I Need help with cyanide

[razvanflorin]

Hello.. So as the title says, i would need some help dealing with a Cyanide gold plating solution.

So i will present the situation:

We got some Gold plating solution that must contain
3 Grams of Gold / Liter (That’s what we was told )
Also they told us that it is Cyanide But didn’t know which kind of Cyanide it is.

So what i want to do is to precipitate, melt and weight the Gold from 100 ml of solution.

I already tested the ph of the solution with a ph test paper and the result was around ph7.

Also i have put some zink and 100 ml of the solution inside a lab Glass to see the reaction . ( i will attach a photo )

What would be the best way to do this test ?
What kind of percipitant should i use ?


Thanks you !

 

[Lino1406]

Zinc is good. Most platers use aluminum but it must be more alkaline!

 

[razvanflorin]

Zinc is good. Most platers use aluminum but it must be more alkaline!

You mean is good as precipitant ?

Also i do have a question.

Does the addition of zink, zink shavings, can Affect the ph of the solution and make it release deadly gas ?

I mention that my fume hood is not working atm so i had to ask this for my safety.

Also i attached some photos.
———————
In the photo:
I made some zink shavings by drilling in a zink bar (not pure) and put them in the solution, first it started fizzing, after several minutes it looks like Gold plated , then they get a maroon(coffee like color)
——————-

 

[Lino1406]

The gas is hydrogen. Alkalinity will prevent free HCN from evolving as hydrogen saturation with the liquid

 

[patnor1011]

Use zinc powder if you can. Much faster and better to deal with later when you will have to dissolve it all.

 

[kurtak]

You NEED to raise the Ph (preferred 10.5 - 11.5) at Ph 7 you are risking the production of HCN gas which is the gas that kills you --- sodium hydroxide will work for raising the Ph

Ether zinc or aluminum will work to cement the gold from the cyanide solution

If you use zinc then zinc powder works better then heavy shavings & that is because with the heavier shavings what is happening is that it starts out with the gold "plating" to the zinc - that then prevents the solution from coming in full contact with the zinc thereby slowing &/or preventing all the gold from cement out of the solution --- that is why you are seeing the purple mud after first seeing the gold plating - the purple mud is ultra fine gold cementing out because the first gold plating is preventing good contact of the solution with the zinc which is why zinc powder - with stirring works better - the zinc (powder) gets more full contact with the solution

Aluminum "foil" will also work (because its thin - heavy chunks will cause the same problem as heavy zinc above) - I cut the aluminum foil into 1 inch to 1 &1/2 inch wide strips & then "crumple" the foil strips "just enough" so they don't stick together when put in the solution

The problem with aluminums is when you go to use the HCl to remove any traces of remaining aluminum after cementing the gold from the solution is aluminum dissolved with HCl can end up being very thick & therefore hard to filter


This part is VERY important - before treating the gold cemented from the cyanide solution with HCl - make SURE you have washed ALL the cyanide out of the cemented gold - that is true whether you cement to gold with zinc or aluminum

Adding acid to cyanide is what produces the HCN gas - which is the gas that kills you

Short version of the above ------

Get your Ph up to about 11 (not less then 10 not more then 11.5)

When done cementing the gold from solution - wash the cemented gold VERY well to get rid of the cyanide

treat the cemented gold with HCL to get rid of any remaining traces of zinc or aluminum

Remember - HCN gas kills you - no second chance --- therefor I recommend that this be done in a GOOD working fume hood & you should have a HCN gas detector in the lab


You can do it out side in buckets - BUT - you should still have a HCN detector clipped to you shirt pocket or setting "next" to the bucket so you can get away & wait for the detector to stop sounding off


When I was in England at Jon's place we set that life saving detector off several times

A HCN detector is cheap - VERY cheap compared to working with cyanide & possibly producing HCN & not having a detector to tell you - you are about to die - they are cheap on ebay

Kurt

 

[Lino1406]

If aluminum is used, HCl can be spared, NaOH alone will dissolve it without HCN risk. Of course
experience or optimization are the key words for avoiding aluminum slurry