Replacement CERAMIC Crucible for Electric Melting Furnace

[rybak97]

I went out and bought a Hardin Electric Melting Furnace, and I really like it. The fact that I can easily place silver in the crucible, pour with tongs, dial in the temperature pretty accurately to get the desired results (Crystal formation) and not have to build a brick structure or use an open flame is what swayed me towards this design.

Here it is.....

http://www.amazon.com/FURNACE-Recovery-Refining-Melting-Crucible/dp/B007D05CJY

I HATE the graphite crucible. Every time I use the thing the first 4 or 5 pours have black powder on the top of the ingot, ruining the look and just touching it leaves you with graphite powder all over the place. Maybe I’m supposed to wash the crucible out before each use to remove the powder but I couldn’t find any information on this type of maintenance??? The flux does not seem to bind with the graphite powder so that doesn’t help at all.

Here’s the crucible……

http://www.ebay.com/itm/2kg-Graphite-Crucible-4-electric-Furnaces-and-kilns-melting-gold-silver-metals-/321101020949?pt=LH_DefaultDomain_0&hash=item4ac31cbf15#ht_3803wt_932

Are there any manufacturers that make a ceramic drop in replacement for these electric melting furnaces? I've been searching all over and it seems that there are only graphite replacements for this unit.

 

[etack]

You may need to adjust the lid so that it fits more snug. it seems you might be getting air in there that is eroding the graphite away. it might take some ceramic wool or paper to get a good seal with some weight on top of it.

Eric

 

[rybak97]

You may need to adjust the lid so that it fits more snug. it seems you might be getting air in there that is eroding the graphite away. it might take some ceramic wool or paper to get a good seal with some weight on top of it.

Eric

Does the graphite only corrode when air gets to it and its hot? How do I pour multiple 1oz ingots if I have 10oz's of silver in the crucible at once? Every time I open the furnace, remove the crucible and pour the silver it’s going to be exposed to air.

Can I wash out the graphite crucible before each use to reduce the amount of graphite powder there is? There also slag built up in there, can I remove that? This furnace came with NO operating manual, maintenance schedule, nothing!! Im flying blind here.

 

[TomVader]

I have the same furnace. I think the whole idea behind the graphite crucible is that it DOES degrade. Carbon binds with oxygen producing a protective layer of CO2 so that you don't need any flux. Metal comes out pretty clean. It's a great idea, but I also hate the black powder and would rather use flux than deal with it. I found a ceramic crucible that would probably fit. I E-mailed the seller and they told me it was for an induction furnace. I don't know if it would work with our furnace, but I'm going to gamble and buy one. Here is the link: http://www.ebay.com/itm/280724937132?ssPageName=STRK:MESINDXX:IT&_trksid=p3984.m1436.l2649#ht_1928wt_706 if that link doesn't work search favoriteusa on E-bay.

 

[TomVader]

I wouldn't put any water into the graphite crucible unless you want to spend a couple of hours drying it out. 2 hours at 400F should do it.

 

[Harold_V]

While I don't have a link to offer, both GSP and I have discussed furnaces of this nature. Neither of us like them. I had a Handi-melt, purchased new, that sat on the shelf and went with my refining business when it was sold. I hated that damned furnace, and did not enjoy the high cost of crucibles, especially considering their very short lifespan.

You can not pour precise ingots. Doesn't matter how hard you try, even if you melt a specific amount of metal, some may not pour, and will then most likely report in your next heat. Small ingots are typically struck if a specific weight is expected, with the planchet having been punched from rolled stock, which allows for control of the weight. The best you can hope for, assuming you don't have the capabilty to roll your material, and punch the planchet and ingot, is to mark them according the their actual weight.

Some folks like to pour an ingot slightly heavy, then adjust the weight by filing. Problem is, any disfigurement of an ingot can be evidence of weight being removed---so I do not promote that idea.

Harold

 

[its-all-a-lie]

http://i1302.photobucket.com/albums/ag123/barnesjerry77/100ozccc.jpg http://i1302.photobucket.com/albums/ag123/barnesjerry77/topof100ozccc.jpg This bar was drilled, when i bought it i assumed it was drilled to perform an assay or to check the possibility of it being filled with lead, as it turned out it had been drilled to achieve an exact weight of 100.00 oz.

 

[pgms4me]

I know someone who makes his own.Good idea if you intend to do lots of casting. You can order or buy castable refractory in 10-50# bags for about 1-2.00 per pound. I have seen some that is good to 2700 degrees F. Take your old crucible and make a mold. I understand that when you pour castable refractory it needs to be tamped in the mold to insure there are no air bubbles or pockets of air. this,of course,would lead to early failure. i never did a crucible but poured lots of replacement firebrick slabs for specialty stoves in the past.

 

[NobleMetalWorks]

I have, and have used a Kerr.

It's very simple to solve the problem with your crucible degrading around the top edge so fast. You simply coat it with refractory cement. Just glaze it. It will be affected over time but you can continue to glaze it with a very thin coating of refractory cement.

I only use mine for casting anode bars, and use a gravity mold even at that. For everything else I either use a torch, or a crucible furnace.

Also, you don't really want to use too much flux in those crucibles, it degrades them much faster, but it is the flux that removes the black material you are having an issue with.

Besides all the other problems that have been discussed to exhaustion about these types of furnaces, you also have to pay strict attention to the crucible, and stop using it before it degrades to the point it might break. When they break, and spill molten metals on the inside of the furnace you will probably have to purchase another heating element, which can be very expensive.

Scott

 

[TomVader]

rybak97, I bought one of those ceramic crucibles. it fits into the furnace but it's pouring spout prevents the lid from closing all the way. It seems to work OK though. I only used it once so far, for sterling.