Non-Chemical How to refine kt gold ( for dummies )

[Harold_V]

The ammonia treat in the step is used to neutralize the renmant acid or to get rid of the silver chloride present?

The ammonia cycle removes not only silver chloride, but, surprisingly, often copper. It was my experience that if copper was present, the ammonia would change to a light blue color. Gold precipitated from dirty solutions is sure to contain traces.

That ammonia kills traces of acid that are present is not the reason it is used-------it is used because ammonia has the potential to remove substances from gold that may not be removed by HCL alone. It's one of the steps one can take to move the quality of gold closer to 9999, which is not easily achieved.

How many times we have to rinse it with water?acid and ammonia make an exotermic reaction.There is also this danger....

My policy was to boil the solution for a period of time, maybe 10 minutes, then add water. Decant, then boil in water. Decant, then boil in HCL and water once again. The amount of ammonia that may interact with acid is very small, so there are no problems with heat reactions. All of this work is best done in a fume hood.

At step 4 the gold chloride is diluited three times and drops of sulfuric are added.But sulfuric acid get rid also of the nitric if the solution is heated?

I don't know that the addition of sulfuric would be a significant factor in eliminating nitric. Its purpose is to precipitate traces of lead, so it can be filtered from the chloride solution. Very little acid is used, just a few drops, and I always added it to the evaporating dish, long before filtration. If it helped in eliminating nitric, it had ample opportunity to do so as the solution evaporated. I'm of the opinion you would not want to use any more than that. Could be the final solution would be dilute enough to permit filtration without problems, so more could be used. Regardless, I didn't rely on H2S04 to eliminate nitric, I always evaporated my solutions, following instructions set forth in Hoke's book. I was more than pleased with the results, and refined on a full time basis for years.

Harold

 

[paveprince]

ok so i have 2800 grams of karat gold scrap jewelery. it would be best to melt this into shot? not a problem. if i understand this right i will need 2800 grams of silver in order to properly disolve the gold???wow this all sounds good but i dont want to screw up.

 

[Noxx]

If your gold is more than 14k, you can use plain AR.

 

[Harold_V]

If your gold is more than 14k, you can use plain AR.

Careful with that advice, Noxx. If you have 18K green gold, it's entirely possible it won't work at all. I'm not convinced you'd have good luck with 18 K yellow, either. On the other hand, white or rose gold can be processed directly with AR---no need for any preliminary processes.*

Because of the nature of silver, which will be found in yellow and green gold, you can't make blanket statements. To insure success if you're processing karat gold, inquart, regardless of need. It's a fast and easy way to get at the gold, and guarantees a much nicer outcome.

*Precipitating gold from a solution that contains a myriad of elements beyond those desired typically yields dirty gold, and it may or may not wash well, resulting in gold of questionable quality. Seems a shame to go to so much trouble, only to compromise on the outcome.

If quality is your objective, try to not avoid preliminary treatments, which are intended to eliminate the unwanted materials.

Harold

 

[Noxx]

You're right Harold.

But I was talking about yellow gold. I did refine yellow gold over 14k with good success over the past. But with some failures too... At that time, I didn't know why some of my scrap gold was turning black in AR.

 

[paveprince]

sooooo...was that a yes ,ido need 2800 grams of silver

 

[Harold_V]

That "turning black" thing really screws you up. In the end, you spend far more time trying to get back on track than you'd spend doing it right in the first place. That's why I suggest routine inquartation. Once mastered, it takes almost no time, and you incinerate the gold in the process, a valuable step in keeping solutions clean and gold free of floating on solutions.

You can believe me when I tell you I tried every damned dodge in the book when I first tried refining, in spite of having read of proper procedures, and why they worked. In the end, I had to eat crow. I wasn't clever, and I didn't know more than Hoke. If you follow the advice dispensed in her book, regardless of your objective, one thing is guaranteed-------it will work, and work well. It is for that reason I endorse and recommend her book to each and every person that intends to refine. Regardless of the number of books in one's library, it is not complete without hers. She makes refining possible for people that don't know an Erlenmeyer flask from an evaporating dish.

Harold

 

[Noxx]

Thanks for the advice. 8)

 

[Absolutsecurity]

I just did some Karat in AR and ended up with the grey silver chloride deal myself - I knew I should inquart from reading other post and even have a new air/acetelyne torch I want to try out but went ahead with the AR any way - I dropped 18 grams of the cleanest looking light brown powder I have even done and that was very close to my mark by equating K to weight of the starting material ( maybe because of the tech grade chems I used?) or ( the lab glass instead of plastic buckets LOL!) or maybe I just got lucky!

Next time I will inquart for sure and just use nitric to get to gold powder and refine it later with other batches!

Glynn

PS. Thanks Harold, I read and retain your advice and you and the other guys have really helped me acheive results I couldnt before!

 

[peter i]

I’ve performed gravimetric analysis of silver a number of times, and I fully agree on the “never dry out the silver chloride”-statement.

In the particular analysis the sample is dissolved in nitric acid, diluted with boiling demineralised water and precipitated with hydrochloric acid.
The precipitated AgCl is washed several times, and collected in a dried (and weighed) Gooch crucible and dried to constant weight at 110 °C. Calculating the amount of silver in the sample is trivial based on the mass of dried silver chloride.

The silver chloride dries to a pellet reminding of a mentos in hardness, and resists reduction for quite some time. And just when you think you are finished, you will find the “mentos” may be smaller, but its still there!

Cleaning the Gooch is easy using ammonia solution.

 

[Irons]

I once melted about 100 or so grams of Silver chloride. It has some interesting properties. It is flexible, like a stiff rubber and if you melt it in a beaker like I did and make a disk, you can hold the disk by the center and if you strike the edge, it rings just like a piece of metal but the ringing isn't dampened like holding a piece of metal would. It's an interesting effect and would make a good physics paper.

BTW, you will have to break the beaker to get it out.

 

[CarlClassen]

Sorry for restarting this old thread but I’ve found this is the one thread that explains the whole process of refining jewelry into gold the best for the basic steps. I’ve been reading other threads for each step to try and understand each one. This part confuses me though.

(2) Nitric Dissolving. Under a fume hood, dissolve all of the non-gold metals in 50/50 nitric acid, leaving the gold undissolved. The gold is now a brown powder. Save the solution for silver recovery, so you can use the silver to inquart more gold,

(3) Aqua Regia. Separate the nitric solution from the brown gold powder. Dissolve the powder in aqua regia.

(4) Silver and Lead Removal. Dilute the aqua regia 3 times to drop the silver. Add sulfuric acid to drop the lead.

OK from what I understand in step 2 the silver is dissolved in the nitrate solution(making silver nitrate?!). Then I saw the video on www.goldrecovery.us where the silver is removed again using copper to reuse for Inquartation. But in Step 4 is says dilute the aqua regia to drop out the silver. Wasn’t the silver removed in step 2??

 

[goldsilverpro]

Step 2 is a gross removal of the silver. You'll get close but will never get 100% of it. Step 4 gets that last little bit, that will make a difference in getting 990 gold or 9995 gold.

 

[Noxx]

GSP, if you do not remove the AgCl in AR and you precipitate with SMB, I suppose you will get Silver Chloride traces. But do you think they could be removed with an ammonia water wash ?

 

[Roxx]

I'm still a little confused with step 4. What are you supposed to dilute the AR with? Water? and with how much each time?

-roxx

 

[goldsilverpro]

It's so easy to dilute 3/1 and filter out enough silver to be able to easily produce 9995 gold. I don't think a final ammonia leach, as a substitute, is reliable enough to get the same results. Both is best.

 

[Noxx]

I see... What kind of filter are you using ? Does the AgCl precipitate is large enough to be retained in a medium speed filter ?

 

[Noxx]

Roxx, you dilute with water. Only once. This way, any silver in solution should precipitate.

 

[goldsilverpro]

Roxx,

Here's the deal. Strong aqua regia will dissolve enough silver to severely affect the purity of the gold. If you dilute with tap water, the silver is less soluble and will, therefore, precipitate out as silver chloride. This is removed from the equation by filtering. The result is higher purity gold.

 

[goldsilverpro]

Noxx,

When filtering out the AgCl, I always look at the filtered solution. If it's clear, it's OK. If it's not, run it through the same filter again, and again. I switch the same filter back and forth between 2 filtering vessels (I use buckets). No matter what paper you're using, it will eventually run clear. Once it's clear, it will continue to run clear.