Author Topic: Where are the most valuable components in PCB for recycling  (Read 3721 times)


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Where are the most valuable components in PCB for recycling
« on: October 02, 2019, 11:17:09 PM »
Basically, Au, Ag, Sn, Pd,Cu is probably the right sequence of commoditi es value in e-scrap material recycling . which metal to recover is usually depends on operator's facility and technical capacitie s etc.
Eco-goldex provides a sequentia l stripping procedure that will help operation to recover multiple metal commoditi es in sequence:
  • Surface Au-Ag-Pd stripping
    Surface Au-Ag-Pd refers to those precious metals that are plated on the surfaces of electroni c component s such as the golden fingers on RAM, the pins of CUP, connector s, all kinds of pins and the plated wide print circuits on telecom board.
    these surface gold/silver/ palladium can be easily stripped off with eco-goldex E series agent solution. 
  • Solder Stripping
    Many recycling operators haven't noticed the economic importanc e of solder in e-scraps. solder (mainly composed of Tin(Sn) and some Ag and Pb) can be easily recovered through either hydrometa llurgical method or thermal process (heavy smoke pollution). Eco-goldex provides its own hydrostri pping method that can easily strip Solder on PCB, at the same time to loose those component s attached on PCB such as IC chips, capacitor s.... most of the component s will fall off the PCB. After the solder stripping step, the PCB will become bare boards. these bare PCB can be either further crushed and pulverise d to recover copper and epoxy/plastic fibres that can realise zero disposal in the recycling process. the pop off component s will then pass a screening mechanism  that sort different component s into different slots. one of the slots will receive IC chips.   
  • Internal Au-Ag-Pd leaching
    The IC chips collected from solder stripping step are then crushed and pulverise d into about 200 mesh powder. the IC chips powder is then leached in an agitating tank in there gold/silver fine particles will be leached out into solution. through a compressi ng filtratio n process, pregnant solution from the leaching solution will be separated from the  IC hips powder sludge. the pregnant solution is then sent back to electrowi nning machine to recover gold/silver/palladium.

Eco-Goldex has analysed gold/silver/palladium grades in several different common IC chips and bare PCB boards after stripping . Results indicate that all the IC chips container high grade gold, some of them contain considera bly high silver. palladium grade is not impressiv e or a that high as claimed by some operators . our conclusio n is that for most of the hobbyists, it will be good enough to recover Au-Ag, Pd can be counted as a credit if process quantity of high. the bare PCB has not significa nt value since Au-Ag-Pd are low.

Below is table showing assay results of Au-Ag-Pd (all in ppm unit) grade in various IC chips. These IC chips powder are digested in AR to ensure all metals are completel y dissolved . AR solution is then assayed for Au-Ag-Pd concentra tion with AAS (Atomic absorptio n spectrome try).