solar_plasma
Well-known member
very very seldom...in fact only once
Neutralizing Acid
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very very seldom...in fact only once
Okay. I'm wondering if maybe when I ordered the SMB if maybe they sent me the wrong mateial or something because the material I have reacts violently with HCl. Maybe they sent me sodium metabisulfate instead of sodium metabisulfite or something...
solar_plasma
Well-known member
Here is one right equation (and will also ease your last wondering):
lazersteve (http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=51&t=895&p=10627#p10627):
So,... I am curious.... engineer in chemistry....in which country did you say you've made your degree?
A
Anonymous
Guest
Mr Foster-
Take the advice you've been given here but with one piece added please. Try a little humility as well. These guys know an awful lot about what they are talking about. If you assume that you know nothing and are like a blank piece of paper and act like that then you'll get lots of freely given help from everyone here.
Like a few others I'm a little worried that a guy with a chemistry degree would add ammonia to this solution just to see what happened. Trust me on this sir. Go back to the beginning and get the basics right because you don't appear to have done so.
I knew very little when I came here, and the little I did know was wildly wrong so I read, learned, and took my lumps from the pros here. Eventually I got the gold thing nailed on. The fun starts when you can make mistakes and look at the mess and say " Arrghh I KNOW what I did there and here's how to fix it."
Start with all this again mate. You'll love it I promise.
Jon
Take the advice you've been given here but with one piece added please. Try a little humility as well. These guys know an awful lot about what they are talking about. If you assume that you know nothing and are like a blank piece of paper and act like that then you'll get lots of freely given help from everyone here.
Like a few others I'm a little worried that a guy with a chemistry degree would add ammonia to this solution just to see what happened. Trust me on this sir. Go back to the beginning and get the basics right because you don't appear to have done so.
I knew very little when I came here, and the little I did know was wildly wrong so I read, learned, and took my lumps from the pros here. Eventually I got the gold thing nailed on. The fun starts when you can make mistakes and look at the mess and say " Arrghh I KNOW what I did there and here's how to fix it."
Start with all this again mate. You'll love it I promise.
Jon
niteliteone
Well-known member
If memory serves me correctly, it would take over a pound of Urea to neutralize an excess of 50ml of nitric from your AR solution.
Not a good choice in my opinion.
It takes 0.79ml nitric and 3.27ml HCl acid to dissolve 1 gram of gold.
I noticed you made your AR using the old formula of 3:1 (HCl : Nitric) so it will be assumed you have way too much nitric in your solution.
Their are 3 ways to solve this.
1. Is by adding more gold to use up the excess nitric. (Hokes book and search forum)
2. evaporate to remove excess nitric (Hokes book and search forum)
3. add copper to cement all values and re-refine the resulting powders. (search forum)
Here we teach to cover your material with HCL and then make small additions of nitric waiting for the reaction to complete before each subsequent addition, until all gold is dissolved.
How much solution do you still have that needs to be processed ???
Some corrections on your above statements.
HCl DOES dissolve copper. (search forum for AP process)
SMB has only fizzed on me when I had an excess of nitric in my solution, otherwise it doesn't.
Not a good choice in my opinion.
It takes 0.79ml nitric and 3.27ml HCl acid to dissolve 1 gram of gold.
I noticed you made your AR using the old formula of 3:1 (HCl : Nitric) so it will be assumed you have way too much nitric in your solution.
Their are 3 ways to solve this.
1. Is by adding more gold to use up the excess nitric. (Hokes book and search forum)
2. evaporate to remove excess nitric (Hokes book and search forum)
3. add copper to cement all values and re-refine the resulting powders. (search forum)
Here we teach to cover your material with HCL and then make small additions of nitric waiting for the reaction to complete before each subsequent addition, until all gold is dissolved.
How much solution do you still have that needs to be processed ???
Some corrections on your above statements.
HCl DOES dissolve copper. (search forum for AP process)
SMB has only fizzed on me when I had an excess of nitric in my solution, otherwise it doesn't.
You actually want the SMB to react with the HCl, in order to produce the SO2 that is needed to precipitate the gold. If you had only HAuCl4 and HCl in the solution, the gold would drop very quickly and efficiently with the SMB.
What fouls this up is when an oxidizing agent (HNO3, in this case) is also present. It seems obvious to me that you still have a lot of free HNO3 in the solution. You first leached with HNO3 (which is good) to eliminate the copper and, if you didn't rinse the HNO3 out of the residue before using AR, that would be part of the problem. Then, you used a 3/1 AR mix. Combined with about 4 to 5ml of HCl, it only takes about .8 - 1ml of nitric to dissolve 1g of gold. I would guess that you exceeded that amount. If you do have a HNO3 excess after dissolving the gold, it won't precipitate any gold until it all has been destroyed by reaction with the SMB. Actually, it's sort of a chicken and egg thing. Does it not precipitate because the SMB much first react with the free nitric or, does it precipitate and then immediately redissolve due to the presence of both HCl and HNO3 (aqua regia). Theoretically, it takes about 1.5g of SMB to eliminate 1ml of free nitric acid. This only works for small amounts of free nitric. When it takes a large amount of excess SMB to react with a large excess of free HNO3, you can start having solubility problems with the by-products.
Here's how you should have used the AR. First cover the gold foils with conc. HCL. Use a little more than you'll need. Heat the HCl fairly hot but don't boil. Add HNO3 in small increments. Allow it to react. When the reaction slows down, add another small increment. When a small addition produces no reaction, stop adding. At this point, if you had an excess of HCl to start with, all the gold should be dissolved.
In the 40 some years that I refined professionally, I tried using urea once or twice but didn't have much success. The trick is to only use enough nitric to barely dissolve all of the gold. If, with a heavy hand, you have added too much HNO3, you should eliminate it by using the standard AR evaporation process that has been well covered on the forum. Another option is to use sulfamic acid (search), which destroys the nitric and produces nitrous oxide and sulfuric acid. The nitrous (laughing gas) goes off as a gas and the sulfuric doesn't interfere with the SMB precipitation.
I don't know where you stand now. You keep telling us about having done new things to the solution each time you post. It sounds like you were processing plated material. If so, most gold plating is worth in the range of $.05 to $.50 per square inch. If you don't have much gold value in your mess, I would forget about it, start a new batch, and do it right. Keep this batch and worry about it later on, when you know more.
What fouls this up is when an oxidizing agent (HNO3, in this case) is also present. It seems obvious to me that you still have a lot of free HNO3 in the solution. You first leached with HNO3 (which is good) to eliminate the copper and, if you didn't rinse the HNO3 out of the residue before using AR, that would be part of the problem. Then, you used a 3/1 AR mix. Combined with about 4 to 5ml of HCl, it only takes about .8 - 1ml of nitric to dissolve 1g of gold. I would guess that you exceeded that amount. If you do have a HNO3 excess after dissolving the gold, it won't precipitate any gold until it all has been destroyed by reaction with the SMB. Actually, it's sort of a chicken and egg thing. Does it not precipitate because the SMB much first react with the free nitric or, does it precipitate and then immediately redissolve due to the presence of both HCl and HNO3 (aqua regia). Theoretically, it takes about 1.5g of SMB to eliminate 1ml of free nitric acid. This only works for small amounts of free nitric. When it takes a large amount of excess SMB to react with a large excess of free HNO3, you can start having solubility problems with the by-products.
Here's how you should have used the AR. First cover the gold foils with conc. HCL. Use a little more than you'll need. Heat the HCl fairly hot but don't boil. Add HNO3 in small increments. Allow it to react. When the reaction slows down, add another small increment. When a small addition produces no reaction, stop adding. At this point, if you had an excess of HCl to start with, all the gold should be dissolved.
In the 40 some years that I refined professionally, I tried using urea once or twice but didn't have much success. The trick is to only use enough nitric to barely dissolve all of the gold. If, with a heavy hand, you have added too much HNO3, you should eliminate it by using the standard AR evaporation process that has been well covered on the forum. Another option is to use sulfamic acid (search), which destroys the nitric and produces nitrous oxide and sulfuric acid. The nitrous (laughing gas) goes off as a gas and the sulfuric doesn't interfere with the SMB precipitation.
I don't know where you stand now. You keep telling us about having done new things to the solution each time you post. It sounds like you were processing plated material. If so, most gold plating is worth in the range of $.05 to $.50 per square inch. If you don't have much gold value in your mess, I would forget about it, start a new batch, and do it right. Keep this batch and worry about it later on, when you know more.
A couple of quick notes in random order as I thought of it....
1. I strongly suggest that you take the guided tour of the forum, look at the signature of Lazer Steve. Follow every link and read the topics they cover. That will show you a lot of the processes we recommend here on the forum.
2. How much material did you start with? Maybe you did precipitate your gold but it was so little you couldn't see it.
3. How do you know you have gold in solution? Look up testing with stannous chloride and come out of the dark.
4. How do you know the stuff you got after adding ammonia to the AR is gold? Have you tested it or melted it? To me it sounds more like iron hydroxide. From a dirty solution as yours I would suspect a very black precipitate of gold.
5. The reaction between HCl and SMB that you wrote down creates SO2. That is the reactant that precipitate gold. You would have known it if you had read Hoke or the forum.
6. You claim to be a chemical engineer but makes a rookie mistake as "added a SMALL amount of ammonia to the AR solution in order to lower the pH". Ammonia would increase the pH. Maybe it was a honest mistake but it doesn't bring credibility to your other claims. We get a lot of newbies here, claiming a lot but soon the truth is revealed. As one of the moderators have in his signature "You are what you write!"
7. When digesting base metals (or silver) dilute it to half strength, it works better if it isn't concentrated.
8. There is no silver nitrate in AR solution, it will form a precipitate of silver chloride and only trace amounts will be left in solution.
9. From a gold chloride solution without excess oxidizers a gram of SMB precipitates circa a gram of gold.
10. What is the color of your AR? If it was pure gold chloride it would be yellow or orange. With some copper in it you would have pale neon green.
11. Was there any undissolved metals left? It would cement gold and rob the AR of any gold in solution.
12. Have you tested your AR yet? Why not, I wrote it a couple of paragraphs above. It's important to test so you know where the gold is. So important that I write it twice!
Oh, almost forgot, welcome to the forum. You will see that the expertise here is second to none on the internet. Be humble and you will see it pays out in the end.... often with a small golden button. 8)
Göran
1. I strongly suggest that you take the guided tour of the forum, look at the signature of Lazer Steve. Follow every link and read the topics they cover. That will show you a lot of the processes we recommend here on the forum.
2. How much material did you start with? Maybe you did precipitate your gold but it was so little you couldn't see it.
3. How do you know you have gold in solution? Look up testing with stannous chloride and come out of the dark.
4. How do you know the stuff you got after adding ammonia to the AR is gold? Have you tested it or melted it? To me it sounds more like iron hydroxide. From a dirty solution as yours I would suspect a very black precipitate of gold.
5. The reaction between HCl and SMB that you wrote down creates SO2. That is the reactant that precipitate gold. You would have known it if you had read Hoke or the forum.
6. You claim to be a chemical engineer but makes a rookie mistake as "added a SMALL amount of ammonia to the AR solution in order to lower the pH". Ammonia would increase the pH. Maybe it was a honest mistake but it doesn't bring credibility to your other claims. We get a lot of newbies here, claiming a lot but soon the truth is revealed. As one of the moderators have in his signature "You are what you write!"
7. When digesting base metals (or silver) dilute it to half strength, it works better if it isn't concentrated.
8. There is no silver nitrate in AR solution, it will form a precipitate of silver chloride and only trace amounts will be left in solution.
9. From a gold chloride solution without excess oxidizers a gram of SMB precipitates circa a gram of gold.
10. What is the color of your AR? If it was pure gold chloride it would be yellow or orange. With some copper in it you would have pale neon green.
11. Was there any undissolved metals left? It would cement gold and rob the AR of any gold in solution.
12. Have you tested your AR yet? Why not, I wrote it a couple of paragraphs above. It's important to test so you know where the gold is. So important that I write it twice!
Oh, almost forgot, welcome to the forum. You will see that the expertise here is second to none on the internet. Be humble and you will see it pays out in the end.... often with a small golden button. 8)
Göran
For me it is the opposite, it almost always fizzes when I add SMB to my gold chloride. I have found it is easier to drop gold from a solution with quite a lot of HCl.solar_plasma said:
The one time I had problem to get a reaction was when I had gold chloride dissolved in water. It refused to drop until I added a bit of HCl. Then it precipitated instantly.
Having too much HCl isn't good either, then the SMB turns into gas too fast and leaves as SO2 bubbles without reducing the gold chloride to elementary gold.
Look at this picture, you can see how bubbles moves up through the gold chloride and making brown tracks until the SO2 runs out. I add SMB as a saturated water solution. I really liked how this precipitated. 8)
Göran
solar_plasma
Well-known member
@göran
I have to try this tomorrow. I have always lots of HCl and it never fizzed.....- only once, when I had about 3 ml excess nitric in 250 ml HCl (can't remember concentration). First it fizzed, then additional smb didn't fizz.
...maybe concentration or temperature make the difference? I use mostly 25% HCl, mostly cold and often a bit more dilluted when I precipitate
I have to try this tomorrow. I have always lots of HCl and it never fizzed.....- only once, when I had about 3 ml excess nitric in 250 ml HCl (can't remember concentration). First it fizzed, then additional smb didn't fizz.
...maybe concentration or temperature make the difference? I use mostly 25% HCl, mostly cold and often a bit more dilluted when I precipitate
solar_plasma
Well-known member
goldsilverpro:
Since he has urea in his AR, how is that solution treated safely? Have I understood right, that dried solids from it, are a problem?
Since he has ammonia in his AR, given it is pregnant with gold, have I understood right, that is it safe only as long as the solution is under pH7? And if so, shouldn't the gold be cemented out, before the solution is treated as waste?
Since he has urea in his AR, how is that solution treated safely? Have I understood right, that dried solids from it, are a problem?
Since he has ammonia in his AR, given it is pregnant with gold, have I understood right, that is it safe only as long as the solution is under pH7? And if so, shouldn't the gold be cemented out, before the solution is treated as waste?
I haven't tested exactly where the limit is between fizz and no fizz concentration wise, but some water added turns off the fizzing to manageable amount. It could also be depending on other dissolved gases and minerals, I use tap water to everything. For example, I live in a place without chloride in the tap water, I can mix it with silver nitrate without slightest clouding. :mrgreen:
Göran
Göran
A
Anonymous
Guest
Goran (sorry please tell me the key stroke to set the O properly?) that's a very lucky place to be in many ways.
I daren't use tap water in the UK if I'm doing anything with Nitric or silver at all mate.
I daren't use tap water in the UK if I'm doing anything with Nitric or silver at all mate.
Pantherlikher
Well-known member
That was the reason for my asking how he disposed of the solution. Neutrilized? how? It's well writen in the forum as to how which drops anything and just about everything in solution giving you Salt water and solids.
You may have tossed the baby out with the bath water as I've heard described.
A test would have told you exactly where your gold was.
A good analyticle chemist would have the proper procedures and tests required to make sure the results were correct and have an understanding of what happened. To see if reality is exactly as formulated.
For instance what does Nitric acid dissolve? And what does it not dissolve and why?
B.S.
...most times humility is very hard to swallow but is worth the price to be humbled enough to follow guidance...
You may have tossed the baby out with the bath water as I've heard described.
A test would have told you exactly where your gold was.
A good analyticle chemist would have the proper procedures and tests required to make sure the results were correct and have an understanding of what happened. To see if reality is exactly as formulated.
For instance what does Nitric acid dissolve? And what does it not dissolve and why?
B.S.
...most times humility is very hard to swallow but is worth the price to be humbled enough to follow guidance...
solar_plasma
Well-known member
What makes me wonder is, ...the fizzing stopped right after about 3g smb (well I always say smb, but I use potassium MB)
I have to try, if the fizzing appears in a HCl, which is too dilluted for fizzing, if there is nitric in it...
I have to try, if the fizzing appears in a HCl, which is too dilluted for fizzing, if there is nitric in it...
solar_plasma
Well-known member
(sorry please tell me the key stroke to set the O properly?)
type:
[alt] 148
the numbers have to be typed on the number block
http://www.irongeek.com/alt-numpad-ascii-key-combos-and-chart.html
type:
[alt] 148
the numbers have to be typed on the number block
http://www.irongeek.com/alt-numpad-ascii-key-combos-and-chart.html
A
Anonymous
Guest
Cheers Göran (Akk sorry cheers plasma!)
Appreciate it. Sorry for the hijack guys. Thread back on track.
Jon
Appreciate it. Sorry for the hijack guys. Thread back on track.
Jon
Pantherlikher said:
You have to give me more details. What do you want to know how to neutralize? What concentration do you have? How do you want to dispose of it? Etc.
Perhaps you should read a general chemistry book. I would advise steping away from the chemicals until you have a firm understanding of how to properly neutralize and dispose of waste chemicals or else you might as well look up "Ways to hurt yourself" on Youtube...
A
Anonymous
Guest
cfoster78 said:
Really?
The guys here are trying to help, and you're kicking it back in their teeth. You're behaving like a spoiled child.
I figured that was how everyone talked to one another/treated each other on this board since that is how I was spoken to when I typed my first question as a new member on this site. I was simply trying to fit in with the crowd...
Although I must say, a few people actually were very helpful without any negative comments. To those people I say thank you - I really appreciate your insight.
Although I must say, a few people actually were very helpful without any negative comments. To those people I say thank you - I really appreciate your insight.
