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.

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.

kadriver · Aug 29, 2014

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

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

kadriver · Aug 29, 2014

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

I then used to 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.

kadriver · Aug 29, 2014

I use 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.

kadriver · Aug 29, 2014

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

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.

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

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

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".

kadriver · Aug 29, 2014

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

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.

kadriver · Aug 29, 2014

Ive 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

kadriver · Aug 29, 2014

I transferred the liquid to a 2 liter beaker

kadriver · Aug 29, 2014

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

kadriver · Aug 29, 2014

I added a little sulfuric acid to precipitate lead

kadriver · Aug 29, 2014

Stannous Test

kadriver · Aug 29, 2014

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

kadriver · Aug 29, 2014

I then began filtering the liquid

kadriver · Aug 29, 2014

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

Jewelers Polishing Wheel Waste Experiment

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