Where is my gold? The gold is missing!

[[AuCl4]-]

Hello, I have let the solution cool and sit uncovered for 18 hours. I notice a mild smell of Cl. When I swirl the solution I get a strong smell of Cl. I am going to let it sit for longer..... The solution is now fairly clear with a greenish yellow colour. The sediment at the bottom is now a dark green..............Thanks

 

[patnor1011]

You can heat that gently, chlorine will decompose faster.

 

[[AuCl4]-]

Wow, you replied in seconds!

I heated the solution covered and noticed a lot of fumes building up in the container. Should I have heated it uncovered?

Thanks............

 

[patnor1011]

Heat gently, you have to see faint vapour not fumes. Open or it may explode from build up pressure.

 

[[AuCl4]-]

Heat gently, you have to see faint vapour not fumes. Open or it may explode from build up pressure.

Thanks...got it!!

 

[[AuCl4]-]

Ok, so the smell of Cl was mild after heating very lightly again. I filtered and washed the sediment and bottle with water and the solution turned a bit cloudy but now has cleared up.



I waited 30 minutes and a very tiny amount of white sediment was on the bottom. I washed the filter with HCl and tested SnCl2............Very faint purple almost pink.


I filtered the solution again with toilet paper under filter as you said patnor.. It is now crystal clear!


Toilet paper under coffee filter was great idea! It trapped quite a bit of sediment that the filter did not!


I have to go now but I am very excited!! Many thanks to you both!!

 

[Geo]

that doesnt look right to me.you didnt toss any of the sediment , did you? it should be very purple. for some reason, i believe the gold could be in the dark sediment. redissolve the sediment and check it with stannous chloride to be sure.

 

[[AuCl4]-]

Im Back.........

Put one spoon Sodium Sulphite( Dont have SMB) into warm water and added to solution and stirred.

After 15-20 seconds the solution turned clear.

About a minute later it started to darken to a grey dirty colour.........


Tested with SnCl2............The colour is dark brown. Is this normal?


Added half as much SS..........test again...........dark brown


Colour of solution getting lighter/almost clear after 15 minutes...I can see black sediment on the bottom...........


Third stannous test..........Lighter brown...


Excitement has turned into nervousness.........I'm going to stop here. I really hope I didn't mess up again. Will wait for your input...........Thanks

 

[Geo]

you definitely added too much sodium sulfite. brown stannous test is a false positive, it occurs when theres too much SMB added. that doesnt mean that theres no gold in the test, its just that the color was overpowered by SMB. give it a day and see what drops.

 

[[AuCl4]-]

that doesnt look right to me.you didnt toss any of the sediment , did you? it should be very purple. for some reason, i believe the gold could be in the dark sediment. redissolve the sediment and check it with stannous chloride to be sure.

Oops..I missed your post geo. No I didnt toss anything. I save everything. The light purple was the test on the sediments washed with HCl after filtering the olive green solution. These were patnor's instructions. I put about 10ml HCl through the filter with the sediments and tested. This wasn't the test on the yellow solution, just the sediments in the filter.........sorry about the confusion.

 

[[AuCl4]-]

you definitely added too much sodium sulfite. brown stannous test is a false positive, it occurs when theres too much SMB added. that doesnt mean that theres no gold in the test, its just that the color was overpowered by SMB. give it a day and see what drops.

NOOOOOOOOOOOOOO.........I had a feeling something was wrong. The first addition of sodium sulphite was a teaspoon and I got the brown test. Just one teaspoon.

Ok.....I'll let it sit....................Thanks for your help!

 

[Geo]

as a rule, only add equal amounts by weight you expect to get in gold (2 grams gold = 2 grams of sodium sulfite) i know that this being your first recover and refining, you have no idea how much gold was in solution. thats why testing is so important, add a few gram of precipitant and allow it time to work and then test. it cuts down on false positives due to too much sodium sulfite.

 

[[AuCl4]-]

as a rule, only add equal amounts by weight you expect to get in gold (2 grams gold = 2 grams of sodium sulfite) i know that this being your first recover and refining, you have no idea how much gold was in solution. thats why testing is so important, add a few gram of precipitant and allow it time to work and then test. it cuts down on false positives due to too much sodium sulfite.

Thanks, I understand my mistake now. So add a little at a time, wait and test. If positive add a little more and test until negative. Or calculate how much gold and add accordingly.

Is brown false positive test always too much ss/smb or can it also be something else?
Is the black powder gold or sodium sulphite that fell to the bottom because I added too much?

The solution looks pretty much the same as last night-it has been 12 hours.i notice a bit more black powder. I nudged it a bit and noticed that most of the very fine powder does not stay on the bottom but flows with the solution . There is some larger powder that settles quickly. The rest settles after about 5 minutes.



The stannous test is very faint light brown.........


Edit: there is considerably more black powder on the bottom not just a bit
Thanks much!

 

[Geo]

a false positive can be caused by copper, it also gives a brown reaction, but the two look slightly different. sodium sulfite is a salt and will dissolve in water. i wouldnt think any of the black powder is sodium sulfite. any residual salts that are water soluble and will be removed in the first hot water rinse.concentrate all the black powder by tipping the pot up on one side and let the powder collect on the other side. gently decant the spent solution into a clean container and see if anything else precipitates (it may take a week or more). be sure to stop short of pouring out any powder. add water to the powder and heat. no need to boil yet. again, tip the pot to collect the powder and decant. neutralize this small bit of acid and discard. add a small amount of fresh hcl and warm.did the color change? it should darken or become green. allow to cool and test with stannous chloride. is it positive? if it is decant to a clean vessel and precipitate.if not, decant and add to your stock pot.now the powder should be a lighter shade of brown. if you want it really pure, you will dissolve it again with hcl/Cl and wait 24 hours and precipitate. follow with Harold's wash's and rinses.

good luck.

 

[[AuCl4]-]

Great, thanks geo.............I will get on that.

Do you still want me to redissolve the black sediment in the filter that I washed with 10ml of HCl. I'll probably do it anyway to get some practice and hone my testing. I need all the practice I can get!

Many Thanks.............

 

[[AuCl4]-]

Hello, ok I let everything sit for 24 hours and tested with SnCl2.....negative, no colour change

concentrate all the black powder by tipping the pot up on one side and let the powder collect on the other side. gently decant the spent solution into a clean container and see if anything else precipitates (it may take a week or more). be sure to stop short of pouring out any powder. add water to the powder and heat.

Some of the powder was very fine so I waited half an hour and it settled.
Tip pot and decant/siphon into bottle

add a small amount of fresh hcl and warm.did the color change? it should darken or become green. allow to cool and test with stannous chloride.

The solution is slightly green and black powder has clumped together
Test with stannous - no colour change - negative

now the powder should be a lighter shade of brown.

The powder is still black/ dark brown

Is this colour a problem ? I remember reading in Hoke that it might be black

I'm gonna stop here - gotta go.................Thanks

 

[Geo]

its still black because it has some impurities. its clumped together, which is a good sign, but only means it cleaned the outside of the large particles.now when you dissolve the powder and precipitate it again, it will leave even more of the impurities in solution. follow with Harold's washes and rinses, and you should have at the least 99.5 and at the most 99.99 but that would be if the final wash leaves the powder a light tan color.

do the next dissolution with hcl/Cl. add just enough hcl to cover the powder with the container tipped up. add bleach a drop at a time from a dropper, it should take only a couple of drops. with the amount you have, a test tube would work perfectly.

 

[[AuCl4]-]

Great! Thanks geo!

 

[[AuCl4]-]

Hello,

do the next dissolution with hcl/Cl. add just enough hcl to cover the powder with the container tipped up. add bleach a drop at a time from a dropper, it should take only a couple of drops. with the amount you have, a test tube would work perfectly.

I transferred to a small gIass and added HCl to cover powder. I added HClO bleach a drop at at a time. Some little grains of black powder would not dissolve even after agitating and a little heat. I let stand overnight and some white sediment was on the bottom.

I filtered and transferred to a little garlic bottle..


After filtration.


Learned my lesson about adding too much SS Put the bare minimum in 2ml water


Added SS/Water to solution

stir solution...everything went cloudy brown and after 5-10 minutes all the light brown powder settled to bottom and solution was clear.


............test with SnCl2 -- negative!

Tan powder on bottom!!


IT WORKED!! I didnt mess up this time..............Thanks to your kind help.

My lasting gratitude to you geo and patnor...................Many thanks.........

 

[jimmydolittle]

If I might suggest, your hot plate should be contained in a tub, ceramic if possible, if not then plastic. I’ve had my container break on the hot plate, and loose everything.