Help with pins

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nmlfreitas

Well-known member
Joined
Dec 19, 2011
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Hey guys.
I've made a first try with pins.
I had more less 800g of pins from motherboards and others.
I putted them on a jar with nitric, it released orange fumes.Turned blue and i have a lot of a dark grey powder on the bottom.
The pins are clean with no gold in it, the problem is that i don't see any gold flakes, have i done something bad?
 
There shouldn't be any pins left. A complete digestion would have dissolved them entirely. And like was mentioned, if there was any trace of HCl present it could have dissolved the gold and it could then cement out on the remaining pins.
There is also the chance that if the pins did not dissolve completely they may have simply cemented base metal over the gold on the pins.
 
I don't have any traces of hcl on the jar.
The pins look like they have been burned. I only have the grey stuff and blue solution and no gold flakes.
I used only nitric acid, should the pins be dissolved and have no pins on the nitric bath?
 
was there solder on the pins? did you sweat them off with heat or did you cut or shear them off.
 
tin in nitric acid makes makes metastannic acid. it can be grey if theres a presence of sulfuric acid at all.http://en.wikipedia.org/wiki/Mosaic_gold

the precipitate will be in the form of white metastannic acid and brown stannic sulfide which will appear to be grey in color. most refiners add sulfuric acid to precipitate the lead from AR.
 
Geo said:
....most refiners add sulfuric acid to precipitate the lead from AR.
Click to expand...

Hey Geo, interesting, i personally, after ashing, after sulphuric acid digest, after hlc digest, the resulting material is treated with boiling sodium hydroxide, this will remove any lead or tin compounds, making them soluble in this medium as plumbates and stantates, hot filter, hot rinse wash, then re-ash, and then AR. Not sure if the last ashing is necessary though, hmmm.

Now why is the resulting sodium hydroxide solution brown?? Still working on that one. 8)

Deano
 
chances are, the gold is still on the pins.theres some information missing that would help finding an answer. did you dilute the nitric acid or use it concentrated? we discovered there was tin in the mix, so theres got to be metastannic acid in there. when acid is introduced to mixed metals, it will attack the metal thats most reactive first. it wont effect any other metal until all of the first metal is dissolved. it could be, the acid was depleted before the foils was liberated. when you dissolve metal, it takes on a slight positive charge.metal that has yet to be dissolved still has a slight negative charge. some of the dissolved metal in solution will be attracted the negative charge and cement back onto the gold plate making it discolored.

filter the solution you have now and test with stannous chloride. check any solids for gold flakes. if you dont find any, its still on the pins. rinse them, dry them and rub with a piece of cloth to see if the gold color will show through.
 
hey Deano, if i understand it right. strong bases will dissolve some values, especially if the temperature is high enough. when you get done with your washes and your sodium hydroxide is spent, try lowering the PH to below neutral and see if anything drops out.
 
When dissolving pins with nitric, you generally have to do it completely to assure that you get all the gold. You had 1.76 pounds of pins and, therefore, it would take about 1.76 gallons of 50/50 nitric to do the job. That must have been a big jar.
 
Geo
My Nitric acid is concentrated.
I checked the pins and they are all black, no sign of gold. On the jar i have the solution without the pins, i have on that jar the grey stuff below and i can see a very small and tiny gold flake or two.
 
As promised here it is:
I did what butcher told me, dilute nitric with water and added small portion of the grey mash that i had, it got with this colour
 

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seperate the blue liquid from the powder, filter this liquid hang a bar of copper into the solution to cement any metals of value, the silver powders I would wash again in dilute HNO3.
 
butcher said:
seperate the blue liquid from the powder, filter this liquid hang a bar of copper into the solution to cement any metals of value, the silver powders I would wash again in dilute HNO3.
Click to expand...

Having q long time in refining, even nearly saperating hardest metals like rh IR from ores but I process pins 100 times and every time is was fail :x :x
Many time saperate magnetic, non mqgnatics, process saperate. Failed.
Recently I mix up all the pins, not saperate magnetic or non magnetic.
Use battery acid with nitric to dissolve copper and iron based pins.
Acid is green with a lot brown gray powder, not white, wash the pins.
Pins are still there and nothing happens to them. Reincinirate and use HCl, nothing happen. Still pins are same, a lot pins sho copper on Thiers surfaces some are still white shiny,
Have gold plated watch bands many kg, some clean saperate pins, want try sulfuric cell next time but it's on now what should I do to these pins.?????

Once earlier happens while processing another batch of pins. Use HCl+water, small increment nts of nitric, solution becomes black, filter the solution, using urea was unreactive. So Aqua failed. Leave the pins. They turn first gresn yellow on surface as copper oxidise then a layer of copperash irony look. Today I reincinirate and crush them, maximum pins are gone, gold flakes are mix in sludge!!!! Is here any post that can describe pins processing with different methods, with expecting errors. And their solution?
 
Hi Ashir.
This may be blunt, but I have no bad intentions here:

All the information you need is in here: search, read and study.
I'm not sure we are doing you any favors by guiding you step by step, better that you study and gather an understanding of what you have been studying.
You have been all over the forum, asking and asking in ways that make me cautious about if you read and take in the information you are given.

Regarding pins, the AP and HCl leach is just to remove the base metals before you dissolve the remains in whatever method you prefer.
If you use AR on pins directly you have to dissolve all until all base metals are gone, the black powders could have been your gold precipitating back on the base metals.

PS!!
Just another thing, if the solution has taken color and there is a lot of powders, something has happened to the pins, excactly what is the question.
If you are having issues with a process, mixing in other uncertain factors from other processes you are having issues with, don't make it easier to identify your initial issues.
(POOH sorry about that sentence :wink:)
For instance, if the pins are SS then nitric may passify them.

Edited for writing error in red
 
ashir,
I don't think I will be much help, without seeing what's happening in person, it is hard to tell by reading what all is going on or what that is giving you problems...

Pins can be made different, some are mostly very pure copper a thin coating of nickel and gold, other pins are made from copper alloys like brass mostly copper and zinc alloys, some naval or red brass can be made with up to 30% tin and contain other metals such as lead iron and arsenic, there is also nickel silver alloys used besides copper about half of the alloy can be made of nickel or zinc, and we also have phosphor bronze alloys or beryllium copper alloys.

Some pins the gold is very thick which can make them difficult to process by normal means, not because of the base metal but just because the gold is so thick the acids have a hard time getting to the copper or base metals...
Too much gold can make it hard to get to the base metals.
Too much base metals if dissolving gold and letting it plate back until everything is in solution.

With pins having tin in the composition of the alloy, it is risky to put the gold into solution with the tin involved there is a good chance some of the gold will be lost to colloids.

I cut these pins in small pieces and use them to make nitric acid, cutting them gives the acid plenty of surface area of the base metals to attack, helps to speed reactions...

Too much gold can make it hard to get to the base metals.
Too much base metals if dissolving gold and letting it plate back until everything is in solution


http://goldrefiningforum.com/~goldrefi/phpBB3/viewtopic.php?f=38&t=6199
 

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