Lead casting slag and other melting issues

DukkButt · Sep 3, 2012

What do you do with the slag you skim off the top of your lead after you flux it? I understand lead oxide is hazardous and I don't want to be irresponsible with it. As an aside, I understand what fluxing is supposed to do, but it sure seems to create a lot of that slag. I also understand that having the lead too hot will cause oxidation but would appreciate any other comments on how to best handle melting and mixing lead alloys. Lastly, my Lee melter has the bottom pour feature but it keeps plugging up. I think the antimony doesn't stay completely mixed and solidifies in the opening. Any comments or suggestions?

jake2far · Sep 3, 2012

DukkButt said:
What do you do with the slag you skim off the top of your lead after you flux it? I understand lead oxide is hazardous and I don't want to be irresponsible with it. As an aside, I understand what fluxing is supposed to do, but it sure seems to create a lot of that slag. I also understand that having the lead too hot will cause oxidation but would appreciate any other comments on how to best handle melting and mixing lead alloys. Lastly, my Lee melter has the bottom pour feature but it keeps plugging up. I think the antimony doesn't stay completely mixed and solidifies in the opening. Any comments or suggestions?

What is your lead source? How do you know ya got antimony in it? Do you own a thermometer? How are you skimming the dross? What are you using for flux? How hot are you running the melt? Just a few questions?
Let us know.

Jim

DukkButt · Sep 4, 2012

Lead source was ebay, pure lead ingots. I know I have antimony because I bought some and melted it into my lead. That's a complication, though, because I didn't have any way to cut the large chunk of antimony so I had to melt it into my lead at a high percentage then remelt those ingots with more lead to lower the percentage. I'm trying for a 92-4-4 lead, tin, antimony mixture. I think I have a high antimony mixture on the inside of my melting pot now and that may be what is contributing to the pour spout on the bottom plugging up.

My flux is Buck Beaver's Lead Reloading Flux. I'm skimming the dross with a Lee lead ladle. Was running the lead at full temp of the Lee 20 pound melting pot until I read that caused more oxidation, then turned it down some. Haven't cast in a while so I don't remember what temps I was running, but I do have a thermometer to monitor that.

Mostly I was wondering what people do with the dross and the other questions rolled out as after thoughts.

Vernon

deadshot2 · Sep 4, 2012

I used to, as a part of my job, visit factories that cast lead Wheel Weights. One used a central melting furnace and supplied the molten metal to all the molding stations with what they called a "sow". Just like little piggies lined up for a meal, the molds drew their lead from this channel. It was necessary to "rake" the bottom and sides frequently to bring the dross to the surface.

In another factory, each molding station had it's own separate furnace not unlike a bullet casting furnace. Again it was necessary to "rake" to bring the dross to the surface. Something as simple as a piece of heavy welding rod with a "Tee" formed on the end by a welded on piece of flat bar, sized accordingly to the dimension of your furnace. Once the metal has melted, and you're in the fluxing process, use this to scrape the bottom of the pot as well as the sides. this will make plugging of the orifice minimal as all the oxides and "crud" are now freed up to float to the top.

As for disposal, I would just let it cool, put it in a double plastic bag, and dispose of it in your garbage. The quantity is insignificant and doesn't require any special handling. Double bagging just assures that anyone that might come in contact with it on it's way to the landfill isn't going to pick up any lead or other metal contamination. Within 24 hrs of pickup, the "baggie" will be buried in a fill somewhere.

evltwn · Sep 4, 2012

My Lee bottom pour furnace clogs up while casting. Usually its when I add another ingot of lead, which drops the overall temp of the lead in the pot. As a result, the bottom valve will clog up. When the pot again reaches its normal temp, a small drop of lead will form at the end of the valve. Using GLOVES, bend a paperclip and insert it in the valve. That will open the clog and allow lead to flow again.

On a side note, if your valve dribbles after closing (usually happens in older pots...lol) Rotate the valve rod with a screwdriver and it will stop.

mortre · Sep 4, 2012

I don't have a thermometer either, but I keep the temp gauge on my pot at about 700. Too high will cause tin oxide to form on top of the melt, robbing you of tin. I tried turning the temp up at one point and cooked out all the tin. The lead started coming out thick and fill out was horrible. Dropping sprue/new ingots in will drop the temp and cause the spigot to clog if you don't let it heat back up.

92-4-4 seems pretty hard to me, what are you casting for? I am using isotope lead (96-3-1) for pistol and rifle. To be honest I think I could make do with a softer alloy for pistol. I may add more tin if I decide to try hunting with cast. Not for hardness, but to make it tougher/less brittle. I'm pretty new to this as well though, so I am mostly regurgitating what I have read.

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rose45mee · Sep 4, 2012

I would not throw my dross in the garbage. There are metal recycling buisnessess and scrap yards areound your area that you can drop it off at for free and some of them will even pay you something for it. or trade you lead for it. Depending upon the amount you bring in. This time of year I keep at 695-700 degrees.Less dross and less seperation.