Help Needed: Gold leaching using common bleach

[Anonymous]

Apologies if this has been answered before, but search revealed a large number of related matches, but nothing exact. I also browsed through the literature section, but couldn't find a publication specifically dedicated to chlorine leaching that didn't involve aqua regia or HCl. I have no way of procuring the latter and thus need to make do with household chemicals.

My numerous sluicing trips have produced about a bucket of black sand concentrates, which contain micron (mosquito eye) sized gold. The black sand also has some flakes which are heavy and appear to have a blue (almost sky) color and a number of pinky nail sized black opaque crystals which have a reddish/brownish (almost rusty) color. This color becomes more black when the crystal is taken out of water.

I would like to leach out the gold from my concentrates and am secretly hoping that the brownish crystals are telluride with gold. I wanted to check with the experts here whether the following process would work.
1) Crush and grind all black sand including crystals to talcum powder size
2) Buy a gallon of industrial strength bleach (4-5x stronger than normal bleach and sold at Lowe's) and pour into bucket with concentrates (half-full with black sand).
3) Once a day stir bucket in a well aerated area and allow chlorine in bleach to leach gold for about a week.
4) After a week, run only the fluid through a coffee filter and transfer to a clean vessel (Pyrex glass). Start lowering the pH with cheap household vinegar. Given enough vinegar, pH will drop below 7 and I'll get some precipitate, which should contain only gold (brown or black residue).

Would this work? Also, instead of wasting lots of vinegar (relatively weak acid), can I just leave the bleach out in the sun to evaporate? Wouldn't the remaining dry residue in the bucket contain my gold salts?

Thanks for your help.
Cheers.

 

[Barren Realms 007]

If it were only so easy, Welcome to the forum.

Your HCL is available from Lowe's as concrete cleaner.

You might want to consider a lot of reading here before you process anything.

One of the expert's here will help you soon.

 

[Anonymous]

Ok so start adding concrete cleaner (diluted HCl?) to bucket with black sands and bleach till pH reaches 8.5?

 

[Barren Realms 007]

Ok so start adding concrete cleaner (diluted HCl?) to bucket with black sands and bleach till pH reaches 8.5?

Hold on till someone with ore experience can chime in on this. I can't guide you in this but you will get help, be paitent.

 

[Anonymous]

Hi Charlie,
first thing to do, is screen the concentrates into particles of a narrow size range, then run them trough a clean up sluice to get the gold as concentrated as possible. Also, it is easier to do than chemicals.

Now after running though a sluice you can start to develope a process for recovering the gold, but, with proper seperation you will be able to get very clean gold just by mechanical means.

I process glacially deposited material and with the right screening most gold will be recovered. I always get the raw gold first, then grind up the rest (if it is proven to have gold content) then process to recover the gold.

I do not know about seperating tellurides.

Jim

 

[Richard36]

Tellurium will cause Sulfuric acid to turn into a Deep Red-Purple colored solution.
To which, if you add Distilled water you will get a Gray-Black Precipitate.

This is the test that I use to determine if an ore contains Tellurium.
As for processing your black sand, read my posts on the subject in the prospecting section.

If you still have questions after doing so,
make a post there, I will reply.

Sincerely; Rick. "The Rock Man".

 

[Anonymous]

James, thanks for the heads up. I've actually removed everything that I can get to with a miller table. I know there's still gold there because I can see the micron sized specks mixed with my blacks. Most likely there's still plenty of gold still locked up in my black sand (like an oreo cookie).

Richard, I appreciate the info. Other than breaking open a car battery, I really have no way of getting H2SO4. To keep things simple, I'm assuming that the brownish/purplish crystals are not tellurium and just want to leach the micron gold that I can see in my black sand concentrates. From the little info that I've found on halide leaching, the bleach process doesn't use strong acids and would also leach gold from tellurium.

I've read up quite a bit on extracting gold through leaching. However, seems like 99% of the methods for which there's plenty of manuals talk about using cyanide, iodine, or clorination using HCl and/or other strong acids. I'm hoping to get in touch with people who can recommend a chlorine based process going the base route instead of using harsh acids. From what I've read, that will leach only gold (so I don't have to worry about extracting other metals/impurities) and should work with household chemicals - bleach, baking soda and vinegar.

Cheers.

 

[Richard36]

Nappa and Ace Hardware both sell Sulfuric acid.
Nappa grade works fine, though the type sold by Ace Hardware as a drain cleaner is far more concentrated.

As for how to process your Black Sand in order to recover the fines, (Dust, as in micron and larger)
Amalgamation is the quick and easy way to go.

Follow the instructions I give, carefully, and you will be safe.

Bellow is a copy of a post that I made in relation to processing black sand to recover the fines.

The best method that I know of for recovering your Gold from the Black Sand would be to put your sand into a Rock Tumbler, or a modified concrete mixer with steel balls and a small amount of mercury, then add enough water to completely cover the sand. Turn the unit on, and let it operate until all the sand has been crushed flour fine to recover all the visible fine gold, as well as any encapsulated gold bound up in solid solution with the black sand into the mercury.

Once the sand has been crushed flour fine, carefully pour off the water. The remaining sand can be ran through a "Blue Bowl", "Spiral Concentrator", such as a "Gold Wheel", or carefully panned in order to recover your mercury.

Place a piece of cotton, or filter paper inside a 500cc or larger syringe, then carefully pour your mercury into the syringe, then replace the plunger and depress it, forcing the free mercury out through the tip into a container.

Conduct the following step outside, or in a well ventilated area only.
Wear rubber or latex gloves while working with the solutions.

The "Gold Amalgam" will be left inside the syringe against the cotton, or filter paper. Carefully Remove the cotton or filter paper with the gold, and place it into a Pyrex dish, and cover with a solution of one prt nitric acid, and 4 prts water. Place the dish on a hot plate from an electric coffee maker, and let gently heat up. The remaining mercury will go into solution, and the gold will remain.

Place a coffee filter in a plastic funnel, and then place the funnel into a glass dish in order to support it , and act as a reservoir for the solution containing the mercury. Pour the solution from the dish with the gold into the funnel, and let filter. Rinse the dish with some extra water to make sure that all the gold has been removed from the dish, and is now into the filter. Spritz the filter and gold with clean water to remove any remaining nitric solution containing mercury, and let drip, as well as sit until dry.

Once dry, The filter and gold can be melted with Borax to produce a single mass of gold.

Place a piece of copper plate into the nitric solution, and let sit overnight. The mercury will drop out of solution as free mercury within the solution, with some adhering to the copper plate, which can be scraped off, and the solution filtered to recover the rest.

I hope that this has been of some help to you and others.
Questions, comments, and suggestions are welcome, and appreciated.

Sincerely; Rick. "The Rock Man".

 

[Anonymous]

Hey Richard,

Thanks for the good quality info in your reply. I have some follow up questions on your instructions:
1) If I put one 5 gal. bucket full of black sands in the tumbler, how much mercury do I need to add to that and for how long should I mix (particle size is already speck sized)?
2) Does putting mercury in the tumbler contaminate it -- or can I just leave it out in the heat after I'm done and allow the traces of mercury that are left over to evaporate?
3) Can I use a miller table instead of a concentrator? Don't like using battery powered contraptions.
4) Is there a reputable source where I can procure nitric acid and/or mercury from?
5) Once I've precipitated the mercury out of the nitric acid, how pure is the mercury? Can I transfer it to my main mercury storage vessel? Also, is the nitric acid 100% mercury free -- i.e. can I neutralize with garden lime and dispose in sink?

Thanks again for all the valuable info.

 

[Richard36]

1). A couple of Table spoons of mercury should be enough for a 5 gallon bucket of black sand.

2). Mercury will contaminate your tumbler, but the traces of whatever is left will be insignificant.
The traces can be removed with a quick rinse of 1 part water, and 1 part nitric, or hydrochloric acid, then rinsed again with water.

3). I am unfamiliar with a miller table. I recommend a "Blue Bowl" for separating the mercury amalgam from the sand.
Use what you want, the objective is to recover the amalgam.

4). Mercury and Nitric acid can be procured from "Action Mining" ( http://www.actionmining.com ) and "A & B prospecting supplies". ( 480-832-4524)

5). The mercury will not be pure, but is reusable for further batches. I would recommend storing it in a separate container from your unused
mercury. The acid should be striped of the dissolved mercury, though chances are that there will be traces of mercury left within it.
If you plan to neutralize the acid water mix, and pour it down a drain, use your toilet to do so, not any sink in your home.
Use baking soda until no more reaction, then dispose of the solution.

I hope that this has been helpful.

Sincerely; Rick. "The Rock Man".

 

[bmgold2]

3). I am unfamiliar with a miller table. I recommend a "Blue Bowl" for separating the mercury amalgam from the sand.
Use what you want, the objective is to recover the amalgam.

I'm not sure how good a Miller Table would work for mercury amalgam but, from what I've read, you should be able to recover your gold with one and not use any chemicals or mercury at all. Just have to classify the black sands and maybe crush it to dust and then adjust the angle and water flow to get clean gold. Would take some time but sounds like a great way of recovering your gold (not from scrap refining) cheaply without ANY dangerous chemicals except maybe some JetDry or dish soap to break the water tension.

Here's a link to plans to build and operate a miller table. http://www.scribd.com/doc/28318404/How-to-Build-and-Operate-a-Miller-Table

bmgold2