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Thread: Filtering the lead smelter

  1. #1
    Boolit Bub
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    Filtering the lead smelter

    Hi
    Until now I considered lead smelting in a small smelter in the open. I look at melting range scrap, lead roofing and pipes mostly. I assume an active coal filter with fine dust filtering would be fine.

    However, this fall I will move to a less remote area, with neighbours close by. I’m concerned about airborne lead fallout and other typical lead pollution byproducts. There are swimming pools nearby and ponds, small gardens where people would grow their vegetables. Many children too.

    Does anyone have good experience with DiY filtering hoods and filters? In these digital times stuff like filtering cloth, active coal in bulk and PC fans are just one click away.

    I’m willing to reduce the size of the smelter so it matches the suction/filtration capabilities of a self constructed filtering hood like in the chemists’ lab. I’m looking to do some kind of permanent arrangement in a stone shed where electricity is available. I want my smelter to be hardly noticeable from the smell, and keep my environment clean.

    I would really be ashamed if in the long run anyone would experience trouble from my lead smelting.

    Any advise or helpful insight on how to solve this problem without doing away with a hobby would be very much appreciated.

  2. #2
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    I can only relate my experiences and am not an expert on airborne particulates. My smelting setup is a propane turkey fryer burner in a converted Weber grill. Best part is the lid which also has a temp guage on it. I found that with the lid on you could not really smell anything nor was there barely any smoke. When I took the lid off for fluxing, I would light the pine shavings reducing any smoke. Think for you I would not use a charcoal fire as it just adds more potential smoke but I have not used one for smelting. Good luck
    Ron

  3. #3
    Boolit Master
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    Admitting that I have no real experience dealing with this I’d try building an exhaust pipe shaped like a p-trap and put fine water misters in it. Small drain at the bottom, effluent directed to the sanitary (not storm) drain. This should cool the exhaust and capture a huge percentage of everything coming off the pot. Could do the same with a horizontal pipe just tip it so it drains away from the pot.

  4. #4
    Boolit Buddy Joe504's Avatar
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    Somone else chime in here, I know we have some actual chemist here, but....

    If you keep the lead under 800f or so, there will not be any lead fumes.

    Other crap will come out of smelting, but not lead particulate, as far as I know.

    Sent from my SM-G955U using Tapatalk

  5. #5
    Boolit Grand Master

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    While it is good to consider possible consequences of your lead melting and casting I think you are overly concerned about the issues.

    First, while a lot of people here call melting range scrap and raw lead "smelting" it is not, it is just melting lead at moderate temperatures where lead vapour/fume is not produced... at least in any significant quantity. Smelting is converting lead concentrate, normally lead sulphides, to metallic lead and is conducted in smelting furnaces that run at about 900°c (1650°F) and at that temperature the lead is red hot and boiling, along with other heavy metals, and much vapour and fume is produced. The fume is captured by baghouses as oxide dust and sent to other plants for processing

    Second. the biggest hazard (other than burns) in lead melting and alloying is in handling the lead (hand cleanliness after handling) and in the handling of dross on the lead. The dross contains lead oxides and impurities which can be hazardous if inhaled or ingested but it is not a light fine dust that is easily blown into the air either.

    Lead or lead oxides cannot be absorbed through the skin. They enter the body by inhalation of vapour or dust or ingestion, usually from dirty hands.

    In my opinion the biggest concern is other people's perception of what you are doing. Yes, take precautions by wearing gloves and possible using a respirator, and by handling lead and dross carefully as in don't dump the dross in your garden and keep your lead supply under cover out of the weather. If you go out in a HAZMAT suit and operate your melting operation under a fancy filter system it will be assumed that what you are doing is hazardous to everyone near you which it isn't if reasonable basic precautions are taken.

    I'd suggest that if you are in a populated area with people who don't understand what you are doing watching that you cast out of site and practice safe handling of materials and you are good. If you cast in an enclosed room or garage it would be a good idea to have a vent fan and if you want to be sure nothing escapes use a filter on the fan exhaust. Activated charcoal is not required, just fine dust capture in case dross dust gets airborne.

    II have been a bullet caster for 53 years and have spent the majority of my adult life working in and around a large lead smelter and refinery operation that produces 90,000 tons of lead/year. I have never worn a respirator while casting bullets and seldom do in the lead plants unless there is visible smoke or dust in the air, or unless I am in respirator mandatory areas. I have never tested high for blood lead. To note, the lead bullion pots have vent hoods on them as that is somewhat dirty lead that has been pyro refined in the smelter. Lead product pots do not have vent hoods on them as that is clean lead like what you are melting. The open product pots in the plant hold 235 tons of lead each and there are open mixing and melting pots as well.

    I'd say fire hazard from melting lead is a bigger threat than health or environmental hazards from lead or dross.

    Just my opinion.

    Longbow

  6. #6
    Boolit Master bruce381's Avatar
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    real good information thank you and I agree "smelting" lead for me is just the smoke from my wax and pine wood used as flux.
    I do it in the garage with a fan and at about 100 Lbs lots no one even across the street notices.

  7. #7
    Boolit Master
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    I had a little conversation with a heavy metals toxicologist. What concerned him was not lead vaporizing off the melt (as pointed out it has to get much hotter than our setups are capable of to be an issue) but that lead and lead compounds can hitch a ride on the particulates in any smoke that is generated. Clean metal melting, not much of a problem. Other materials with the lead that burn and produce visible smoke, more of a problem. How much of a problem was not discussed. It may be one thing if the facility is a lead processor that produces tons of ingots daily year round, another if you are a hobbyist making a couple hundred pounds every couple years.

  8. #8
    Boolit Bub
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    Thank you all for your advices and insights. What I take away out of this is that I could benefit from a clean heating source like gas/propane or maybe even making my own electric smelter (solar panels) for not adding combustion fumes. I considered wood to be cheap but I’ll drop that idea because of the additional fumes. I will also take care of reducing the fumes from the melting pot.

    I consider this by making an extraction hood with improvised filter with some replaceable activated carbon layers between filtering cloth (all ingredients can be ordered online) together with PC fans, and provide a spray area in the PVC exhaust chimney with a dripping point that clears the melting area well. Not sure if I should put the carbon filter closest to the hot side of the hood or the water mister first. Probably the latter.

    I will use irrigation mist nozzles, can be had cheaply, drill them in the exhaust and glue it to provide a seal. I will collect the dripping water in jerrycans and dispose of that water in the recycling center. If I tune the mist spraying correctly it will take a few hours to fill a jerrycan while still producing a good mist in the exhaust pipe.

    I think such a permanent melter arrangement can work quite convenient and ergonomically, so I need to stockpile less lead trash around in my basement, and do more frequent and smaller batches of lead melting/purification.

    Thank you all for your insights.

    Any more practical ideas relevant to this idea, or on how to make an electrical lead melter would be very helpful.

    For instance, I’m not sure if the electrical heating element should be in the pot (more efficient heat transfer, less power consumption, but more vulnerable to damage and possible too hot lead contact) or outside the pot (heat loss because no direct heating of the lead) would be the better idea.

    Kind regards
    Pebbles

  9. #9
    Boolit Master
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    There is going to be a trade off with the carbon filter. It will load up fast and reduce air volume, and it will be expensive to maintain. If you put it first it’ll load up in a few minutes, if you put it last and gets damp it won’t work at all and will impede air flow.

    Any disposable media will add cost, so I’d try with none and see how that works.

  10. #10
    Boolit Grand Master

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    If your plan is to use a mister/fogger in the ducting it has to go downstream of your filter regardless of whether you use carbon or not. I wouldn't bother with carbon/charcoal. In fact I wouldn't bother with a filter if you are using a fog nozzle.

    I'd suggest using a fog nozzle on a piece of ducting angled down after the high point the hood so all water runs away from your pot. If you want to find out if there is any lead captured, try running without a filter but with the fog/mist nozzle then get the water tested. If there is no lead or so little it doesn't matter then just dump the water down your drain. I suspect you will get little or not enough to worry about but this could be an education for me.

    As for your heating element if you go electric, yes, you can put it in contact with the lead. That is how the lead launder for the anode casting facility I worked at heated their lead launder (they run 60 tons per hour through that launder). The disadvantage for you is during drossing. Normally I use a piece of wood to stir the molten lead and scrape the insides of the pot to get everything well mixed and scale off the pot. If you have an element immersed in the lead you will not be able to do that, plus when you are adding lead if you drop an ingot or chunk it may damage the element. Personally I like a pot on propane burner. Different strokes.

    Longbow

  11. #11
    Boolit Master
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    Quote Originally Posted by longbow View Post
    If your plan is to use a mister/fogger in the ducting it has to go downstream of your filter regardless of whether you use carbon or not. I wouldn't bother with carbon/charcoal. In fact I wouldn't bother with a filter if you are using a fog nozzle.

    I'd suggest using a fog nozzle on a piece of ducting angled down after the high point the hood so all water runs away from your pot. If you want to find out if there is any lead captured, try running without a filter but with the fog/mist nozzle then get the water tested. If there is no lead or so little it doesn't matter then just dump the water down your drain. I suspect you will get little or not enough to worry about but this could be an education for me.

    As for your heating element if you go electric, yes, you can put it in contact with the lead. That is how the lead launder for the anode casting facility I worked at heated their lead launder (they run 60 tons per hour through that launder). The disadvantage for you is during drossing. Normally I use a piece of wood to stir the molten lead and scrape the insides of the pot to get everything well mixed and scale off the pot. If you have an element immersed in the lead you will not be able to do that, plus when you are adding lead if you drop an ingot or chunk it may damage the element. Personally I like a pot on propane burner. Different strokes.

    Longbow
    What he said. I hadn’t thought about testing the water for lead, great idea. It’ll be dirty from all the junk that burns off from the scrap, but it may not have enough lead to matter.

  12. #12
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    Quote Originally Posted by Joe504 View Post
    If you keep the lead under 800f or so, there will not be any lead fumes.
    Other crap will come out of smelting, but not lead particulate, as far as I know.
    I used to know a guy who'd worked at the old Dallas Lead plant for about 20 years.
    That's what he told me when I was first starting out and had Lead melting/smelting related questions.

    I can't remember exactly, but I think he told me the fumes won't come off until it gets even hotter that that.
    I want to say it was around 1200 F, but that may not be right.
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  13. #13
    Boolit Buddy
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    Washing your hands and wearing a respirator is a really good idea if you are melting scrap lead. Water near a lead melting operation will eventually result in severe burns if you get a drop of water in the lead pot. Water at 600 degrees goes to steam and the expansion of the gas involved will throw lead all over the place. Forget the carbon filter unless you want a lead dust-carbon thermite reaction. Once it starts there is no practical way to put out the fire. Do your melting outdoors or with good ventilation. Don't over think the operation.

  14. #14
    Boolit Grand Master


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    Longbow’s first post sums up most things. Although we often call it smelting, it’s not, it’s just remelting recycled lead. Much lower temperatures and the lead shouldn’t vaporize. You are most at risk from breathing fine lead particles or ingesting them.

    One of the reasons most of us recycle lead is to get inexpensive boolits to shoot. Before going to a great expense consider buying an alloy to cast with. And as was already mentioned, if you go doing too much, your neighbors may start thinking you’re up to something, a lot more dangerous than it is and cause problems for you.

  15. #15
    Boolit Grand Master
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    I just wait for a breezy day and re-melt to my heart's content. Nobody around me has ever complained in the "hood".

    NEVER attempt it indoors!!!!!!!!


    I usually pick all the carp (rubber etc) before starting so there is very little smell even though there is smoke to a small degree.

  16. #16
    Boolit Master Jim22's Avatar
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    In my garage in Alaska I set up the pots on an outside wall. Above the melters I installed a cheap range hood and ducted it through the wall, The hood had two speeds and, of all things handy, a light. The fumes went through the expanded metal filter that came with the hood. Outside I installed a 4"x10" regular vent with a flapper. The whole thing worked really well.

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