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Author: Subject: Procedure for refining brass?
joshRobb
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[*] posted on 15-3-2018 at 19:34
Procedure for refining brass?


I would like to be able to take scrap brass and refine it into it's constituent metals. I would then take these metals and alloy them in specific quantities so I have a known alloy to use in metalworking projects.

It looks like electrolysis in a copper sulfate bath is the typical way to get the copper from brass, but it makes a zinc solution that needs to be dealt with. Also, what about the other metals like lead? I've read that lead interferes with the electrolysis significantly. It would be best if the zinc saturated copper sulfate solution could be recycled.

Or could this all be done with acids, dissolving the metals and precipitating them out with various reactions? If some chem wiz could lay out a procedure that would be awesome, or even just cite a good source where I could learn how to do this. Thanks!
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[*] posted on 15-3-2018 at 21:35


Wet chemistry CAN separate Cu alloys into constituent metals, but it does not pay to do so industrially.

Generally, when going to recycling/scrapping/metal salvage, brass is not refined to the individual elements constituting it. That would not usually be economical. Instead, recycled brass is smelted into a batch of ingots of uniform makeup, tested and then used to make up whatever Cu alloys are desirable and make economic sense from a particular batch.

Any large ammounts of alloying materials tend to make electrolytic Cu refining go poorly.

You CAN boil most of the Zinc out of smelted brass, capture the ZnO and use it to make up a different alloy, or reduce it to pure Zn. In fact, most brass foundries do their best to capture Zn escaping a melt, often adding it to a subsequent batch of brass.

What is your target alloy? Which brasses do you have for raw material.




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Anjali
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[*] posted on 15-3-2018 at 22:39


he main component of brass is copper. The amount of copper varies between 55% and 95% by weight depending on the type of brass and its intended use. Brasses containing a high percentage of copper are made from electrically refined copper that is at least 99.3% pure to minimize the amount of other materials. Brasses containing a lower percentage of copper can also be made from electrically refined copper, but are more commonly made from less-expensive recycled copper alloy scrap. When recycled scrap is used, the percentages of copper and other materials in the scrap must be known so that the manufacturer can adjust the amounts of materials to be added in order to achieve the desired brass composition.

The second component of brass is zinc. The amount of zinc varies between 5% and 40% by weight depending on the type of brass.
A diagram depiding typical manufacturing steps in 6rass production.
A diagram depiding typical manufacturing steps in 6rass production.
Brasses with a higher percentages of zinc are stronger and harder, but they are also more difficult to form and have less corrosion resistance. The zinc used to make brass is a commercial grade sometimes known as spelter.

Some brasses also contain small percentages of other materials to improve certain characteristics. Up to 3.8% by weight of lead may be added to improve machinability. The addition of tin improves corrosion resistance. Iron makes the brass harder and makes the internal grain structure smaller so that the metal can be shaped by repeated impacts in a process called forging. Arsenic and antimony are sometimes added to brasses that contain more than 20% zinc in order to inhibit corrosion. Other materials that may be used in very small amounts are manganese, silicon, and phosphorus





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Fulmen
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[*] posted on 16-3-2018 at 01:28


Honestly it's a terrible idea, refining any real amount of metal will take a LOT of time and energy. If you simply want to make your own alloy you're much better of starting with copper scrap and zinc.



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MrHomeScientist
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[*] posted on 16-3-2018 at 05:47


Or as Bert said, melt it all together and test it to figure out the overall composition. Then you can add in extra copper or zinc to get you to your desired brass ratio.
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