Gold Recovery From Surface Mount IC CHIPS
Surface mount ic chips have a good quantity of gold. Gold quantity is also different in different ic chips. In this tutorial, we will learn about gold recovery from ic chips (black surface mount ic chips recycling). In this tutorial, only gold shall recover from ic chips. I will make another tutorial about gold, silver and palladium recovery from ic chips.
Note. These ic chips can’t recycle to use this method.
This method is very easy and gives 100% gold recovery. For Ic chips recycling, we shall need
- Sulfuric Acid
- Nitric Acid
- Hydrochloric Acid
- Hydrofluoric Acis
- Sodium Metabisulfite
- Filter Paper
- Stainless Steel Pot
Note; This procedure contains some dangerous fumes.
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Put ic chips in a stainless steel pot. Add sulfuric acid in a pot until ic chips dip. Sulfuric acid should be 1 inch above from ic chips. Now give a normal flame heat. If you give a strong heat then ic chips will stuck and can’t process anymore. After some time, dissolving will start in H2SO4. If your acid starts to boil and increase its volume with black foamy acid. Add more sulfuric acid to get the black foam. When acid completely settled down then check is chips. After complete dissolving black material, your ic chips will seem like below picture.
When you feel all ic chips have dissolved. Turn off heat and leave it to cool down for two hours.
Note; Don’t leave it for a long time.
After 2 hours all metals will be settled down. Now, pour black acid to another pot carefully. If some gold wires will go with black acid. Then you can recover them from second pot. After pouring wash carefully ic chips with water three times.
Note; Use strainer for every washing and pouring.
Now, add water until material dip and add nitric acid for base metals removing. Nitric acid will be added until reaction. When reaction finish, double volume of solution with water. Wait for all materials settled down and then pour solution. If you see some copper or other base metals then treat again with nitric acid and add some sulfuric acid for a better result. Then wash with water three times.
If you see aluminum and fiber fabrics then add some hydrofluoric acid. Hydrofluoric will eat all aluminum, fiber and all extra things. When the reaction has done wash with water. Now add some nitric again and wash with water three times. After washing you will see gold wires like below picture.
Now, convert gold wires to the beaker or plastic bucket. Make aqua regia and add to the gold wires. Gold wires will dissolve in aqua regia. This gold solution is also called royal water. Leave it for two hours for reaction.
Note; Shake solution three to four times.
After two hours, filter the gold solution. You can use vacuum filtration but I will recommend you gravity filtration. It works best and filter paper does not stuck. Wash 5 to 6 times and don’t let gold solution in filter paper. Add urea until reaction for neutralizing the nitric acid. After this make SMB solution. You can add directly SMB to the gold solution but sometimes it does not work better. Take the double quantity of SMB to estimated gold. Or add until gold water become black and bubbles color becomes white. Leave it overnight for a better result. All gold dust will settle down.
Now filter gold dust. Wash filter paper 3 to 4 times until all acid goes down. Dry and burn filter paper and melt the gold dust. Click here to learn about GOLD MELTING.
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