Building a chemical fume hood with a plain steel blower _hood_

[4metals]

This little scrubber handles everything passing the condensor of a 12 liter reaction flask just fine. It only has a 3 cfm flow rate from the eductor that powers it but in a sealed reaction that's plenty. The hood moves a lot of air, as Irons says to remove the whiffs of reagent while filling and emptying the equipment and make the environment for me in front of the hood better. It's all about me! :lol:

 

[philddreamer]

I used your design when I built mine. Works great!!! 8)

The left colum holds 4 litters of distilled water/peroxide; the middle 5 litters distlled water/peroxide; the right 5 litters of distilled water/sodium hydroxide.

Thanks!
Phil

 

[kurtak]

Nice Phil - thats my plan in the very near future

4 metals - I saw that back when you first posted it - the one I pictured is my fast cheap build just so I can keep playing till I get one like Phil's built --- it's called don't shut the operation down while you are working on bigger & better - only about 2 hours to build the fast cheap version

Kurt

 

[bmgold2]

I used your design when I built mine. Works great!!! 8)

The left colum holds 4 litters of distilled water/peroxide; the middle 5 litters distlled water/peroxide; the right 5 litters of distilled water/sodium hydroxide.

Thanks!
Phil

Are the contents of the columns useful for anything once they have been used? Do they collect acid that can be reused (specifically the 2 distilled water/peroxide ones)? Do they catch any PM's that might escape?

 

[sharkhook]

Distiller water/peroxide and distilled water/sodium hydroxide, what would the right mixture to use for each of these?

 

[philddreamer]

Are the contents of the columns useful for anything once they have been used? Do they collect acid that can be reused (specifically the 2 distilled water/peroxide ones)? Do they catch any PM's that might escape?

Yes.
If you ONLY scrub nitric, when the time comes to change the solution, you can use the solution for processing silver. If you scrub nitric and AR fumes, like I've done, then I use the solution when I make more AR.
The Lye I will use for neutralizing waste. I believe there are many more uses, our fellow experts will chime in with more ideas.

Distiller water/peroxide and distilled water/sodium hydroxide, what would the right mixture to use for each of these?

I don't remember right now, but 4metals shared that information before; I'm sure he'll help us out.

I believe I used 3.75 liters of water and 8 oz of peroxide...

P.S.
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=40&t=18481&p=186085&hilit=scrubber#p186182

 

[kurtak]

:lol: :lol: :lol: :lol: - Phil - I am laughing because I just got done going back & reading the your thread about your new shed build - then I saw you had posted here again so checked in here to see what you had to say & see you provided a link to that thread - that was a good thread back then & was well worth going back to again

I have a question - what kind/size vac pump are you running on that size scrubber

I ask because I have 2 vac pumps one is 2.5 CFM the other is 3 CFM & not sure that enough to run a larger scrubber

When I was working with the scrap yard we had a scrubber set up pretty much like yours only about twice the size but we also had a large vac pump - don't remember the CFM on that pump but it would collapse a plastic 55 gallon drum in a heart beat

Kurt

 

[4metals]

The one benefit of using the glass erlenmeyer flasks, other than the fact that they were free, is I am able to see when the red fume is passing off the top into the next vessel. Then I just add either more peroxide or more caustic.

I found that the full 4 liter volume of each flask worked well with each of the first 2 flasks having 100 ml of 35% hydrogen peroxide and 3900 ml of distilled water. And the last flask has 1 liter of 50% liquid caustic and 3 liters of water. This scrubs an entire karat scrap reaction of 50 ounces without further additions. I re-use the dilute nitric from the first 2 vessels as make-up water for nitric digestions and the liquid from the last vessel I use to neutralize acid waste.

For quite a while I was buying 1 to 1 1/2 kilos a week of scrap gold and melting it and processing lots up to 50 ounces in size in a 12 liter flask. This small setup worked well and I never experienced NOx fumes in my lab or outside near the vent from the scrubber. I had a small setup and rarely ran more than 1 reaction a week and generated no more than 10 liters of waste a week, which was small enough to treat properly and evaporate the waste water.

 

[kurtak]

The big scrubber we made at the scrap yard was used for leaching CATs - it was made of 8" PVC pipe 5' long

The reason for the big scrubber was we were using 15 gallon plastic drums with the snap ring type lids on top as our reaction vessels - to keep the plastic drums from collapsing under vacuum we cut round spreader/stiffener's out of industrial plastic cat walk grating (used in corrosive environments) --- on top of each layer of CAT combs we would set a spreader/stiffener --- the 15 gallon reaction vessels (3 of them) sat in a cattle watering tank (plastic) with 2 cattle watering tank heater elements for a hot water bath

Being a closed vacuum system we would re-dose the reaction vessels with CL (bleach) in the same way (using vacuum)

To check on whether the scrubber was becoming acidic we used a piece of litmus paper inserted through a removable plug hole on top of each scrubber tube

And yes the scrubber was set up so we could drain off some NaHO & then add more under vacuum when needed - so the vacuum was used for both adjusting chemistry in the reaction vessels & the scrubber

The reason that venture came to an end was between the competitive CAT market & the huge volume of waste to deal with it just wasn't worth it --- but hey we gave it a go & it was a heck of a learning experience for putting together a new set up here at home back on the hobby level --- lots of improvements are "under way" as I work on setting up again here at home

Kurt

 

[rewalston]

I found the thread with which Pawnbroker Bob was talking about his "AB TRAIN" would this work with PVC as Kurt used? I'm looking for something that I can use on buckets when running reactions from AP and HCl/Cl. And what would I need to change if anything?

 

[philddreamer]

I ask because I have 2 vac pumps one is 2.5 CFM the other is 3 CFM & not sure that enough to run a larger scrubber

Kurt, mine is a 2, I believe. Now, I don't run mine in a "closed vacuum. The cover on the reaction vessel is loose, but there's enough suction to draw the fumes thru the scrubber.

The vacuum pump is a THOMAS K48ZZEPB3533.

Phil

 

[kurtak]

Rusty

the "AB TRAIN" that Pawnbroker Bob talked about in that thread is pretty much the same thing 4metals, Phil & I are showing here --- 4metals (like Bob) is using flasks - Phil & I are using PVC (or CPVC)

The key to using buckets (plastic) as your reaction vessel with a scrubber that works on vacuum is keeping the buckets from collapsing when the vacuum is applied

so you have to have some kind of spreader/stiffener inside the bucket so the bucket holds its shape & does not collapse when under vacuum (as explained in my post about leaching CATS in 15 gal drums)

I have not done this with 5 gal buckets yet but intend to (now that I am back home working on a smaller scale) so I can't take & show any pics (yet)

Here is the plan (in part) cut the stiffener/spreader out of the bottom of a milk crate & using plastic threaded rod with plastic nuts & washers ether make legs so it stands about half way up from the bottom of the bucket - or hang it from the lid (plastic rod/nuts/washers) so it hangs half way down into the bucket when the lid is put on

then plumb the bucket so it can be hooked up to the scrubber

Kurt

 

[kurtak]

Thanks Phil

I saw that pic& was wondering how well that worked - I have thought about doing the same but didn't think my small pumps would be big enough to work on an open vac at the reactor & still pull the fumes through the scrubber

Now I am going to have to give it a try :mrgreen:

Kurt

 

[philddreamer]

Rusty could do something similar on the top, of the bucket cover. As long as there's a bit of outside air sucked in, there will be no chance of collapse, IMHO.

 

[Clneal2003]

Now when you need to pour waste into a drum it is no longer a funnel full of stinky acid poured while holding your breath, it is simply uncapping the pipe, inserting the funnel, and pouring inside the vented hood.

Amen! I'm totally going to use your model here as my first hood if you don't mind. Did the fumes just blow out a duct on top of your shed? I'm still really small time but am constantly looking for ways to simplify this...

Right now I march back and forth from the house grabbing jug after jug of solutions and jars. Constantly putting stuff up and pulling stuff outside depending on the weather.

Oh yeah... What material did you use for the interior?

 

[4metals]

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