# Jewelers Polishing Wheel Waste Experiment



## kadriver (Aug 29, 2014)

Here is 260 grams of waste removed from the hood of a jewelers polishing wheel.

It is course grit with some kind of wax as the binder for grit.

We scooped it out of the back of the hood with a plastic spatula.

I placed the material into a clean Corning ware casserole dish and put it on high heat.


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## kadriver (Aug 29, 2014)

After about 30 minutes on high heat the material began to bubble and smoke.

It smelled like burning wax, this is how I concluded that wax was the binder for the grit used by the jeweler to polish gold jewelry items.


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## kadriver (Aug 29, 2014)

I wanted to use a small propane torch to aid in the incineration of the material, but it immediately ignited as soon as I put the torch to it.

Not wanting things to get too hot, I covered the dish to extinguish the flames.


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## kadriver (Aug 29, 2014)

After a couple hours the material became brittle with most of the wax burned off and I began to break it apart with a metal spatula

I then used a torch to burn the remaining wax away from the material. 

It ended up as porous looking cinders that were dry and very brittle.

This process took about three hours to this point.


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## kadriver (Aug 29, 2014)

I used the shiny end of a mortar and pestle and carefully broke the pieces into as fine powder as I could being careful not to let any escape from the dish.

This was not difficult because the material was very crumbly and broke apart with little effort - a testament to the benefit of incineration in this recovery process.

This took me about 1/2 hour to get the material to this state.


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## kadriver (Aug 29, 2014)

I then added about 1/2 liter (500 ml) hydrochloric acid to the now incinerated and powdered material.


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## kadriver (Aug 29, 2014)

To this slurry mixture I added about 15 ml concentrated nitric acid and there was an immediate mild reaction.

I covered the dish and set it inside of a larger dish just in case it tries to boil over.

I left it this way in my fume hood to leach overnight.

More to follow on this experiment tomorrow.


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## Harold_V (Aug 29, 2014)

I processed literally thousands of pounds of that material through the years. 

I don't think much of your procedure. There are far better ways, and I've covered them extensively in posts on this board. I think you'd benefit by reading them. 

Harold


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## kadriver (Aug 29, 2014)

I'll look at those today Harold, before I proceed. 

There is much more material as this is only a sample.

Thank you


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## kadriver (Aug 29, 2014)

Harold, I found an outline you wrote on how to process this material.

Looks like I skipped the sifting, magnet, and straight HCl treatments and went straight to AR - just like a rookie would do.

Just goes to show that I am still just an advanced beginner.

This person approached me with this material and I dived in.

We started with 75 grams of polishing sweeps and I got 3.8 grams of pure gold (I was astonished at the amount of gold)

Now that I have started with this I must finish using the process I developed myself - but I like yours better, Harold.

And I'll use it on the next batch which will probably be half a kilo.

Should the pan be made of cast iron - in your outline it just said "pan".


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## kadriver (Aug 29, 2014)

Old stainless steel pan from Goodwill - found it after re-reading your post.


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## kadriver (Aug 29, 2014)

I said I was astonished at the amount of gold I got from the small sample.

But now I am flaberghasted - I completed this in just 12 hours

I will post the rest of the process I used.

I was able to recover and refine 15.9 grams of pure gold from this batch of 260 grams of polishing sweeps!

Here are some photos of the finished product.

More to follow.


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## kadriver (Aug 29, 2014)

I've got a few minutes so here is the rest of the process I used.

I started around 11am today by heating the mixture and letting it "cook" for about an hour.


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## kadriver (Aug 29, 2014)

I transferred the liquid to a 2 liter beaker


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## kadriver (Aug 29, 2014)

I added more HCl and nitric to the slurry to do another extraction


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## kadriver (Aug 29, 2014)

I added a little sulfuric acid to precipitate lead


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## kadriver (Aug 29, 2014)

Stannous Test


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## kadriver (Aug 29, 2014)

After an hour or so I added the second extraction using HCl to rinse all the solids into the beaker


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## kadriver (Aug 29, 2014)

I then began filtering the liquid


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## kadriver (Aug 29, 2014)

I kept pouring distilled water thru the solids until the filtrate ran clear of color


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## kadriver (Aug 29, 2014)

The solids are running clear and all the gold bearing solution is in the big flask filtered twice


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## kadriver (Aug 29, 2014)

Transferred the solution to a clean 2 liter beaker


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## kadriver (Aug 29, 2014)

To save time I added sulfamic acid to kill any excess nitric acid - Time is of the essence, my friend wants to see his metal TONIGHT!


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## kadriver (Aug 29, 2014)

I then began to add Sodium MetaBisulfite to precipitate the gold


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## kadriver (Aug 29, 2014)

After allowing it to settle a few minutes I began to filter out the gold powder


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## kadriver (Aug 29, 2014)

Filtering complete, I transferred the filter with the gold in it to a 400ml beaker and added about 100ml hydrochloric acid


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## kadriver (Aug 29, 2014)

Then I began adding small amounts of concentrated nitric acid - I only had to add about 6ml to dissolve all the gold - added low heat too.


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## kadriver (Aug 29, 2014)

In a short time the gold was all dissolved so I added a little more sulfuric acid to precipitate any lead that made it this far.


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## kadriver (Aug 29, 2014)

I added a couple ice cubes to cool the solution before filtering

The filtered solution was clear and completely free of contamination


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## kadriver (Aug 29, 2014)

The clean gold solution was transferred to a beaker and then SMB was added to precipitate the gold again


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## kadriver (Aug 29, 2014)

The gold came down quickly and cleanly so I threw it into a filter and then into a melt dish, filter and all, and covered with about a table spoon of borax.

I then poured the pure gold into cold water, dried and weighed it.

This was much fun as it was all new to me and it came out way better than I expected.

Of course my friend was very happy to see his metal this evening.

kadriver


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## butcher (Aug 30, 2014)

kadriver,
I always enjoy reading and seeing your posts and videos, you do a very good job at helping others to see what is going on with a few pictures.
I think you did a good job in this experiment, and with what you're learning from Harold you will only improve on the process.

Great job and thank you for sharing.


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## Harold_V (Aug 30, 2014)

kadriver said:


> I said I was astonished at the amount of gold I got from the small sample.


And now you understand why I have insisted that in order for the home refiner to be (really) successful, he/she should have jewelers as customers. They provide waste materials that are high in content, and also become a source where one can sell their recovered gold for spot price. 

Processing wastes from a jeweler's bench kept me so busy I refused to process escrap. I couldn't justify the time spent doing so. 

A comment. 
If you circumvent the preliminary HCl wash, you're going to encounter solutions that are difficult, if not impossible, to filter. Beyond that, because the vast majority of contaminants are removed in the wash and rinse, before dissolving values, the quality of gold that comes from the process is often as good as that which comes from a second refining. 

I NEVER used a Buchner for filtering gold chloride. Two reasons. One of them was that I used an aspirater to create vacuum, and on more than one occasion it added water to the solution when filtering other substances. I also experienced the Buchner picking up the filtrate, running it to waste. Both were unusual circumstances, but they occurred on more than one occasion. I was not willing to experience the risks. 

Harold


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## kadriver (Aug 30, 2014)

Thank you for your comments.

I am not a big fan of e-scrap either.

My friend gave me another 400 gram batch of polishing sweeps and I have already started on that.

He also gave me a bag of filings to process.

This too will be my first try at this type of material.

I'll be sure to review Hoke's processes for filings - he said it does have just a little platinum.

Of course I'll review any posts here on the forum for jewelers filings.

kadriver


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## kadriver (Aug 30, 2014)

I found Harold's PDF file on how to process filings.

I was able to save it to my iPad so I can use it as a guide when I start working on these filings.

http://goldrefiningforum.com/phpBB3/download/file.php?id=18196

Thank you Harold!

kadriver


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## 4metals (Apr 29, 2015)

The moderators would like to thank all of the members that contributed to the original thread upon which this thread was based, as well as those that asked questions showing what was missing. Because of the extra length and interest in this thread we have created the above consolidated version making for an easier read. We encourage all members to read, comment, and ask questions in the original thread, Jewelers Polishing Wheel Waste Experiment.

The Library threads should not be considered to constitute a complete education. Instead, they're more like reading a single book on the subject of recovery and refining. There is so much more information on the forum, and it is impossible to include it all in these condensed threads. Members are strongly encouraged to read the rest of the forum to round out their education.

For those who prefer a printed copy, a pdf file of this thread is provided below.


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