PCB precious metals recovery concept

[kjavanb123]

All,

I have been thinking about this method, please add your comments.

Using MBMMLLC PCB recycling system, produce concentrates and tailing from boards, then using two different tank to leach tailing and all 3 concentrates with weak cyanide to avoid plating gold on the copper and other base metals, cement the gold and silver with zinc, then smelt the concentrates with copper to produce impure copper plus palladium and sell that to a copper refinery setup based on analysis.

Tailing can also be sold as low grade sweeps that contain trace amount of Pd.

Please advise

Best regards
Kj

 

[anachronism]

Are you talking about ewaste or mining ? I ask because you mention tailings.

 

[kjavanb123]

I am talking about ewaste. Although, they have been calling e-waste recycling, "urban mining".

If you take a look at Mt. Baker Mining and Metals Ltd website, under their video section, there is a link to a system that shred and mill the whole circuit boards and run the fines on a shaker table that has 4 outputs.

Three of those output ports are metallic particles from circuit boards and last output is what I refered to as tailing because it contains all the plastics and non metallics.

The reason I suggested cyanide leaching the tailing and concentrates is faster recovery rate for gold and silver, which can offset the cost of purchasing new materials.

This could be an alternative as far as speed to commonly practice of smelting the concentrates and casting the copper dore followed by electrolysis and slime processing.

Regards
Kj

 

[4metals]

Why zinc? Try a cell like this one that uses steel wool.

http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=86&t=13614

I think the ratio of Palladium to copper overall on circuit boards will make your assay too low to have payable Palladium.

 

[autumnwillow]

I think smelting would be the way to go.

Using a cyanide leach would require you to wash well the leached materials after the leach. Maybe three or more times as some of the PCB materials would tend to absorb it.

Smelting is as simple as mix w/ flux and collector then melt.

Edit to add:
You'll have to treat the cyanide wastes after unless you use electrolysis to recover the gold. It will also take a lot of time for cyanide to dissolve the large prills assuming they get into your tailings.

I would pyrolize and incinerate first before I smelt though. It could all be done in a well designed furnace.

 

[kjavanb123]

Autumnwillow,

As I mentioned copper smelting is what has been done by larger refineries, handling large volumes of boards.

If one wants to process a ton of boards daily, then copper smelting the concentrates would not be attractive to a refinery since the copper dore would be too small for them.

Processing in-house the produced copper dore would take weeks plus some details in ph level controls and monitoring the cells, then you get to separation of anode slimes to get to the PMs.

In order to avoid that I suggested cyanide leaching, since I know for instance in gold mines it usually takes 48 hours of leaching, to completely dissolve the gold and silver, and a day or less to percipitate it.

Except minor mintoring for oxygen level and pH levels, cyanide leach can be small scale too.

Please advise.

Regards
Kj

 

[autumnwillow]

I think you are already familiar with the cyanide process. If not search for goldsilverpro's posts.
Try to half your batch. One for cyanide then one for smelting.
Then balance out the time spent, materials used and recovery losses. See which one works for you.

I am not sure why copper has been a choice for large refineries, I would use silver instead.
A silver cell is easy to setup or you could process it directly in a 50/50 nitric leach (filter when decanting the liquid).

Read this thread: http://goldrefiningforum.com/~goldrefi/phpBB3/viewtopic.php?p=260940#p260940

Though we are talking about different materials, I think your e-scrap tailings would tend to absorb more of the solution than my clay crucibles which could end up with more losses.

Reprocessing your tailings twice or trice in the table should probably suffice. I think the costs for processing the tailings on a smelt or cyanide will be more than the value of the PMs recovered.

Study most of Deano and goldsiverpro's posts if you decide to go the cyanide route.