Heating nitric acid

Shop deals on ebay
Advertise with us
shop deals on amazon
xelexo
Gold Refining Forum

Help Support Gold Refining Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
M

mikeinkaty

Well-known member
Joined
Nov 30, 2012
Messages
408
I see a lot of writing and discussion about a 'low boil' when dissolving silver and base metals out of karat scrap.

I'm thinking I would like to put my beaker in a corning ware dish with the dish setting on my electric hot plate. Then put about 1" of water in the dish.

Would this transfer enough heat to the beaker contents? If it will then the water will act as a buffer preventing the beaker from getting to hot and the corning ware dish will act as a catch basin in case the beaker cracks for some unknown reason.

This same idea can be used when distilling spirits to prevent scorching the contents. Also because ethanol starts boiling off at around 173° or there abouts.

Mike
 
if you have to boil, always cover the vessel with a watch glass or other non-metallic heat resistant cover that condensation and aerosol mist can drip back into the heating vessel.a glass or porcelain saucer will work in a pinch.
 
Geo said:
if you have to boil, always cover the vessel with a watch glass or other non-metallic heat resistant cover that condensation and aerosol mist can drip back into the heating vessel.a glass or porcelain saucer will work in a pinch.
Click to expand...

"If you have to boil"? Can you explain the conditions where you would have to boil? I would always cover the beaker with a watch glass or maybe even a small pyrex bowl filled with ice, at least when the reaction is going full steam. I'm thinking the ice would aid with refluxing.

Goldsilverpro -are you saying that the water in the dish WOULD transfer enough heat to the reaction? It would give a more even heat transfer too.

Mike
 
there are some processes where boiling is required. knowing when and how to boil a solution or material correctly is key to keeping your values where they are suppose to be. there are pictures on the forum of work spaces and fumehoods where people have swabbed them down with stannous and the purple stains were everywhere. when you boil or a reaction is taking place, tiny bubbles are being generated, an aerosol of your solution is being made at the surface and the steam pressure is taking it out of the vessel. whether its boiling or not, this is still happening. there are measures you can take to minimize the losses (like covering reactions and processes) and cleaning your work area periodically.use paper towels and dry clean (wipe down) all surfaces inside the fumehood and around work space where reactions take place. lastly,use a weak AR solution and wipe it down again. be sure to wear PPE's. place all rags and paper towels with your filters for future processing.
 
an example of needing to boil is processing sweeps. boiling in AR is about the only way to recover all the values. platinum will barely dissolve in AR at ambient temperatures. ash is another material that needs to be boiling in AR.if the ash contains a mix of precious metals, keeping the mix agitated with the boiling action is a good way to make sure that all the material is exposed to the acid. ash can be from incinerating electronics to carpets and rugs from a jewelers shop.

these are just a couple of examples but there are many more. learn when and how to boil correctly and you will do good work.
 
I'm thinking I would like to put my beaker in a corning ware dish with the dish setting on my electric hot plate. Then put about 1" of water in the dish.
Click to expand...

It would be more a gentle heat but tending the water level would be a pain. I don't find it necessary to have water in the corning catch dish all the time but I have added water to the catch dish to quiet a rising foam over.
 
I agree with qst that monitoring the water level and making additions to replace that which evaporates is not ideal. Consider replacing the water with a layer of sand. It provides the same heat buffering benefits, it can be heated to above the boiling point of water if needed, and it won't evaporate.

Dave
 
I usually just process with my values and acids directly in the corning ware dish, on a solid cast iron electri burner, (too much powders in the bottom of a pyrex dish can crack the vessel from uneven heating or hot spots), this does not seem to be a problem for the corning ware ceramic dish, the dish can go from material being incenerated inside it, to washing and dissolving the powders or metals almost through the whole process leaving insoluble in the dish through the whole process.

when just heating solutions then I will use the pyrex vessel filled with liquids sitting in the corning ware dish as a heat spreader or just in case of breakage.
 
I have a coil type electric hotplate like you see on older stovetops. I'm thinking of cutting a 6" circle of 1/4" aluminum plate to cover it. Would that be a wise idea for providing more even heating? I noticed that Aluminum is not to reactive to hno3.

I just discovered that the wife has almost a dozen older corning ware sauce pans of varing sizes all of the high-heat variety. These were inherited from her mom and my mom mostly. I don't think she will miss a couple!
 
mikeinkaty said:
I just discovered that the wife has almost a dozen older corning ware sauce pans of varing sizes all of the high-heat variety. These were inherited from her mom and my mom mostly. I don't think she will miss a couple!
Click to expand...

I have never been married, but even I know you better ask first.

Jim
 
mikeinkaty said:
I have a coil type electric hotplate like you see on older stovetops. I'm thinking of cutting a 6" circle of 1/4" aluminum plate to cover it. Would that be a wise idea for providing more even heating? I noticed that Aluminum is not to reactive to hno3.

I just discovered that the wife has almost a dozen older corning ware sauce pans of varing sizes all of the high-heat variety. These were inherited from her mom and my mom mostly. I don't think she will miss a couple!
Click to expand...

Aluminum melts at about 1220F. I once put a piece of Al about 1/2" x 1/2" x 3" directly on the coils of an electric hotplate and it melted. Quite a mess.
 
goldsilverpro said:
mikeinkaty said:
I have a coil type electric hotplate like you see on older stovetops. I'm thinking of cutting a 6" circle of 1/4" aluminum plate to cover it. Would that be a wise idea for providing more even heating? I noticed that Aluminum is not to reactive to hno3.

I just discovered that the wife has almost a dozen older corning ware sauce pans of varing sizes all of the high-heat variety. These were inherited from her mom and my mom mostly. I don't think she will miss a couple!
Click to expand...

Aluminum melts at about 1220F. I once put a piece of Al about 1/2" x 1/2" x 3" directly on the coils of an electric hotplate and it melted. Quite a mess.
Click to expand...


Thank you! That is very good to know. I do have a small cast iron plate. Mike
 

Latest posts

Back
Top