What are my acid fume Concentration %'s?

[ZPHELPS]

Hello All, Does anyone know the approx concentration percentages for acid fumes (nitric, hydrochloric, sulfuric) that are produced/created during the refining process?

I'm refining gold filled scrap jewelry and designing an acid fume carbon filter for my fume hood. I will be running 500-600 grams of gold filled scrap per run.

Here is what I'm using:

Concentrated Nitric Acid 70% Solution (68 -70% HNO₃), ACS Reagent Grade
Hydrochloric Acid 37% Solution, ACS Reagent Grade
Sulfuric Acid 96% ACS Reagent Grade Solution (95-98%, Concentrated H2SO4

I've searched on here and read Hoke but can't seem to find this info. Thanks, any help is much appreciated.

 

[FrugalRefiner]

Don't use carbon. The nitric fumes with carbon create an explosive.

Dave

 

[ZPHELPS]

I misspoke by describing it as carbon. Purafil which is a Filtration Group company and Camfil have asked for the proposed concentrations of each gas to determine the required adsorption media and residence time for the vapor capture.

 

[Yggdrasil]

I misspoke by describing it as carbon. Purafil which is a Filtration Group company and Camfil have asked for the proposed concentrations of each gas to determine the required adsorption media and residence time for the vapor capture.

With your volume a vacuum suction system through water/peroxide bottles will do and as a bonus it reclaims some of the Nitric.
Gas scrubber can also be used, then you have columns with wetted fillers and a suction fan in the top.
Retention time needed is about 9 seconds in liquid.
Read the thread about making your own fume scrubber.

 

[Yggdrasil]

I misspoke by describing it as carbon. Purafil which is a Filtration Group company and Camfil have asked for the proposed concentrations of each gas to determine the required adsorption media and residence time for the vapor capture.

Search fro fume hoods in the Library.

Here is more material to study:

We ask our new members to do 3 things.
1. Read C.M. Hokes book on refining jewelers scrap, it gives an easy introduction to the most important chemistry regarding refining.
It is free here on the forum: Screen Readable Copy of Hoke's Book
2. Then read the safety section of the forum: Safety
3. And then read about "Dealing with waste" in the forum: Dealing with Waste

Suggested reading: The Library

 

[ZPHELPS]

Thanks so much Gents

 

[Yggdrasil]

Direct link to one thread here:
https://goldrefiningforum.com/threads/new-fume-scrubber-design.22553/post-236355

 

[slsmp40]

I misspoke by describing it as carbon. Purafil which is a Filtration Group company and Camfil have asked for the proposed concentrations of each gas to determine the required adsorption media and residence time for the vapor capture.

It sounds like you are sizing a fume hood system. You are building it yourself? You get to choose your flow through. How big of a blower are you going to use? Less volume of air higher concentration of exhaust gases. You have to size that up, and that means you have to do the math. Tell them what you are doing and they will size it up for you. If they don’t seam to be into that, then you are not telling them what they need to know and they will blow you off. They are not being rude if so. They just have no interest in being in the liability loop of unskilled/untrained people who are playing with chemicals. So do your research and know what you need to tell them and they will be happy to take your money and give you the filtration system that dreams are made of. My vote for filtration systems Is Millipure. fumes, vapor, liquid with hot and cold to boot they have never messed up anything i asked them to do. Prepare for sticker shock when you get the bill.