# 250 OPT Gold in our Black Sands



## mneher (Mar 18, 2012)

I have a small gravimetric circuit running at 10 - 12 TPH, final phase is a triple deck Deister set into a #6 Deister finish table. We produce roughly 100lbs of black sand concentrate that consistently assays at about 220 - 250 OPT gold. Without being at least 30% gold, we are unable to smelt this concentrate, can someone tell me the most common approach to recover the gold, a blue bowl or panning seems way too low volume as we run 10 hours per day, producing a 1/2 ton of black sands per day. 

Thanks in advance,
-Matt


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## mneher (Mar 18, 2012)

The largest gold particles are about 60 mesh and there is lots for very fine, <50 micron gold...


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## nickvc (Mar 18, 2012)

Forgive me if my thinking is wrong as I'm no expert on minerals, or much else, but aren't some black sands magnetic, if so try removing as much as possible magnetically. Deano, Noidea has posted a home made wet magnetic separator, it will need to be scaled up for your needs but it might be one method worth investigating,from what I understand most black sands tend to be fairly chemically resistant, plus the amounts needed and the costs of disposal would add up rapidly.
If this is totally wrong my apologies, we have several very knowledgeable members with vast experience with minerals and ores who might be able to give you better answers.


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## shaftsinkerawc (Mar 18, 2012)

Did you have a Multi element assay run or did you just assay for Au? There could be many other things worthwhile hiding in the heavies.


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## Hard Rocker (Mar 19, 2012)

mneher said:


> I have a small gravimetric circuit running at 10 - 12 TPH, final phase is a triple deck Deister set into a #6 Deister finish table. We produce roughly 100lbs of black sand concentrate that consistently assays at about 220 - 250 OPT gold. Without being at least 30% gold, we are unable to smelt this concentrate, can someone tell me the most common approach to recover the gold, a blue bowl or panning seems way too low volume as we run 10 hours per day, producing a 1/2 ton of black sands per day.
> 
> Thanks in advance,
> -Matt


If you are producing 1000 lbs of consentrates a day, there would be no way you could process that amount with a blue-bowl. If it were me, I would remove all the magnetics and save them for further processing and run the remainder of the cons in either a gold-cube (if your gold is 60 to 200 mesh) or better yet invest in a wave-table. They have some that will finish process 2000 lbs an hour. regardless of what final consentator you choose, I would classify those 1000 lbs of cons to -60 to +100, -200 and even down to 300 mesh and process those sizes individually. 125 ounces per day could buy you the right equipment...


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## Traveller11 (Mar 19, 2012)

If you are producing 1000 lbs. of concentrate per day and it assays at 200-250 ounces per ton, you would have roughly 112 ounces of gold, in concentrate, at the end of each day. At today's prices, that is 112 x $1600 = $179,200 worth of gold each day. Why not just charter a helicopter and sling it to the refiner's and let them refine it?


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## mneher (Mar 19, 2012)

We are in the process of putting in a mag separator, should be in circuit by Tuesday, we know that we have to remove about 90% of the total con weight, it's made up of both Magnetite and Hematite, lots of garnet as well. The issue is smelting or chemically processing the remaining concentrates. It seems that the concentrate will still be less than 30% gold in order to smelt. We currently have about 340 tons of material to run and this is a bottleneck for us. Any suggestions on an alternative to smelting our next gen concentrate? BTW, yes we have multiple ICP studies on both our concentrates, high levels of palladium, micro amounts of platinum, PT is not worth chasing. The #6 Deister table is a finishing table, not sure a wave table would do a better job.


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## Traveller11 (Mar 19, 2012)

You have 340 tons of concentrate?


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## RGJohn (Mar 20, 2012)

Have you considered froth flotation? Cells are commercially available in sizes from bench/lab scale to tremendous. Clean gold floats well using only pine oil and pine oil is biodegradable and acceptable to the folks like the EPA.


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## nickvc (Mar 21, 2012)

Chemical or acid treatment of ores is usually a no no due to the complexities of the make up of the ores and the high cost of acids and disposal but in certain circumstances can be used but it's a trial and error process to get it right. If you are aiming to smelt but need a higher concentration of metals to have an effective smelt have you thought of bulking up your concentrates with copper powder and using that as the collector. I'm afraid as I've said before I'm a total newbie with ores and smelting so if that suggestion is worthless please forgive me but to my mind it should work


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## mneher (Mar 22, 2012)

We have 340 tons of Run of Mine ore, we've stopped the trucks from the mine until we figure out a good solution on treating the cons, we run at 10 TPH and produce about 100lbs of concentrate that is consistently running 250 - 260 OPT. We're in the process of putting a small closed loop leach circuit in place but I'm afraid the iron will kill the leach. We're also playing with a centrafuge in hopes that we can remove 90% of the silica and blacksands...Was hoping that someone on this site has been here, done this before. Thanks in advance.


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## nickvc (Mar 22, 2012)

This could be one for Dr. Poe his specialty is ores and concentrates and he has a good handle on what will and what won't work.


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## rookieminer (Mar 23, 2012)

I'm no expert, but. If you could get it closer to the 30%, but not quite, you could try adding silver to your smelt as a collector.
Most of the cost of the silver would be reimbursed by farther refining, or from a refinery.

That's what I'm thinking about trying, on a much smaller scale than you of course.

rookieminer


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## Hard Rocker (Mar 23, 2012)

Good morning Matt, did you get your mag-separator on line yet? 
Please do not get me wrong, as it is easy to do on these message boards but I have looked into your #6 Deister table and it does not appear to be a finishing table, rather than a production table or a primary concentrator. It does appear to be working as it is designed if you are getting these cons in rough form as you have described. I believe that a good finishing table would end all of your problems. Of course I would still recommend to remove the magnetics and the single most important factor in gravity separation in my opinion is still going to be "classification". I recommend you to look at these videos, they are from a company in Oregon that makes this wave table. I recommend that you take the time and watch the longer video as well, it is very informative, 

http://www.actionmining.com/page11a.html

This video is a little longer but is more informative.....
http://www.youtube.com/watch?v=bZaHmFsvnXE

For the record, I have no affiliation with these people, I just believe that this may help you out...

I PM'd you my phone # if you need any further assistance.

Nick


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## rookieminer (Mar 23, 2012)

My brother and I purchased one of these tables a few months ago. I have been buried with building my house while trying to work for the last 7 months, and haven't had the time to use it much yet, but it seems to work very well. When I'm able to run larger lots of ore through it I'll let you know how it is working.
I did run some placer cons that I had run through a blue bowl twice, and got a fair amount of very fine gold (100 mesh and smaller) out of them.

rookieminer


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## Iron (Jul 8, 2012)

mneher said:


> We are in the process of putting in a mag separator, should be in circuit by Tuesday, we know that we have to remove about 90% of the total con weight, it's made up of both Magnetite and Hematite, lots of garnet as well. The issue is smelting or chemically processing the remaining concentrates. It seems that the concentrate will still be less than 30% gold in order to smelt. We currently have about 340 tons of material to run and this is a bottleneck for us. Any suggestions on an alternative to smelting our next gen concentrate? BTW, yes we have multiple ICP studies on both our concentrates, high levels of palladium, micro amounts of platinum, PT is not worth chasing. The #6 Deister table is a finishing table, not sure a wave table would do a better job.



Hi Matt,
We have done some experiment with small Induction machine, result was impressive, but still need some improvement. My Black sand mix of hematite and magnetite. I would love to know your experiences and result of smelting. which flux do you use?
Ian


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## Lou (Jul 8, 2012)

Sounds like a really easy job for smelting.

Where, approximately are you located?


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## Iron (Jul 10, 2012)

Lou said:


> Sounds like a really easy job for smelting.
> 
> Where, approximately are you located?



Hi Lou,
I am located in UK. 
If some one is just smelting black stone that is different , but it is require some skills to separate the gold from molten slag at the right temperature. We achieved this. but what I really like to know is what would be the best to separate the gold from molten iron, what kind of collector need to be use for the best result, any suggestion?

Ian


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## Lou (Jul 10, 2012)

Silver...it's insoluble in iron and good for gold. Realistically though, there are fluxes that'd handle that mix quite well and slag the iron off as a feerosilicate.


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## Iron (Aug 18, 2012)

Lou said:


> Silver...it's insoluble in iron and good for gold. Realistically though, there are fluxes that'd handle that mix quite well and slag the iron off as a feerosilicate.



Yesterday I received the assay result from Assay Office. gold yield is over 7000gr per ton from well concentrated ore


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## Lou (Aug 18, 2012)

Still looks like a good smelter feed.


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## butcher (Aug 18, 2012)

Iron, I would crush to powder, recover the free gold with gravity, then assay the tailings, and smelt them if profitable, that ore looks to have free gold, as far as I can see from the picture.


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## qst42know (Aug 18, 2012)

That nugget was produced by smelting?

Could better results be had via flux adjustments?


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