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Procedures to recover gold from dust


#1

I have a jewellery manufacturing unit where 15-20 workers make gold
18K jewellery, i need your advise and help in collecting gold from
floor sweep (dust), as i am getting nothing from there and that is
causing me a great loss in my business… so request you to please
help me in letting me to know the procedure to recover gold…what
chemicals and in what quantity i should use so that i can recover
maximum gold from floor sweep… hope to see your great response soon.

thanks ,
Sudhanshu
India


#2
jewellery manufacturing unit where 15-20 workers make gold 18K
jewellery 

Well, for 15-20 workers you have really only two options - gather
your sweeps, which you should be doing anyway. Keep tabs on the bench
filings and polishing dust, too. Hopefully you have some security
procedures in place to keep idle fingers out of everything - that’s
another issue. Then you can either send it out to a refiner, which is
what most people do, or setup your own in-house refinery department,
in which case you need to hire someone knowlegable to run it. That’s
too much material to just casually expect to get some beakers on a
desktop.

I Shor presumably still carries a desktop refinery system that I’ve
never used, but I gather some people get good results with it.


#3

In a jewellery factory working with gold, employing many people, it
is of the first importance, to keep a daily record of the weight of
gold issued to each worker compared to the weight of the finished
work plus all off cuts and filings when the work is given back to
you on completion. this will identify whether gold loss is taking
place through workers keeping gold for themselves.

You will need to assay on a random basis each workers returning
gold. The workshop floors need to be of a cotton woven material on
top of plastic sheeting so the gold dust can be recovered from
burning the cotton to ash.

Also it is usual for there to be special long U traps in the waste
water system to recover gold from hand washing. Then there is the
gold to be recovered from a central vacumn system connected to each
polishing, and or sanding machine. Also each work bench has to have
its proper apron to catch all filing and sawings.

The workers need to remove outside shoes and wear inside shoes you
supply so gold on the shoes can be recovered. Finally work overalls
need to be issued by you and washed by you to recover the gold on
them.From the above it is therefore possible to make your business
calculations to decide on the correct pricing of your work and to
establish the causes of gold loss.

Hope this helps.


#4

Read “Refining Precious Metal Wastes” by C M Hoke it will give you
the basics of the processes. The technology in it is over 100 years
old but is still used by many. The main thing to be aware of is that
safety knowledge and concerns have changed significantly over the
past 100 years so all the processes in that book need to be reviewed
to make certain they are done in accordance with current safety
practices. You can buy a hard bound copy from many jewelry supply
companies in the US or download a PDF copy at

James Binnion
James Binnion Metal Arts


#5

Dear Sudanshu,

What are the types of jewellery being produced hand crafted or
casted?

What does the work bench consist of?

What the operating procedures?

What are the refining methods being followed?

A detailed scrutiny of the workshop & work practices will help in
better yields.

Regards
Umesh.G.Chavan
Mumbai


#6

I have to agree with the Donivan’s here but also if you search the
ganoksin archive Nanz Aalund posted a very easy ( accurate) method
for recovering gold about a year ago if not two- search , i would
guess by her name and the recovery process will be there ( using aqua
regia/nitric acid). You should also consider installing a mat that
has what is essentially a giant piece of adhesive paper on it at the
doors. All you need do then is tear it off and put each piece in a
wastebin destined for your refiner when you send in all your refining
on whatever schedule you have adopted for your factory. Weighing the
gold given to each employee is critical as well as assaying it
randomly ( as some company’s do drug testing - without warning and
without anyone else’s knowledge of when it will occur, not even your
secretary. ). you should personally collect the samples from each
employee’s work. I had to fire a long time employee three years ago
when i found out he was substituting 14kt gold for 18kt and in some
pieces using gold filled material for jump rings that were supposed
to be 14 karat gold ( for strength we sometimes use 14 karat gold on
pieces that are 18-22karat if the part ( usually a jump ring that
gets a lot of wear or stress) as long as each length of wire used for
the ring is stamped 14kt or the equivalent. The employee had access
to our alloying equipment for years and I didn’t catch it until I
took some scrap to a refiner using XRF equipment and it proved the
guy was stealing casting grain at about an ounce per week…in fact
I found out some unfinished chain product we were getting from a big
name vendor ( whom Almost ALL metalsmiths use at some point due to
their advertising presence and sponsorship of sites, like this one-
but who I won’t name because the company did make it right after I
sent them the label/tag from their mill product with the remaining
length of chain and the testing from that refiner) - so it pays to
double check on your precious metal inventory and employees-I thought
i could trust this person who had worked for and with me on and off
for over 20 years ( i have been involved in goldsmithing for over 38
years) but once I discovered his decit I had him arrested for grand
larceny as it had been going on for over 10,000.00 worth of theft.
I am normally trusting but this changed my world view a bit. Now any
alloying I do myself and any gold or Pt, or even fine silver is
weighed before and after anyone handles it other than myself when
it’s more than a simple repair. It is no fun to think that people one
trusts are even remotely capable of anything like this when being
paid well, treated well and given free run of one’s studio and
equipment…rer…