Marble chips are usually white, those do not appear to be marble, which is recrystallized limestone.
A gallery of home built hoods and fume scrubbers _hood_
- Thread starter 4metals
- Start date
Help Support Gold Refining Forum:
Yes but a spherical glass marble has less surface area than a structured packing like bio balls. And the surface area is what helps with retention time. Glass marbles will work if you have nothing else. I have seen whiffle balls used as well as hair curlers and short segments of PVC pipe. Just use whatever is inert and has a lot of surface area.
Yes sir, I know I have the marbles but I shared these pebble pics as Ill have to make a purchase. They come cheap. Otherwise Ill have to go miles out towards the other side of the city to get them for free..
I do have an idea of what you're saying, ive seen it too. Not as in scrubbing though but in fish tanks as bio balls.. Would these ceramic bio balls work?
Attachments
The ceramic bio balls you pictured would not work well for a few reasons. First, they are porous because their intent is to have bacterial populations grow on and in the pores. What we are looking for is a non porous substrate that is insoluble and creates a large surface area for the chemical reaction to take place. The porous ceramic bio balls will not be ideal.
You have the marbles or you have the pebbles which you showed in the photo? If you have no alternative I would use the glass marbles and not the pebbles. I am sure the staff at GRF feels terrible, as I do, that you may have to go out of your way to get glass marbles, but it is what it is.
Ohh alright alright.. it's very interesting to learn a new thing everyday.
I'm awfully grateful for the concern of the staff here as it is... Actually it was the pebbles that I had to go over to the other side but you just saved me that trip!! Although i do have the marbles I still have to find them.
As of now I'm in the process of perfecting the last end of my scrubber. I'm figuring out whether vacuum pump or venturi. I'm done testing the pump and now I need to figure out the pressure of the venturi. My diaphragm water pump gives me 5.5L/min, would that be enough to generate the required pressure to create the vacuum??
Many thanks for your time again
Edit: grammatical errors
Last edited:
Hello again,
Im trying to create a spiral inside my cylinders for added retention but im facing a problem. Thep pipes tend to bend instead of the curve. What do I do to fix this issue to obtain a more of a uniform curvature all the way to the top, does anyone have an idea? The pipe im using is the orange ponaflex hose pipe 8.5mm 2250 PSI
Thanks!
Im trying to create a spiral inside my cylinders for added retention but im facing a problem. Thep pipes tend to bend instead of the curve. What do I do to fix this issue to obtain a more of a uniform curvature all the way to the top, does anyone have an idea? The pipe im using is the orange ponaflex hose pipe 8.5mm 2250 PSI
Thanks!
Attachments
Correct me if I am wrong here but is the tubing you are using is to deliver the fume to the bottom of scrubber cylinders? If so, being any longer (by being in a spiral) will not do you any measurable good. The retention time for fume in a column is the time the fume spends in contact with the chemistry in the cylinder not the time it takes to get there.
Yes sir you're absolutely correct, that is what i intend to achieve here.
Also if I'm not mistaken, I drew inspiration from one of your older posts. I dont remember where I read it but it was one of your posts where you suggested a spiralling scrubber since the tubes may also hold some chemistry being a part inside it. I hoped to achieve the same for some added retention if any.
Im only a little skeptical of the time the fumes may spend in the these cylinders, hence my thought came down to this.
The spiral riser I was referring was in an older style gas scrubber used to convert mixed cyanide gasses into sodium cyanide for analysis. The spiral was a glass upside down screw shape that allowed bubbles to spiral upward in the solution and increase the contact time. Different application but the gas being treated is exposed to the solution, your thought would not allow the contact.
Ohh alriight.. must've been a mistake. But then I carried out some earlier tests using this, and I noticed a backflow of water. Wouldn't it be possible that the tubes could infact be holding the chemistry inside it as well?
My finger is at the point where the tube is attached allowing an intake of the fumes.
Attachments
Hi 4metals and everyone,
Please help clearing for me this, if the 6" pvc tube filled with neutralized liquid (Di water / caustic ), and the red tube go down 48" to the bottom of the scrubbing tube, is it first be flooded with caustic/water, will the vacumn could draw this water out of red tube first, then followed by the Nox fume and bubbling through the drilled holds on 5 ways Tee?
The drawing shows the tube a bit full.
The idea is that the vacuum draws the fumes into the bottom and then are bubbling up to the surface. What ever fumes are left will go out the top and over to the next tube or vacuum pump.
Yggdrasil,
First, thank you for replying.
In big picture, i could understand how to fume being sucked out and passing the flask train. But my stucking point is, when the pump stop working, there is no vacumn at all, the red pipes (1/2") those go down at the bottom, will being flooded back physically for a length of nearly 48" height of the 6" pipe (x3 1/2" red pipes in x3 6" pipes). I've just wondered when starting the pump in the next day of work, will the vacumn could easily clear out the flooded liquids first, then come after NOx fume in bubbles form.
Sorry if i could not make my question more clear
If you run a water driven venturi system the vacuum end is not important.
And if you fear a drawback to the reaction vessel put an empty "bottle" in front of it.
Anyway the risk is negligible since it is run open in the reaction end.
If the vacuum fails, it just stops.
If the venturi eductor you choose is properly matched with the pump it should have no issues pulling the scrubbed fume through the flooded cylinders. But in the description of the venturi tank, notice there is a vent valve. If you do not vent the suction line when you shut the pump, it will draw up liquid from the reservoir and require draining to get suction line to draw properly.
Much appreciate for you advices.
I will give it a try of building this setup from now.
I will give it a try of building this setup from now.
Hello Sir @4metals ,
I'd like to clear a couple of queries :
1, :
How do we figure this one out? I was about to order the venturi device, but now I need to be sure of the right item.
2, Earlier you said that the scrubber may get clogged, how do we figure that out or what is the tell that it may be clogged even if we have a way to check the pH?
3, You mentioned that you kept the chemistry pH of the caustic fed scrubber at 9. I guess about a 100 grams of NaOH in a litre of water would shoot the pH to around 12 easily with that being a suitable pH for a fight between the acid fume and the base for efficient scrubbing. So what was the reason when you decided to keep it at 9?
Many thanks for your time once again
I'd like to clear a couple of queries :
1, :
How do we figure this one out? I was about to order the venturi device, but now I need to be sure of the right item.
2, Earlier you said that the scrubber may get clogged, how do we figure that out or what is the tell that it may be clogged even if we have a way to check the pH?
3, You mentioned that you kept the chemistry pH of the caustic fed scrubber at 9. I guess about a 100 grams of NaOH in a litre of water would shoot the pH to around 12 easily with that being a suitable pH for a fight between the acid fume and the base for efficient scrubbing. So what was the reason when you decided to keep it at 9?
Many thanks for your time once again
Flex PVC carries a reasonably inexpensive venturi and they even have a you tube video about how it works and how to size it. See that HERE
The fumes react with the caustic and form a sodium nitrate salt which builds up in the scrubber. Eventually it gets to the concentration where the salts start to drop out of solution because it is over saturated and this is what clogs a scrubber. I normally deal with much larger scrubbers where the water trickles down over the packing as the fume moves up past the packing. With these scrubbers you measure the pressure drop with a manometer to determine when the airflow is diminishing and the solution needs changing. I suppose you could put a manometer on the feed into the scrubber and do the same thing, I have never have done this with a small scrubber as we described in this thread, I just learned how much caustic would start the airflow to diminish and kept track of caustic use and changed the scrubber fluid as needed.
Again I am used to larger scrubbers and all are controlled with dosing pumps and pH controllers so a pH of 9 is sufficient because it is controlled and maintained automatically. Smaller systems with manual additions will perform well even at a pH of 12 as it will go down as it is used.
