Questions about processing black powder`

[Metaphore]

Set up a cell, processed some pins, got some black powder, rinsed it until the siphoned liquid is clear and I think I am ready to process the black powder.

As is suggested often and by many on this forum, I did lots of reading and am trying it out on a very small batch.

Here are some question I have on this process:

1. Distilled water is specified in many of the processes I read about. Would reverse osmosis filtered water (<5ppm) do as well? I get the idea that it is the chlorine in the tap water that is the problem. If that's the case, wouldn't a simple charcoal filter remove that?

2. Before AR or HCL-CL, is it a good idea to boil the powder in Nitric to get rid of copper?

3. From what I've read and seen, it seems that AR takes hours while HCL-CL takes minutes. It also seems that AR is harder to handle and is more dangerous. Are there pluses to using AR instead of HCL-CL?

4. Early on, when reading about AR and precipitation, I made a list of chemicals I'll need. Now I find myself looking at a bag of Urea, wondering where I will need it. I'm not quite clear on its role. Is it just in case I add too much Nitric in AR? Is it used at all with HCL-CL?

Thanks you all very much for your help and tolerance.

 

[Harold_V]

1. Distilled water is specified in many of the processes I read about. Would reverse osmosis filtered water (<5ppm) do as well? I get the idea that it is the chlorine in the tap water that is the problem.

All I can say is that I used tap water for everything except for making standard solutions, and for operating my silver cell. The traces of chlorine present never created a problem for me, not even when washing gold.

2. Before AR or HCL-CL, is it a good idea to boil the powder in Nitric to get rid of copper?

Eliminating traces of base metals is always a good idea. However, before a nitric wash, I'd also recommend incineration, which will eliminate other unwanted substances. It also prevents any dissolution of values by eliminating traces of chlorides, should any be present.

3. From what I've read and seen, it seems that AR takes hours while HCL-CL takes minutes.

I fully expect you have that backwards. Heated AR reacts so fast it can be violent.

It also seems that AR is harder to handle and is more dangerous. Are there pluses to using AR instead of HCL-CL?

Depends on your objective, and if you have nitric at your disposal, or not. I used AR exclusively, but I also had access to unlimited and inexpensive nitric.

4. Early on, when reading about AR and precipitation, I made a list of chemicals I'll need. Now I find myself looking at a bag of Urea, wondering where I will need it. I'm not quite clear on its role. Is it just in case I add too much Nitric in AR?

Correct. I also recommend you don't use it, as it isn't necessary. One can evaporate, or one can work carefully and use only the amount of nitric necessary to accomplish the task. Alternately, added gold can be used to consume any excess nitric.

Is it used at all with HCL-CL?

No, it is not. Any free chlorine can be easily expelled simply by heating, or allowing the solution to sit idle for a day, exposed to the atmosphere.

Harold

 

[Anonymous]

Metaphore asked some very good questions and Harold_V gave some great answers too. Some of these questions were on my mind, but now they seem to be answered, like

question 1. Although I do filter my drinking water, I bet I can save money using that instead of 100% distilled water for 100% of my work. I agree with using distilled water when making solutions. I even wash my beakers with dawn dishwashing liquid, rinse real good with tap water, then give them just a quick distilled rinse. That's been saving me money and it hasn't hampered any of my refining.

question 2. Harold_V answered something I was thinking about but never tried. I have some black powder now that have been sitting in distilled water for about a week now. I'll definitely try that, instead of dropping the gold and then trying to clean it with the Nitric. It seems to me that this procedure in that order would get the unwanted materials out long before using SMB. Good question and great answer too.

question 4. I have some Urea that I bought about 3 years ago and I have used it just once. I see no need for it. It you aren't trying to measure the Nitric down to the ml for what you have and just add enough to dissolve your metals, along with some heat, there's no need to use Urea.

Thanks for the answers Harold_V.


Kevin

 

[Metaphore]

Thank you very much for very clear answers.

Eliminating traces of base metals is always a good idea. However, before a nitric wash, I'd also recommend incineration, which will eliminate other unwanted substances. It also prevents any dissolution of values by eliminating traces of chlorides, should any be present.

What's the best way to incinerate black powder? Would filtering and burning with the filter using a butane torch work?

 

[Harold_V]

What's the best way to incinerate black powder? Would filtering and burning with the filter using a butane torch work?

That's what I used to do, although my torch was natural gas/oxygen. Even without pre-drying, the filter was placed in a small stainless fry pan and heated from below. When the filter was consumed, I'd add additional heat with the torch, then play a little pure oxygen on the contents of the pan to ensure all carbon was eliminated. If the pan is hot enough, traces of carbon glow readily when oxygen is applied, so it's a great way to determine if the job of incineration is complete, or not.

Small stainless fry pan. I've mentioned this before, but for those who likely haven't read those old posts, look in second hand stores (Goodwill and the like) for those small pans used by the boy scouts. A perfect size for incinerating small lots.

I used to use a three burner natural gas fired hot plate for all of my processing. One burner was adjusted for maximum heat output, and that's the one I used for incineration (all in my fume hood----and the reason why I built a fume hood that was not combustible).

Harold

 

[jason_recliner]

Here's a great post on incineration, also by Harold_V.
http://goldrefiningforum.com/~goldrefi/phpBB3/viewtopic.php?f=38&t=1997

I stumbled upon it in my first weeks here, but it took me ages to find again when I needed it. Now I have it and several other key threads saved in my browser favourites (bookmarks). You might find that practice useful too.

{Harold just beat me to it again.}

 

[TomVader]

In regard to tap water vs. distilled. I have well water and it is loaded with iron and minerals. I think rinsing in tap water is OK but I follow it with a distilled rinse just to get the minerals out. I guess it depends on how many decimal places you're shooting for!

 

[Metaphore]

Here's a great post on incineration, also by Harold_V.
http://goldrefiningforum.com/~goldrefi/phpBB3/viewtopic.php?f=38&t=1997

Thank you very much for a very informative article!

Harold, if I didn't see that section on not incinerating whole boards, I would have tried it. It was on my future list of things to try. I'm very glad you decided not to remove it.

 

[Anonymous]

Metaphore

question 2. Harold_V answered something I was thinking about but never tried. I have some black powder now that have been sitting in distilled water for about a week now. I'll definitely try that, instead of dropping the gold and then trying to clean it with the Nitric. It seems to me that this procedure in that order would get the unwanted materials out long before using SMB. Good question and great answer too.

Kevin

Just to pick up on a point Kevin. You wouldn't really be wanting to clean your gold with Nitric would you?

Jon

 

[Anonymous]

Metaphore

question 2. Harold_V answered something I was thinking about but never tried. I have some black powder now that have been sitting in distilled water for about a week now. I'll definitely try that, instead of dropping the gold and then trying to clean it with the Nitric. It seems to me that this procedure in that order would get the unwanted materials out long before using SMB. Good question and great answer too.

Kevin

Just to pick up on a point Kevin. You wouldn't really be wanting to clean your gold with Nitric would you?

Jon

I'm confused as to the question. Hopefully you'll explain it differently.

What I'm saying is that, instead of rinsing the black powder with the water, then the ammonia, then water, then the Nitric hot bath, and then the final rinsing, and then dry the powder, and then refine it again in that order, the Nitric bath would eliminate unwanted material in the powder. From there, I could do my rinsing with boiling water, then boiling ammonia, and then hot water again.

I hope that made sense. I once ran into a not so good rinse after using nitric after refining the powder, and when I dried the powder, I placed it in a piece of aluminum foil for about a day or so and placed it in a drawer I have. When I came to put the gold in a glass jar, I noticed that the nitric had eaten some of the aluminum foil away. That there let me know that I didn't rinse my powder good enough.

So, I'm thinking that by doing the nitric wash first, and then the ammonia and water rinses afterwards should eliminate all of the nitric.

I also remember when I was going to refine some powder for the 2nd time, by the time I placed it in a beaker, and then added some HCL to the beaker, it immediately started turning brown, which let me know that nitric was still in the gold powder. I am going to start putting more water in my rinses to almost half full in the beakers to make sure I'm weakening the nitric. I also forgot about my pH test strips that I could be using to test the rinses to make sure I got all the acids out.

Kevin

 

[Barren Realms 007]

Metaphore

question 2. Harold_V answered something I was thinking about but never tried. I have some black powder now that have been sitting in distilled water for about a week now. I'll definitely try that, instead of dropping the gold and then trying to clean it with the Nitric. It seems to me that this procedure in that order would get the unwanted materials out long before using SMB. Good question and great answer too.

Kevin

Just to pick up on a point Kevin. You wouldn't really be wanting to clean your gold with Nitric would you?

Jon

I'm confused as to the question. Hopefully you'll explain it differently.

What I'm saying is that, instead of rinsing the black powder with the water, then the ammonia, then water, then the Nitric hot bath, and then the final rinsing, and then dry the powder, and then refine it again in that order, the Nitric bath would eliminate unwanted material in the powder. From there, I could do my rinsing with boiling water, then boiling ammonia, and then hot water again.

I hope that made sense. I once ran into a not so good rinse after using nitric after refining the powder, and when I dried the powder, I placed it in a piece of aluminum foil for about a day or so and placed it in a drawer I have. When I came to put the gold in a glass jar, I noticed that the nitric had eaten some of the aluminum foil away. That there let me know that I didn't rinse my powder good enough.

So, I'm thinking that by doing the nitric wash first, and then the ammonia and water rinses afterwards should eliminate all of the nitric.

I also remember when I was going to refine some powder for the 2nd time, by the time I placed it in a beaker, and then added some HCL to the beaker, it immediately started turning brown, which let me know that nitric was still in the gold powder. I am going to start putting more water in my rinses to almost half full in the beakers to make sure I'm weakening the nitric. I also forgot about my pH test strips that I could be using to test the rinses to make sure I got all the acids out.

Kevin

The best way to make sure you have removed it is to incinerate your powder between your washes.

 

[Anonymous]

Metaphore

question 2. Harold_V answered something I was thinking about but never tried. I have some black powder now that have been sitting in distilled water for about a week now. I'll definitely try that, instead of dropping the gold and then trying to clean it with the Nitric. It seems to me that this procedure in that order would get the unwanted materials out long before using SMB. Good question and great answer too.

Kevin

Just to pick up on a point Kevin. You wouldn't really be wanting to clean your gold with Nitric would you?

Jon

I'm confused as to the question. Hopefully you'll explain it differently.

What I'm saying is that, instead of rinsing the black powder with the water, then the ammonia, then water, then the Nitric hot bath, and then the final rinsing, and then dry the powder, and then refine it again in that order, the Nitric bath would eliminate unwanted material in the powder. From there, I could do my rinsing with boiling water, then boiling ammonia, and then hot water again.

I hope that made sense. I once ran into a not so good rinse after using nitric after refining the powder, and when I dried the powder, I placed it in a piece of aluminum foil for about a day or so and placed it in a drawer I have. When I came to put the gold in a glass jar, I noticed that the nitric had eaten some of the aluminum foil away. That there let me know that I didn't rinse my powder good enough.

So, I'm thinking that by doing the nitric wash first, and then the ammonia and water rinses afterwards should eliminate all of the nitric.

I also remember when I was going to refine some powder for the 2nd time, by the time I placed it in a beaker, and then added some HCL to the beaker, it immediately started turning brown, which let me know that nitric was still in the gold powder. I am going to start putting more water in my rinses to almost half full in the beakers to make sure I'm weakening the nitric. I also forgot about my pH test strips that I could be using to test the rinses to make sure I got all the acids out.

Kevin

The best way to make sure you have removed it is to incinerate your powder between your washes.

Now that sounds like a plan to implement. It makes sense too. I'll start doing that. Thanks for the tip Barren Realms 007


Kevin

 

[Geo]

Kevin, There's a name for washing gold in nitric acid after melting, it's called pickling. Used to enhance the appearance of resistant metals, it is considered shady practice. If you are using nitric to wash precipitated powder, You should roast the powder first to remove the previous acids. When the question about storing gold was asked, Storing in a container that has a top that will fasten down serves two purposes. One is to contain the gold without allowing it to spill. The second is to keep the gold from being contaminated until you are ready to do the next step. HCl 32°baume, fumes in ambient temperatures and will stick to any cool surface. It is the biggest source of contamination of HCl that I can think of.