kurtak
Well-known member
To which I replied
So here we go - & this is just the "tip of the iceberg"
First of all you need to understand what & where the "values" in CBs (Circuit Boards) are &/or how to then recover those values
The target values (metals) we are after in the "processing" of CBs are the copper, silver, palladium (one of the six platinum "group" metals) & of course the gold
To clarify those are the values we are after in the actual "processing" of the CBs & they are the values that the BIG BOYS payout on - there are other values you get out of the electronic "equipment" when you tear the equipment down to get to the CBs such as aluminum, iron & copper (as wire etc.) which is sold to scrap yards
There are two ways to recover values from CBs
1) is the process of smelting wherein the CBs are first shredded then incinerated, then milled & then smelted somewhat like the process I provided you a video link to from Advanced Chemical which only showed the process up to the point of smelting but did not include the actual smelting process - which is a process in & of itself that requires an understanding of HIGH temperature (2,000 plus degrees F) carried out in a furnace along with an understanding of the flux chemistry that takes place in the furnace in order to recover the target values & "slag off" the garbage
2) is a wet chemistry process wherein the values are "leached" out with chemical solutions such as acid leaching, cyanide leaching, iodine/iodide leaching etc. etc.
Of those two processes only one of them will recover ALL of the values in the CBs & that is the smelting process & that is because in the smelting process the "target metals" all become molten in the furnace - slagging of the garbage in the flux - resulting in a recovered dore metal which is an alloy of the target metals - & then that recovered dore metal still has to go through "different" wet chemical processes in order to separate each of the target metals from the dore metal alloy that was recovered in the smelting process
It is next to impossible (if not impossible) to recover ALL the values out of CBs with wet chemistry processing
And that is because you can't simply shred a CB & put it in any one leach solution to recover ALL the target metals in that one leach solution & that is because the different metals in the CBs "require" different wet chemistry processes
And as well - all the different target metals we are after in & on CBs are found in the many different "components" on the CBs - so - you first need to figure out which components contain which metals so that you can figure out which wet chemical process will best work for the recovery of that particular target metal(s) --- & as well some component have little or NO value in them
So - you first need to strip ALL of the components from the board - you then need to know which components have values & which components have little or NO value
Side note here; - though some components will have "some" value in them the cost of the chemicals to recover those values will be greater then the value of metals you recover from those components with "little" value
So after stripping all the components off the boards - you then need to sort the components with values from the components that have no value (&/or the components with so little value it will cost more in chems then value of the metal that can be recovered - by wet chemistry)
Then once you have sorted the components of "good" value from the components of little or no value --- you still need to sort the components of "good" value into "batches" that can be processed by the different leaching processes that target the particular metals in the different components
AND - then there are some components on the CBs that simply DO NOT lend them selves to wet chemical leaching - &/or require a LOT of prep work before you can proceed to the wet chem part of the process
Just as a couple examples ----------
1) ceramic disc capacitors - some of which (but NOT all) have a good silver & palladium recovery value in them & though yes you can chemically leach them doing so is a HUGE mistake --- it will break the ceramic down to an ULTRA fine ceramic clay like mud which is "impossible" to get all of the leach solution washed out of (meaning some of the values stay tied up in "the mud") & by the time you get most (but not all) the values washed out of the mud you are going to have a HUGE amount of VERY diluted solution - that then needs to be evaporated down before you can go to recovering the silver & palladium back from your leach solution
Therefore - with ceramic capacitors that have good values in them (& you need to know which ones do & which ones don't) you are FAR better served with recovering the values with a smelting process then with a leaching process as ceramic capacitors simply do NOT lend themselves well to a leaching process
2) Epoxy IC chips (not the ceramic IC chips) which have gold bonding wires in them - you can not just put these in a leach solution to get the gold out of them as the bond wires are "incased" in the epoxy
The gold bond wires are VERY small - like near microscopic in size - in other words - it is near impossible to see a single bond wire without magnification
So - the gold needs to first be liberated from the epoxy --- this is done by first incinerating the chips to turn the HARD epoxy to soft carbon - that soft carbon then needs to be milled/ground to a very fine powder (like 80 - 100 mesh powder) the milled powder then needs to be sifted through an 80 or 100 mesh screen (which the bond wires will go through) in order to remover the over size garbage such as "larger" copper & iron legs (that you see on the outside of the chip - but also go into the epoxy) as well as the silicon dies (the part that makes the chip work) & the heat spreaders the die sits on inside the chip
Then - once you have the over size sifted out you end with a VER SMALL amount of gold in a HUGE amount of very fine carbon powder
Leaching the small amount of gold out of that much carbon would be somewhat like trying to leach silver & palladium out of ceramic capacitors (different but somewhat the same results = A BIG MESS)
Therefore - after all of the above - you still need to put all that carbon through a washing process to wash away the vast majority of the light weight carbon leaving you with a better concentration of the heavier gold bond wires along with now MUCH less carbon & other stuff that ends up in the concentrates -such as silica binders used in the epoxy & "small" pieces of the silicon dies broken up during milling & small enough to go through the sifting screens --- & you have to be careful with this washing process or you will wash away the VERY SMALL bonding wires --- you can then ether leach this concentrate - or smelt it
AND - as i said - this is just the tip of the iceberg of trying to recover ALL of the values from CBs - by means of wet chemistry processing
And the learning curve for all of this is HUGE (takes years) starting with small hobby experiments - with processing on the recovery of one type/part/component of the CB - getting that process down pat - then moving on to other types/parts/components of the boards - &/or moving on to larger batches
So - lets see some pics of what you keep & we will help you with getting you started down the "right" path to learning to do this - on a hobby level - a hobby I think you will enjoy
Kurt
