Air emission factors for melting, cuppellation

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methos1480

New member
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May 29, 2015
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Is there somewhere I can find air emission factors for different processing in refining (e.g. precious metal melting, cuppellation, etc)?
 
In New York State, you are exempt on venting and exhaust systems from laboratory operations as well as for exhaust or ventilating systems for melting of precious metals.

It varies state to state but I always considered NY state to be more strict. But you have to check to be sure.
 
New York City requires all emission sources to be permitted including what would be considered de minimus. Is there any source for emission factors for these processes?
 
http://www.dec.ny.gov/docs/air_pdf/exemption.pdf

Go to the miscellaneous section on the bottom, this is NYS but I have seen this exemption applied in NYC. To most of the gold buyers on 47th street.

The exemption is from requiring a pollution control device on the emission point, in NYC you pay for every emission point, even a dust collector vented indoors! It's all about the money!
 
EPA AP-42 for combustion. You will need to do mass balance to estimate everything else.

In my case, using 10 grams lead for cupellation, emissions are approximately 1 gram per cupel. For you it will vary depending on cupel used, time, etc.

Look for and take advantage of all possible exemptions.
 
They certainly don't regulate the melting of fine metals--my commentary to the EPA was that we can't afford to lose ounces up the stack, let alone tpy (tons per year).

Generally, there are exemptions for laboratory operations done in the fume hood, because if one thinks about it, logically your batch size is kind of limited. Thing they don't want to see happening is people having 5000 gallon reactors just vented to sky with NOx pouring out.


Keep in mind that the de minimus exemption is all well and good but you damn well better be able to support your claim with meticulous batch records and science. Thankfully, the EPA likes math.
 
Lou said:
Thankfully, the EPA likes math.

Yes they do! When i use to build sweat furnaces i would have to get each one certified by the EPA. The calculations alone can baffle the mind. I hired an engineering company to submit all the paperwork on each one. They never looked at the first one. It was all nothing but formulas and math! Come to think of it it wasn't cheap either!
 
Depending on where you are located, the federal, state and local regulations, what volumes you are processing, what processes you are using and what chemicals are used in those processes, you may be required to do nothing, register as an emission source, or get a permit (there are 2 or more permits available depending on total emissions).

If you are required to get a permit (usually total emissions have to total 10 tons per year or more) you will also need to at least submit an annual emissions report. That is where the AP-42 emissions calculations come in (for natural gas combustion), plus your emissions estimates for process pollutants (based on reasonable estimates such as mass based calculations).

IF you are considered a major source, 100 tons per year or greater, there are much greater hurdles to get through. Not many precious metal refiners fall into this category.

If you fall into the permit category, you will need the help of an environmental engineer because you will be doing pollutant modeling to submit with the permit application.
 
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