Zinc Precipitating

[minero74]

Hello guys
Merry Christmas’s to all You .

I do an experiment with some Ore and I use a precipitation using a piece of Zinc metal.
and the precipitation turn very brown and coagulate very fast
I never had that kind of Brown color before
and it was way fast.

When i precipitate before ,I always had Black and very dark brown
precipitation .

I will post the pictures so you guys can judge my work .
and can give me any advice.
Thanks

Edited.
I add two pictures of the pan with
the concentrate and i believe it is gold there.

 

[Martijn]

It can be anything below zinc on this list:

Do you have some more info? How did you dissolve the ore? And did you concentrate in any way?

Or, you could take a bit of the precipitate and test if it is a base metal or a precious metal.

The way it floats makes me suspect it's reacting with the solution, floating on its gas bubbles.

 

[minero74]

Thanks for the info
what I do was

I crush the Ore ,i panned out
and i get the concentrate.

i notice lot of sulfides
I use a solution to clean up the concentrate and oxidize the sulfides

decant the solution ,washed few times with hot water.

i use a method to dissolve the gold that I will not posted .

and then add a piece of Zinc metal.
and that Brown powder precipiate from the solution.
i wonder if it is gold?.

because gold precipitate as a Brown powder.

 

[minero74]

I have been precipitating copper before

and copper precipitation looks like red/pink in color
In this pictures below is copper precipitation
notice the difference in color
are like red/pink in color

 

[Yggdrasil]

I have been precipitating copper before

and copper precipitation looks like red/pink in color
In this pictures below is copper precipitation
notice the difference in color
are like red/pink in color.

The problem about using Zinc is that it drops "all" metals present including Iron.
The fluffy material resembles Iron Hydroxides and most Sulfides contain Iron as well.

 

[Martijn]

i use a method to dissolve the gold that I will not posted .

Then we can only guess, I guess.

Test a bit of the precipitate. Wash pH neutral and dissolve in HCl.
If anything remains, repeat and wash in nitric. If anything still remains, dissolve in AR.
It will depend on how much and how rich ore you concentrated to be able to see any values.
A stannous test after nitric and AR will tell.

Next time cement on copper to get only values out.
Do you know the reactivity series?

 

[minero74]

Thank you for the answers guys

The problem about using Zinc is that it drops "all" metals present including Iron.
The fluffy material resembles Iron Hydroxides and most Sulfides contain Iron as well.

Thank you for the answer.
I going to wash the precipitation in dilute Hno3.
to see if that Brown stuff of the first batch of pictures
stay or get dissolve it .

 

[minero74]

Then we can only guess, I guess.

Test a bit of the precipitate. Wash pH neutral and dissolve in HCl.
If anything remains, repeat and wash in nitric. If anything still remains, dissolve in AR.
It will depend on how much and how rich ore you concentrated to be able to see any values.
A stannous test after nitric and AR will tell.

Next time cement on copper to get only values out.
Do you know the reactivity series?

Thank you

Yes i read the reactivity series.
i don’t post all the details
because it was just an experiment.

but i get confused with the Brown color of the precipitation.

I washed the concentrate with Nitric acid.
before dissolved .
and after filtration and denox.
I add more HCL to the solution just to keep any base metal in the solution .
and i get that Brown Precipitation.

today i going to washed with dilute it Hno3
to see what I get .

 

[Martijn]

Thank you

Yes i read the reactivity series.
i don’t post all the details
because it was just an experiment.

but i get confused with the Brown color of the precipitation.

I washed the concentrate with Nitric acid.
before dissolved .
and after filtration and denox.
I add more HCL to the solution just to keep any base metal in the solution .
and i get that Brown Precipitation.

today i going to washed with dilute it Hno3
to see what I get .

Zinc will displace metals that will dissolve in HCl, so it may continue cementing and dissolving?

Testing will tell.

A short test would be straight in AR and then stannous or cementing on copper.

 

[minero74]

Zinc will displace metals that will dissolve in HCl, so it may continue cementing and dissolving?

Testing will tell.

A short test would be straight in AR and then stannous or cementing on copper.

Thank You guys for the advices
I will do what you told me .

I will dissolve it again in AR today and I will divide it in two part
one I will cementing with copper and the other part
I will use SMB .

next time i will roast the concentrate.
and see what it happen.

is an Experiment I need to know how to extract the gold from that new Ore that I found in an abandoned mine.

 

[4metals]

You seem to be using zinc to drop a bunch of metals when the truth is you really only care about the precious metals. And, it seems for the most part you are not using any fire assay or other analytics to determine the precious metals in the samples. So why do you choose zinc? If you choose copper it is much more selective and will leave all of those pesky base metals in solution and only drop out the values you seek.

I notice in your photo's of using copper you end up with a red pink insoluble which tells me one thing. You have used too much copper. If you allow copper to dissolve and displace the PM's and no extra it can be more of an analytical tool. A filtered solution without free nitric will allow a polished piece of copper wire to simply indicate precious metals but to take it a step further, a column full of copper shavings would allow all of the base metals to pass in solution while removing and allowing the precious metals to be separated.

Years back in Ecuador I used zinc shavings on gold cyanide leach solutions and it was very effective. I would think a column with copper shavings used on aqua regia that has no free nitric acid may be effective. Just something to think about and get some other opinions.

 

[Martijn]

I notice in your photo's of using copper you end up with a red pink insoluble

This was a picture of cemented copper he showed to let us know he knows what copper cement looks like.
He did not cement that on copper.

 

[4metals]

This was a picture of cemented copper he showed to let us know he knows what copper cement looks like.
He did not cement that on copper.

Often refiners add too much copper, especially powdered copper, to drop the PM's and end up with a copper colored sludge, That is what I assumed he did in those photo's. Good mixing, often by tumbling, allows slow copper additions to drop much cleaner metals with minimal copper remaining undissolved. Just chucking in a handfull of copper powder won't do it.