrap-metal-recyclers-need-to-know-their-steels/

 

[Frank Peters]

Separation or sorting by type of steel = manual. Sometimes impurities (not alloying metals) are removed by electrolysis during the melt.
See: https://www.thermofisher.com/blog/metals/why-scrap-metal-recyclers-need-to-know-their-steels/

I did not realize that scrap recyclers performed elemental analysis on their product. I thought that they only separated ferrous from non-ferrous scrap and sent the all the ferrous material together to the mill as one big collection.

So manual sorting of the ferrous material based on a chemical analysis is the method used.

But one question still remains. Is there a chemical or physical method to separate the components of a steel alloy? I would tend to think that it's not possible to do so. That is, if we have 4140 steel, can the molybdemum, vanadium etc, be separated from the iron either chemicaly or physically?