[Jewelry making - Article 00432] - Re: [Orchid] Recycling Polish Dust...Take 2

[JETT Research]

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>        I am wondering if anyone recycles, or knows how to recover,
>     silver or gold from polish dust to reclaim lost metal? Our local
>     refiner doesn't want to process the raw dust. Is there some process
>     that can be done to refine the raw dust so our refiner will process
>     it? I have maybe 30-40 investment drums full of raw polish dust.
>     Anyone? our factory is in Bali, Indonesia 

    Dear Mr. Marcus Terrey, My idea on what you can do to help yourself,
    while effective, is not very enviromentally friendly so I say this
    only as information and not necessarily as a suggestion.  What every
    refiner does with that kind of material is first to burn it.  The
    burn must take place in a low turbulance situation so that your metal
    particles don't go up the flu or out over the ocean.  It is best to
    use indirect heat with the "sweeps" on a large steel pan with just
    enough heat to slowly incinerate the burnables.  US refiners use what
    is called a "bag house" to capture the solid particles to prevent
    them from poluteing the atmosphere.  This burning reduces the amount
    of waste considerably and inceases the percentage of metal greatly. 
    So your 30 - 40 drums of raw polishing dust will likely become 1 or 2
    very heavy drums of ash etc...  What can then be done is using a very
    large crucible in a pretty hefty furnace, add this (ash, etc...) with
    generous amounts of about 75% borax and 25% boric acid comparitively
    on the top.  What the boric does is float the "crap" on the top and
    the heavier metal will sink to the bottom.  You then drag off the
    "slag" which in a perfect world would not contain any metal and
    discard it appropriately.  (Note: I don't live in a perfect world.) 
    Eventually you would have a lump of metal in the bottom of your
    crucible that consist of various metals.  You could then send this
    to your refiner who would hopefully handle it appropriately.  All
    this takes a lot of work. 

    In the real but not so pleasant world the burnt material is ball
    milled (broken up into very small homogenous ash), sampled and then
    some refiners assay that and pay based on that assay.  Sometimes they
    do the Boric thing first, ball mill the remaining boric slag, assay
    both the metal and powder, and then pay based on the two sets of
    numbers.  If your refiners won't take the burnt material then you
    have a whole new problem.  Often the burnt material ends up in open
    pits of cyanide solutions in copper mines in 3rd world countries. 
    Hopefully the cyanide lakes don't leak or don't overflow when it
    rains.  The cyanide dissolves the metals, the liquid is pumped off,
    and the metal is dropped out by various chemical means.  This is one
    of the dirty little secrets of the jewelry industry that we pretend
    doesn't happen. 

    I am not sure if this will help you or scare you.  My intentions
    were honorable in any event. J. Tyler Teague JETT Research 
    (Jewelry Engineering, Training, & Technology)


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