hi, my name is jason gaber with mt. bakermining and metals, and today i wanted to do a video on smelting. we get a lot of guys who ask what to do withtheir black sand concentrates off of the table. and they have high sulfide concentrates intheir number one and number two high grade, after they pan out all the free gold. i wanted to do some experiments here, getthem on video, and i’m really interested in comments and tips from you guys, who havemore experience with smelting than i do. so i’ll show you what i’m going to do,how i’m going to do it, and all the tools i’m going to use, and let’s see what youguys think.
here’s some of the high-grade concentratesthat come off the shaker table. and this is the number one and number twoport. and i’ve panned out all the free gold. i’m not going to roast this stuff, i’mgoing to smelt it as is. and the strategy there is i’m going to actuallyhave the mat form, then reprocess the mat using a different flux. but the reason i’m doing that is becauseit’s really hard to roast a bunch of material. it’s easy to roast about a quarter cup orhalf a cup. but when you want to do pounds and poundsof material, it takes a long time, and you
got to have it all exposed to the oxygen inthe air and get it to 12 to 1300 degrees fahrenheit. so i’m going to try to force it into a mat-phasewith the first smelt, and then after the first smelt, i’m going to take the mat and reprocessit using potassium nitrate, which is a very extreme oxidizer, and some iron filings, soi can avoid the roast. i took one cup of the high grade number oneand number two, and mixed it with two and a half cups of chapman flux, and added abouta pound of fine copper wire to the mix as a collector metal. i’ve found if you don’t have enough metalin the charge, that when you pour the material in your conical mold, you don’t get thebutton at the bottom, it all stays suspended
in the slag. so you need a collector metal to filter downthrough the material and capture the gold and other precious metals, and bring it downto the bottom in a button, or a little pyramid. so i use copper. lead is another one, it’s the one they usein fire assay, but a lot of guys want to stay away from lead since it’s toxic. a lot of companies won’t take lead and refineit, whereas copper & gold refining is common and easy to do. i’m going to put another one pound of finecopper wire to the top, so as it melts it’ll
trickle down through and act as a collectormetal. so here’s the chapman flux recipe that i’mgoing to be using. the sodium tetraborate is borax, and it’scovered up there a little bit but it’s 40%. sodium carbonate is soda ash at 20%, silicais just quartz, and manganese dioxide as an oxidizer. here are the two other pieces that we madeto go along with this. this is a conical mold we made. you can pour a number 10 crucible in thereand it comes just to the top. and these are some tongs we made to get thecrucibles in and out of the kiln there.
and like we said earlier this is really anr&d experiment. i got the kiln for a couple reasons, one itwas fairly cheap. but also you can put a pretty good size crucible,i have- sitting over there- i have another segment that can go on top of there, so ican actually put about a number 80 or 100 crucible in there, so i can do a really bigsmelt once i get the hang of it, in an oven that’s pretty cheap. i probably have less than 500 dollars in this,including crucible and flux. let’s take a real quick peek in there. i don’t know if you can see anything inthere.
i’m going to give it a stir, then wait anotherhalf hour, then another stir, then we can pour. so there’s our conical mold, with pour init. so we’ll let that cool, and then we’lldump it out, and see what the button looks like. so there you go, a couple taps on the table,and the slag and stuff fell out of the mold. and you can see the copper and metal all camedown to the bottom, and the slag was sitting on top. so i’ve broke our three different phasesapart here, here is the metal pyramid at the
bottom of the cone. this section here is the mat that formed,it’s the artificial sulfide because it didn’t get all oxidized because we didn’t roastit. and this black stuff is all the slag. so here’s our copper pyramid from the smeltwe did. and it weighs 1 pound, 2.75 ounces. and i went and polished a side here and hadit analyzed with an xrf gun that my friend has, and i think i can post a picture of theresults. so by doing the math with the results of thexrf gun, i can calculate the amount of gold
we recovered. and we recovered right around 8 grams of gold,by doing our copper collector metal smelt on the number one and number two table concentrates. so here’s the composition of the potassiumnitrate flux i’m going to be using to process the mat. and you can see there’s quite a bit of boraxin there, and i’m going to add a little bit more silica. so here’s a look at our potassium nitrateflux, and here’s some of the iron filings i’m going to be using.
and i’m going to add about one part flux,one part iron shavings, and one part mat, and see how it goes. and here’s a separate smelt i did on themat that was recovered from the first smelt we did. so i took all the mat from the first smelt,broke it off, and re-smelted it with some potassium nitrate and iron filings. and as you can see, i didn’t use any copper,but we recovered copper from the mat. by adding iron filings to the smelt, the ironremoves the sulfur from all the different types of sulfides in the mat, and forms fes,which is soluble in the slag.
and the only problem i had here is i addedtoo much iron and not enough slag, so the slag couldn’t absorb as much iron sulfideas i added. so i essentially created an iron sulfide mathere, which is okay because most of the precious metals and base metals ended down here inour copper button anyway. so it was a successful processing of the matfrom the first smelt, and we got away from roasting any of our sulfides. so i really appreciate you guys watching myvideo on smelting. and i’d be really interested to hear fromsome of your tips and tricks on how to smelt, and how i can improve my process, becauseas i said, a lot of our customers are interested
in the process about how to recover some oftheir gold from concentrates they have on their table after recovering free gold. i’ll also post some links in the descriptionof the video that i found really useful when i was figuring out how to get the processfigured out. so be sure to check those links for more informationon smelting and fire assay. so thanks for watching and feel free to emailme with any comments or questions you have.
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