Can we use 100% pure aluminum scrap for EC Grade Aluminum Rod continuous casting process? What will be the disadvantages of this?

Hello Chandra,

I suspect your biggest worry will be aluminum alloys getting into the aluminum 1350 rod (Formerly EC Grade).

I once had a recycled metals company ask us if we wanted to purchase 3/8" rod made from recycled "pure" aluminum for magnet wire applications. It was manufactured on a Conform machine and they were regularly making fairly low grade aluminum deox rod for steel mills. We declined because of the possibility of contamination and stayed with our regular supplier of aluminum 1350 rod.

In your case, I think you need to purchase and carefully read the appropriate specifications from ASTM to be fully acquainted with all the metallurgical restrictions. www.astm.org/

Here is the information:

ASTM B233-97(2007) Standard Specification for Aluminum 1350 Drawing Stock for Electrical Purposes
Prior to 1975, aluminum 1350 was designated as EC aluminum.

Referenced Documents
B193 Test Method for Resistivity of Electrical Conductor Materials
B354 Terminology Relating to Uninsulated Metallic Electrical Conductors
B557 Test Methods of Tension Testing Wrought and Cast Aluminum- and Magnesium-Alloy Products
B830 Specification for Uniform Test Methods and Frequency
E227 Test Method for Optical Emission Spectrometric Analysis of Aluminum and Aluminum Alloys by the Point-to-Plane Technique
E34 Test Methods for Chemical Analysis of Aluminum and Aluminum-Base Alloys
E527 Practice for Numbering Metals and Alloys (UNS)
E55 Practice for Sampling Wrought Nonferrous Metals and Alloys for Determination of Chemical Composition
ANSI H35.1 Alloy and Temper Designation Systems for Aluminum
Handbook

Purity
Al 99.5% min.
Si 0.10 % max, Fe 0.40 % max, Cu 0.05 % max, Mn 0.01 % max, Cr 0.01 % max, Zn 0.05% max, B 0.05% max, Ga 0.03% max, V+Ti 0.02% max , others-each 0.03% max, others-total 0.10% max,

Tensile strength
From 85 to 135 MPa max. within a range of 15 MPa

Kindest regards,
Peter J. Stewart-Hay
Principal
Stewart-Hay Associates
www.Stewart-Hay.com

I think the choice of words says it all; 100% "pure" scrap. It brings to mind the old adage that you cannot make a silk purse out of a sows ear.

I don't think that you can expect to take "pure" scrap and end up with a product as good or better than the original product.

Peter as you mention there are a number of ways to test the recycled aluminum to determine the quality. Also as you mention there is the danger of mixing alloys and since most all aluminum wire/scrap to the naked eye looks the same.

Below is some info showing conductivity for copper and aluminum or links to see such.

Table 2. Comparative Electrical Conductivity of Wrought Copper Materials
Alloy % IACS
Coppers
Electrolytic (ETP) 101
Silver-bearing, 8 oz/t 101
Silver-bearing, 10 to 15 oz/t 101
Silver-bearing, 25 to 30 oz/t 101
Oxygen-free (OF) 101
Phosphorized (DLP) 97 to 100


Aluminum Conductor Materials. It was early learned that the electrical resistivity of aluminum is markedly increased by impurities; electrical conductor grade (EC) metal, containing approximately 99.5% Al, was established for most conductor uses. At present, aluminum producers offer EC with a minimum of 99.6% Al and conductivity of 62.0% IACS on a volume basis, although ASTM specifications permit 99.45% Al minimum and 61.0% conductivity. EC wire has a tensile strength range of (83-200 MPa), depending on temper. www.key-to-metals.com/Article116.htm - 23k

The following article by Dr. Pops talks about copper but as you can see it takes only a very little bit to make a big change in conductivity.
www.litz-wire.com/pdf%20files/Metallurgy_Copper_Wire.pdf

Thank you for the inputs RB.

Best Regards
Peter J. Stewart-Hay
Principal
Stewart-Hay Associates
www.Stewart-Hay.com

Peter,
Do I take it by your comments that unless you are really, really careful and do lots of testing that if you need or want the best conductivity, that recycling scrap might not be the best choice.

I know years ago that when we (and even W'house which had what they called a WSCR ) shaved continuous cast copper rod, that the shaving and clipped the ends were not fed back into the melting pot because thats were all the "bad stuff was" and putting it back into the pot only increase the overall amount of "bad stuff". Bad stuff being inclusions, oxides, and any other materials that would not be vaporized.

That is what led to my silk purse comment. Don't know if they use that one out of the US south.

rb