High temp lead melting setup

  • 1.9K Views
  • Last Post 09 June 2016
Bisley posted this 16 April 2016

Here's my situation. I have a supply of antimony to melt into my range lead and tin for alloy. I can dissolve it into lead at casting temperatures, but this does not cause the metals to alloy, I am told. I used to have access to a plumber's furnace which would get me to 1200 degrees plus. I haven't seen or used that thing in over seventeen years as it is in an other state. Can I use a turkey fryer, like several home smelters, to get the required temperature, or do they generate enough heat? How could I modify one? I am thinking of something with a 20-25 pound pot to do the melt, achieving temperatures of up to 1200 degrees like I said. Any help / information? Bisley

Attached Files

Order By: Standard | Newest | Votes
onondaga posted this 16 April 2016

http://www.castbulletassoc.org/view_user.php?id=4645>Bisley

High heat does not help Antimony alloy with lead. 800-900 is fine, the stuff just dissolves very slowly, even at it's high melting point it may take a day if your chunks are big. Antimony in particles like sand dissolves fastest.

If you are having difficulty alloying, it may be the order you add metals. Melt the highest melt metal first, then the next lower ones in order works best. Antimony doesn't follow rules very well.

 Lead  621.5 F.  Tin    445.5  F  Antimony  1,167 F

Melt the Lead first, dissolve the Antimony, but last, lower the temp to 725 before adding Tin as Tin loss is high over 725 F.

If you put the Antimony in last, your Tin will be gone before the Antimony alloys.

Gary

Attached Files

RicinYakima posted this 16 April 2016

All of these metals in the liquid state make solutions. It is BS from the internet that it does not. Does the alcohol separate out of your beer? Like Gary says, smaller is better. I only tried this once, and what worked for me was to pound the antimony very fine with a ball peen hammer on a metal plate. Once you get to 800 F, it is about surface area, higher temperatures don't seem to make much difference.

Attached Files

mtngun posted this 03 June 2016

RicinYakima wrote: All of these metals in the liquid state make solutions. It is BS from the internet that it does not.  Ric, I'm glad you said it so I didn't have to.     :D   :D   :D    I haven't tried melting antimony -- if the need arises I have a heat treat furnace that should be up to the job -- but if you are pounding antimony into powder please take safety precautions because antimony is even more toxic than lead.   Wear a dust mask, vacuum and wipe down the work area, and wash your hands when you are done, etc..

The last time I priced antimony I decided it was about as cost effective to buy the 30% antimony ingots from Rotometals.   It's already blended with lead so no high temperatures required.

Attached Files

Eutectic posted this 09 June 2016

Alloying antimony is not difficult as long as correct procedures are used. Unfortunately there is a lot of misinformation still being circulated about alloying antimony. I have personally used all the procedures detailed here to produce hundreds of pounds of high grade linotype and antimony enriched alloys. These methods are based on the chemical properties of the metals and sound engineering principals.    Metallic antimony goes into solution in melted lead just as sugar does in tea. The sugar in tea produces a true solution that does not settle out, and the antimony/lead solution is a true solution. You do not have to melt sugar to dissolve it in tea; any temperature where the tea is liquid will work. The same is true of the antimony/lead solution; there is no necessity to reach the melting point of antimony (1300F) as stated in some books and articles.  Higher temperature does make the rate of solution faster, but for the percentages needed in bullet alloys, 650 F is very effective.   The problem with adding antimony directly to melted lead alloys is the antimony, being lighter floats on top. At a temperature of 650 F, the antimony oxidizes rapidly. The oxide forms a coating on the surface of the pieces of antimony, and this coating keeps the antimony from going into solution. You end up with useless pieces of oxidized antimony.   In order to get antimony to go into solution, you must prevent oxidation and hold the antimony in contact with the molten alloy. You can do this by physically submerging the antimony. Using the correct flux will speed the solution.   I use a submersion bell method for direct alloying of metallic antimony. The idea is to get the antimony to stay under the surface, I use a ladle bowl with holes drilled in it, mounted inverted on a 1/4 inch steel rod. This is used to hold the chunks of antimony submerged in the molten alloy until they dissolve. In use, I pump the bell up and down occasionally to stir the pot. High temperature is unnecessary, 650 F works very well and greatly reduces vaporization and formation of dross. Any method of holding the antimony under the surface will work. A wire mesh works well, do not use galvanized mesh as you do not want to introduce zinc into your alloy.   In most pots it is possible to use fist size pieces. However the rate of solution is dependent on the surface area, large pieces are very slow to dissolve. The best size for the submersion bell method in home casting pots is in the range of ½ to 1 inch pieces. Tin appears to speed the solution, and provides some oxidation protection, if the alloy requires tin, I add the tin first.   Although the antimony may look shiny and clean, there is an oxide film on the surface that slows solution in the molten alloy. In order to break the initial oxide skin on pieces of antimony, I treat them with a 20% by weight solution of rosin in denatured ethyl alcohol and allow them to dry. This fluxing results in a ~50% decrease in the time necessary to achieve complete solution. I can accommodate ten ounces of antimony at a time in my plunging bell. Ten ounces of antimony in ½ to 1 inch pieces dissolving into a 15 pound melt at 650F takes about 10 minutes, the use of rosin reduces this to 5 minutes. Ten ounces of antimony adds 4% antimony to the melt.  It takes 3 additions to get 12% antimony into the melt, in 30 minutes you can produce a pot of linotype.  from pure lead. Note the rate of solution slows when over the eutectic point which is linotype, 4% tin 12% antimony. Making alloys like Monotype metal with higher percentages of antimony take additional time.   The rosin used is pine rosin; it may be available at your local hardware store. You can use any of several solvents to dissolve the rosin, methyl alcohol (wood alcohol), ethyl alcohol, isopropyl alcohol, or “denatured alcohol". The alcohol must not contain water, so do not use “rubbing alcohol".  If you want the convenience of a spray can, purchase some Cramer “Firm Grip" sold in sporting goods stores to improve the grip on tennis racquet handles etc. “Firm Grip" is a rosin solution, works well, is easy to use, but it is expensive.   Antimony is hard but very brittle, if you purchase a large ingot, you can break it into pieces by putting it in a plastic bag and striking it with a hammer. The plastic bag is to contain the pieces when the antimony shatters.  Dust will be produced; wear a dust mask, antimony is toxic. You should have adequate ventilation and must follow good sanitation procedures, the same as you should follow if you are doing any casting.   Small pieces of antimony, less than 1/4 of an inch in diameter, have a large surface area and dissolve quickly. For the submersion method, you must have a small mesh screen or a bell with 1/16" holes.  The small pieces oxidize very quickly and significant oxidation may occur before they can be submerged. Small pieces should be protected by coating with a rosin flux.  That should get you going. Here is the submersion bell, there are five  1/8 inch holes around the 1/4 inch steel rod. Steve

Attached Files

onondaga posted this 09 June 2016

http://www.castbulletassoc.org/view_user.php?id=6924>Eutectic

Solid method, thanks for sharing!

Gary

Attached Files

Close