Chemical refining gold  

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rayzer13
(@rayzer13)
Estimable Member
Joined:2 years  ago
Posts: 104
07/11/2018 10:11 pm  

It is a little off topic but in the last 4 years or more gold hog mats have been capturing lots of minus 1 to 3 hundred mesh gold  for me and my friends up here and I have been working with a guy down south to come up with what I think might be the best way to get this gold into a sell able product, I hope you enjoy , PS use at your own risk. 

Howdy Ray,

I ran across this message from the first time I reached out to you. I thought I would send it to you just for fun. Because you said you lost all these.

All the Best my friend,
John

 

I watched your refining video and since this is a hobby of mine I thought I would share some information that might help you on your path. These are all things I learned from others and experience, that work well for me.
You are more than welcome to share this information as you see fit, except for my phone number and email please.
A quick word of caution, I see you have good ventilation with your fan but others might not know that the NO and NO2 gas from the nitric acid and Aqua Regia reactions can cause pulmonary edema sometimes delayed by hours. This is bad to really bad, enough about that.
Free advice being worth all you pay, its hard to say what uninvited advice is worth, haha, but here goes.
1. Put your placer in a melting dish and incinerate the gold (heat to red but try not to melt it) this helps to oxidize some of the base metals saving you time and chemicals.
2. Do a boil in 50/50 muriatic acid and distilled water, best method is to sit the beaker in a little bit of sand, I use a ceramic frying pan to hold the sand and beaker in case you brake your beaker or boil over. Heat for 15-30 minutes.
3. Pour through a wetted filter paper and rinse with very hot water, this removes your lead as lead chloride, which is soluable in hot water. This also removes any tin before you introduce your nitric, that's my guess about the white stuff in your video. It's called stannic paste, or stannic acid, most of the other things it's called you can't say in mixed company.
0. Repeat step 1.Put your placer in a melting dish and incinerate the gold (heat to red but try not to melt it) this gets rid of any remaining chlorides.
0. Rinse your beaker well and make enough 50/50 nitric and distilled water to cover your gold by an inch or more. Remember the "add acid to water rule" heat for 15-30 minutes. This wash water will contain silver.
0. Rinse three times with hot water, decanting rinse water and leaving your gold in the beaker.
0. Add all the HCl (muriatic acid) needed to solvate your gold see ratio below.
0. Add 2ml of 3% H2O2 (hydrogen peroxide),this jump starts the production of hydronium in the solution.
0. Heat to around 150*F,
0. Slowly add 25% of the nitric acid, wait for the reaction to slow,
0. Add 25% more, wait for the reaction to slow again.
0. Heat to 190*F, glass candy thermometers work well for this but infrared thermometers are better.
0. Add 25% of the nitric acid and let the reaction slow again.
0. Slowly add only enough of the remaining nitric to dissolve the gold. This step buys you extra gold don't rush it. Do this a few ml at a time and allow the reaction to stop before the next addition.
0. Pour your auric chloride solution through a wetted filter into two volumes of distilled water. As you dilute the solution this will drop any silver as silver chloride and make the solution cloud slightly.
0. Add .5 gram of sulfamic acid crystals, or a couple drops of sulfuric acid if you don't have sulfamic acid. Sulfamic Acid will kill any excess nitric acid and make Nitrous Oxide and sulfuric acid out of it. Which ever way the sulfuric gets in the solution it will drop any lead as lead sulfate. Lead sulfate is insoluble in water as well as this solution.
0. Let stand overnight to settle, and decant or siphon off your bright, clear, yellow solution. You can filter it if you need to for time but I would start with two wet filters and plan to run the solution through twice, it will go slowly because of the silver chloride. If you have a buchner funnel it's faster with a vacuum filter rig.
0. Drop the gold with the SMB like you did in your video.
0. Test and Pour off your now barren solution, save it for now.
0. Rinse your gold mud with hot water, three times
0. Put your gold in a melting dish and incinerate (heat to red but do not melt it)*this step is not required*
0. Boil in 50/50 muriatic acid and water, 15 minutes.
0. Pour into wetted filter rinse with hot water.
0. Place filter with gold in melting dish.
0. Slowly heat filter with low flame to red, then add a pinch of anhydrous borax and melt your now +98% pure gold.
0. The borax will tell you a lot about your gold purity, it will be very clear when your purity is over 99%
0. If you want it to be +99.5% pure, repeat steps 7-22 before melting.
Aqua Regia
Approx 1mL of 70% HNO3 added to 4ml of 30% HCL to dissolve 1g of pure Gold.

Stannic Chloride
You can make your own stannous test solution with a little tin metal; lead free solder, lead free fishing weights or eBay will get you some. Shave the tin into a dropper bottle with muriatic acid, a couple of grams in 10ml of acid. The key is to have a little extra tin in the container to know you have enough. Then just dip a q-tip in your gold solution and put a drop of your stannous on it. It will show purple for gold, the darker the better. It looks black when your lucky. If it turns green or red you have other good news.

Anhydrous Borax
This is the best flux for pure gold, in a pinch though 20 mule team borax works. It will expand ten fold as you heat it up and drive off the water.

Material
If you need Borax or tin, say the word and I can drop a care package in the mail, it would be my pleasure to do so and I have some on hand so no need worry about cost.

Method
The reason for heating the gold to red before melting is to drive off the residual nitrates or chlorides both will volatilize your gold if you don't drive them off before melting.

The reason I said to keep your solution after you drop your gold, is there is a bit of gold left. You mix all your waste solutions together then add a piece of scrap copper. It will drop any silver, gold, and platinum group metals. The precious metals will form as a dark residue on the copper and fall to the bottom. I can help you with those later if you need a hand. After you filter those precious metal residues out, you can use lye to raise the ph to 12 and all the remaining metals will drop as hydroxides, filter those out dry and dispose. Add muriatic to drop ph to 7 and you will have salt water, I evaporate mine to dry salt in an old crock pot.

I hope this might be some help to you 


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