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  1. #41
    Troy Hamon's Avatar
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    Actually, the silver doesn't 'plate' on the steel wool. The silver compound in solution is relatively unstable compared to the same compound with iron in its place. What happens is the iron from the steel wool dissolves as it replaces the silver, and the silver collects like a black sludge at the bottom of the container. In theory, you could completely replace the steel wool with the black sludge, but most people would not go that far because the reaction is less and less efficient as the concentration of iron to silver is reduced. If you hook up two silver recovery chambers in serial you can fully exhaust the steel wool in the first before sending it off to a silver refinery, then move the second chamber to the first position and put a new one in the second position.

  2. #42

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  3. #43

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    Lets not forget all of the crappy prints tossed out from digital users.....

  4. #44

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    The amount of chemistry that I put down the drain is so insignificant to the wast water that is treated for the Phoenix area (Metro Phoenix has over 3 millions folks hanging out) I don't lose any sleep. Large scale users are required to reclaim silver in hypo, the military and other large scale users also reclaimed wast film and prints. In the old days when labs were for the most large industrial units that processed hugh amounts of film and prints it was much easer to enforce environmental rules than it is for hundreds of minilabs. The chip industry has left contaminated ground water, land fills full of computer and other electronic devices with residual heavy metals, what I do has a very small footprint.

  5. #45

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    Quote Originally Posted by scottmillar75
    "The chemicals used in making digital parts are the most toxic on the planet "


    Which chemicals exactly are used?

    Scott
    While perhaps not a specific answer to your question, most high volume chip manufacture is done through chemical vapor deposition (CVD) or metal-organic chemical vapor deposition (MOCVD) crystal growth. The actual gases going in to the growth chamber will vary with the actual material/structure being grown, but most make anything in the darkroom look absolutely benign. Add to that the fact that the chemical reaction rates aren't all that high and you get most of the noxious gas you pump into the growth chamber coming out the other end as waste.

    Then add to that the waste chemicals (acetone, trichlorethane, carbon tetrachloride, hydroflouric and hydrochloric acid being some of the common ones) produced in prepping your substrate for growth and prepping the device for etching and later growth stages.

    I did some graduate work growing substrates with a slower, more benign growth system, but we still pumped out ridiculous amounts of chemical effluent just from substrate cleaning. All of that to grow 2-3 chips (less than 1/2" on a side) every week. If I started thinking about how that scales up to manufacturing levels, I'd lie awake at nights in a cold sweat.

    Steven
    "A friend will bail you out of jail.
    A TRUE friend will be beside you saying 'Damn! That was fun!'"


    "There's more than one way to skin a cat.
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  6. #46
    B-3
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    Quote Originally Posted by Bighead
    Lets not forget all of the crappy prints tossed out from digital users.....

    Right, cause nobody ever made crappy prints while using film.
    :rolleyes:

  7. #47

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    Quote Originally Posted by Bruce
    Right, cause nobody ever made crappy prints while using film.
    :rolleyes:
    You got it! they just did not have enough perfection....

    OTOH A few years back a friend of mine who went to the Cologne show told me something curios. He recounted how all the ink jet printer makers like Epson, HP etc, were putting out reams fo big photographs and how they would collect on the floor and people would just step on them, and he said; " you know, I recall the time when if you saw a print on the floor, not only you would not step on it, but you would make sure to pick it up"

    It seem that even is they are fine photographs, they dont have much intrinsic value......

  8. #48
    B-3
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    But if I could get an inkjet print with the authenticated foot print of the artist, I bet my kid's college education would be paid for...


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