# Has anyone actually smelted their black sands?



## whsnare

Has anyone actually tried direct smelting of con's? I am in the process of getting the required equipment to do so, and for general assaying of new spots, but would like to hear some stories from those who have. Failed or not i would like to hear what you guys have to say about it, get some insight and give it a run myself. Thanks for any feedback.


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## jeneje

I have not smelted blacksand but I do know that there are other types of minerals that can be very toxic to you. Please be very careful when doing your smelting. If you are after the gold, there are other ways then smelting.

Ken

Good luck


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## whsnare

jeneje said:


> I have not smelted blacksand but I do know that there are other types of minerals that can be very toxic to you. Please be very careful when doing your smelting. If you are after the gold, there are other ways then smelting.
> 
> Ken
> 
> Good luck



I appreciate the concern ken. fortunately we have good safety gear. We have looked into other ways and will be using them on the left overs. but for speed and efficiency we want to try the smelt on the black sand as it has the highest gold content. The high Iron content has made the chemical process's a little to intensive for the time being, separating the heavies and processing the rest separately should help.


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## Richard36

Hello whsnare,

What type of smelting process are you using?

Smelting the Ore to lead, and rabbeling in zinc to recover the gold and silver, then skimming off the zinc and running it through a distillation process to remove it, thus leaving the gold and silver as a dore that could be refined by methods on this forum is possible, but expensive as far as set-up costs.

Industrial scorification /cupelation of the lead to recover the values as a dore bead is possible as well.

Just curious as to how you intend to approach smelting black sands.

The above two are the only processes that I know of, and both require smelting to lead.
Sulfides must be roasted first to remove the sulfur, or the sulfur will convert the lead into lead sulfide, 
and seriously mess up the process.

Sincerely, Rick. "The Rock Man".


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## whsnare

Richard36 said:


> Hello whsnare,
> 
> What type of smelting process are you using?
> 
> Smelting the Ore to lead, and rabbeling in zinc to recover the gold and silver, then skimming off the zinc and running it through a distillation process to remove it, thus leaving the gold and silver as a dore that could be refined by methods on this forum is possible, but expensive as far as set-up costs.
> 
> Industrial scorification /cupelation of the lead to recover the values as a dore bead is possible as well.
> 
> Just curious as to how you intend to approach smelting black sands.
> 
> The above two are the only processes that I know of, and both require smelting to lead.
> Sulfides must be roasted first to remove the sulfur, or the sulfur will convert the lead into lead sulfide,
> and seriously mess up the process.
> 
> Sincerely, Rick. "The Rock Man".



1.Roasting, smelting to lead, and cupelation. 

if we get good results. 

2.Direct smelt w/o lead.

check quality and costs . hoping we can get away with no lead. time will tell. not real interested in breaking it down much further, will be sending it to a refiner for that. 

have you ever tried it without lead Mr. Rock Man? and what kind of trouble have you run into with smelting in the past if any?

thanks for the reply


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## Richard36

I haven't tried doing any smelting myself, just read up on the process.

If you try smelting without lead, you will be wasting your time, and money.

The values would have to be "way high" to recover them by direct smelting without lead, 
and it isn't likely that you would be working with Ore of that grade, 
if you were, crushing and sluicing would work, and direct smelting would not be needed anyway.

Sincerely, Rick. "The Rock Man".


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## Dirtdiggaler

I have done smelting. You need at least 30% metals to get any thing to drop out of the flux. If you do not have 30% metals you need a collector like lead or silver. Some people will add silver to smelt there cons and then have the refiner ship the silver back to them. I have never tried to smelt black sands because i think that all the iron would just slagg all of your values. If you were to try to smelt your black sands make sure they were rich concentrates,and make sure you had good ventilation because they could have mercury and many other poisons in them.


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## herbbartley

Hello everyone, I am new here. My name is Herb Bartley. I have been a gold dredger from the early 90's until the recent ban on dredging in California. I have always been a hobbyist, and never gotten that serious about the dredging, mostly because I am a professional welder and I was always too busy to devote much time to it. I, in fact, got out of it for a while, but since the recession I have had a lot of down time and have gotten back into gold recovery. My main focus right now is developing a process that will pay to work the gold bearing gravel deposits that are in nearly all the rivers in California.

I have smelted black sand from my dredging with mixed results. I used to have a little furnace that I built myself. It was Dave Gingery's design from the his book on building a charcoal fired hobby casting furnace. I used homemade refractory, that really wasn't even refractory, it was a building product developed by my ex-wife's grandfather. It had enough perlite in it that it worked pretty well. The first time that I tried it with charcoal was the last, and I switched to propane with forced air. I took some of my black sand from dredging, some Action Mining smelting flux, and some lead, mixed them in roughly equal parts by volume, and fired it. It worked great! Within an hour I had a bead that I then cupelled and got a bead of PMs. I still have it. I later added to it. For my money it just can't be beat. It was fast, easy, and cheap. I eventually destroyed this furnace, like I said, it wasn't really made from refractory, but it lasted long enough for me to experiment some.

I tried to duplicate the results years later with another furnace that I had. This furnace was huge. I got it from a guy that had a salvage business. My little propane tank would get used up, before I was really done. The results were less than satisfactory. The material didn't really get hot enough and didn't collect in the bottom of the crucible. There were little balls of metal throughout the slag, and the only way to get the metal out of the slag was to crush it and it was just way too labor intensive. Also, since it didn't get hot enough, the gold just wasn't there. 

I have just built a new furnace (I am still working on it, but it is far enough along to use), with a different kind of burner. It is a modified Oliver Upwind burner, the plan for which are available online. I also have an injection port in mine that I have been injecting oxygen into. So far all I've done with it is win some silver from electronic scrap and melt some aluminum. When I use the oxygen, the flame gets hot enough that you could melt anything you want with it. I will see about posting some pictures of this and some of the other stuff I have been working on. I need to get some black sand and try it on that. I really want to get my smelting process down to a science, so I can get dependable results. So far, I have just been building some new equipment and trying my hand at salvaging PM's from electronic scrap.

I am going to go to the San Joaquin river soon and try out a new jig. If anybody is in Central California and wants to go, let me know. I am also interested in talking to anyone who has a bunch of black sand that they don't know what to do with. Mining ventures that need somebody who's good at welding, anybody who needs something custom built, let me know. My main focus now isn't as a hobbyist, but in turning this into a paying venture.


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## eeTHr

If anyone is wondering why some folks are looking toward smelting to recover gold from black sands, here are some considerations which may be prompting those thoughts.

I became interested in the "black sands problem" a couple years ago, and read up on it as much as I could. The result is that there have been claims that there is much more to this than merely separating flour gold from black sand. People have reported that after they have removed all visable gold, even checking with microscopes to be sure that what's left is totally black sand, that gold remains in that sand.

The point being that it seems that they have found gold _*inside*_ small grains of black sand. There has been discussion of how the gold came to be completely covered in black material. Similar discussions have been on the mysterious "black gold nuggets" supposedly found, on several occasions, around the Salton Sea area of California, and how they came to be there.

Many have tried the chemical approach, only to find that no acid, or combinations thereof, will remove the black material in every case. Yet fire assays have shown it to contain gold. Is it covered in black silica? But some do report that it seems to be iron, and _*can*_ be removed with copious amounts of acid.

My casual thoughts have been that crushing to a find powder should expose the gold to acids. However, I also see that there may be limitations to crushing sands in high volume. Also, you would need to know which sand concentrates contained gold, and which were merely black sand throughout.

I have also thought that if fire assays can free up the gold, in small sample amounts, then smelting should be able to release it in larger amounts. Of course, not knowing hardly anything about either one, makes my opinion very iffy.

But, from time-to-time, I continue to see reports of gold _*inside*_ black sands. And, although I've dredged a couple of times, and processed with various gravity methods to recover _*visable*_ gold, I've never tried to get inside of any black sands, myself. And seeing all the exaggerations about "micron" gold in water, that come down the pike now and then, I'm cautious about the realities and occurance rates of the "black-gold sand" phenomenon.

Sending black sand to a refiner that you didn't know well, would be about the most unpredictable way of recovering gold from it. Unless you had a way of determining the amount of gold it contained before sending, it would be a total guessing game, and fertile ground for any less-than-honest refiners. And how would you know if you're getting a good sample for assay, if it all looks the same?

Even with multiple samples, the gold bearing sands could be anywhere in a lot. If there was a weight difference, then some kind of weight cut-off point would need to be established, to separate the "good' black sand from the rest. If the black coating over the gold was not magnetic, then some kind of magnet system might be possible.

So far, nobody has reported a proven way to separate the "good black" from the other black.

And the beat goes on....


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## sawmill

eeTHr

I can assure you that there is black nuggets. It is not what lots
of people envision, or a myth,just a simple act of nature. We
have found several on our claims. Most are found in black iron
schist outcrops. They are just iron crusted gold ,and most are
shaped like pumpkin seeds or are flat.

Also I have played with black sand quite a lot. Black sand can be
made up of lots of different types of minerals or rock. Most is
magnetite ,but not all. In some areas some of the black sand is
actually smokey quartz,or other rock.

In an epithermal type deposit there can be all kinds of salts,
minerals,clay,acids,chemicals,than can act as binding agents.
Native gold is rough ,right down to micro size. Imagine a rough
nugget or grain of gold laying trapped at the bottom of a wash
in a soup of micro powdered iron,magnetite,and other black 
minerals. A black crust will form over time in the right conditions.
Throw in a few grains of smokey quartz with native gold grains
actually in the quartz,plus some free micro size gold ,and you 
can see why the black sand thing gets so much attention.

A few black sand areas are worth looking at,most are just
magnetite,and not worth fooling with,unless there is a lot of
free small grains or flakes of gold in the mix. Also gold found
in the roots of live oaks and other desert plants in a wash can
be discolored by the acids in the roots. Some large nuggets will
come out of the ground black as the ace of spades in these places.

I darn near threw away a bunch of black nuggets while panning
concentrates once. They were mixed in with some course chunks
of magnetite. They just had a real thin coat of black stain,darn
near like they had been spray painted flat black. Gold can come
out of the ground looking like anything but gold. It can be coated
in all kinds of crap,depending on where it came from.

There is also places that you can load a train with black sand and
not find one trace of gold. Quartz is the same,some has gold but
most of it doesn't. Gold is found where you find it,and it can be in
some weird places too. Lots of people have too many preconceived
notions ,and read too many books to actually find gold.

There is lots of simple tests for gold in black sand,or coated in
oxides,and various other crap. No use to get anal about mining
black sand ,when a simple test or two will tell you if it is worth
fooling with or not. :lol:


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## shadybear

I had a recreational miner tell me he keeps all his blacksands then heats them in
a cast iron skillet then throws them in cold water, then runs them through a blue bowl
device and always gets a little more gold out of them.


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## eeTHr

sawmill---

Can you please tell what your simple tests are? It would surely save many from the "black sands blues."



shadybear---

Yes, I've heard about that way. The cold water cracks-open the hot sands. It seems like a good method for processing sluice blacks, after gravity methods alone are done. Just stay upwind of the smoke, and the steam!


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## sawmill

eeTHr
Most guys put salt in their concentrates when doing the
frying pan thing. This will take care of the sulfide thing too.

For starters you can spread some of the black sand over a
piece of iron and then crush it with a hammer,or use a mortar
and pestle to pound it. Any free milling gold will flatten out and
you can pan it,for a visual test.

Citric acid will dissolve any oxide or iron coatings too,for
a visual test with a loupe. Vinegar will dissolve most stains,
and carbonates too.

If you just have to know about any gold ,in the salt form,
the AR test tube thing and stannous will reveal that.

This is for black sand, not black nuggets. If you have black
nuggets ,then you don't need any stinkin test. :lol: 

A really good loupe,and mineral knowledge is your best test.
A lot of the sand that appears to be magnetite,will change
when seen through a loupe. It will be transparent smokey quartz
or other sands,that can contain free milling gold. Magnetite is
opaque and will just crush into black powder. In good light a loupe
can detect all the little micro grains of gold hid amongst the black
sand,that is actually free gold.

There is ways to recover the gold,but in most cases,it is not worth
the expense or effort,unless you have a mountain of it.A good roll
crusher and a certain metallic element does the best job. :twisted:


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## Geo

ive seen black sand with no color visible and still have a little gold but its like poor ore, you will be dealing with ounce per tons of material kind of stuff. normally black sand is the concentrate from sluicing or panning and the gold will be very visible. even flour gold can be seen in the bottom of the pan in rich black sand. black sand is composed of many types of minerals, garnett's, magnetite's and silicas just to name a few. i can pass along a trick that a miner showed me a long time ago. use a cast iron pot with a sturdy handle. fill the pot 3/4 full of black sand and set in fire with enough fuel to cause the pot to be cherry red. remove the pot from the heat and as safely as possible pour the sand as quickly as possible into a metal tub with cold water. this will cause the crystal structures of the sand to fracture releasing any small grains of gold lodged within. this also incinerates the material and removes any sap or resins from the visible gold. ive done this with black sand with no visible gold only to see gold when i finished.


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## eeTHr

I've read dozens of pages worth of BS about black sands, but, as usual, the best advice is found here.

Thanks, all you guys.


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## herbbartley

I should add that before I smelt, I further concentrate my black sand. I just take out the pickers and smelt the rest. I've tried the blue bowl and a bunch of other stuff. I really don't want to mess with a spoon. I'm gonna go today and get some more black sand. I will post some pictures later.


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## Dirtdiggaler

you can use a ball mill and mercury to recover gold that is inside the black sand. I use tsp lysol and a little detergent in the water as a cleaner and it works quite well.


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## rookieminer

dirtdiggaler said:


> I have done smelting. You need at least 30% metals to get any thing to drop out of the flux. If you do not have 30% metals you need a collector like lead or silver. Some people will add silver to smelt there cons and then have the refiner ship the silver back to them. I have never tried to smelt black sands because i think that all the iron would just slagg all of your values. If you were to try to smelt your black sands make sure they were rich concentrates,and make sure you had good ventilation because they could have mercury and many other poisons in them.




Is having your silver sent back to you from the refiner a common practice? I was thinking of doing that to bring up the % of values in my smelt. But I didn't know if it would be worth the cost, and fee for separating the two at the refiner.

rookieminer


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## Geo

thats actually the act of refining is seperating the different metals.to refine the gold they would have to remove the silver anyway.


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## The Devils Dog

whsnare said:


> Has anyone actually tried direct smelting of con's? I am in the process of getting the required equipment to do so, and for general assaying of new spots, but would like to hear some stories from those who have. Failed or not i would like to hear what you guys have to say about it, get some insight and give it a run myself. Thanks for any feedback.


Grind your sands after collecting by your gravity methods, you will grind the sands until they are the consistency of flower as in when you touch the dust it’s like your hand just went into a bag of flour, not sure if you are screening far enough micron Au can be seen with the naked eye if you know what you are looking at the nano Au is what you are talking about aka invisible Au, the key behind getting it out is panning until you think you washed it out at that moment don’t dump it fresh water and I mean out of the tap fresh now will enter your pan until the water level is at a 1/4 inch when the pan is tilted as if the pan is going to be submerged at the edge for washing at that angle the pan is at make the water go side to side slowly!!!! And slowly!!!! Tilt as the water leaves a nano Au dust will begin to pile up with very very little water needed for the purpose snuffer the Au you will have to do this several times the gravity of the Au will do what it’s supposed to and stay in the pan but it’s critically important to be gentle at this stage of processing you need to get more sift’s at finer sizes find out what float fractions can be obtained from your cons when you have finally built your concentration from the finely ground sands the Au can be collected a black sand smelt will take patients and time you must recreate the environment in which it was formed lava is extremely hot getting your equipment to take the beating you are about to put it through is the hard part if your ceramic blanket is melting you are now at the proper temperature getting the kiln to last long enough is the battle I work a Pegmatite and it is extremely magnetic W is a problem as well as possible Ti some pgms have melting temps almost as high as W you should be able to get to the materials with an excessive amount of Pb with the large amount of Pb being added to the charge in the form of bombs as the charge continues to reduce you will add Pb and more sand you are looking to push your equipment to the extreme point of failure you will have to have a few failures to understand the life span of the crucible it’s not easily done but it can be done separating your metals by skimming is also an experienced requiring style you need to know the colors of whatever you are working well to identify when to stop the information I am telling you is based upon my materials roasting materials takes time and lots of heat if it is to expensive your only option is the Pb if you end up having to use a large amount of Pb I have learned that setting up a few empty cupels and using a torch I can keep my molten metal hot and heat the empty cupels up some before I use them like a bar mold pouring molten metal into the cupels you can control the size of the Pb button you are making and now with a pair of tongs you can pick up the cupel once the metal has solidified enough to to move on to the oven with them cupel. Best of luck


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## Martijn

Some comments: 

Instructions are best understood with clearly written instructions and punctuality. Small mistakes can destroy lives. Especially in chemistry. 
Was it test it with stannous or taste it with stannous? Hmmm, just choose one and find out yourself...

E.g.:
" I'm giving up drinking strong booze for one month"
Or: "I'm giving up. Drinking strong booze for one month."

To quote another members plead: "Paragraphs, PLEASE!!!!"

Whsnare has not been online since 2011. He might not read it anytime soon. 

Time for a cup of coffee.


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## jphayesjr

I wet tumble black sand in a rubber rock polisher drum with tungsten grains until it is finely pulverized. I sift out the tungsten using an appropriate sized classifier screen. I then mix the black sand powder in an old cast iron dutch oven with borax and oxalic acid. I let it sit in the sun until completely dry. In a very well ventilated area, with very good regulator, back flame suppressor, and a foam fire extinguisher, I then smelt with acetylene, until molten, toss in more borax and oxalic, use an old iron ladle to carefully skim off foaming slag waste. If you worry this contains gold or other pm's, put it aside to cool, smash. classify. The end product in the pot will be a glowing glassy sheet on top of gold. You can carefully break it off. The gold should be 22 to 23.x K. You can further purify using methods in Hoke. My sands contain a high percentage of microcrystalline gold, some silver, and significant PGMs. The pm's often are visible in the larger black granules, both magnetic and other. You be the judge of yours, though. My yield usually is 2 to 3% from black sands. Sometimes higher if I'm working old tailings. Do clean out the tumbler occasionally with an absorbent paper towel, and SAVE them. Once you've got a nice bucket full, You can burn them, and wash out the ashes, hold and evaporate the filtrate, and then repeat the above procedure. Please avoid using toxic heavy metals such as Pb and Hg, always wear PPE including effective gloves and a fire retardant apron. Stuff happens, stay safe.


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## stoneware

The Clarkson Rod Mill for reducing black sand to enable the recovery of fine gold.

Black sand from an inland gold producing area under the microscope.

Flux's used in smelting and their purpose.

The maganese dioxide in Chapmans flux is there to reduce the sulfides.


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## stoneware

A more detailed use of the various flux's.


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## stoneware

Black sand from two different areas.


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