In the June 2002 issue of Professional Jeweler, Peter Shor wrote an article on how jewelers can preprocess their own polishing dust (page 107). While the method described might work (or might send valuable gold up in smoke), some important considerations were absent. While I sympathize with the writers effort to save jewelers money, and in a short article at that, I have some concerns.
First and foremost, safety is the priority. Jewelers polishing rouge can contain toxic and/or cancerous metallic elements, often as the abrasive. This has been proven by chemical analysis performed by California EPA in the mid- 1990s. In addition, since cadmium solders are still in wide use, the jewelry itself will add materials to the dust that must not be inhaled or ingested. Unfortunately, no mention of this was made in the article.
Please consider that most metals are dangerous to inhale, including copper, which is present in nearly all gold alloys. By nature, polishing sweeps are small enough for dust particles to float up into the air, right where they will be inhaled. Most of us would rather use a properly equipped refiner to process noxious waste and to recover our gold.
One must make sure the dust is not ingested in any way during handling and certainly during incineration. What about the people downwind of such fumes, like fellow employees and customers or neighbors? The appropriate equipment not only vents the smoke, but scrubs metals and particles from the exhaust. Only clean hot air should be released. That protects people and recovers more of the materials for recovery (gold) or proper disposal (cadmium or worse). At the very least, it would have been more responsible to include some suggestions about this, such as at least wearing a respirator of the right type to avoid inhaling these materials.
Second, the described process is actually processing hazardous waste under California law. Jewelers do not typically have the equipment or training to do this legally or safely. Any jeweler caught engaging in this process without proper licensing and equipment would be subject to heavy fines or worse. I cannot speak for all 50 states, but many eventually follow Californians lead when it comes to public safety issues. Jewelers need not break state or federal laws to save a few dollars.
Third, a jeweler who uses a burnout oven to incinerate sweeps is using equipment that was not designed for that process. The smoke from the processing could coat the inside of the burnout oven and continue to emit products from the sweeps for some time every time the oven is hot enough. It is only very rarely wise to misuse equipment. That is how valuable metals can go up in smoke or get trapped in the wall of the oven.
Finally, speaking as a refiner and a person who watched his grandfather and father (no relation to PMWest) do their own and others refining for many years, I disagree with the whole notion that refiners overcharge or cheat in general. Not that it has not happened, but it is far more common for long-term established refiners to process your sweeps honestly and charge a fair price. Fair includes being fair to the jeweler, the environment and neighbors. Fair even includes being fair to the employees of the jeweler and the refiner to ensure a safe work area. Then, of course, a fair profit so we can continue.
I would suggest there are safer, more efficient ways for a jeweler to save on the costs of refining. After all, despite some exaggerated claims to the contrary, most refiners actually charge a small percentage of the 24k recovered. Just ask they all have to compete for your business. Generally claiming refiners overcharge or cheat is just a cheap shot to make this whole thing seem more practical than it really is.
Precious Metals West
Los Angeles, CA
Peter Shor Replies
The chemical analysis by California EPA had nothing whatsoever to do with burned polishing sweeps. Instead the EPA referred only to the airborne polishing dust created by the polishing motors. Even then, the EPAs only concern was the silicates or grit in the polishing dust, material that is highly unlikely to be found in the hot exhaust.
The statement about cadmium solder is utterly absurd. The amount of cadmium that would vaporize right in the face of the person who does the soldering is many, many times greater then any amount that would be picked up by a dust collector.
The implication that karat gold is poisonous is just too ridiculous for a reply. And the statement that the particles are so small they will simply float into the air is just plain not true. If it were, 100% of the polishing dust that is burned would simply vanish up the exhaust and disappear.
Now it is true that refining companies burn their dust and have huge exhausts and filters to capture the particles that are sucked up by the exhausts. Actually, they probably dont need such powerful exhausts to do the burning job. There is a different reason for the powerful exhausts: the particles of gold sucked up by the exhausts no longer belong to the original owner of the dust. That gold now belongs to the refining companies and is a source of significant profit. Common estimates are that 25% of the gold in polishing dust is extracted by refining companies in this manner.
The feedback we have gotten is that when polishing dust is burned correctly (as in the instructions provided in the June issue of Professional Jeweler), the amount of smoke created by the burning of polishing dust is no greater, and often significantly less, than the amount of smoke created by a normal casting burnout. Readers who are familiar with the article know the key to proper burning of polishing sweeps is the conversion of all the hydrocarbons (polishing dust grease) to carbon dioxide, a common and harmless gas that is an essential part of our atmosphere and of the photosynthesis process of all plants.
The characterization of polishing dust as hazardous waste is ridiculous beyond words. The only thing hazardous in polishing dust is the silicates, and there are literally millions of times more silicates in casting investment than in polishing dust.
The statement that smoke could coat the casting oven is absolutely absurd. The process of burning polishing sweeps ensures that no residue of carbon or grease can remain in the burnout oven by the completion of the process. In the proper burnout process for polishing sweeps, the oven is brought up to 1350&Mac251;F. Since all carbon (and carbon compounds like polishing grease), in the presence of oxygen, turn into carbon dioxide at 1300&Mac251;F, no residue can possibly remain. The key to burning properly is sufficient air. In the past, this has not been well understood in the jewelry manufacturing industry. It is possible that, if this knowledge becomes widely disseminated and used, it may pose a very serious financial threat to the refining industry.
Finally, Mr. Ballard raises the question of fairness and honesty. Only individual jewelers can judge this. And they can truly judge this only from direct experience. When they have converted their polishing sweeps to metal and can compare that return with the return from their refining companies, they can make a fair judgment.
Shor International Corp.
Mount Vernon, NY
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