Saltyrad Posted February 23, 2023 Share Posted February 23, 2023 Hi all, I am glad I came across this forum as I saw a lot of people had some good info in certain sections. I have been studying up on it for a while and judging by the post I've seen, I have just scratched the surface. So I wanted to ask for some good tips. To explain where I am starting, I was wanting to order a forge kit with a 12k crucible. I wanted to start small with scrap metal, but what I am doing right now is trying to recycling some cans to start. So a few questions if ya'll wouldn't mind teaching me some are... since some cans are steel with a tin coating, will the tin burn off in the high temps needed for steel? (I Will be using a forced burner with propane in a mostly closed container. there is a small hole on top of the lid to let air out) would that small hole be small enough to slow down oxidation? (I would assume in a semi closed space not much oxygen would be left over from the propane burning) If its still not enough then would using the stoichiometric ratio of propane to oxygen be a solution? (just using air so to achieve that I would think first I would have to know the amount of air moving from my blower, then take 21% of that for one side of the ratio. for the other side of the ratio I would need 15.67 of that 21% in propane.) what are the most cost efficient ways to strip the impurities off the can before melting? (preferably no acids since aluminum cant be recovered from its salts, at least from what I know) would the slag reduction be worth it since it would technically result in less aluminum being mixed with impurities? if there is anything besides these questions in tips yall can be give me, I would love to hear it. I do plan on using a face shield for this as well as a leather cover for my front. I definitely value my safety so no need for too much concern. in fact safety tips from your experience will be welcome too. if you've taken the time to read all that and share some info with me then thank you ahead of time. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted February 23, 2023 Share Posted February 23, 2023 What is the intended end use of your metal? Scrapyards often pay LESS for ingots than the original aluminum cans as they can't tell what alloys are in the ingots; but cans are obviously good alloys for cans. So time and fuel costs to make a lower return may not make sense. Do not mix Al and Fe! Quote Link to comment Share on other sites More sharing options...
Saltyrad Posted February 23, 2023 Author Share Posted February 23, 2023 yes, but they will pay more for pure aluminum and I plan to purify the metal myself. I wont be selling to a scrap yard if I can help it, I would save up enough to to sell a ton at a time since pricing for aluminum on the market is usually looked at per metric ton. I wont be mixing the 2 different metals. I have a home made electro magnet to separate the metals. my concern with steel though was when I melted the steel cans to keep it from oxidizing while its being melted. my first guess was using the stoichiometric ratio, but that ratio being 15.67 of propane to 1 of oxygen makes me feel like it would use way too much propane. though I'm not going to rule it out till I plugin some numbers, because while 15.67 times the amount of oxygen sounds like a lot i realize it is only 21% of the air being blown that needs that ratio. Quote Link to comment Share on other sites More sharing options...
LeeJustice Posted February 23, 2023 Share Posted February 23, 2023 I did a search for how many cans it takes to make a ton, and came across this article. https://archive.nytimes.com/green.blogs.nytimes.com/2012/06/12/toward-a-greener-soda-can/ It may help you to decide whether or not you want to proceed in your endeavor. Quote Link to comment Share on other sites More sharing options...
Saltyrad Posted February 23, 2023 Author Share Posted February 23, 2023 I appreciate it, but there is no need to show me this. I realize what im getting into. please assume I know the basics of what I would need to know. I am looking for more advanced information about the process. dont get me wrong though i thank you for taking time out of your day to find something for me that you thought would be helpful Quote Link to comment Share on other sites More sharing options...
Latticino Posted February 23, 2023 Share Posted February 23, 2023 If you know the basics, then you know there is a significant difference in the level of difficulty and danger in melting steel vs melting aluminum. If you are looking for advanced information you will more likely find it on a site more dedicated to casting than this blacksmith centered site. Depending on your plan for the steel pucks created, it is non trivial to maintain the carbon content and homogeneity, and this variation can have an impact on your end product. Asking about maintaining a stoichiometric ratio without describing how you are going to measure the air/gas ratio used is not necessarily productive. If you keep your flame slightly reducing, you should have less oxidation, particularly inside a closed crucible. However I'm still finding it hard to see this as an economical process based on the effort involved in closely packing a consumable crucible with steel, cost of fuel, replacement of crucibles and relative value of questionable steel material produced. If you can look up the correct ratio you should also be able to look up the temperature that tin volatilizes at, and see how that compares to the melting point of steel. If the tin doesn't volatilize and escape through the "small hole at the lid", it will stay in the fluid container with the steel. Due to a combination of these factors I would recommend sticking to melting aluminum and finding some other method to recycle the tin coated steel cans. As previously stated, even melting the aluminum for scrap is a questionable economic solution. Now if you were to melt it and cast it into something that had some more intrinsic value than scrap, it might be worthwhile (but then you might want to use recycled cast aluminum stock instead (i.e. automotive wheels, engine blocks...) Quote Link to comment Share on other sites More sharing options...
George N. M. Posted February 23, 2023 Share Posted February 23, 2023 Welcome aboard from 7500' in SE Wyoming. Glad to have you. First if you put your general location in your profile we will know better how to answer your questions. This is a worldwide forum and we don't know if you are in Kansas, Lapland, or Tasmania. Also, you mention a "12k" crucible. !2,000 what? Cc? Kg? Pounds? Gallons? You can make your own decision about the economics of melting scrap and selling the ingots. Here in the US you would probably spend more on equipment and fuel than you would make in sales. As to the actual process all I can offer is to be very careful and have plans B and C in place for if something goes wrong. Finally, make sure that you are using some sort of flux to protect the molten metal from oxidation. "By hammer and hand all arts do stand." Quote Link to comment Share on other sites More sharing options...
Terry Griner Posted February 23, 2023 Share Posted February 23, 2023 Hello, I don't post out here much, most folks out here know more than I do. With that said, I have a question. What are you planning to do with the metal once it is melted? Are you going to cast Tools, Decorations, Art? What do you plan to cast into, Green sand, Oil sand, Investment molds? I have been casting off and on since 1979, in everything from a Electric furnace to a charcoal fire, And all the non ferrous Metals (Copper, Brass/Bronze, and Pewter. I have avoided Lead.) Head Foundry Imp Dancing Rabbit Foundry Quote Link to comment Share on other sites More sharing options...
Steve Sells Posted February 23, 2023 Share Posted February 23, 2023 For someone only wanting advanced information and not basics, you seem to have missed some basic things, like you dont normally buy a forge to melt metals, you want to use a furnace, and using extruded alloys like Al Cans are made from, are not suitable for casting. but what do I know Quote Link to comment Share on other sites More sharing options...
Saltyrad Posted February 24, 2023 Author Share Posted February 24, 2023 19 hours ago, Latticino said: If you know the basics, then you know there is a significant difference in the level of difficulty and danger in melting steel vs melting aluminum. If you are looking for advanced information you will more likely find it on a site more dedicated to casting than this blacksmith centered site. D Your right, I know the means to look it up, but I also value others experience too so thankyou for your reply. so atm it may not seem economical, but I also am starting small so I can get experience myself and work out a good process that I can scale eventually. I was going to build my own large forge, but as I mentioned I want to work out the process first in a hands on way. so for the stoichiometric ratio, starting with the blower I was going to measure the air velocity and take the diameter of the pipe which would give me the 2 variables I need to get the air flow rate via this formula. Qair = uair * π. D2/4. then take 21% of that to get the amount of oxygen moving through the pipe. then convert the PSI measurement from my control valve on the propane tank, convert it to flow rate as well to get the the other variable. with 2 of the same units of measurement (cubic feet per minute) I can dial what I need from there. that would be my first approach. as for the logistics of it, I'm not too concerned about it until I get more experience to create a better process that works for me. Also I don't plan on making money now, but plan on the future of changing market conditions, which they will and I'm a patient man 19 hours ago, George N. M. said: Welcome aboard from 7500' in SE Wyoming. Glad to have you. First if you put your general location in your profile we will know better how to answer your questions. This is a worldwide forum and we don't know if you are in Kansas, Lapland, or Tasmania. thankyou for the reply, I live in the US in good ol TN. sorry for the typo though there was meant to be a g there so kg. is there a chart you know of that relates the metals reactivity to oxygen at specific temps? so that i can gage what is good measurement for the amount of flux I would need for a certain material. Quote Link to comment Share on other sites More sharing options...
Saltyrad Posted February 24, 2023 Author Share Posted February 24, 2023 6 hours ago, Steve Sells said: For someone only wanting advanced information and not basics, you seem to have missed some basic things, like you dont normally buy a forge to melt metals, you want to use a furnace, and using extruded alloys like Al Cans are made from, are not suitable for casting. but what do I know so when I say basics I mean chemistry, physics, etc.. that's why I ask for advanced info, because I don't pretend to be a metallurgist but as mentioned I have enough background in these other subjects including being an engineer myself to fully understand what might be told to me. that's why I asked to basically skip the logistics part about warning me and go straight to the info that you would believe I need to know to do it right. i hope that makes it a bit more clear what I meant. so with that said i would be glad to learn what i can here Quote Link to comment Share on other sites More sharing options...
George N. M. Posted February 24, 2023 Share Posted February 24, 2023 A chart of the relative reactivity of metals is found at: https://byjus.com/chemistry/reactivity-series/ Note that silver and copper, relatively nonreactive metals, still need to be fluxed in the crucible. "By hammer and hand all arts do stand." Quote Link to comment Share on other sites More sharing options...
Saltyrad Posted February 24, 2023 Author Share Posted February 24, 2023 11 hours ago, George N. M. said: A chart of the relative reactivity of metals is found at: https://byjus.com/chemistry/reactivity-series/ Note that silver and copper, relatively nonreactive metals, still need to be fluxed in the crucible. awesome, thankyou very much for that. I saved the website to my favorites. I would imagine not all flux is created equal? is there some brands I should stay away from? also I changed my profile like you mentioned. Quote Link to comment Share on other sites More sharing options...
Latticino Posted February 24, 2023 Share Posted February 24, 2023 33 minutes ago, Saltyrad said: I was going to measure the air velocity and take the diameter of the pipe which would give me the 2 variables I need to get the air flow rate via this formula. Qair = uair * π. D2/4. then take 21% of that to get the amount of oxygen moving through the pipe. then convert the PSI measurement from my control valve on the propane tank, convert it to flow rate as well to get the the other variable. with 2 of the same units of measurement (cubic feet per minute) I can dial what I need from there. that would be my first approach These are indeed the basic physics of what you would need to do, but the practicality is something else. First you must consider how to source an air flowmeter that is accurate in the ranges of CFM for the size blower outlet. There are a number of options, but you most likely will have to either cobble something together or purchase a fairly costly instrument (a multipoint pitot-static array with calibrated magnahelic would be nice, but I don't think it will work all that well in the turbulent air you will most likely get with a blower assembly not designed for same and the relatively small duct diameter. Perhaps an orifice meter with a fixed cavity calibrated for that level of flow and static pressure? I saw one CDI meter that seem to be close to that range for a 2" pipe, only around $1,000 and may not be all that accurate at the flows involved). Another option might be to source a characterized blower with a known blower curve, measure the discharge pressure and associated RPM directly and calculate the flowrate from that. Then you have the problem of getting the flowrate from the propane valve. Unless you are planning on using a rather expensive characterized pressure regulator style control valve I don't think you are going to find any kind of simple relationship that will directly apply to your gas train. All of this can be done, with the right application of test equipment and the time and knowledge to utilize same. I think as a budding melter on an admittedly slim budget, you should start a little slower and just get the basics of melting and pouring relatively low temperature metals without causing accident before starting to worry about steel. You can play with your furnace atmosphere at the initial stage the same way most of the rest of us do (loosely metering the level of oxidation or reduction by judging the exhaust by eye and the sound of the burner) and learn the basics of casting before jumping into the deep end. Please consider there may be a reason you don't see a bunch of backyard tin can melters or at least give us some idea of what you plan on melting the steel for so we can offer better advice on how to achieve those aims. Quote Link to comment Share on other sites More sharing options...
Saltyrad Posted February 24, 2023 Author Share Posted February 24, 2023 your right, it definitely is different practically. I know I wont be able to just be one and done with it per say. It will take some tinkering and learning some hands on experience to get the feel for it. I just like to take in as much info as possible because I always have questions. I do plan on starting small because similar to what you said, every auditory and visual que is something to take in and get the feel for. which I think I could grow a passion for and collect material along the way. the orifice meter is appealing, but it cost so much. I would definitely have to invest in one of those in the future though. For now what I would have to do is rely on some math to get by for my propane line. I can use the Psi and the density of the gas (2 known values) to get the velocity. once I have the velocity I can use the cross sectional area of the line and velocity values to find the flow rate. probably wont be the most accurate thing, but better than nothing I suppose. at least with propane I feel better about using those formulas since the gas is mostly pure. As for the blower I think what you mentioned for the blower with a known curve is perfect. those curve charts give a lot of info that I could use. thankyou, i took the time to read up on things you mentioned here. like the orifice meter, I did not know it was named that. lingo is something im going to have to learn here too. do you think a Venturi meter would be a suitable replacement for a orifice? Quote Link to comment Share on other sites More sharing options...
Saltyrad Posted February 24, 2023 Author Share Posted February 24, 2023 thanks to yalls replies so far, I've learned some things. I would like to record my steps through the process when i start so i can get some critique along the way. my main saftey concern would be that the refillable tanks are not exactly pure so I was thinking about a flash back arrestor for the propane line too. is it really needed though? Quote Link to comment Share on other sites More sharing options...
Latticino Posted February 24, 2023 Share Posted February 24, 2023 Flashback arrestors are not typically needed for propane. Venturi meters are superior to orifice meters IMHO. A characterized pressure regulator will give you some indication of flow vs propane pressure (see below), but simply knowing the pressure in the pipe at a single point in the fuel line will not necessarily give you the flow velocity unless you have done testing for that particular gas train with a calibrated flow meter. Since you have ignored my request to elaborate on you eventual aims for this steel casting exercise, I'm done here. Quote Link to comment Share on other sites More sharing options...
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