hi everybody in this video I will
demonstrate how to recover the gold plating from
connector edges AKA – “fingers”. the fingers are found in
most the fingers are found in
most scrap computers and servers warning the process shown in this video
involves highly corrosive acids and should only be done outside or
in a fume hood using safety gear such as gloves goggles
and a respirator is mandatory let’s begin the fingers are placed in a
plastic strainer here we have some hydrochloric acid a little bit up copper chloride solution and a small DC powered your bubbler the plastic to goes under the strainer
with the fingers right at the center now the fingers are covered by the acid
and the copper solution and some water to make sure all the
fingers are covered by the solution turn on the bubbler and that’s it for the next week or so so here we are twenty-four hours later the solution color turned olive green
and doesn’t seem like much has happened let’s kill the air and see what’s going
on NICE… we can clearly see some gold
foils floating around seems to be working well cover plate is placed back on and the
air tube is connected here we are again forty-eight hours into
the process the solution colors now very dark green in here we can clearly see that some
of fingers have been completely dplated day 6 seems like the majority of the
gold plating is now loose let’s keep it in the solution one more
day just to make sure now you might ask yourself what exactly
is going on in this process and every common printed circuit board
there’s basically three layers of metal plating copper nickel in gold the point is to
slowly etch away the copper and nickel to free the
gold layer. to be honest chemically speaking the
copper chloride etching system is quite complex. however
there are three simple things that will push this process forward and
are important to remember: first is having free hydrochloric acid second is the presence of copper ions
in the solution and the third is dissolved oxygen.
maintaining these three parameters will ensure the aging process will
continue on the next batch of fingers. here we are in the seventh day it’s time
to recover the gold falls from the solution and what’s left on the fingers. I’ll let
the main solution with the majority of the gold oils settle for a little while and begin
to wash the fingers and collect the coils that are still
hanging on the fingers. the fingers in the strainer are washed
with plain water in a five gallon bucket. This will take a
while you probably get the point just shake until
all the gold falls off. Let’s fast forward we still haven’t finished with the
fingers, it is now set aside to dry completely will return to that later. And now for the main better gold foils. After
settling for a while the bulk of the etching solution is
filtered first by pouring just the solution on top. You could see the
filtrations flow-rate is quite fast. and here’s our recovery product nice and
shiny gold foils the etching solution is moved to storage
and will be reused on the next batch the foils from the fingers wash is now added to the main batch of foils now the bulk of the foils and powder
are drained filter. The filter and the foils are placed in a
regular open mouth beaker which is placed on top of a hot plate The gold foils and filter are now
covered with a diluted hydrochloric acid half water in half
acid the plate is turned on to medium heat and the beaker is covered with a watch
glass now that the solution is quite hot the
addition of concentrated nitric acid begins. There’s about three milliliters
of nitric in this pipette. this is enough to complete the task at
hand. As the acid is added we can clearly see
an immediate reaction. Hot aqua regia his so corrosive that aside from dissolving the gold foils it
will also disintegrate the filter paper down to a pulp. By the way remember the fingers we set
out to dry? Well, once they’re dry we can squeeze out
a little bit more gold than we got earlier just shake it hard !!! See that gold…? this goes into the aqua
regia solution as well Here we can see the gold-bearing
solution and the pulp settled to the bottom of
the flask. The gold-bearing solution is filtered one last time to get rid of the pulp and any other
solid particles Let’s flute the filter real quick… And wet it… the pulp and the solution is poured into
the filter and allowed to drain all the way through. When all of the original gold solution
has been drained, and the filter and the pulp are washed
several times until it becomes white again. The gold solution is now ready for the
rest of the refining steps such as reduction up the gold, washing it
and melting it the steps are already covered by my
other videos so just click on these boxes below to
see the rest of the processes. And here’s the result of the recovery
process from a about 505 grams of clean-cut gold fingers. Do you have a guess of how much
pure gold this batch yielded? Write it down in the comment section below.
thank you for watching my tutorial please comment share and subscribe.