disposing of nitric acid

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castlemaine

castlemaine

Member
Joined
Nov 20, 2010
Messages
6
Location
australia
Hi all ,i have been reading this forum and the old one for a few years on and off with different memberships that are now long forgotten .I have also been collecting ceramic cpus and fingers from hard rubbish collections in that time and have only just in the last 5 days started my first refine . I started with 40 ceramic cpus clean put in a big beaker added nitric 70% with equal amount of water to cover the cpus and left on a paver in the back yard to remove base metals . left to stand with no heat just the occasional shake around for 4 days and around 60-70% of the pins fell to the bottom of the beaker , so i go up to kmart and buy a little electric frypan ,put the beaker on it and set it to low for 2 days . All of the pins have now fallen to the bottom of the beaker , it is obvious there is base metals in solution now because of the colour but looking closely at the pins on the bottom they are not hollowed like i was expecting .Now my question is this : is my dilute nitric solution saturated and unable to take anymore base metals? and should i drain off this solution and maybe add a smaller but more concentrated amount of nitric to the pins alone ? any help would be very much appreciated . i did write out a plan on paper after hours /days of reading but this wasnt part of my plan . PS i have read hokes book and have respirator/ chemical gloves /face shield all precations are being taken seriously .
 
Try adding more water, perhaps with the water content is now too low to hold all of the metals with the vapors lost from heating.

If water doesn't get things going again I would try a fresh dose of dilute 35% nitric on the pins by themselves to see what happens.

A second possibility is that the pins are gold plated kovar which is really difficult to dissolve with nitric acid. These types of pins are found on Pentium II, III, and some IV cpu's (and their AMD counterparts) as well as the black fiber MMX style cpus. These cpus pins are held on with a solder that is easily dissolved in nitric, but the pins themselves are kovar under a thn layer of gold plating.

If it turns out they are Kovar, try boiling the pins with some HCl for a few hours and see what happens.

Steve
 
Ok will try the water to start , thanks steve for the quick reply . also if the water doesnt help ill put in a new beaker with a chunk of iron to drop the copper . correct? then put in a bucket of water dilute to under 5% and add bi carb soda in small amounts to make safe/ferilizer ?
DSC_2461.jpg
 
your solutions now contains some silver and copper, you can add more copper to drop the silver out, or do as I do and add table salt and drop the silver as a chloride, be sure to filter off this liquid from your gold before adding the salt or copper then convert the chloride to a meltable form using instructions found on other postings and steves website. To remove the copper from the solution let the chloride settle and filter off the liquid then add an iron bar or nails and leave for a few days this is now a bit more environmentally friendly but should also be neutralised. As for the covar this is difficult, you can use HCL but i've found H2SO4 works quite well as it gets the iron under the covar as well.
 
hi geo , thanks for the tips . i think ill try boiling the pins in hcl for getting rid of kovar since i have that already . will also drop the silver , didnt think there would be enough to bother with but ill drop it and see . i like your avatar, love being out there when i get the time to swing the minelab.
 
40 ceramic cpu's, yeah there should be a few grams of silver. make sure you rinse in water and boil really well when going from HNO3 to HCL and vise versa other wise you will dissolve some of the gold. the silver chloride will need to be converted before melting (you will need a little bit of Sulphuric acid for that). Steves website has a step by step video for that.
 
ok so i got all the pins out and all the ceramic pieces out of the solution filtered it , then put a bit of copper pipe in , took about 10 minutes to dissolve the copper , now when i first dipped the pipe in it got a thin coat of silver i thought it would work so i went inside and watched it through the window .
now the reaction is finnished i see that the silver has gone back into solution . is this because i used too much nitric to begin with ? is the whole purpose of adding the copper to saturate the nitric which in turn pushes the silver out? if so this could mean i have to keep adding copper untill no more dissolves could be a whole kg or more ?
 
that is most likely the reason, and one of the reasons i use the salt method (which you can still do) it's a simple process just takes a couple of extra steps and time and a bit of sulphuric acid, you should be able to get some people buy it for refurbishing truck batteries, some car places sell it if not where you got your nitric acid should have it.
http://www.goldrecovery.us/
http://www.goldrecovery.us/goldrecovery/videos/ShowVideo.aspx?id=silvercl
http://www.goldrecovery.us/goldrecovery/videos/ShowVideo.aspx?id=agcl2
 
thanks mate will try the salt , just got the weirdest look from the checkout girl at the supermarket when i bought 4x500g boxes of bicarb ,she mustve thought i was baking a huge cake or cutting something illicit
 

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