ph ????

[frosty]

hi all , yes I read hokes book, This is want I did, I got some e gold. then i put it in a flask with hn03 and heated to remove the base metals, then I used urea to neutralize the solutions and filtered and dumped the solution. I than used hcI and did the same thing, then i used smb to drop the gold, but nothing happen??? the solution is green, I know gold is in the solution.
so what did do wrong.????? Thank you for the replys.

 

[Geo]

frosty,

normally i would have already posted a reply but i was waiting to see what you were going to say about testing. you did test with stannous chloride to make sure you had gold in solution, right?

what did the test look like? you said you know you have gold in solution so the test must have been a strong positive?

find the formula for making stannous chloride test solution. make some. test your solution. let us know what the results are and then we will be able to help you.

 

[steyr223]

wow! hu? wait... what did i miss

frosty wrote

" I got some e gold. then i put it in a flask with hn03 and heated to remove the base metals, then I used urea to neutralize the solutions and filtered and dumped the solution. I than used hcI and did the same thing, then i used smb to drop the gold, but nothing happen??? "

i dont see any hci and nitric together or acidl/bleach when u dumped your solution after filtering did you put the hcl into that solution or just by itself

can you nutrralize / denox only nitric? wouldn't that make it not no3?? then when combining with hcl it would not form A/R???

when you say dumped solution what do you mean mind you i am very neww so please forgive me if i really did miss something. :lol:

 

[steyr223]

hay geo
i might be reading this wrong but i think in solution to some one new means theres gold flakes in your a/p solution or nitric.

it took me a while to stop saying this that way

unless he tested but i dont belive he did and i would guess your question means you dont either
:roll:

 

[Geo]

hay geo
i might be reading this wrong but i think in solution to some one new means theres gold flakes in your a/p solution or nitric.

it took me a while to stop saying this that way

unless he tested but i dont belive he did and i would guess your question means you dont either
:roll:

he tried to dissolve everything in AR and now he has metal solids still in solution wondering how to get the gold out of his solution that isnt in solution because it plated out on un-dissolved base metal. (assumption on my part) but what im trying to pass along is he is assuming he has gold in solution even though he says there was still metal un-dissolved. he didnt test to see if there was gold in solution and now has a big discussion going and wants to know how to get his gold back. when he figures out that the solution is barren then we can help him find his missing gold.

 

[Harold_V]

hi all , yes I read hokes book, This is want I did, I got some e gold. then i put it in a flask with hn03 and heated to remove the base metals,

Did you inquart? If not, was the gold greater than 10K, which would be marginal at best, for that type of treatment.

then I used urea to neutralize the solutions and filtered and dumped the solution.

Blink! Blink!

Can you tell us why you did that?

I than used hcI and did the same thing,

Same question. Can you tell us why you did that?

then i used smb to drop the gold, but nothing happen???

What did you expect to happen?

At this point, you have treated the gold improperly in every possible way.

the solution is green, I know gold is in the solution.
so what did do wrong.????? Thank you for the replys.

Can you tell us how you "know" the gold is in solution? Did you test with stannous chloride? If so, what was the result of your test? Can you describe what you witnessed?
When you had finished with your work, did you have any solids remaining? If so, can you describe what you saw?

It is my opinion that you may have gone through Hoke's book, but you learned almost nothing. Please go back to the book and read with the idea of retaining what she teaches. Read it as many times as it takes for you to understand what she's teaching you. You didn't get one thing right.

Harold

 

[freechemist]

Hi 4metals,

Among a lot of other important statements on the use of urea you wrote:

"I think it is time to discuss how urea is used and get all of the opinions aired out all in the spirit of having better informed forum members."

I dislike urea, too, especially for destroying/neutralizing excess nitric acid, simply because I think it doesn't do this job. But still, urea has become a valuable tool for me as an easy to handle, precisely weighable source of ammonia, be it for neutralization of excess acid as a base, or to prepare some important PGM-ammine compounds in a simple, well controlled manner. To me, use of urea is an important theme, and so I propose, to discuss it in a new, separate thread.

Regards, freechemist

 

[freechemist]

Hi Dr. Poe,

In your reply you wrote:

"I address this only to the newbies that want an easy answer to dropping gold at the proper pH.
Once the nitric is dispelled, raise the pH to 1.5 if you were working scrap gold or to 3pH if you are working mine concentrates...."

Especially for newbies, this is false information, which may mislead them into futile and frustrating neutralization-attempts. It is not necessary to raise the pH-value, in order to precipitate gold with SMB. In my own lab- and production-practice this functioned always well, without exception, with solutions containing an average of 50-60 grams of free HCl (about 1.5 moles) per liter, which corresponds theoretically to a negative pH-value, that
means, a value below 0.

Regards, freechemist

 

[Harold_V]

Hi Dr. Poe,

In your reply you wrote:

"I address this only to the newbies that want an easy answer to dropping gold at the proper pH.
Once the nitric is dispelled, raise the pH to 1.5 if you were working scrap gold or to 3pH if you are working mine concentrates...."

Especially for newbies, this is false information, which may mislead them into futile and frustrating neutralization-attempts. It is not necessary to raise the pH-value, in order to precipitate gold with SMB. In my own lab- and production-practice this functioned always well, without exception, with solutions containing an average of 50-60 grams of free HCl (about 1.5 moles) per liter, which corresponds theoretically to a negative pH-value, that
means, a value below 0.

Regards, freechemist

I'm afraid I have to agree. In all of my years of refining, I don't recall ever having to adjust pH before precipitating gold, and I know my solutions always had a serious excess of HCl, so much so that, on some occasions, I'd experience filter failure. I don't recall even one instance of experiencing any difficulties in achieving a complete recovery of values.

Harold

 

[4metals]

I have never adjusted pH before adding urea. In fact the only time I've measured pH of the solution was after the gold was dropped and the barren solution was treated for precipitation of base metals as hydroxides.

Even at this stage of the game the pH starts out at a reading of zero before caustic additions begin.

 

[4metals]

At the request of Freechemist, I have started a thread on the use of urea in the Chemicals
section.

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=48&t=13102

 

[butcher]

I was under the impression that adding urea raised the pH in the reaction with aqua regia,
(I never measured the pH, or tried it so I cannot say for sure this happens).

some how I posted this by mistake (double post),on the new topic 4 metals started, on the subject of useing urea.

 

[samuel-a]

I was under the impression that adding urea raised the pH in the reaction with aqua regia,
(I never measured the pH, or tried it so I cannot say for sure this happens).

some how I posted this by mistake (double post),on the new topic 4 metals started, on the subject of useing urea.

Urea combat the nitric by producing urea nitrate, which is oddly enough an ionic bonded compound and is electrically stable (neutralized) much like any other salt.
I won't even try and pretend i understand in full the chemisty behind this reaction, this info is out of Wiki and this is my understanding of it.

Were you to have only nitric acid solution, obviously, pH will shift up upon adding Urea, but AR, in most cases contain excess of HCl. As long as the free HCl is maintined above 1M, the pH of AR will not budge from zero.

-------

I too never adjust pH for gold precipitation, i guess now the good Dr. will send us all back to the classroom...

 

[Skip55]

Im new to leaching,but I believe I have a good leach.After leaching,I poured off the liquid and I didnt change the PH I used a small amount of zinc and dropped all the other metals.I cut off thin zinc foil with a sissors into the leach and let it sit a short while to separate. Then I poured off the cleared solution that was left from the dropped pgms, silver, and then brought the ph to as close to 7 ph as possible and dropped the gold separately. (added zinc also.) The gold dropped out quickly. Was very simple and was quick to drop.I have not seen the leach I used published anywhere,and it worked on ore that had gold silver,copper produced a green color in the leach.Some of the leach tests on other ore I had was brown with less acid but I found that more acid was needed,wasnt strong enough on cons that were course ground,can see a little gold in my microscope.It well take practice to know how much acid on cons.Skip

 

[Harold_V]

Skip,
I'm having more than a little trouble with the idea that you managed to precipitate silver with zinc, all the while leaving gold in solution.

Are you positive that was the results you achieved?

If so, perhaps someone can explain why it worked as you suggested.

Harold

 

[Meteoriterocks21]

Yes, their oxidation power is decreased @ pH 3. Since they form similar oxy-acids to the thionates, often only cementation
will recover the gold. Even more strange is that they can hold silver chloride in solution along with gold so oxalic acid should only be used for the final refining. On a positive note, titration is often possible (The precipitation of single elements by slow addition of reducing agents like powdered zinc or copper. Hydrogen works well, but is too dangerous for a newbie. A newbie's best bet is to cement all values, roast the precipitate, then re-refine. Dr. Poe 8)

Omgosh thank you... Ive been wondering why I can't precipitate from my disaolves concentrates... Only copper cementation has been working. Is roasting cemented values absolutely neccesarily though? I have no way to roast.

 

[Yggdrasil]

Omgosh thank you... Ive been wondering why I can't precipitate from my disaolves concentrates... Only copper cementation has been working. Is roasting cemented values absolutely neccesarily though? I have no way to roast.

Dr.Poe has not been here since 2015 and will not come back.
Normally it is not neccessary to roast post cementing.
What kind of leaching did you do?