Author Topic: Where are the most valuable components in PCB for recycling  (Read 4657 times)

Eco-Goldex

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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 the operator's facility and technical capacitie s etc.
Eco-goldex provides a sequentia l stripping procedure that will help the 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 the 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 lose 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 pulverize d to recover copper and epoxy/plastic fibers that can realize zero disposal in the recycling process. the pop off component s will then pass a screening mechanism that sorts 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 pulverize 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, the pregnant solution from the leaching solution will be separated from the  IC hips powder sludge. the pregnant solution is then sent back to the electrowi nning machine to recover gold/silver/palladium.

Eco-Goldex has analyzed 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 hobbyists, it will be good enough to recover Au-Ag, Pd can be counted as a credit if the process quantity of high. the bare PCB has not significa nt value since Au-Ag-Pd is low.

Below is a 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).

 

« Last Edit: July 02, 2021, 05:01:40 pm by Eco-Goldex »