Turning SCRAP Electronics into GOLD BARS!
Linus Tech Tips
·Linus Tech Tips
·2018-05-06
·
1,314 words · ~6 min read
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When you think of electronics manufacturing in Asia, understandably
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there are a lot of words that probably pop into your mind. Toxic chemicals, air
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pollution, hazardous waste, e-waste,
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heavy metals. And you know what? These are real problems that anyone with half
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a brain can hopefully agree that we need
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to solve. So then what is being done on
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the small island nation of Taiwan where according to the economist 40% of their
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annual exports are electronic devices
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manufactured by companies like ASUS, HTC
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and Acer. To find out, we went about an
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hour out of the city to sit down and chat with Mr. Stan Sue, the president of
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Sue Recycling Technology, Inc.
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Cooler Master's 25th anniversary edition
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Cosmos 2 features a unique dual cool
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curved tempered glass side panel. Check it out now at the link
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below. In circuit board manufacturing,
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as in baking, there is always some leftover material when the finished
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product is cut out. But unlike baking,
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you can't just fold it up and cut again. So, what do you do? To answer that, SRTI
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was kind enough to take us deep inside the bowels of one of their four
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facilities here in Tawyen, Taiwan, where they're using techniques created in
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collaboration with several universities under the supervision of the
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Environmental Protection Bureau to extract valuable metals like gold,
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silver, and platinum from leftovers so
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they can be reused instead of ending up in a landfill. or a pile in a developing
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country somewhere. And the goal is to do this in the most ecologically
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responsible way possible. So, some of
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the e-waste coming in the door takes a pretty familiar form. Printed circuit
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boards, integrated circuits, and the like. These get picked up from partners,
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shredded right in front of the partners to protect their valuable intellectual
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property, and then the shreds get placed into these stainless steel cages.
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They're round so that they can be spun around like a clothes dryer to optimize
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contact with the solvent that you have got to be kidding me cyanide. I
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immediately I was like is that safe? And they were like of course not. What a
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stupid question. That's why we have these gas detectors, fume hoods, and
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goofy clothes. So anyway, the crane grabs the cage and submerges it in the
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cyanide, spins it around, and then as little as 3 to four minutes later,
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depending on the elements in the waste, it can be pulled out, washed, cooled,
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dried, and then opened to reveal some
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scraps from LED production. So what you
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see here is a stripped gold copper
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alloy. Any exposed gold has actually
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been dissolved into the cyanide. So, it
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gets put into these one-ton drums for further processing. But we'll come back
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to that a little bit later. First, we need to take a look at some of the
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e-waste that you might not recognize as potentially valuable. These bags are
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full of cloths that were used to clean
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electronic parts during manufacturing. So they pick up trace amounts of
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valuable metals like aluminum, silver, and maybe even gold that can be
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extracted by the coolest means possible
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with fire. But burning these cloths
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normally would release toxic and environmentally harmful chemicals called
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dioxins. So that's where the furnace, as
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it's been nicknamed, comes in. Unlike some crude burn barrel, it uses two
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combustion chambers. A primary one to
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burn down the fabric and melt metals like silver and a secondary chamber that
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takes the exhaust and turns it up to
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around 1,000° C to destroy the dioxins,
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then rapidly drops the temperature down to 200° C to prevent them from
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reforming. This process can yield as
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much as a kilogram of silver per 100 kg
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of cloth and a lot of ash that can
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actually be used for concrete production. The remnants from the
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burning process come with us to the next station. They're heated up in a titanium
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container in a king's water bath. This
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mixture of hydrochloric and nitric acid dissolves gold and platinum, but not the
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other so-called noble metals. Then
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anything that we don't need gets filtered out here before the yellow
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liquid is carted over to the next station, electrolysis. They are used to
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extract the gold from both our king's
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water and cyanide solutions from before.
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The negative terminal is on the left and the positive is on the right with a
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stirring motor in the middle. The terminals will collect other things
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while the gold in a porous form called
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sponge gold collects in a titanium container. This process continues for 24
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hours and the voltages applied to extract this purity of gold are
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apparently trade secrets that they wouldn't allow us to show. Once all the
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gold is extracted, the liquid gets transferred to another facility where
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they're focused on taking out silver.
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Leading us then finally to where the magic really happens, the casting room.
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Our sponge gold is heated to over
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a,000°. The vapors you see being captured by the fume hood are small acid
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impurities. Then some regular household
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borax is added to act as a flux and purifying agent. And the gold gets
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poured into a
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cast. Yes, my friends, you are witnessing the birth of a gold brick.
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The cast gets poured into water to cool and harden it. Then it's actually still
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pretty warm when it comes out. Our 4 to
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59 fine grade 2 kg gold brick is ready
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for polishing and transfer to the vault
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which they unfortunately wouldn't let us inside. So I don't even know how much
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what's 2 kilos of gold worth.
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Take out the mass and see your smile.
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So how how much is this one worth? Uh
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maybe 40,000 N. Oh, like a 100,000 Canadian or
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so. Sorry.
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No, no, not so much. So each month then
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the 130 people working at SRTI turn
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about 200 metric tons of what would otherwise be e-waste into 100 kg of
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gold, 800 to 900 kg of silver, and about
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a metric ton of copper. Unbelievable. A
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huge shout out to them for allowing us behind the scenes to see how they've
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built an amazing business out of reusing and recycling precious materials while
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minimizing the environmental impact of the electronics manufacturing taking
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place on their island
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