Setting up a vacumn still

[phxdale]

I just aquired an old beatup air compressor that doesm't work good enough to use for compressed air but I hooked up the intake to a vacumn connection on my still and seems to make a pretty good vacumn.
Although I don't mind making fuming acid with it, it doesn't store well and people smarter then me say I shouldn't use it. So the plan is get it anywhere from 60-68%, I'm more concerned about making it consistantly the same for each batch.

One thing I don't have and don't know if I need it, is a way to measure how much vacumn I am drawing. At this point all I know is that I was not able to get water to distill with just a vacumn. I'm thinking its 10-15 inches or so. I guess what I can do is hook up the vacumn and then slowly heat the water and see how hot it is when it starts to boil and then I can figure out how much vacumn I am drawing.
Is knowing how many inches of vacumn you have a critical thing?

How much vacumn do I need to make a high quailty clean, clear nitric?
What ratio of nitrate salt, water, and 98% sulfuric to use? I usually use sodium nitrate but potasium is easy for me to get in small amounts.

I am not allowed to put nitric acid in the freezer any more, so I can't use the cold method and then distill it, but could I use the cold method ratio and just distill instead of freeze? Or is there a better ratio I should use?

I assume I would want to heat it to a point just below boiling for the distillation.

 

[butcher]

In my opinion whether you have vacuum or not is not important, especially when distilling to get azeotropic nitric acid.

The boiling point, (and temperature) are more important, how you distill, and your distilling rig, temperatures and controlling the boiling so that you do not have carry over.

Let me try to explain what I mean.

We can distill under atmospheric pressure, or we could even distill with the vessel under pressure, or in a vacuum.
What is the difference the nitric acid in the boiling flask forms gases, and these gases rise and are condensed into a solution of more pure nitric acid.
The difference is the temperature, in a vacuum the boiling point is a low temperature, in atmospheric pressure the temperature needs to be higher (than the same solution in a vacuum), and if the boiling flask is under pressure we need still yet a higher temperature to distill off the acid.

With fuming nitric acid and controlling decomposition of the acid (NOx gas) distilling under a vacuum can have a slight advantage, but is not necessary in my opinion.

Carry over is where you can contaminate your nitric acid distilled off, this is basically where you are carrying over impurity's such as salts or metals or other impurity's that would normally stay in the boiling flask, how your distilling rig is set up, or made, how hard your run it, organics, oils, dirt, or other impurity's in the liquid being distilled (such that might cause foaming or burping, bumping, of solution)...
carry over will be the biggest cause of your nitric of not being pure or clean.

If you are worried about the nitric being the same concentration every batch (personally I am not concerned a bit by that), you can make it slightly below azeotropic and evaporate to 68% azeotrope, then you would have every batch would be the same concentration.

I really doubt you could get the same consistent concentration, by trying to make 98% and diluting it with water to get a consistent percentage nitric acid every time, as you would with the method above.

I do not care if the nitric acid I use is more dilute in most any process of recovery or refining I do, in fact many times I prefer it more dilute, because I use heat with these processes and my acids concentrate with heat, and actually in many cases that extra water in my acid is beneficial, it can help to keep my nitric in solution longer,make my acid go further, it does not decompose as fast at the beginning of a process and waste my acids as brown NOx fumes, these are redissolved to act on metals in solution, I can heat solutions for longer periods of time to dissolve hard to attack metals...

I will try to answer more questions in this post (and delete your other post on this same subject please do not double post your questions).

 

[butcher]

The compressor probably has bad or dirty valves or rings, it would not be good to use for a vacuum pump, would not last long either.

You could use a vacuum gauge to measure vacuum, if you wished to know what vacuum you are pulling.

You have to get a fairly deep vacuum before you can boil water without heat, in refrigeration work we pull 29" Hg, ant that is just to boil off slight amounts of moisture in the system, it takes a very good vacuum pump to get to 29" Hg, normal mechanical vacuum pumps cant get to a much deeper vacuum. and your weak air compressor I am sure will get that deep of a vacuum.


"I am not allowed to put nitric acid in the freezer any more?"
"I can't use the cold method and then distill it, but could I use the cold method ratio and just distill instead of freeze? Or is there a better ratio I should use?"

WHY
You can use ice and salt in a pan (kind of like how we made ice cream when I was a kid) to chill your jar of nitric if Mom, or your wife will not let you put it in her fridge.
I have a small fridge just for my chemistry work.
But in winter the cold outside air, or snow is helpful to chill things.

A thermometer in the vapors of your boiling flask is helpful for determining temperature.
That would be more important than pressure or vacuum.

 

[Pantherlikher]

So in plain and simple terms...
Keep your compressor for your future furnace as an air pusher and make alot of ice cubes in the freezer.
And concentrate more on the setup for purity.

B.S.

 

[phxdale]

The compressor is shot, found it in an alley on bulk trash pickup day. They did not pick it up. Its amazing it even runs, looks like a section of the cylinder wall is patched with some kind of epoxy and the reed valve was replaced with a section of a putty knife? maybe. Could not put enough air out to pump up a bicycle tire.

I like the idea for using it for a air pusher for a furnace though.

Salt and ice in cooler would work, I do have a cooler I could use.
I'll never see enough enough snow to do any good in Phoenix. I have lived here 41 years and walked in snow in my front yard the first time last year. I have a picture to prove it. Plenty of sun to kill off any free nitric though. When a batch looks done, throw a little more silver in and put out in the sun.

I should probably get a 3 way to put on top of the column to measure the vaper temps before it goes through the condensor rather then use the remote thermometer that I got to measure the oil in my turkery fryer. Other then that I think the setup is fine for what little I will use it for. This time everything was nice and clean no cloudy solutions and the cemented silver looks great. I refined a bunch of scrap brazing ribbon silver, copper and titanium. Nice stuff.

Any use for titanium in refining silver? I think what I have is fairly pure,

Last time using undistilled nitric, I ended up just turning it all to chloride. That was interesting. I will never do that again. If one goes that route I think aluminum foil and pool acid and a garage sale blender is best way to get it back.I tried them all. The was the main reason I setup the still, get away from silver chloride and silver sulphate.

Next project is my ultra low budget silver cell using 2 liter bottles and rechargable D cell battery,

 

[butcher]

Palm trees in the snow, looks like the best of both seasons.
Snow in Phoenix well I guess we will have to blame that one on global warming, maybe its the nitric you have been cooking, are you sure it just didn't snow around your house?
I guess Santa doesn't know if he needs his sunglasses or snowshoes down there.
The titanium could come in handy in some electrolysis cells.
An old compressor tank could be made into a ball mill.

 

[phxdale]

The best part was watching people drive. I was looking out at someone that went sideways taking a right turn too fast. Ball mill?? Never thought of that, it does have a desent size tank to it too.

 

[butcher]

I lived in Arizona for a short time when I was very young, after my mother died, I lived on and in the Grand Canyon with an uncle who was a ranger, a guide, and parks service worker for the Grand Canyon, back then it was not the city it is now (more like an Indian reservation) with a few tourist coming to watch the Indians at certain seasons, my Uncle did not Have a house, we lived on the South Rim or in the Canyon in winter, and He would fire watched in the summer on the north rim where we stayed in a small camp trailer at the base of the watch tower provided by the forestry dept.

I thought the Arizona desert was some of the most beautiful country in the United states.

I remember we drank powdered milk, we could not buy milk at the Canyon, once we drove to the big city of Phoenix and we bought some store bought milk,(not as good as real cows milk), but that stuff was like drinking a bit of heaven.
Our diet was mostly pinto beans and deer meat my uncle hunted, I still love deer meat and beans, but I will die of thirst before I will drink that darned powdered milk.

It was funny to me, and I wondered about it for many years later, I did not understand how one side of the canyon could have snow and the other side would not, I remember the north rim of the Grand canyon was closed in winter due to snow (in the middle of the desert), but it only rarely snowed on the south rim, that was a mystery to me for many years, but after I was grown and when I came up north here, I stopped by the canyon, both south and north rims, my uncle gone I could not see him again, his daughter still lives at marble canyon, ran the store and motel (I think the population of that town may be about 3 people) then it made sense to me the north rim is like in the mountains compared to the desert.

My Uncle actually had a big part in re-discovering and fixing up the lonely dells ranch of (Lee's ferry crossing near that crossing of the Colorado river), (the ranch of John D.Lee),and fixing it up on his own time, kind of a retirement project,as He loved the ranch so much, he spent the last part of his life fixing up the old orchards, and the cabin there, which later became a park of the forestry service, the Mormon church made Him an Honorary bishop, for his contribution to their History, and he Is mentioned in one of their small history books of the history of the ranch. I was given a copy of that history book along with a copy of the paper naming him an honorary bishop, He wanted to be buried on the ranch but was not allowed by the parks service, but they did allow for his ashes to spread there,after his family went to a heck of a lot of trouble with government red tape, I guess in a way he is still taking care of that clump of fruit trees in the middle of the desert, fertilizing those old fruit trees today, he worked so hard on in his last years, He cleaned out much of the old irrigation trenches to bring water to those ole thirsty trees, and He is still taking care of something he found in the desert and loved so much.
http://en.wikipedia.org/wiki/Lee%27s_Ferry_and_Lonely_Dell_Ranch

 

[phxdale]

Great story. Very cool. The desert in places is pretty neat but I never have like cacti very much. Expecially jumping cactus, have been too close to those a couple of times. Chasing quail and riding motorcycles. We have all these cacti in pots all over the backyard and the stickers allways end up in my feet since I don't wear shoes much for most of the year. Big difference in the desert here compared with the high desert of Nevada. Its just desolate.