Gold dissolved in Nitric and salt.

[qst42know]

There are companies that incinerate powder coat paint hooks. They have the proper equipment and incinerate as a service. Having this step of the process done for you might be less trouble and expense than the chemical stripper you are using, or the labor of hand stripping.

Keep in mind this is just an idea and not from experience.

 

[patnor1011]

I do not want to discourage anybody but... 99% of forum members are hobbyists. 1% make living refining. Out of that 1% most of them refine karat gold. I have yet to see somebody who is making living processing just boards.
Some people can have comfortable and nice income from recycling or recovery operation. That mean they take whole electronics and separate. Bulk of their income comes from selling scrap metals. As I have said, I do not know anybody who can say he make enough for living just processing motherboards. It cant be done without proper and costly equipment and know-how.

 

[Ardibash]

Hi, sorry I was busy building equipment.

I understand that big refiner use destructive pyrolysis to process broads. But one has to start from somewhere.
I built a disordering station with a catering grill (365C) and sand, works OK ... but some components, which have SMDs on both sides can not be done this way, so I put them in an HCl bath. I noticed that 25 L of HCl can depopulate about 300 boards. In average, a ton of mixed boards (with heat sinks) contain 1200 PCBs. Depopulation with HCl would cost me about £200. The gold (only gold) refined would be about 100 g according to a reliable source. (see attached data from Umicore group). So at the end depending on the price I pay for a ton of PCBs the chemical depopulation would be an option for me (for now).


I'm thinking of building a pyrolysis furnace. If anyone knows any ting about it and can help me to make the drawings, please let me know. I will build it, and post detailed description in the forum.

I'm working on 7 machines

20L vacuum filter,
boiling station with condenser,
titanium reactor,
wet scrubber,
semi-automated depopulating bath,
neutralisation and base metal recovery apparatus
and base metal leaching reactor which uses combination of acids to digest base metals apart from lead, tungsten

and will post the manufacturing process in in few weeks.

 

[butcher]

For the scale and materials your talking about you would need a furnace with an after burner, and possibly ash collectors and fume scrubbers.

You should check with your local authority's DEQ, EPA. Or pollution control officials to find out the requirements, and follow their instructions.

Without following their advice you could find yourself with big problems costing you more than any gold you can dream of getting.

 

[seawolf]

Somewhere in my searching I found te artical below:

An electro-dissolution method has been developed by Pozzo and coworkers (1991) to remove solder coatings from printed board scrap to facilitate the recovery of copper. Rotating trammel screen baskets, each 20 cm long, and made of stainless steel or mild steel are used as the anode and a semi-cylindrical shaped sheep of stainless steel as the cathode in the electrolyte cell. The anode is rotated with an electric motor at 40 RPM. The electrode setup and the electrolyte solution are placed in a rectangular container made of polypropylene of a capacity of about 22 liters. Sodium hydroxide is found to be the right electrolyte as it dissolves both lead and tin rapidly. Eleven liters of 1 mole solution is used. Samples of printed circuit board scrap with a bulk weight of 500 grams are charged into the basket anode. With a cell voltage of 2volts both tin and lead dissolve rapidly and selectively from copper. An increased rotation speed of the reactor basket improves the dissolution rate, while the percentage extraction of lead and tin remains nearly the same even when an increased amount of scrap is charged. Power consumption in the removal of the lead averaged 97 MJ (27kWh) per ton of the charge.

I have no idea if this might be a solution to cleaning the tons of boards or not. Some of the other members might know more and pass it along or show why it won't work. (nothing was said about recovering the metals before the solution was disposed of) Mark

 

[Ardibash]

I will try that and post the results. Right now I'm experimenting with stabilised nitric looks promising, once I have results will post here.