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smeltng-coper-msg -6/27/07

 

Comments on small-scale smelting of copper.

 

NOTE: See also the files: metals-msg, HaS-Repousse-art, Non-Ferrous-bib, metalworking-msg, pewter-msg, repousee-msg, P-tale-MWIFO-art, mining-msg.

 

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This file is a collection of various messages having a common theme that I have collected from my reading of the various computer networks. Some messages date back to 1989, some may be as recent as yesterday.

 

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    Mark S. Harris                  AKA:  THLord Stefan li Rous

                                          Stefan at florilegium.org

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From: Charly the Bastard <nitecrawler7 at worldnet.att.net>

Newsgroups: rec.org.sca

Subject: Re: smelting your own copper

Date: Tue, 03 Aug 2004 13:18:51 GMT

 

Matthew Montchalin wrote:

 

> Can someone point me to a link where I can read about small scale

> smelting of copper?

>

> We had some rock removed from a vein in some land that we have way

> out in the country, and after it was assayed, they say it appears

> to have 30% copper, and 1% silver.  Most of the rest is some kind

> of junk quartz, but I'll bet we could put even that to good use

> somehow.

>

> It is my understanding that the copper revolution in Europe began

> somewhat before they actually had a use for silver. Is that true?

> Do archaeological digs produce more copper implements than silver?

>

> Also, I intend to build a kiln from concrete cinder blocks and get

> the heat going with propane torches.  That may or may not be enough

> to raise the ore to the right temperature that the copper just

> liquefies right out of it.  Or am I being naive here? A link with

> diagrams and blueprints for building a kiln that can be built around

> at a later stage, is the way I figure I would do it.

>

> Any helpful advice would be welcome.

>

> How do the rest of you smelt your copper or fire your bricks?

 

First... DO NOT use cinder blocks. They will not withstand the heat

needed to melt copper and will disintegrate on you at the worst possible

moment.  Molten metal is soooooo nasty, use the right tool for the job!

This is not a place to be trying on the cheap, molten metal can maim you

for life in a heartbeat.

 

Second... you'll need more than propane torches unless you expect

batches about the size of a quarter.  Think about coal, or natural gas

and a forced-air blower.  Copper melts at about 2200F, so you'll need

about 2500F the get it hot enough to survive the trip to the pour

without freezing in the crucible.

 

Tooling... you'll need tongs that will support the crucible without

putting a squeezing force on the sides, while gripping it securely so

you can control it during the pour. I suggest handles about thirty

inches long with a closing stop to prevent crushing the crucible in a

moment of excitement.  This will have to be made to fit the crucible, so

you'll get some smith work in on this as well. Commercial crucibles are

made of carbon, handle like eggs.

 

Workspace... outdoors, stand upwind. Toxic fumes! Stay upwind at all

times. Leave plenty of clear space to Jump Back into in case of

problems. Wear protective clothing if available, even a leather jacket

can make the difference. EYE PROTECTION is a must, hand protection too.

I cannot stress too strongly the need for safety here; first, last,

always.  If anything goes wrong, Jump Back, let it fall, stuff can be

replaced, fingers and toes cannot.

 

I've done some bronze casting, with better than average results. I still

have all my fingers and toes and both eyes because I RESPECTED the

material I was working with. The instant you stop respecting this stuff,

it'll Bite you Bad.

 

HL Charly the Bastard  the Last Dworf in Ansteorra  Head Metal Forger In

Charge, Dwarven Metals

 

 

From: Andy Dingley <dingbat at codesmiths.com>

Newsgroups: rec.org.sca

Subject: Re: smelting your own copper

Date: Tue, 03 Aug 2004 17:21:23 +0100

Organization: Codesmiths, UK

 

On Sat, 31 Jul 2004 01:33:42 -0700, Matthew Montchalin

<montch at aracnet.com> wrote:

>Can someone point me to a link where I can read about small scale

>smelting of copper?

 

Not sure for modern references, but Agricola's 16thC "De re Metallica"

has a cheap reprint from Dover Press and that's certainly worth a

read.

 

On the whole, I'd expect a stamp mill to crush ore to be more trouble

to produce than a smelter. Any chance of building a watermill ?

 

>It is my understanding that the copper revolution in Europe began

>somewhat before they actually had a use for silver. Is that true?

 

What's the "Copper Revolution" ?  Native copper metal was worked right

back in the early days of the middle east civilisations. Bronze (alloy

of copper and tin) wasn't that much later - trading out to Britain for

tin has an ancient history too.   Being a typical alloy, bronze has

advantages over the pure metal of both better hardness and wear in

service, and lower melting points for manufacture. Copper has a

certain usefulness for easily cold-worked sheetmetal (bowls etc.) but

bronze is superior for cast or forged work.

 

In the 16th century there was a "brass revolution" (although I've

never heard it termed that) when the first successful smelting of zinc

metal changed the way brass was made. Previously it had been made from

copper metal and zinc ores by the slow and costly cementation process,

afterwards we see it made by direct alloying of the two metals. This

appeared early on in Agricola and the brass wire works of Tintern

Abbey, then later as the 17th century brass working boom of the Avon

valley (Bristol, UK). It's a subject I'm just starting to research,

partly as it's on my doorstep.

 

>Do archaeological digs produce more copper implements than silver?

 

Neither generally - for many reasons, bronze was the favoured metal

for a very long period.

 

>Also, I intend to build a kiln from concrete cinder blocks and get

>the heat going with propane torches.  

 

As Charly says, you need real firebricks and burners.

 

Even firebricks don't last very long, so make sure you buy some spares

of the same size. Particularly with spills on the surface, they'll

erode or crack under heat.

 

:>This is not a place to be trying on the cheap, molten metal can maim you

:>for life in a heartbeat.

 

Agreed. Leather welder's jackets etc. are dirt cheap (but they're

modern chrome leather and velcro fastenings, so the rest of the SCA

uses aren't up to much). Proper boots and a full-face mask are a

little more costly, but still essential.

 

:>Second... you'll need more than propane torches unless you expect

:>batches about the size of a quarter.

 

Depends on your burner. One of Ron Reil's burners will cheerfully

forge iron or melt bronze, yet they're still basically "natural

draught propane burners".  You can make your own (descriptions on his

website, or read alt.crafts.blacksmithing) or you can buy one

ready-made.   If you're buying from a welding shop though, you'll

probably find what I use, oxy-propane, to be more useful.

 

> How do the rest of you smelt your copper or fire your bricks?

 

I've no interest in smelting metals from ores - that's a bit _too_

rudimentary for me, I'm happy enough to start with metal stock.

Collect your copper pocket change - a good bronze alloy, and cheaper

than buying it.

 

Remember also that you're talking about a smelter here, not just a

melting cupola. It's a bit harder to heat, and a _lot_ more awkward in

terms of the reducing agents you add and the flue gases you need to

dispose of.

--

Smert' spamionam

 

 

From: Charly the Bastard <nitecrawler7 at worldnet.att.net>

Newsgroups: rec.org.sca

Subject: Re: smelting your own copper

Date: Wed, 04 Aug 2004 11:32:53 GMT

 

jk wrote:

> I think he wants to smelt it, not just melt free metal, in which case

> he needs a lot of heat and a reducing atmosphere. Some ones suggestion

> of a hole in the ground sounds like a good idea, with charcoal layered

> with the ore, and a blast fed in from the bottom.

 

He can get a reducing atmosphere by covering the crucible and throwing in a

spoonful of sawdust to flash off the trapped oxygen, and smelt small batches

from ore in the crucible. It'll form a button on the bottom, with a lump of

ore slag on top. The hole in the ground is essentially the same thing, just

no crucible to contain the metal. Carbon crucible lids are usually available

from the same jobber as the crucible, try Rio Grande in Al- Barron.

 

Charly

 

 

From: Russell <rmine at iinet.net.au>

Newsgroups: rec.org.sca

Subject: Re: smelting your own copper

Date: Wed, 04 Aug 2004 21:27:38 +0800

 

On Wed, 04 Aug 2004 11:32:53 GMT, Charly the Bastard

<nitecrawler7 at worldnet.att.net> wrote:

>He can get a reducing atmosphere by covering the crucible and throwing in a

>spoonful of sawdust to flash off the trapped oxygen, and smelt small batches

>from ore in the crucible.... etc

 

Just a thought - he was originally talking about smelting ore.  If

it's a sulphide mineral then he'll need an oxidising atmosphere to rip

off the sulphur (emitting it up the stack as SO2 .. lovely)

After that the process was to then roast the buttons of copper (and

copper oxide I assume) with flux (and carbon?) to eventually pour an

ingot of good copper.

 

BTW  Bronze and brass (both appropriate for early medieval items) melt

at noticably lower temperatures than straight copper.  

When using a acet/air torch or charcoal and air blast to melt brass if

you over-work your metal (eg by recycling it one time too many) and

burn off too much zinc you can find yourself with an apparently

refractory lump on the bottom of the crucible.   It's just an alloy

that melts too high for such easy techniques.

 

For an interesting read have a look at Anders Sšderberg's "how to"

article on Viking age bronze casting techniques  here:

http://www.frojel.com/Documents/Document02.html

I've taken part in one of his workshops and small scale work (using

hand built crucibles, moulds and furnaces pumped by hand bellows) is a

lot of fun.

As in previous warnings, all objects that come into contact with the

melt are pre-fired and hot.

 

 

From: Charly the Bastard <nitecrawler7 at worldnet.att.net>

Newsgroups: rec.org.sca

Subject: Re: smelting your own copper

Date: Thu, 05 Aug 2004 14:11:53 GMT

 

Matthew Montchalin wrote:

> On Wed, 4 Aug 2004, Russell wrote:

> |Just a thought - he was originally talking about smelting ore.

>

> I would also like to inquire into the easiest way of milling ore

> that starts out as big as a football and ends up as a big as a

> handsized charcoal briquet.  Isn't it true that it breaks up that

> much easier if it has been heated up to a few hundred degrees

> and dropped on the ground, over and over again? Although the

> Middle Ages may have been known for the readily available cheap

> labor, I don't want to get stuck in a wage-for-labor situation.

 

Ten pound sledge. Take a tire carcass, lay it on its side, and put the

ore in the center, WHACK! The tire catches the flying chunks for you.

Repeat.  Great for the old cardio-pulmanary...

 

Charly

 

 

From: Ralph E Lindberg <n7bsn at callsign.net>

Newsgroups: rec.org.sca

Subject: Re: smelting your own copper

Date: Sun, 01 Aug 2004 07:27:10 -0700

 

Matthew Montchalin <montch at aracnet.com> wrote:

 

...

> I'd hate to have to pump a coolant over the exterior, as water would have

> to be pumped in from a nearby creek, and I shudder at the idea of running

> pipes for 1/4 to 1/2 mile to do so.  Anyway, a coolant of some other kind

> might be more feasible.  Then route it through conduits inside the cinder

> blocks themselves to maintain an ambient temperature, perhaps.  But there

> should be some way of using cinder blocks for exterior housing purposes,

> with an interior consisting of more heat resistant materials.

 

  Ah, I wouldn't do that either.

 

  Call around see if you can get some of the blocks or castable mix,

that are used in ceramic kilns. I know I have some that I use for a

casting (melting) furnace.

 

Ralg

 

 

From: mikea at mikea.ath.cx (Mike Andrews)

Newsgroups: rec.org.sca

Subject: Re: smelting your own copper

Date: Mon, 2 Aug 2004 13:45:41 +0000 (UTC)

 

Russell <rmine at iinet.net.au> wrote:

> Um...  careful..

> water leak + molten metal & slag = water encapsulation ->  steam

> explosion.

 

> ie this could be a real hazard.  Even a small leak that has soaked

> into the cinder blocks could crack and break them.

> A larger failure could cause a very nasty situation involving flying

> molten material and  the sort of outburst of steam you get when 100

> degrees C boiling point water meets 1200 degrees C molten copper.

 

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**              In _SPADES_, What He Said.                 **

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Three friends of my wife were splashed with molten steel about 18

months ago, when a steam explosion occurred as rejected castings were

being added to an existing melt in an open-hearth furnace. One or more

of the castings had some water in it because the bake-dry procedure

hadn't been followed.

 

Two of them merely lost arms, legs, an eye, a kidney, some bone, some

muscle tissue, and so on.

 

The third died after about a day in the nearest burn center, with

third-degree (and worse) burns to more than 60% of his body.

 

The only saving grace of burns that bad is that the pain sensors are

destroyed.

 

Molten metal and water -- _any_ amount of water -- are a particularly

nasty accident Just Waiting To Happen, and *will* cause horrible and

permanent injury.

 

You can't be careful enough.

--

Mike Andrews /      Michael Fenwick     Barony of Namron, Ansteorra

mikea at mikea.ath.cx

 

<the end>



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