Gold Refining!

[Geowizard]

Hi Guys and Gals,

Taking "raw" GOLD to the next level by refining can be a challenge.

One method that is relatively easy is using a process described here:

https://www.youtube.com/watch?v=6mCFCmwLEWY

The science of refining GOLD is interesting and learning how to refine GOLD gives prospectors important knowledge about the chemistry and process of purification of the GOLD they find.

- Geowizard

[Micropedes1]

I refine mine using a wet method with aqua regia to put the gold into solution, which is then poured off. Neutralize the nitric, and then precipitate the gold with sodium meta-bisulfite. (or simply bubble sulfur dioxide thru the solution). Filter the precipitated gold and fire in a crucible with borax. First run usually gives me .975 fine. If I desire greater purity, I will melt the gold and pour thru a shot maker and go thru the whole process again (pouring as shot speeds up the dissolution). The second melt is .993fine or better. If you have appreciable amounts of silver in your beginning gold, this is about as good as you can get as you will get a bit of silver "drag-out" with each precipitate. Repeating the process a third time will give a tiny amount of improvement, but the improvement does not justify the cost of the chemicals. .999fine can only really be obtained by electroplating the gold out of solution onto a stainless steel electrode, which is then fired to recover the gold.

I know that the major gold producers claim high purity gold thru crucible refining with the proper fluxes, but it just ain't so. Mainly, it is fired to put it into a form that is easily transported (without chance of loss or spill) to the electro-refiner for further processing.

[Jim_Alaska]

Good post about your wet refining Glen. Definitely not for the weekend prospector though. There is a learning curve to the method and appropriate safety measures should be observed. Thanks for taking the time to post about your method.

[Geowizard]

I posted the link to provide a demonstration of this LESS risky - but effective process;

Bleach and Muriatic Acid can be bought at local stores. The Sodium Meta-Bisulfite is bought as Stump Remover made by Bonine from a Hardware store. All reactive chemicals should be used with care. That includes using appropriate lab safety equipment, a fume hood or do it out doors. Don't breathe the vapors. I recommend small batches with small amounts of reactive chemicals as shown in the video. All of this requires adult supervision and should not be attempted by young adults or anyone that is not familiar with chemicals and chemical reactions.

The video is part one of three parts. SREETIPS also demonstrates many other refining methods for precious metal refining. An emphasis is always placed on safety.

- Geowizard

[Geowizard]

ABOVE average prospectors;

The process of recovering and refining metal involves Chemical (Hydrometalurgical) or Fire (pyrometalurgical) methods. Recovery might be as straight forward as using gravity to concentrate the heavy metal.

Fire and Chemicals are Dangerous;

Refining takes on a higher level of understanding and responsibility. It is expected that anyone that enters into this endeavor assumes personal responsibility for their actions.

I don't know what an "average" prospector is. I know prospectors are ABOVE average people. The average prospector is an ABOVE average person. Prospecting requires above average understanding, initiative, organization, planning, and execution of a plan. Prospectors have a "DRIVER" personality. DRIVERS have ambition and move forward toward an objective with determination, understanding and forethought. Anyone reading this Forum is probably a prospector or has interest in prospecting. This is where we collect, assimilate and share knowledge so that others may learn.

- Geowizard

[Micropedes1]

Free chlorine from HCl and bleach is just as toxic as the brown gas (nitric oxide) evolved from some AR mixtures. Both are dangerous to the untrained. Cyanide is actually safer as long as you have a way to monitor pH and keep it basic pH (greater than 8 with a safety margin)

Better, I think, to use muratic and peroxide.

[Geowizard]

GOLD is good;

Maybe consider my original post on the patio process. Just plain old salt. But, more people suffer and die from high blood pressure from salt than all of the more hazardous chemicals.

Yes, SREETIPS covers the Muriatic and Peroxide process for those that would like to learn more about it.

Caution and good judgement along with safe operating procedures are emphasized.

Goodness is dependent on access to the required chemicals, the time required for the process and the quality of the lab environment where the work is to be done. Watching the process in a video while someone else goes through the necessary steps and taking notes on how much of each of the chemicals is needed is a good first step to learning both the process and proper laboratory procedure.

- Geowizard

[Micropedes1]

Better, I think, to stick to recovery. And leave the refining to those trained to do it.

[Geowizard]

Selling raw GOLD;

When a prospector discovers a GOLD deposit, he or she may decide to go through the process of developing a GOLD mine. At the end of the day... the miner grabs up their poke and makes a trip to a refiner to SELL the proceeds...

A refiner charges an up-front FEE for the cost of refining - usually on the order of $200 (USD) per LOT that the miner brings in the door. The refiner pays a percent of the "net" GOLD content.

The most salient point supporting refining your own GOLD is removing the DOUBT that the refiner is honest about the impurities that are deducted from the payment.

- Geowizard

[Geowizard]

GOLD refining...

By definition, "GOLD refining" is the process of removing impurities.

So, refining involves dissolution of impurities; Copper, lead, silver using Nitric Acid.

"Inquartation" is required to do this;

The GOLD is reduced to 25 percent of the total mass (one quarter) hence in-"quart"-ation using added silver.

For example, one ounce of GOLD to be refined... add 3+ ounces of silver and melt in a melting dish.

The inquartation is dissolved. The remaining GOLD is subjected to additional dissolution of impurities in Nitric acid until no impurities are detected. The remaining GOLD is melted into a bar of "Refined" GOLD.

Refine further;

An option is to dissolve the refined gold at this point in aqua-regia and precipitate the GOLD using Sodium metabisulfite. Repeating the melting/ dissolution and precipitation improves the fineness of the GOLD.

Note: All chemical reactions involving acids require proper training in safety, and understanding of laboratory procedures.

Capture the nitrous oxide;

Nirous oxide can be captured using a liebig condenser and recovered as Nitric acid. This avoids wasting nitric acid and avoids having nitrous oxid fumes escape into the environment!

- Geowizard