From CPU


GOLD in CPU

From 10 kg P-III & P-IV processors you can get approximately 6 grams 24 carat gold.

In this guide we will give a complete process for the GOLD recovery from CPU's.

CPU's does differ in their design and materials from the ceramic type and therefore needs to be treated in separate way.
The leads (pins) of fiber CPU are attached to the body of the CPU with regular solder.

Fiber CPU's contains recoverable gold mostly on the pins and sometimes on the inner side of the heat sink plate.

Two more components to consider when dealing with fiber CPU's are; (1) The heat sinks that are sometimes
Gold Plated (2) And the Monolithic Ceramic Capacitors that contain Palladium. Those two components are to be kept separately for later individual recovery of Gold or Palladium.
Once the three components (pins, heat sink,) are removed from the CPU, discard it to your low grade e-scrap pile.

Note: Information and process recovery details are mentioned by doing research on related field to the best of our knowledge.

 So, request to all is to be cautious during the recovery since you are dealing with all type of basic as well as hazardous chemicals. So you will be held responsible if the method goes wrong. So take care when you proceed.

Abstract of the process:

A- Gold Plated Pins separation from the CPU body using a torch.
B- Gold and Base metals separation using a Hydrochloric Acid leach.

A- Gold Plated Pins separation from the CPU body using a torch:

CPU's Pins are obviously gold plated and usually gold plating thickness is 10-30 micro inches.
Older fiber CPU's may utilize a high copper alloy as base metal underneath gold plating.

For this step you will need:
Torch
Lock grip Pliers.
Metallic bowl or a pan.

1- Grab the corner of the CPU with the pliers and start heating the pins on the far corner from the pliers. Use the lowest flame possible on your torch, the idea is to heat the solder enough to melt it without burning the fiber body of the CPU.

You will know when the solder is molten once you hear and see it pops. At this point just swish the CPU's towards the bowl to create enough pressure for the pins to cut and land in the bowl.

In some types of CPU's the pins will not detach from the body that easily, so just mount the pliers above the bowl, heat and scoop down the pins to the bowl with a small metal rod.

CAUTION: MOLTEN SOLDER, BURNING PLASTIC & EPOXY PRODUCE HIGHLY TOXIC FUMES!! PREFORME THIS STEP OUTDOORS OR UNDER FUMEHOOD

Now that you have the gold plated pins all separated from the body, it is time to separate the gold from the base metals.
The separation is done chemically by boiling the pins in a solution of 30% Hydrochloric acid (HCL).



     Steps as Follows:

1)     Hot plate(Any heating element)
2)    Flask to setup Hcl of about 30% (must be half of the flask)
3)    Weighing the pins put them into the to the flask.
4)    Place the flask on hotplate and let the solution boil gently. Don’t over heat
5)    Let the solution boil for some couple of hours.
After boiling, the solution will turn almost black. The black solution indicates saturation of the solution. You will also notice Gold Flakes and foils floating on top.
6)    Decant the solution with all gold foils and powder to the filter, leaving any un-dissolved pins in the flask and allow complete draining.
You might see some un-dissolved pins that can still trap a bit of gold, you can add fresh acid to dissolve them or just wash them thoroughly with plenty of water and decant to the filter.
Wash the foils and the filter well with water until its back to white color.
7)    You now have the gold foils and powder in the filter. With the gold, there will be small amount of un-dissolved base metals and left over organic matter.

This is the end of the Gold Recovery stage.