gold filled processing

[Andybrum]

First of all I'd like to say hi I'm new to the forum. Ive been lurking for a while but only just decided to register. I've been recovering and refining for a few months now successfully (although not at first (learned my lesson though)) with electronic scrap only.
I'd like to ask a question if I may? I've come into about 1/2 a kilo of gold filled items and also some gold plated in this, mostly watches but includes a pair of 95 year old temple arch glasses and some pendants.
Is it best to just use a nitric leach? I'm wondering because of the sheer amounts of base metal if there's a better leaching method and nitric acid is quite expensive for me (I don't have the facilities to heat up nitrates). I know I can't just use hcl leaching beause of any silver present.
In fact now I'm writing this it sounds like a stupid question a better question should be is it best to scrape the pieces so the base metal is attacked easier?
Many thanks
Andy

 

[FrugalRefiner]

Andy,

Welcome to the forum.

Cut the gold filled into little bits and pieces to give the acid more surface area to attack. Unfortunately, nitric is the best approach for gold filled if you're in a hurry. If you have more time than money, AP can be used, though you can run into problems depending on the particular feedstock. Silver isn't likely to be too much of a problem in gold filled, but zinc, lead and tin can be.

The gold plate is better processed in a sulfuric stripping cell.

It sounds like you could benefit frome some more reading, so I'll give you my standard new member links. The first rule is to be safe in everything you do. Before you jump into any of the processes you see discussed here, be sure you understand the potential hazards and do everything you can to minimize the risks. Read EVERYTHING in the Safety section of the forum, especially the Dealing with Waste topic. No amount of precious metal is worth jeopardizing your health or the health of those around you.

I strongly encourage all new members to follow the Guided Tour created by LazerSteve. It will provide an introduction to the forum and numerous valuable links including the General Reactions List. Be sure to follow the link to his web site as he has many outstanding videos, a collection of great reference documents, and he sells a lot of the supplies needed to get started including detailed instructional DVDs. Samuel-a also has a lot of videos, guides and tutorials at his web site Gold-N-Scrap.

Download C. M. Hoke's book. There is a digital copy you can read on screen here: Refining Precious Metal Wastes. If you prefer a printed copy, you'll find a link to a printer friendly version in my signature line below. You'll see her book mentioned repeatedly here on the forum for good reason. It is probably the best book ever written for the beginner who wants to learn refining. It is written in layman's terms and will provide a solid foundation that will help you understand everything you read here on the forum. You'll also find a tremendous amount of information in the two Forum Handbooks compiled by aflacglobal, Forum Handbook Vol 1 and Forum Handbook Vol 2.

Best of luck,
Dave

 

[Andybrum]

Thankyou for helping, I would've gone for ap, but I can't find peroxide anywhere except for 12% in a tiny hair bleach cream.
Thanks for the hokes link i will have another read, I did try reading it before but I found it hard to relate it to modern scrap then I lost the link so cheers.

 

[butcher]

Hoke's book page 67 (some special cases) gives a couple of alternative methods for gold fill material.

Harold has some very good posts on dealing with gold fill, a search of the forum would locate these.
You can also look into alternative methods of getting the chemicals you need, that you may not be able to find, like making your own nitric acid from nitrate fertilizer, or distilling HCl from a salt brine solution and sulfuric acid...

For"ap" I assume your are discussing the miss-named acid peroxide leach which should actually be called the copper II chloride leach, you do not need strong hydrogen peroxide, 3% hydrogen peroxide used as medicine on cuts or rinsing out your mouth will work for making the copper II chloride leach, a stronger peroxide would dissolve gold (in this case with your base metals), so then it would no longer be a copper II chloride leach, but would be a solution with a strong enough oxidizer to put base metal and gold in solution together, in this case it would not be much different from using HCl and NaClO (bleach) to oxidize the gold. or aqua regia which would also oxidize base metals with gold.

 

[nickvc]

Andy you can get hydrogen peroxide in any chemists here in the UK or try a hairdressing outlet, nitric is also fairly easy to get try Scientific and Chemical supplies in Bilston. If your going the AP route get a cheap aquarium bubbler to speed the process.

 

[Harold_V]

Thanks for the hokes link i will have another read, I did try reading it before but I found it hard to relate it to modern scrap then I lost the link so cheers.

I'm the one who started promoting Hoke's book, many years ago. As you alluded, it does not relate to electronic scrap. However, the principles involved in refining are fully covered at a level by which you, or anyone, can process virtually any type of material, once the information has been digested. It is for that reason we promote her book----the information is critical to success, as once gold has been recovered from materials, regardless of the source, the process of refining is pretty much universal. Beyond that, her recommended exercises are exceptional, as are her instructions in making and using test solutions. All of this is critical to you becoming independent.

The board has promoted processing by various work-around methods, as acquiring some of the chemicals (such as nitric acid) has become very troublesome, to say nothing of quite expensive. It is for that reason that one should read the forum, to gain an understanding of the methods that can be used by those who are hampered by the inability to purchase needed supplies.

I encourage you to read, and read until you understand everything you read. Until you do, you will be faced with countless problems that you can't solve. For lack of better description, you'll be held captive by your ignorance. You can resolve that only by gaining the required knowledge.

Read Hoke. Read Hoke again. Read Hoke until you understand what she teaches.

Harold

 

[Andybrum]

Hi nickvc I tried that place in bilston, they said they only sell to companies with vat numbers, so ill just keep getting it from where I was and be a bit more sparing or process bigger batches.

 

[Andybrum]

And thanks to everyone for their help