Introduction: Gold Recovery Correctly
I will detail a SAFE process of turning old electronic parts into little round lumps of pure gold. There are many tutorials that claim to offer methods of gold recovery such as "Cupellation"*. These processes are DANGEROUS and put the user at the risk of inhaling vaporized metals.
No over the counter breather will protect you from these dangers; Only lab grade isolated breathing systems can protect against metal vapors. ********************************** SEE HEALTH HAZARD ON STEP 6***************************************
**** a Side cautionary note, This process is not suitable to purify Panned Gold or KARAT (Gold Alloyed with silver.) This Guide is best suited for gold plated or pure gold object.
THIS SHOULD ALSO NEVER BE ATTEMPTED INDOORS.
*Cupellation is a refining process in metallurgy, where ores or alloyed metals are treated under high temperatures and controlled operations to separate noble metals, like gold and silver, from base metals like lead, copper, zinc, arsenic, antimony or bismuth, present in the ore. The process is based on the principle that precious metals do not oxidise or react chemically, unlike the base metals; so when they are heated at high temperatures, the precious metals remain apart and the others react forming slags or other compounds
Step 1: SAFETY FIRST, Always.
In this instructable you will be working with basic house hold chemicals. By themselves these chemicals can be fairly harmless. The combination of such chemical which will be presented in this instructable can be EXTREMELY hazardous; By such there are a couple of safety items which are not Optional. THE FOLLOW ITEMS ARE REQUIRED. FAILURE TO OBTAIN THESE ITEMS BEFORE HAND CAN POSSIBLY COMPROMISE YOUR HEALTH.
Item # 1.
Breathing equipment. You will need a chemical mask rated AT LEAST as a P100. If you dont know what a P100 rating means It is your responsibility to yourself to find out.
Item # 2
Heavy duty Gloves. pvc or rubber is fine, do not use Latex or Nitrile gloves.
Item # 3
Safety Glasses. Any pair will work as long as It is safety rated and solvent rated.
Step 2: Equipment Needed.
Helpfull items which can make doing these experiments easier.
1. Borosil glass labware.
2. 2 1/2 gallon bucket.
3. a 1 gallon bucket with holes drilled in the bottom. - to be used as a strainer.
4. a 60 ounce pickle Jar
5. Coffee filters
6. Filter holder from a coffee machine.
7. Spray bottle.
8. Mini scale with the ability to measure Grams and Oz.
9. some pipettes and test tube.
Step 3: Chemicals Required.
I have used a number of chemicals these I have found to be the most widely available.
1 gallon of Clorox Bleach. or Sodium hypochlorate at 6%
2. Muriatic Acid 34% HCL ~ Baume.
3. Hydrogen Peroxide - 3% but no greater then 5%
4. Stumpout by Bonide. or Sodium bisulfate - 99.9% as specified in the Msds or Sodium Meta Bisulfite.
You cannot substitue with these chemicals trying to do so will no give the required reactions.
Step 4: Selecting Materials to Be Recovered.
I was taught by the method of Crap in Crap out. You want your materials to be as clean as possible with the least Amount of Garbage as possible.
Gold fingers are typically found on PCI cards, ISA cards, or on Memory sims/dimms/etc. They create the corrosion free connection between the computer and the expansion card.
This process can also be used to recover gold from CPU such as Pentium Pro, or Cyrix or older 486 and lower generation chips.
Step 5: The First Chemical Bath.
Objective of this first chemical bath is to remove a large majority the base metals, Such as nickle, zinc and copper.
After cleanly removing your plated sections of computer parts. remove any visible capacitors transistors, or other components. be sure to also remove any steel or iron parts attached. These metals can foul the reaction causing poor results.
100 ML beaker, 1 gallon bucket, 2 1/2 gallon bucket.
Muratic acid, and hydrogen peroxide.
Materials you are looking to recover.
First step, place your 1 gallon stainer bucket, into your 2 1/2 gallon wash bucket. But first place your parts to be recovered inside your 1 gallon strainer bucket. as pictured.
Add enough muratic acid to cover your fingers about 1 cm above your materials. keep track of how many MLs are added. you want to keep your waste Acids to a minimum. second. To activate the solution you want to add your Hydrogen peroxide 3 - 5% solution in a 2 to 1 ratio. two parts muratic acid to one part hydrogen peroxide.
after the Peroxide has been added to your muratic acid the mixture should start to bubble, and the base metals should begin to dissolve. At this point you should be wearing your safety gear because a few unfriendly fumes are being released.
This process can take up to 24 - 48 hours. this works best at the temperatures of 80 - 90 F.
When this has been completed you will see a batch of gold foils floating in your now dark green acid.
Step 6: Filtering the Gold Foils.
- coffee filters
- filter holder
- 60oz pickle jar. or glass container large enough to contain waste acids.
Simply Poor the contents of the two gallon bucket into the pickle jar using the coffee filters to catch any foils that are floating on the surface of the acid. Once you have pored off all the acid you will be left with a pile similar to what is in the picture. scoop these from the bucket into another container for future processing.
Congratulation you are about 50% finished. **********
************************************* HEALTH WARNING ***************************************
Melting at this stage may lead to the following health hazards.
Inhalation of zinc oxide fumes can occur when welding or cutting on zinc-coated metals. Exposure to these fumes is known to cause metal fume fever. Symptoms of metal fume fever are very similar to those of common influenza. They include fever (rarely exceeding 102o F), chills, nausea, dryness of the throat, cough, fatigue, and general weakness and aching of the head and body. The victim may sweat profusely for a few hours, after which the body temperature begins to return to normal. The symptoms of metal fume fever have rarely, if ever, lasted beyond 24 hours. The subject can then appear to be more susceptible to the onset of this condition on Mondays or on weekdays following a holiday than they are on other days.
Beryllium is sometimes used as a alloying element with copper and other base metals. Acute exposure to high concentrations of beryllium can result in chemical pneumonia. Long-term exposure can result in shortness of breath, chronic cough, and significant weight loss, accompanied by fatigue and general weakness.
Mercury compounds are used to coat metals to prevent rust or inhibit foliage growth (marine paints). Under the intense heat of the arc or gas flame, mercury vapors will be produced. Exposure to these vapors may produce stomach pain, diarrhea, kidney damage, or respiratory failure. Long-term exposure may produce tremors, emotional instability, and hearing damage.
Inhalation and ingestion of lead oxide fumes and other lead compounds will cause lead poisoning. Symptoms include metallic taste in the mouth, loss of appetite, nausea, abdominal cramps, and insomnia. In time, anemia and general weakness, chiefly in the muscles of the wrists, develop. Lead adversely affects the brain, central nervous system, circulatory system, reproductive system, kidneys, and muscles.
Cadmium is used frequently as a rust-preventive coating on steel and also as an alloying element. Acute exposures to high concentrations or cadmium fumes can produce severe lung irritation, pulmonary edema, and in some cases, death. Long-term exposure to low levels of cadmium in air can result in emphysema (a disease affecting the ability of the lung to absorb oxygen) and can damage the kidneys. Cadmium is classified by OSHA, NIOSH, and EPA as a potential human carcinogen
Disposing of your waste acids.
Place your acid in a separate container, I choose used 2 liter or 3 liter bottles, Label these bottles as CLCu2 with a black sharpie marker. under that write may also contain trace amounts of NICKLE and ZINC, BERYLLIUM, CADMIUM and LEAD. You can take these items to your local hazard roundup or recycle your acids with a method I plan on detailing in another instructable.
DO NOT dump your acids down the drain or on the ground. it is IMPORTANT to be responsible with wastes.
Step 7: Creating Stannous Cloride.
These foils are about 80% gold, and copper 20%
In order to reach a higher level of purity a second bath is required. For that we will need to create a test Chemical called Stannous cloride or Sn CL2
This metal is essential for Identify how much gold is left in our 2nd chemical bath.
For this you will need 1 beaker, and about 30 ML or muratic acid. 1 gram of tin metal powder or shot. Weigh it out using your Scale.
it takes appox 4 hours to completely dissolve the tin metal shot. or instantly for the powder.
The resulting solution should be bright yellow.
Step 8: The Second Chemical Bath Refining Your Gold Foils.
THIS STEP SHOULD NEVER BE ATTEMPTED without your CHEMICAL MASK.
For this chemical bath I will be reproducing the process on small scale. this is by far the most hazardous step and with the most reactive wastes.
For this step I am going to use a 100 ml beaker a portion of recovered foils, about 3 grams.
I will be using Muratic acid, and clorox.
I will be adding only enough Muratic acid to cover my 3 grams of foils, Using a Pipette I will slowly add Clorox until all of my foils have dissolved. you can use a glass rod to help felicitate the process.
After your foils have dissolved the resulting solution will be a deep golden yellow maybe a little orange in color.
it may be desirable to filter your solution with the coffee filters 1 more time, depending on if little bits of green plastic from the board found their way into this step.
Step 9: Filtering Particles.
After Dissolving ALL the foils you might notice a small amount of inductors, caps and transistors that wormed their way into the final process. This is normal.
Simply Filter again using a long neck funnel and a tall flask. The resulting solution should be a Deep and bright golden yellow..
Step 10: Testing Your Solution for Gold.
Ok, this is the exciting part and one where you get to see some real chemistry at work..
you will need:
Stannous cloride created earlier, 1 coffee filter paper, 2 pipettes or glass droppers.
Simply place 1 dot of recovered solution on a piece of filer paper, Next place one drop of your stannous cloride on the other. The resulting reaction should turn purple.
If your did CONGRADS you have created AURIC Cloride Or Aucl3 a gold bearing solution. If your test drop didnt turn purple, add a little more tin to your stannous cloride and heat gently with a alcohol burner and BOROsiicate test tube. Repeat Test.
depending on how much gold is in your solution it may appear black.
Step 11: Recovering Your Gold.
Recovering your gold in solution is one of the Coolest steps.
Whats needed, a plastic spoon, and the sodium Bisulfate or Stumpout.
Simply add very small amounts of stumpout, Your Mixture should start to look like the pictures I have provided. This is caused by the SO2 Gas which acts to chemically displace the gold in solution.
When the reaction has finished you will have driven out a majority of the chlorine, and replaced it with Sulfur. Any gold which was trapped in the solution has now be come a brown precipitate at the bottom of your beaker.
Retest with Stannous chloride, if your reaction still turns purple you need to add more stumpout.
It will take appox 10 hours for the gold to competely settle, the solution should be clear at this point.
Step 12: Melting
OK this is the last stop, At this point you have drained off the last ot the solution with your pipette the bottom of your beaker should be coated with what looks like dried cinnamon.
THATS PURE GOLD. Put that powder onto a fire brick that has been treated with a flux material like borax. Melt the borax till it becomes glassy. Apply your powder,
Heat with a MAPP torch or something more aggressive, careful not to blow your powder off the firebrick.
TADA Pure 24Karat gold.
TO date I have used this process to recover approx 1 pound of gold from computer chips and the like.
P.S. For more information about this process Visit this website.
http://goldrefiningforum.com/ This is a community of some of the brightest people I have ever had the pleasure of speaking with.