the first 10 pc`s i processed i cut off all the pins with a wood chissel, then i pulled all the pins out of the plastic (time plus time plus time) i was wondering if i realy neaded to pull all the pins out of the plastic, since the ap eats all the base metals it seems to me that everything should just fall out of the plastic :?: it sure would save a lot of time.
time saving
- Thread starter callicom
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acid peroxide will slowly dissolve copper from pins (not heavily gold plated type), most plastics are not a problem, but there are some plastic (usually white) that will soften and begin to break down, if you monitor these can be removed before causing any trouble.
Geo
Well-known member
PVC plastic will break down readily in hcl acid as hcl is a solvent for polyvinyl chloride or PVC.carbon based plastics hold up better.the way to tell the difference is whether it bends or breaks under stress.PVC can be totally dissolved in hcl given enough time.
Geo
Well-known member
actually the one that bends before it breaks is PVC.carbon based plastic is normally very hard and hard to break,like the green colored plastic on your circuit boards.the plastic on the CPU connector are normally carbon based to withstand higher temps,but some of the small brown CPU connectors are PVC that wont break and are a real pain to deal with.with these and any other small bits of plastic that have gold in them keep separated and when you have enough to warrant processing just go straight to hcl+clorox.it may take a few moments longer to digest the metal out of the plastic but the outcome will be the same.after all the metal has been digested filter the plastic out and precipitate your gold.the small bit of copper in the pins wont effect the process but you may have to repeat the hcl+clo process after you precipitate to get out any impurities.dont mix this auric chloride with the other that you have refined already.callicom said:
Geo. Your info about pvc breaking down in the presence of hcl struck a chord of concern for me. Can you please explain where your info is from. I used pvc in my fume hood based on this article from pipemakers.
Acids
PVC-U is highly resistant to strong acids, although some oxidising acids in high concentration attack it. Hydrochloric acid can be used at all concentrations at temperature up to 60°C. Sulphuric acid at less than 90% concentration has no effect at temperatures up to 60°C, but acid of 90-95% concentration should not be carried at temperatures in excess of 50°C. Cold nitric acid is satisfactory at concentrations up to 50%, but hot concentrated nitric acid attacks PVC-U.
FULL ARTICLE HERE>>>>>http://www.pipemakers.com.au/about_pvc.htm
I would like to verify which source of info is correct before any thing bad happens at my hood....
Acids
PVC-U is highly resistant to strong acids, although some oxidising acids in high concentration attack it. Hydrochloric acid can be used at all concentrations at temperature up to 60°C. Sulphuric acid at less than 90% concentration has no effect at temperatures up to 60°C, but acid of 90-95% concentration should not be carried at temperatures in excess of 50°C. Cold nitric acid is satisfactory at concentrations up to 50%, but hot concentrated nitric acid attacks PVC-U.
FULL ARTICLE HERE>>>>>http://www.pipemakers.com.au/about_pvc.htm
I would like to verify which source of info is correct before any thing bad happens at my hood....
Barren Realms 007
In Remembrance
glondor said:
Your hood should be fine with what you have in place.
Geo
Well-known member
my source of info on this is two parts.the first is very technical and i dont understand all the chemistry involved.i do know that PVC is made with vinyl chloride as the major component(if i had studied more i may have been able to explain better) with hydrochloric acid as the main reagent with a organic monomer added.glondor said:
the second is first hand knowledge.i dont think mist or vapors will have a more drastic reaction to PVC pipe as much as,lets say direct sunlight,but if you immerse PVC in hcl acid long enough it will turn into goo.when i first started my AP process i was using a nebulizer pump as my bubbler air source and thought that was too much air for one bucket so i went and bought some polyvinyl T's and went from bucket to bucket for four buckets then a T for each bucket with a bubbler stone on each side.after ten days my hoses were floating and i thought the stones dissolved but the stones were still there but the T's were not.
qst42know
Well-known member
Nylon is a common fitting material that has a poor resistance to strong acids.
Are you certain your fittings that dissolved weren't nylon?
Are you certain your fittings that dissolved weren't nylon?
Geo
Well-known member
i bought the fittings at ace hardware and asked for pvc connectors, i know they have nylon connectors they are white and semi-clear. the connectors i bought were black, that's not to say they may have given me the wrong connectors but after they dissolved i did a web search and found that you can distill hcl acid from pvc. now I'm no chemist by any means but wouldn't that make hcl acid a solvent for pvc? also from Wiki, it states that pvc is resistant to weak acids but says nothing about immersion in concentrated acid such as AP.qst42know said:
Black sounds like ABS to me, ABS is not the same as PVC.
