dropping out gold

[geonorts]

i am new to refining and this forum. I am aware of the many ways to drop gold out of Aqua regia but I need to know if sodium hydrogen sulphate will work as I have instructions that say to use hydrogen sulphate. my only other feasible option is oxalic acid but i know that is a bit more complicated

please help

 

[Harold_V]

Why don't you have other options? One of them is dead easy and can be made at home if necessary. You can usually buy ferrous sulfate from garden supply stores, and it's an excellent precipitant.

Sorry, can't comment on your choice of precipitant----I have no experience in that regard.

Harold

 

[geonorts]

what can be made at home? Would it be possible to make enough SO2 and bubble it through as its made using sulphur or my sodium hydogen sulphate?

 

[stihl88]

Geonorts,

Perhaps you can go down to Kmart tomorrow and get yourself a few small tubs of Sodium Metabisulphite in the homebrew section and use this instead. It must be Metabisulph "i" te and not Metabisulphate. I think their in small 250g or 500g containers with an orange colored label. Dissolve enough, usually 2.5g of the sodium if you expect 2g of gold in say 150-200ml warm water and pour into your gold solution. You must neutralize your AR solution with Urea first though...

 

[Harold_V]

what can be made at home? Would it be possible to make enough SO2 and bubble it through as its made using sulphur or my sodium hydogen sulphate?

Ferrous sulfate. Dissolve scrap steel in sulfuric acid, then use the (filtered) solution to recover gold, or buy the crystals from a garden supply store, as I said.

The most convenient method of precipitation is the use of a cylinder of SO2. It is used in the gaseous state, and can be used directly from the bottle without a regulator. I used that method for precipitation for years. I regulated delivery with the valve on the bottle, then in later years I had the bottle plumbed in and used a stainless valve at the fume hood for controlling the delivery.

It may not be easy to find a source for the bottled SO2, so ferrous sulfate may be your next best choice if you don't want to use SMB, which is virtually the same as using SO2.

Harold

 

[geonorts]

thanks everyone this forum is more helpfull than i was expecting and its good to now there are other aussies using it. I planned to use formic acid to neutralize is that okay?

 

[Harold_V]

thanks everyone this forum is more helpfull than i was expecting and its good to now there are other aussies using it. I planned to use formic acid to neutralize is that okay?

I was a dyed-in-the-wool user of evaporation. I don't promote other methods, but that's only my personal preference.

Harold

 

[butcher]

I would use Iron not steel to make ferrous sulf-Ate (FeSO4). and as Harold suggests can get at garden center but make sure they are green and not oxidized brown.
-------note ide ate ite ----endings in these names-----
some stump remover (Bonide brand stump remover), called sodium pyrosulfite, which is same as sodium metabisulfite (Na2S2O5),wine making supply, can also look for sodium sulfite Na2SO3, or generate SO2 gas but that would be challenging, can always concentrate your values using copper then refine the concentrates later.
hope this helps a little.

 

[Harold_V]

I would use Iron not steel to make ferrous sulf-Ate (FeSO4).

That's actually not a good choice, unless the source of the iron is from laminations in motors or transformers. Of necessity, they are made of carbon free iron.

I'm assuming the common guy will use something like angle iron, or other structural shapes that are commonly available. Unless the choice is laminations from transformers or motors, steel is far better in that it contains very little carbon, which will be released as a black powder and should be filtered from the solution. Iron, as we know it (cast iron) has several percentage points of free graphite, so the solution would be quite dirty with carbon.

I would suggest avoiding objects made of material that has been heat treated. Good chance they will contain various elements used in alloying.

Harold

 

[butcher]

I was speaking of Iron not steel, or cast, and transformer laminate's is the source I use, burning off oil and contaminates helps also, dilute sulfuric seems better than concentrated, good point Harold.

 

[Harold_V]

Ayup! I agree on diluted sulfuric. Information I read early on in regards to processing slimes from silver cells indicates that the slimes were boiled in concentrated sulfuric acid in cast iron kettles, to remove residual silver. It was generally the predominant metal present, but finely divided. I found that to be the case when I processed the slimes from my silver cell.

As long as the sulfuric remained concentrated, it had little to no effect on iron. Add the least bit of water and that changed drastically.

Harold

 

[geonorts]

thanks stihl88 got the sodium metabisulphite from kmart you suggested and got my other chemicals i needed today now when i've got a weekend free I can dissolve my gold. Still waiting on if formic acid will be okay to neutralize the nitric after dissolving? also without heating how long roughly does the AR take to dissolve about 5 grams of gold plated pins and would it be better to leave it for a week or is it okay to drop the gold out after say a few hours?
thanks

 

[Platdigger]

Geonorts,
If you disolve 5 grams of plated pins in AR, you may not have enough gold precip to even see, let alone gather.

Better to do a larger amount, and to first remove the base metals with either hcl and heat, A/P, or dilute nitric.
Then, after rinsing away the disolved base metals with water, proceed to AR or A/C.

 

[geonorts]

thanks, i wanted to do a small batch first it was 25 ceramic cpus have done the nitric bath for a week then hcl for a week, 5 grams was a guess it is probably more like 10-20 with still some other metal in them hoping to get rid of this by washing the precipitate from AR with HCL, but if you recommend doing more then I might do the other 175 ish that I have.

any ideas on my other issues?

 

[Platdigger]

No Geonorts, I had just read in the above post were you were asking about disolving 5 grams of "plated" pins.
5 grams of nearly pure gold, is another matter entirely.

If you were to disolve this gold in hcl with small aditions of chlorox........you won't need to "kill" or remove nitric before precipitation.....because there won't be any.

Either way, AR or A/C will work, and it won't take much. And yes, do your rinses first before either.

 

[geonorts]

still after an answer on my formic acid question and I put up a new post about my results. i will test my solution to see if the gold has droped out, or where it is but i need to order that. Anyway i have decided to go with the technique that more people use, so I want to ask do i need to order urea in powder form or is it liquid, what conc, how much will i need to use, do i need to heat the AR basically how to use it?
thanks heaps

 

[makmur mulia]

Harold, Butcher, friends. I always use SMB, it works great. I never use Ferrous Sulphate (copperas). However I just bought this green pellet, after reading your discussion with GSP on producing high purity Au, promoting the idea to use different precipitants for 1st and 2nd process.
Then I need practical suggestion from you guys, to use copperas. Hoke mention about using a pound of copperas for each 50 pennyweight (50 times the weight of a penny coin?) to 1 quart water, add a little HCl to this solution, then pour slowly to the yellow Auric Chloride solution.
Is this the practical way to use copperas? Does the same black cloud appear? Concerning rate of precipitation, which one is quicker, SMB or copperas? In SMB, Na ion dissolved fully. curious whether Fe2+ ion goes down together with Au. Tons of thanks. :idea:

 

[jimdoc]

20 pennyweight (dwt) is one troy ounce.
Or 1 dwt is 1.56 grams.

 

[Harold_V]

Hoke mention about using a pound of copperas for each 50 pennyweight (50 times the weight of a penny coin?)

No. A pennyweight is an ancient measure, and denotes the amount of 1/20 of a troy ounce. It is displayed as dwt. Considering gold and silver are weighed in troy ounces and pounds, a troy ounce contains 480 grains of gold. A troy pound consists of twelve troy ounces, so the troy pound weighs 5,760 grains. A gram contains 15.432 grains. A troy ounce contains 31.10348 grams.

to 1 quart water, add a little HCl to this solution, then pour slowly to the yellow Auric Chloride solution.

Here's a little better way to approach the use of copperas (ferrous sulfate). An avoirdupois ounce will precipitate a troy ounce of gold. A little extra does no harm, and insures that you precipitate all the gold present, assuming you have eliminated free nitric. Dissolve the measured amount of ferrous sulfate in a volume of water sufficient to dissolve the entire lot. As a guideline, consider using roughly 50 ml of water per ounce. Dissolve the ferrous sulfate, then drip HCl into the solution and stir. When the solution shifts color slightly, and comes very clear, it is ready for use. Simply pour the solution into your gold chloride solution. I'm assuming it contains no solids. If it does, it should be filtered, or they should not be allowed to enter the process when you pour.

Does the same black cloud appear?

Instantly! When you precipitate enough (highly concentrated solution) the cloud is brown or tan.

Concerning rate of precipitation, which one is quicker, SMB or copperas?

Assuming you pour each of them, each should react about the same time-wise. Using SO2 gas from a cylinder is a different matter. Because it is bubbled to the solution, it doesn't precipitate instantly, and is known, on rare occasion, to absorb the gas without much change, then suddenly the entire solution flashes, looking very much like bronze paint. That is a rather uncommon phenomenon and can't be created at will. I have no explanation for how or why it works, but I have witnessed the reaction several times in my many years in the lab.

In SMB, Na ion dissolved fully. curious whether Fe2+ ion goes down together with Au. Tons of thanks. :idea:

Yes, the gold will contain traces of iron, but in solution. They wash out very easily using HCl and water. I recommend you follow the process I outlined long ago when washing your gold. My gold quality left nothing to be desired, and I used that exact process, although I used SO2 instead of ferrous sulfate. That was a decision based on convenience more than anything. By using SO2, I could keep my solutions highly concentrated, which was a space saver for me.

Harold

 

[makmur mulia]

Harold, thank you so much. This is really a great forum.