# Silicon brass **URL:** \ **Category:** Factual Questions\ **Created:** [July 7, 2017, 7:14pm UTC](https://boards.straightdope.com/t/silicon-brass/790714 "2017-07-07T19:14:17Z")\ **Posts on this page:** 16\ **Page:** 1
**Author:** ![DPRK](https://avatars.discourse-cdn.com/v4/letter/d/4491bb/32.png) [@DPRK](https://boards.straightdope.com/u/DPRK)\ **Post date:** [July 7, 2017, 7:14pm UTC](https://boards.straightdope.com/t/silicon-brass/790714/1 "2017-07-07T19:14:17Z")
I have a brochure warning me never to recycle silicon brass scrap with lead brass scrap. Why? ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [July 7, 2017, 7:17pm UTC](https://boards.straightdope.com/t/silicon-brass/790714/2 "2017-07-07T19:17:04Z")
> [@](#): > > Scrap stream contamination > It is important to keep leaded brass scrap separate from scrap used to produce lead-free brasses which should not contain lead by definition. Even within lead-free scrap, strict segregation is needed to keep scrap containing certain elements such as silicon and bismuth separate. These elements can irreversibly concentrate up over time in the metal stream and are impossible to remove from the melt with economic production technology. The presence of any undesirable impurities can cause problems such as hot shortness which causes expensive failures during casting and hot extrusion. Strict segregation of brass scrap is therefore essential to protect the viability and economic advantages of all brass products. Segregation of primary scrap returns from screw machine houses is much easier to control as compared to segregation of secondary, end-of-life scrap which is rather difficult to control. From: > **[a7035-Brass-Scrap-Stream.pdf](https://www.copper.org/applications/rodbar/pdf/a7035-Brass-Scrap-Stream.pdf)** > > 880.29 KB ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [July 7, 2017, 7:22pm UTC](https://boards.straightdope.com/t/silicon-brass/790714/3 "2017-07-07T19:22:35Z")
[This site](http://www.abymc.com/tmoranwms/Casting_Alloying.html) doesn’t mention serious problems except for weakening of metal. I’ve seen other things in the past that mention the danger of lead vapors. Of course these metals, actually bronze in my terminology but often called brass anyway often contain other harmful metals, and in particular zinc in real brass. Take my word for it, no one wants a case of zinc poisoning. But mainly I would assume the resulting alloy with unknown amounts of differing metals has unpredictable characteristics. Copper alloys can be produced with specific characteristics or strength, hardness, malleability, and the tonal qualities needed in bells and other musical instruments but the ratios of metals need to be rather precise. Scrap mixes can be adjusted when the their constituents are known by the addition of other metals such as tin, lead, etc., but the addition of other metals can make it impossible to produce a known result. ---
**Author:** ![DrCube](https://avatars.discourse-cdn.com/v4/letter/d/a3d4f5/32.png) [@DrCube](https://boards.straightdope.com/u/DrCube)\ **Post date:** [July 7, 2017, 9:13pm UTC](https://boards.straightdope.com/t/silicon-brass/790714/4 "2017-07-07T21:13:39Z")
If the I can separate them, why can’t the recycler? And conversely, if the recycler can’t differentiate them, how am I supposed to? It kind of reminds me of the Red Cross’s pre-donation questionnaire about whether you have HIV. Given the consequences, I sincerely hope they’re not relying on a survey to keep their blood supply safe. And given the consequences of mixing recycled brass (whichever those are), I hope they’re not relying on the average Joe to segregate them. ---
**Author:** ![mixdenny](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mixdenny/32/2962_2.png) [@mixdenny](https://boards.straightdope.com/u/mixdenny)\ **Post date:** [July 7, 2017, 9:25pm UTC](https://boards.straightdope.com/t/silicon-brass/790714/5 "2017-07-07T21:25:31Z")
> [@DrCube](#): > > If the I can separate them, why can’t the recycler? And conversely, if the recycler can’t differentiate them, how am I supposed to? > . You need to have the certificate of origin to get the best scrap value. Although most scrappers have the laser gun to check metals today. Dennis ---
**Author:** ![watchwolf49](https://avatars.discourse-cdn.com/v4/letter/w/e9c0ed/32.png) [@watchwolf49](https://boards.straightdope.com/u/watchwolf49)\ **Post date:** [July 8, 2017, 3:46am UTC](https://boards.straightdope.com/t/silicon-brass/790714/6 "2017-07-08T03:46:48Z")
> [@DrCube](#): > > If the I can separate them, why can’t the recycler? And conversely, if the recycler can’t differentiate them, how am I supposed to? … [snip] If your shop is milling silicon brass, then you have silicon brass recycling … if your busy enough, you’re hauling the stuff out by the dump truck load … keeping them all separate at the industrial level isn’t that hard … ---
**Author:** ![Mr.Goob](https://avatars.discourse-cdn.com/v4/letter/m/c77e96/32.png) [@Mr.Goob](https://boards.straightdope.com/u/Mr.Goob)\ **Post date:** [July 8, 2017, 9:28pm UTC](https://boards.straightdope.com/t/silicon-brass/790714/7 "2017-07-08T21:28:25Z")
I run a machine shop, we keep separate bins and barrels for as much as we can. Off the top of my head I’ll say we last got .88 cents a pound for clean dry aluminum clip. Meaning no cutting oils or chips. About.25 cents a pound for mixed aluminum. I don’t remember prices from the brass, bronze and copper, but the same idea. ---
**Author:** ![Musicat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/musicat/32/20189_2.png) [@Musicat](https://boards.straightdope.com/u/Musicat)\ **Post date:** [July 8, 2017, 9:41pm UTC](https://boards.straightdope.com/t/silicon-brass/790714/8 "2017-07-08T21:41:44Z")
> [@Mr.Goob](#): > > Off the top of my head I’ll say we last got .88 cents a pound for clean dry aluminum clip. Meaning no cutting oils or chips. About.25 cents a pound for mixed aluminum. Really? Less than a penny per pound for aluminum, a quarter-penny for mixed? Wouldn’t it be cheaper to send to a landfill? ---
**Author:** ![ZurBob](https://avatars.discourse-cdn.com/v4/letter/z/71e660/32.png) [@ZurBob](https://boards.straightdope.com/u/ZurBob)\ **Post date:** [July 8, 2017, 10:19pm UTC](https://boards.straightdope.com/t/silicon-brass/790714/9 "2017-07-08T22:19:42Z")
> [@DrCube](#): > > If the I can separate them, why can’t the recycler? And conversely, if the recycler can’t differentiate them, how am I supposed to?..\ > I hope they’re not relying on the average Joe to segregate them. > [@mixdenny](#): > > You need to have the certificate of origin to get the best scrap value. Although most scrappers have the laser gun to check metals today. Most serious recycling facilities and foundry works employ a handheld X-ray fluorescence spectrometer to give them an accurate alloy analysis, not laser beams. Kind of pricey, so the fly by night scrappers use their eyeballs and experience to determine metal content, usually to the detriment of the seller, in order to lowball the price they offer you. Any certificate of origin they may require is merely an attempt to deter sales of stolen metal, not for the determination of it’s particular alloy. This is not the same as a certificate of analysis, that is typically available only at the original foundry. ---
**Author:** ![drachillix](https://avatars.discourse-cdn.com/v4/letter/d/48db29/32.png) [@drachillix](https://boards.straightdope.com/u/drachillix)\ **Post date:** [July 8, 2017, 11:28pm UTC](https://boards.straightdope.com/t/silicon-brass/790714/10 "2017-07-08T23:28:52Z")
> [@Musicat](#): > > Really? Less than a penny per pound for aluminum, a quarter-penny for mixed? Wouldn’t it be cheaper to send to a landfill? $0.88 probably. ---
**Author:** ![PastTense](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pasttense/32/14550_2.png) [@PastTense](https://boards.straightdope.com/u/PastTense)\ **Post date:** [July 9, 2017, 12:27am UTC](https://boards.straightdope.com/t/silicon-brass/790714/11 "2017-07-09T00:27:42Z")
nm ---
**Author:** ![boytyperanma](https://avatars.discourse-cdn.com/v4/letter/b/4491bb/32.png) [@boytyperanma](https://boards.straightdope.com/u/boytyperanma)\ **Post date:** [July 9, 2017, 1:48am UTC](https://boards.straightdope.com/t/silicon-brass/790714/12 "2017-07-09T01:48:16Z")
> [@Musicat](#): > > Really? Less than a penny per pound for aluminum, a quarter-penny for mixed? Wouldn’t it be cheaper to send to a landfill? I’m pretty sure he meant $.88 which would be a rather good rate for aluminum. In reality getting anything for scrap is better than paying to have it removed as garbage. ---
**Author:** ![Melbourne](https://avatars.discourse-cdn.com/v4/letter/m/b5e925/32.png) [@Melbourne](https://boards.straightdope.com/u/Melbourne)\ **Post date:** [July 9, 2017, 9:42am UTC](https://boards.straightdope.com/t/silicon-brass/790714/13 "2017-07-09T09:42:34Z")
> [@boytyperanma](#): > > I’m pretty sure he meant $.88 which would be a rather good rate for aluminum. > > In reality getting anything for scrap is better than paying to have it removed as garbage. We were at the contract factory in China, and they threw some scrap in the rubbish. We were appalled, and wanted to rescure it. “Don’t do that” they said. “The people who pay to take our rubbish away will recycle it” ---
**Author:** ![Mr.Goob](https://avatars.discourse-cdn.com/v4/letter/m/c77e96/32.png) [@Mr.Goob](https://boards.straightdope.com/u/Mr.Goob)\ **Post date:** [July 9, 2017, 5:22pm UTC](https://boards.straightdope.com/t/silicon-brass/790714/14 "2017-07-09T17:22:19Z")
Sorry about the decimal point confusion. I meant 88 cents a pound. It was all a specific grade, unmixed, clean and dry with certification. It was mostly all big clips. Picture a square sheet and cut a circle out of the middle. We used the circles and scrapped the corners. The price fluctuated over the years. The 88 cents was the peak. I remember a story about a scrapyard, there was a shipping container with all sorts of electric motors. Big ones you could only move with a forklift to tiny ones for say an electric drill. I asked what do they do with them. They ship it to China where the motors were unwound by hand for the copper. Ugh what a job that would be. ---
**Author:** ![Musicat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/musicat/32/20189_2.png) [@Musicat](https://boards.straightdope.com/u/Musicat)\ **Post date:** [July 9, 2017, 7:09pm UTC](https://boards.straightdope.com/t/silicon-brass/790714/15 "2017-07-09T19:09:36Z")
> [@Mr.Goob](#): > > Sorry about the decimal point confusion. I meant 88 cents a pound. Good that you understand that _units_ are important. 🙂 > [@](#): > > I remember a story about a scrapyard, there was a shipping container with all sorts of electric motors. Big ones you could only move with a forklift to tiny ones for say an electric drill. I asked what do they do with them. They ship it to China where the motors were unwound by hand for the copper. Ugh what a job that would be. Since my grandfather (ca. 1930) invented motor winding machines that did the whole assembly job without handwork, I imagine a motor UN-winding machine wouldn’t be that difficult to make, 90 years later. G’pa isn’t around to do it, but I’ll bet the Chinese will do just fine. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [July 9, 2017, 7:20pm UTC](https://boards.straightdope.com/t/silicon-brass/790714/16 "2017-07-09T19:20:01Z")
> [@Musicat](#): > > Since my grandfather (ca. 1930) invented motor winding machines that did the whole assembly job without handwork, I imagine a motor UN-winding machine wouldn’t be that difficult to make, 90 years later. G’pa isn’t around to do it, but I’ll bet the Chinese will do just fine. The one shop I know of that you can still walk into and they’ll rewind a starter motor or alternator for you has unwinding machines.