Hi everyone, welcome back to Cody's Lab. This is episode 2 of my precious metal refining series and today we're going to be doing some actual gold jewelry. Now I got my super inaccurate, Walmart scale here and a lot of you had mentioned that there's a little switch on the back that you can push to switch it between ounces and pounds, to grams and kilograms. Which I have done and uh, obviously messed up the zero here. But now, the scale is much more accurate. You can see that it measures in 300 grams. See.. See this is the kind of thing that I have to deal with. Look at this. Okay, so now it measures in grams, which is much more accurate than the ounces it was measuring in. And I have here, is some gold jewelry which I will weigh up... You can see I've got 32 grams of gold jewelry here which is 14 karat. That's of course including the gemstones. So I guess the first thing I need to do, is get rid of those stones. And by the way since the last episode, I've actually ordered a precision scale like the one you'd use in chemistry, which measures out to the miligram so I'm pretty excited for it and hopefully it'll get here before I'm doing all these things that I need a bit
more precision for weighing the smaller bead that'll come out of it. You can see I've removed the gemstones from the rings. Now I know you guys are going to ask so this one is definitely a diamond, this is a pearl, and this here is an amethyst. I'm not quite sure what these two are but I'm a geologist and I'll probably figure it out soon. You might notice there's a little bit of weight lost this was 32 grams, now it's 31. That's because there was a lot of dirt inside of this ring here that I dug out so, definitely lost a bit of weight there. The way that I got the gemstones out most of them I was able to just pry the little fingers up and then the gem stone fell out nicely this one here, I had to open with a pair of cutters. Okay, so now let's see what these weigh without the gemstones. Should be pretty easy. It's now 28 grams, so it's lost about 3 grams worth of rocks. Now some of these rocks might be valuable and I'll keep them around for later projects but until then let's start working on this gold. Now this ring here you'll notice is actually a different color than the other ones. Because this is actually white gold you can see it's a silvery color rather than the gold tone and uh, that is because this is alloyed with either nickel or palladium. And uh, I guess it'd be a good idea for me to check to see which one it is alloyed with whether nickel or palladium I have a pretty easy test for that. You see, palladium is a platinum group metal and if I heat it up, it will not oxidize. Whereas nickel will oxidize almost immediately. So let's warm this up a little bit in this fire and see what happens to it. If it oxidizes, that will confirm that it's nickel and I'll just add it to the other metals, 'cause it won't really change anything. If it's palladium, I'd have to do a different whole process in order to uh, purify it So I'd have to make another video out of it. Yeah, it's definitely oxidizing. It's definitely discoloring from the fire. So it's definitely Nickel. Oops. [laughter] Now since this is 14 karat gold, and 24 karats is pure gold, this means that this is about 58% gold. If I multiply that by 28, which is the
weight of the gold that I have you can see that I have 16.3 grams, if I managed to extract all of the gold from it. And that is of course assuming that the 14 karat is accurate, which sometimes it's not. Now unfortunately since this is 14 karat gold, I can't just put this in the aqua regia
and then expect it to dissolve because the silver content, which is what the base metal here is. Uh, this one has nickel so I could probably drop this one in, and be fine. But these ones contain silver, and silver does not dissolve in aqua regia. In fact if there's any more than about 10% silver the silver will actually form a coating on the gold, as soon as it hits the aqua regia. And it will make it either not dissolve, or it will dissolve very, very slowly. So in order to be able to refine these I'm actually going to mix the gold with some copper approximately an equal mass to the 14 karat gold because I want to decrease the gold content down to about 25% That way I can actually dissolve the metal in nitric acid and that will leave me with gold powder silver and copper in solution silver of course will be easy to recover and I'll have some gold powder to work with. Okay here's the gold along with a bunch of copper let's put this together and I'm going to put it in the furnace and melt it down. I'm going to pour it into water to disperse it into tiny droplets to make it dissolve faster. Okay here goes. [molten metal hitting water and boiling] There we are and yes as you can see I cleaned the stairs I saw a few comments about that people wanted me to clean up all those leaves so I didn't start a fire or something so while this was melting I did that another thing that people were commenting on a lot was the fact that I showed my mistakes in the last video and you know what I'm going to do that because if you guys make the same mistake at least you'll be able to see how i solved them anyway I'm going to add a little bit of distilled water to this because dilute acids work more efficiently you know it will use less acid overall it may work a little bit slower now I'm going to add in some nitric acid, this is straight nitric no hydrochloric so it should only dissolve the siver and copper leaving the gold behind which is exactly what I want. Now I'm just going to add a little bit in for now and then when this is all used up I'll add a little bit more just like when dissolving the gold in aqua regia this produces nitrogen dioxide gas so it's better to do this outdoors where it's well ventilated as you can see I'm busy dissolving it away I've been using 50% strength of the 70% nitric acid and every now and then I pour off the material that way I can keep the acids concentration up that way I can dissolve it at maximum speed and with the greatest efficiency in the acid. Now you can see that this stuff is already begun to crumble up into a brownish powder. I like to crush it up a little bit between batches you know to flake the gold off to make it react better After dissolving away the copper and silver with nitric acid you can see what I'm left with A brownish powder which is almost pure gold Now I could melt this down right now and have probably 98% gold Or I could run it through acid and be able to make uh maybe 99.9% gold I think I'm going to do the second one now since this is very finely divided the acid should dissolve it very quickly since is suspect that there is about 15 grams of gold here I'm going to add in 60 milliliters of hydrochloric acid [liquids being poured] There we go Let's just fill it right to the 60 milliliter mark [glass clinking] and now I'm going to add in some nitric acid, but I'm not going to add it in all at once I'm just going to add it in like a ... couple of milliliters at a time until the gold stops dissolving There we go I've dissolved the gold with what appears to be 5 milliliters of nitric acid. See, like I said, you'll be very surprised at how little you actually need. Okay, so the next day and this has been dried out. so hopefully there's no nitric in there also hopefully I didn't get it too hot and bake the gold out. [liquid fizzing] and ya know what, I think we're good. It looks like it's all dissolving Right here is the solution that I poured off of the gold This contains all of the copper and hopefully the silver Now I need this beaker so I'm gonna transfer it into this other container for now And actually let's dilute this with a bunch of water and let's precipitate the silver out now you'll remember silver is incredibly insoluble if there's chlorine in the solution so I got some hydrochloric acid here let's put this in, and you'll uh watch the silver fall out [liquid pouring] there it is looks like cottage cheese is clumping up in there that's your silver chloride I don't know if you can see, but there's just a tiny little bit of silver in there and that's what I was trying to remove by putting it through acid again Now I'm going to pour in some boiling water here we go ya see there's three things that affect settling rates the first one is, of course, the particle size Now I can't really change that and the particle size here is going to be incredibly small in fact, positively microscopic The second thing that I can change is the temperature, because the higher the temperature, the faster it'll settle out that's why I'm using boiling water to make this as hot as I can get it And the third thing that affects settling rates is the uh dilution like, the more concentrated the solution, the slower it will settle out because the particles like run into each other on their way down Now I'm going to use my preferred method of precipitating the gold and that is to make some sulfur dioxide and bubble it into the solution Sulfur dioxide is of course made by reacting sodium metabisulfite which came from stump remover Not the potassium nitrate stump remover They actually make stump remover with sodium metabisulfite I'm gonna put some hydrochloric acid into the metabisulfite and that is going to produce sulfur dioxide gas which is going to bubble through the solution and cause the gold to precipitate out there you go, you can see the sulfur dioxide bubbling out already [bubbling, sizzling sounds] there we go, looks like I dropped out quite a lot of gold very nice there's still a bunch in solution so I'm gonna set it here to stay warm as it settles out could take quite a while and once it settles out I'm actually going to check it with stannous to make sure I got all the gold out uh so I just took a piece of tin metal ya know, mettalic tin and I put inside this bottle with some hydrochloric acid very simple, and then I let it sit for a few days hydrochloric acid dissolves the tin in the solution and I have a solution of acidic, stannous chloride which is exactly what you want when testing for precious metals in a solution let's uh demonstrate this real quick okay so here's some uh pure water i'm going to add some stannous chloride to it, and you can watch what happens so I put in quite a bit there give it a stir but as you can see there's no color change, whatsoever I have a little bit of gold chloride here which i'll put in using my stir stick here we go let's put in a little bit of that now you can see the color's changing see that? see it kinda gets to a purple color that's because it precipritates out a colloidal gold as the tin is another thing that will make gold fall out of a solution looks like all the silver's all settled out as you can see i've washed most of the copper out of the silver chloride and now, to check to see that is silver chloride and not lead chloride I'm going to hit it with my laser. Alright, and you should see it darken because the light actually knocks the chlorine atoms off of the silver leaving silver metal in a finely divided state, which will be a darkened color looks darkened to me so now let's turn this into silver metal it's probably not really worth doing, but uh I think you guys wanna see it anyway first thing I'm going to do is mix it with potassium hydroxide to convert the silver chloride into silver oxide and then I've never tried this before, but I'm going to try reacting it with fructose to see if that'll actually turn it into pure silver metal if not, I'm just going to smelt the silver oxide and that'll leave a nice bead of silver anyway. Okay, so here's the potassium hydroxide just dump this in oh look there was a little bit of copper in the solution oh well It won't be pure silver but we'll definitely convert this back to metal yeah this should uh turn to a nice dark color yep becuase it's turning it into silver oxide and the potassium hydroxide is taking the chlorine making potassium chloride and it's leaving the oxide for the silver to take alright, let this work for a little while now let's see if that sugar trick will actually work here's some fructose and I think I need to heat this up a little bit you know what, I think it is actually working. Uh, camera can't see anything because it just fogged up now the particle size is not any different than it was so it's not gonna look like shiny or anything but it's definitely whiter so I can definitely tell now that it is in a metallic form so this is metallic spongey silver here Welp, I'm just going to melt this down now okay, we're up around 2,000F let's pull it out of there take this have to do this one-handed, I know... Let's pour it out There you go, nice little bit of silver. That's really not very much is it? Yeah... That's probably less than a gram... So, while the silver was melting I took the liberty of washing and drying out the gold powder. As you can see here. Let's put this in the crucible now and uh melt it down, too. Look at that. it almost fills it actually it does fill it yeah there it is it'll melt down can't wait to see that button it's gonna be big Alright, I think the gold should be melted by now. Let's have a look at it... Well, I can have a look at it There it is. Think my uh tongs popped and some rust fell into it, but otherwise it looks pretty good! Yeah, look at that it's a shame about that little blemish on the top but uh, you know what I'd say it's pretty... Well... pretty! Oh, it's got a cavity in the back, too. Maybe I cooled it too soon... Anyway, let's go weigh it nice fat bead of gold put it on the scale 17 grams well the scale's not super accurate so that's probably just over 16 then very nice So, here's what I've gotten so far you can see that I took that little blemish out of this bead here I just put it in some hydrochloric acid and dissolved the rust away and uh this is the bead I got last episode and heres a little piece of silver now there's much less silver than I was expecting and I was a bit confused about that until I looked over at my waste jug here and look at this that... is some silver chloride in the bottom of it so what must've happened is uh again the pH was too high for the silver to drop out or something and when I pour it off into this bigger jug it all settled out yeah so there's probably quite a bit of silver in there still at least I know where it is I'll extract it out of there eventually there's a couple more things i'd like to mention first that uh Daniel Dezdan sent me some uh catalytic converter material he sent me some catalytic converter material so I'm gonna extract the platinum from this so which means that uh this series I guess is no longer exclusively gold so I'm going to change the name of it to uh "Precious Metal Refining" and the last thing I'd like to mention it that uh I'm just an amateur. I'm doing this for fun. I'm by no means a professional and if you want to do this yourself I recommend doing some extra reading and research on your own. and I definitely recommend this book here trying to get to the title page written by C. M. Hoke "Refining Precious Metal Wastes" It's a very good book it's kind of expensive I managed to find this on eBay but uh I'll definitely link a place on the internet when you can get a free copy of this anyway hope you enjoyed I'll see you next time! ♫♫ [outro music] ♫
As a chemical engineer this video was like porn.
Man I wish these were being pumped out. They're so interesting! I want MORE.
Cody's Lab is one of those youtube channels that is just plain enjoyable to watch.
Holy shit... That's over $900 dollars worth of gold at current market prices
TIL you get silver from Powerade and gold from Gatorade.
This guy definitely knows how to cook meth.
I was up to 3 last night watching Cody's videos. My wife think's i'm weird. His videos are some of the most fascinating i've seen on youtube...
Do you have to study chemistry to become a geoligist?
Say I wanted to start extracting metals from PC parts. Anyone have idea what it might cost to start something like this up? Maybe a link to a relevant subreddit if there is one?