Large iron ingot molds

[danny987]

Where can i find iron ingot molds? I want to melt copper and pour it into large bars (1/2 pound+).

 

[Palladium]

http://www.lurecraft.com/catalog.cfm/molds/do~it-molds/cast-iron-ingot-mold:2268

 

[Harold_V]

One thing you can consider doing is welding plates on the ends of angle (heavy web only, nothing less than ¼"), which has been cut at an angle so there is draft built in. The plates would be welded on the outside only, and become the legs that hold the mold at the proper angle.

If you choose this route, make sure that the end result is such that molten copper can't key to the mold.

Ingot (pig) molds are generally made of cast iron, ductile being preferred. They should be very heavy in wall thickness, so they can absorb the heat of the pour without risking soldering. Pay close attention to that comment. When you pour molten metals to a metallic mold, it should have a heavy protective layer of carbon (lamp black) applied to isolate the molten material from the mold, and to fascilitate easy dumping of the end product. Do not pour molten metal to a mold not so prepared, for you risk soldering the pour to the mold. Once soldered, it can be removed only by machining, or by destroying the mold.

If you are doing this from the position of recovering copper from solution, with the idea of capitalizing on the resale value of the copper in lieu of dumping it at the land fill, it is likely to be a losing proposition, but I commend you for doing the "right thing".

Harold

 

[butcher]

Some more rambling on, what about trying in a furnace dug into ground rocklined and lid like ancient people did, using carbon source(to convert copper oxide to CO2 gas and elemental copper, and air blown in, kind of how the ancient people, they done it why can't we? maybe you will just get blooms which will need further hammering and heat treatments? old time copper smiths made objects like this, and if nothing else maybe make into brass? I have not tried yet but plan to, if things ever slow down for me would be fun to cast or forge something from this metal we watched change states chemically, maybe we can get the mikey mouse guy to help us cast a mickey mouse for garden or doorstop? coal or homade charcoal and air, I believe would work getting hot enough and provide the carbon source to convert oxides, would need to look into use of flux, which may help shield melt from excess oxygen being introduced for temperatures needed, to prevent from converting the copper to oxidized metal slags, in Iron straw was also used to give carbon to melt.

 

[Anonymous]

the thing with copper is that it radiates so much heat, be sure you are prepared for that, given that I do not think it is beyound doing.
there are many furnace plans out there. At one time I was plugging the holes in the bottom of flour pots and putting scrap copper in with some flour and a little busted up glass. I have a furnace that runs on propane, I was just simply melting the stuff and leaving it cool to solid in the pot then busting the pot. I sold quite a few of these when copper was high but have not done anything since the price is now so low.

I never was able to get the best price because of contamination but the price was fair and based on analysis by some kind of gun that my local junk guy uses it does some sparking and prints out a slip with metals and percentages. I never had lead as a contaminate and he seemed to like that, did not really mind seeing nickel in there or silver, I usually had these in less than .025 percent so I usually got number #2 price.

Jim

 

[danny987]

When you pour molten metals to a metallic mold, it should have a heavy protective layer of carbon

How do i go about this? could i use graphite powder?

 

[4metals]

You can purchase graphite mold release in spray cans, or if you have an acetylene torch you can choke off the holes at the base of the torch so the burning gas creates black soot. Stand your mold on end and allow the soot from the burning acetylene coat the mold.

Be careful to coat the entire inner surface of the mold. This technique was often referred to as carbonizing the mold.

 

[goldsilverpro]

I used to brush a thin layer of motor oil in cast iron molds. Instant carbon when the molten metal hits it. One refinery I knew sprayed on WD-40.

 

[butcher]

cheep, how about old cast iron skillets,need small they made cast iron ashtray skillets or corn bread cast pans.I have an ole cast iron melting laddle.
don't forget about moisture and hot molten metals. raining molten metals can not be fun.

 

[scrapdealer]

Normal cast iron tends to crack very easily. If you are going to have some moulds made use SG - Speroidal Graphite, which I believe has a small percentage of Mag added. They last far longer than the normal moulds.

 

[Harold_V]

When you pour molten metals to a metallic mold, it should have a heavy protective layer of carbon

How do i go about this? could i use graphite powder?

What 4metals said, or you can go to a foundry supply and purchase prepared lamp black. It can be brush applied, with a thick layer if required. The proper name escapes me, but if you ask for pig mold dressing they'll know what you're talking about.

Harold

 

[Harold_V]

Normal cast iron tends to crack very easily. If you are going to have some moulds made use SG - Speroidal Graphite, which I believe has a small percentage of Mag added. They last far longer than the normal moulds.

That's the ductile iron I mentioned. The magnesium you mentioned causes the free graphite to form spheroids instead of flakes. That's the only difference between gray iron and ductile iron.

Harold

 

[61 silverman]

Butcher , Sorry but Disney objects to mickey being a door stop or scare crow or garden KNOME especially LOL
Mark..
Over the past 20+ years at work I have used heavy cast iron ingot molds and shop made JUST LIKE HAROLD described PIG MOLDS,, Maybe we were lazy or uneducated but we never pre-coated our molds prior to using , they were allways pre-heated...
The shop made PIG mold lasted many years,, by the time it was replaced it was so warped it could only hold maybe half what it could new,, it was a four ingot spots for Bronzee it made about 15#er's.. The cast iron molds we used for silver 100oz size, again we never used a pre-coating Only pre-heated they would set on the warm up oven next to the heat exhaust tipically they would get to about 300F, the metal would solidify in seconds and get dumped out asap.. I AM NOT SUGGESTING TO NOT PRE-COAT your molds, i am only stating my experience with ingot-ing metal ( Bronzee and Silver ).

 

[Harold_V]

Maybe we were lazy or uneducated but we never pre-coated our molds prior to using , they were allways pre-heated...

Could be you were very fortunate. In my years of refining, I had molten metal solder to molds on two different occasions. Remember, I even coated my molds with lamp black (commercially prepared stuff I recommended).

One of the problems I isolated was pouring in one spot. That seemed to scrub through the coating. Also, I was casting reasonably large items--such as the 200 ounce, or slightly less, anodes for my silver cell. The other experience was pouring to a cone mold, pouring silver. In that case, it could be I was betrayed by the flux! :lol:

Harold

 

[61 silverman]

Harold, You are probably correct about pouring into one spot causing problems..And about being lucky .. When we would pour our ingot material we were right at the end of time before the metal ( SILVER ) would solidify, we had things timed out to where the castings and the metal were ready at the same time get the molds poured smoothly and ingot the extra melted for insurance.. Lost wax castings...weight calculation to know how much metal we would melt upto 2000 oz. induction furnace.. We used a special process to eliminate oxygen from entering the casting.. This was .999 Fine Silver...we never did anything to stop oxygen from the ingot, they would solidify in seconds,and be dumped out and cooled.. The casting thou we kept a starved flame over the cup until solid and cover with fiber frax while solidifing.. the starved flame would consume oxygen before it could reach the molten metal allowing a nice pipe to form in the pour cup,,another method for keeping oxygen from rest of casting was in use...the starved flame ( Block air intake on propane torch ,, DUCT TAPE. )
MARK

 

[Harold_V]

Mark,
Your description makes sense. Pouring near the solid point can be quite useful, assuming you get a complete fill without cold shuts. Because I was pouring only buttons, or anodes, I wasn't concerned with temperature, so it's entirely possible I poured too hot when I had problems. At that time, I had no pyrometer. Very different now----I have two, one of which will read exceedingly high temps (greater than 4,000°F)

Induction melting! That's the best system going. It not only melts quickly, but stirs the heat as well, so if you're working with alloys, they're sure to be homogeneous.

I used to cast silver ingots (although not by choice) and relied on the starved flame to yield a decent surface. If you mastered pouring pure silver, my hat is off to you. It's not the easiest material to handle. Strangely, the addition of the 7½% copper to make sterling seems to alter its behavior completely.

Harold

 

[Oz]

The take away message here in MHO is that it is better to spend a few moments coating a mold than the time and cost involved in separating a precious metal pour from the mould chemically. Those of you that have been forced into that situation know all too well.

 

[Harold_V]

The take away message here in MHO is that it is better to spend a few moments coating a mold than the time and cost involved in separating a precious metal pour from the mould chemically. Those of you that have been forced into that situation know all too well.

It doesn't stop with extracting the material, either. Because it gets firmly attached, you not only must remove all of the solder from the mold to restore it to usefulness, but the material is now of questionable quality, so it must be refined once again. Mold blacking is a very cheap insurance.

Harold

 

[Montecristo]

We use 3 in 1 oil to coat the mold when we pour. Besides being a flaming smoky mess it seems to work pretty well. (But we're melting scrap gold, not pure) Would the mold black be a better choice, hopefully with less smoke and smell?

 

[Harold_V]

We use 3 in 1 oil to coat the mold when we pour. Besides being a flaming smoky mess it seems to work pretty well. (But we're melting scrap gold, not pure) Would the mold black be a better choice, hopefully with less smoke and smell?

In my opinion, yes, it would be a better choice. For one, it doesn't smoke or ignite. It does slowly reduce to CO2, however, so the surface, after the first pour, will have an appearance of ash, similar to that which one gets from a charcoal barbeque. It's very thin, and adheres to the mold quite well. If the coating is not replenished, it would eventually be gone. Once I understood the nature of the problem, I rarely poured a second time without recoating the mold. Pouring to a cone mold was one of the exceptions, where, if the mold was not superheated, the resulting button usually had a thin film of flux surrounding the metal, with the balance of the flux on top, as it should be.

Gold alloy melts at a lower temperature than pure gold, so what you're doing is likely somewhat more forgiving of soldering.

Harold