HNO3 work temperature

[teclu]

The temperature in my "lab"= outside temperature.Which is the minimum temperature at which work HNO3 50/50? I know that at the cold the reaction is much slower but I am interested if the HNO3 35% dissolves the base metals below zero degrees, and which are the limit below zero degrees?

teclu

 

[lazersteve]

Last winter I dissolved 17 pounds of sterling silver for a customer. I did this outside with 35% HNO3 over the course of several days. I added the scrap 100 grams at a time to two separate 5 gallon buckets of premixed acid over the course of these days. I added more scrap periodically as the reaction died down.

At the end of the reaction I had two 5 gallon buckets full of silver/copper nitrate with a thick layer of silver nitrate crystals in the bottom. All of the stones, trash, Rhodium plating, and Gold plating was at the bottom of the buckets mixed in the silver nitrate crystals.

I also found two platinum items mixed in with the sterling scrap! :shock:

The outside temperature was between 30-50 F everyday.

Steve

 

[teclu]

Last winter I dissolved 17 pounds of sterling silver for a customer. I did this outside with 35% HNO3 over the course of several days. I added the scrap 100 grams at a time to two separate 5 gallon buckets of premixed acid over the course of these days. I added more scrap periodically as the reaction died down.

At the end of the reaction I had two 5 gallon buckets full of silver/copper nitrate with a thick layer of silver nitrate crystals in the bottom. All of the stones, trash, Rhodium plating, and Gold plating was at the bottom of the buckets mixed in the silver nitrate crystals.

I also found two platinum items mixed in with the sterling scrap! :shock:

The outside temperature was between 30-50 F everyday.

Steve

Steve,
Thanks you sir!, this means that the temperature was between -1 degree and +10 degrees Celsius.
Whoever used nitric below -1 Celsius degree ? I mean between -10 degrees and -20 degrees Celsius.

teclu

 

[Anonymous]

A lot of the reactions produce heat. I warm the chemicals in my home, then take them out to the shed for use.
Wrap the containers in fiberglass blanket insulation and they pretty much keep themselves warm.

Another thing I do is to heat a big 8qt stainless pan of water set that in the shed and warm the glassware chemicals with it to
get things started, then wrap with the fiberglass blanket.

hope this helps
Jim

 

[teclu]

A lot of the reactions produce heat. I warm the chemicals in my home, then take them out to the shed for use.
Wrap the containers in fiberglass blanket insulation and they pretty much keep themselves warm.

Another thing I do is to heat a big 8qt stainless pan of water set that in the shed and warm the glassware chemicals with it to
get things started, then wrap with the fiberglass blanket.

hope this helps
Jim

Jim,

Thanks for your advice sir, I hope that this blanket to be useful here at -10 to -20 Celsius degrees.I am not in my lab daily, only once every 3-7 days. I wait and other opinions.

teclu

 

[4metals]

Even if you work your refinery full time it is difficult when it gets below freezing outside to keep the reactions warm. The air exhaust requirements make heating a refinery cost prohibitive. I have had good luck by providing outside air to the inside of the hood so the exhausting of the room air is less but that does little to help the chemistry.

I have purchased heat bands made for plastic pails, they are a rubberized heat blanket which warms the pail nicely, often that will help get a reaction going. To keep your chemical storage area from freezing I have built small well insulated storage rooms and heated them with incandescent light bulbs on a thermostat. If you're using glass beakers there are heating mantles made for 4 liter beakers which will allow you to boil the contents if you need to.

 

[teclu]

Even if you work your refinery full time it is difficult when it gets below freezing outside to keep the reactions warm. The air exhaust requirements make heating a refinery cost prohibitive. I have had good luck by providing outside air to the inside of the hood so the exhausting of the room air is less but that does little to help the chemistry.

I have purchased heat bands made for plastic pails, they are a rubberized heat blanket which warms the pail nicely, often that will help get a reaction going. To keep your chemical storage area from freezing I have built small well insulated storage rooms and heated them with incandescent light bulbs on a thermostat. If you're using glass beakers there are heating mantles made for 4 liter beakers which will allow you to boil the contents if you need to.

Mister thanks you!


But from your experience, what do you can tell me about 35% HNO3 under zero degrees work temperature?

teclu

 

[4metals]

All of my experience is from professional refineries where it is never an option to let it get that cold when they have a reaction going on. I have seen aqua regia at 40 F just sit there barely reacting on karat gold, it takes some heat to get it going.

 

[markqf1]

An electric heating pad (think back problems) works well to keep the temp up as well.
The one that I have will keep your solution at about 110f if you put it in a cooler.

Mark

 

[glorycloud]

Here are a few links for 5 gallon bucket heaters for about $75.00:

http://www.heatingsolutions.org/product/IND-5
http://www.caulkwarmer.com/proddetail.php?prod=5-Gallon-Bucket-Warmer



There also seems to be some heating tapes available:

http://www.oemheaters.com/entity/tabid/59/entityname/category/categoryid/72/sename/heating-tapes/default.aspx

Keep those reactions warm and your gold dropping out of solution!! 8)

 

[teclu]

markqf1 and glorycloud,

Good ideas, I will think about it, many thanks.

teclu