# SUCCESSFULLY PAST HOKE PAGE 44 - THEN A BUMP



## INDY864 (Sep 19, 2011)

After two evaporations to remove the nitric, filtering, raising the ph to 1.0, I was really siked. I had a beautiful golden brown solution. I studied the handbook online, and Steve's video. I added the SMB. It turned black. Then it turned back to the golden brown. Then nothing. It didn't drop.
Should I slowly reheat the solution to concentrate it and add more SMB? Kinda stuck.


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## martyn111 (Sep 19, 2011)

Sounds like you still have oxider in your solution, re dissolving the gold as it precipitates.


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## Geo (Sep 19, 2011)

yep. you still have free nitric acid in your solution.


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## INDY864 (Sep 19, 2011)

Wow! 2 evaporations, urea, and SMB, and still got Nitric.
Thanks guys. Back to work. 
Evaporate again or first try more SMB?


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## Geo (Sep 19, 2011)

you can neutralize nitric with smb but it will take much more than necessary. did you test to make sure you have gold in your solution? nitric acid boils at 121 degrees C, just cover your glass pot with a watch glass or i have found a glass dinner plate works good too untill the solution gets thick and no more NOx fumes are present.


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## Harold_V (Sep 20, 2011)

Geo said:


> you can neutralize nitric with smb but it will take much more than necessary. did you test to make sure you have gold in your solution? nitric acid boils at 121 degrees C, just cover your glass pot with a watch glass or i have found a glass dinner plate works good too untill the solution gets thick and no more NOx fumes are present.


Covering to evaporate is counter productive. The point is to evaporate, not evaporate and condense. 
Evaporation should be conducted at a temperature below a boil, so values are not lost. It's all in Hoke. 

Harold


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## Palladium (Sep 20, 2011)

Do you have any urea? Even if you don’t use it for neutralizing the excess nitric you can still use it for testing purposes. After you evaporate your solution down and add more hcl you can add a peril of urea and if you observe fizzing you still have free nitric.


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## Geo (Sep 20, 2011)

Harold_V said:


> Geo said:
> 
> 
> > you can neutralize nitric with smb but it will take much more than necessary. did you test to make sure you have gold in your solution? nitric acid boils at 121 degrees C, just cover your glass pot with a watch glass or i have found a glass dinner plate works good too untill the solution gets thick and no more NOx fumes are present.
> ...


maybe thats why i could never get it to work right for me. it would eventually evaporate but it took forever. thanks for clearing that up.


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## INDY864 (Sep 20, 2011)

Thanks guys,
I am dealing with a small amount of gold I am refining from mining. It is very pure. I have had a reaction that puzzles me.
After adding SMB, the liquid turned black, then brown, then light brown, then 14 hours later to a pale lime green.
Does anyone have any input?


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## eeTHr (Sep 20, 2011)

INDY---

If nothing but gravity separated gold is dissolved in aqua regia, and SMB is added, there is nothing in there which will produce all those strong colors.

:?:


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## INDY864 (Sep 20, 2011)

eeTHr,
Sorry man, I don't follow you. It's like the SMB bleached out the color. And the gold vanished. I know that's not the case.


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## eeTHr (Sep 20, 2011)

Indy---

Oh, I thought you said that after dissolving the gold, your solution was a golden brown. If you had just, as you described it, "very pure gold" dissolved, your resultant solution should be yellow or, if lots of Au, orange. With a little contamination, maybe light brown.

After adding SMB, the solution should go from yellow or orange, to clear, and there should be tan power on the bottom of the container. With a _*little*_ contamination, the solution could be greenish or bluish or brownish, but it should be light colored and transparant.

Those dark colors you described don't sound right, if you started with "very pure gold," and real SMB.

What was the actual color of your dissolved solution, and how transparant was it?

Is your SMB sodium metabisulf_ite_ or sodium metabisulf_ate_?


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## eeTHr (Sep 20, 2011)

Indy---

Sorry, I guess the "black" threw me. I just reread, and see that it ended up "pale lime green."

You can simply hang some solid copper into the solution, and cement out all the PMs, then refine it over again, limiting the amount of nitric this time. That would be a good way of getting sight of your gold again, so it's not "lost."

Let it sit overnight, then test the solution with stannous chloride. If any PMs are still in solution, decant the solution and leave the copper hanging in it for a week or so. In the meantime, you will have your gold in solid form, to prove it's not "gone."

If you actually started with gold ore, you should probably do this as step one, anyway, as a recovery process, then refine the powders.


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## INDY864 (Sep 21, 2011)

eeTHr said:


> Indy---
> 
> Sorry, I guess the "black" threw me. I just reread, and see that it ended up "pale lime green."
> 
> ...


Thanks eeTHr,
Hoke says on page 45 that the gold solution, if mainly gold, is a yellowish brown. That is what I am going by. I just got my tin wire to make stannous chloride. i don't mind doing stupid stuff if I am learning. I think I am dealing with too small a gold result. I have saved my nitric wash. I started 2 threads by mistake. I did a hcl, water 3 times, nitric, water 3 times, wash then A/R. BUT I KEPT THE NITRIC WASH! Figured I might lose some gold in the wash. (My ADD is kicking in).
All that said, I am going back and starting to test everything with stannous chloride. I had ordered some tin wire from Israel. I got started without the tin and I paid for it. BUT the learning is priceless. Oh Yeah, the SMB is SULPHITE.
indy


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## eeTHr (Sep 21, 2011)

Indy---

Since this has evolved from a refining problem into a recovery problem, you would probably be best helped if you posted in the Prospecting, Mining, Ore Concentrates & Geochemical part of the MINING & METAL DETECTING section of this forum.

There are some very knowledgeable people who could help you with your initial recovery from the ore, which can be very different from refining processes.


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## INDY864 (Sep 21, 2011)

eeTHr said:


> Indy---
> 
> Since this has evolved from a refining problem into a recovery problem, you would probably be best helped if you posted in the Prospecting, Mining, Ore Concentrates & Geochemical part of the MINING & METAL DETECTING section of this forum.
> 
> There are some very knowledgeable people who could help you with your initial recovery from the ore, which can be very different from refining processes.


Thanks! I never thought of that. That's exciting. THANKS AGAIN!


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## Harold_V (Sep 21, 2011)

Geo said:


> Harold_V said:
> 
> 
> > Geo said:
> ...


If you understood the level of contempt I have for people that discuss evaporation by speaking of BOILING, maybe you'd rephrase your comments. 

Why in hell do you suppose people keep evaporating too fast? Could it be because people like you insist on talking about boiling, when they shouldn't be?

Can you say **evaporate**?

Harold


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## Geo (Sep 21, 2011)

done.


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## Harold_V (Sep 22, 2011)

Thank you. 

I strive for the use of proper terminology on this forum. When falsehoods are repeated endlessly, those that don't think clearly assume that what they read can be taken literally. That creates a never ending source of people that have the same problems, time and again, and it could all be eliminated by people giving proper instructions at the outset. 

None of us are perfect, in particular, me, but we all must strive for excellence in conveying our messages, otherwise no one benefits. 

If you must use evaporate and boil in the same sentence, they should be separated by the words *DO NOT*.

Harold


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## INDY864 (Sep 22, 2011)

Harold_V said:


> Thank you.
> 
> I strive for the use of proper terminology on this forum. When falsehoods are repeated endlessly, those that don't think clearly assume that what they read can be taken literally. That creates a never ending source of people that have the same problems, time and again, and it could all be eliminated by people giving proper instructions at the outset.
> 
> ...


harold,
You took me to task several months ago about boiling. I have taken it to heart. However I have made the mistake of leaving the sample on what I thought was a low temp only to find it boiling. I get confused with LazerSteve's video. He boils his solution. But it's not Nitric or A/R. He does boil HCL. I'm learning not to boil regardless.
INDY


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## goldsilverpro (Sep 22, 2011)

Some thoughts on boiling.

In thinking back, there are certain things I boiled. Also, Harold has mentioned that he boiled certain things, although I can't remember what. 

As a general rule, I never boil anything in which any values are dissolved, since there could easily be losses in the vapors. On the other hand, if I am leaching out base metals away from the values, I think it's usually safe to boil. 

For example, I used to run a lot of 10K class rings in 4 liter beakers. I found that, in reality, most were closer to 9K, and I could leach out the silver and base metals with nitric acid. This was easier and faster than inquarting or dissolving directly in AR. However, this nitric dissolving went slowly. To speed this up, I used a fairly strong nitric, about 2/3, by volume, and boiled the solution. After a couple of hours, I had a fairly pure gold sponge, still in the perfect shape of the original class rings - I could still read the words and see the emblems on the brown ring. When I probed the gold rings with a stir rod, they fell apart. If I felt any solid portions, I continued the nitric. Then, I poured off the nitric, rinsed a couple of times, and easily dissolved the gold sponge in AR. I'm sure I lost a little silver in the vapors but, it wasn't much and, at that time, silver was low and I wasn't that concerned about it. 

Another place I often boiled, especially with small quantities, was when dissolving Kovar away from gold plate and gold braze on IC package lids or when dissolving the base metals away from the gold on entire all-gold CPU packages. Kovar dissolves slowly and boiling really speeds it up and insures 100 dissolution.

I also have boiled when leaching gold-filled with nitric. 

In any case, when I did boil, I always covered the container. With beakers, I used watch glasses. If I had no watch glasses, non-porous acidproof and heatproof saucers from the kitchen are of similar shape and they worked almost as well. When boiling, I first covered the material with water, heated it below the boiling point, and then added the nitric in increments, small ones at first. After it got going well, I increased the temperature. This, along with not running too much material at one time, helps prevent boilovers.

This whole thing about boiling or not boiling depends on the situation (and, sometimes, the equipment available). In some cases, it's OK and even desirable. In other cases, you should never do it. It reminds me of the rule, "Never add water to acids. Always add acids to water." With very concentrated acids, such as concentrated sulfuric, you must ALWAYS follow this rule. If you add the water to the acid, it will immediately heat up at the point of entry, turn to steam, and splatter acid in your face. Even when you properly add the sulfuric to the water and make up a 50/50 sulfuric solution, it will get close to the boiling point. However, with less concentrated acids, such as 70% nitric or 32% hydrochloric, it is perfectly safe to add the water to the acid, as anyone doing this for awhile knows. All of these things require knowledge, though, and you should definitely follow the general rules until you have enough experience to know what you are doing.


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## eeTHr (Sep 22, 2011)

An AR solution will have a higher boiling point temperature because of the nitric. So, if you are evaporating at a heat above the boiling point of water/HCl, as the nitric evaporates out, the boiling point will be lowered to that of water/HCl at some point. At that point, the water will suddenly turn to steam at the hottest places in the beaker. This creates a series of small explosions which toss solution out of the beaker. It gets very messy, and you can lose a lot of solution directly.

After precipitation, when there is no _*dissolved*_ gold, boiling during the washes is recommended, however. With the gold in solid form, none is lost in vapors, and boiling also agglomerates the gold and makes it easier to decant. That's one that Harold mentioned recently.

I've also seen it stated that platinum is usually dissolved in boiling AR. I've only had small amounts of it, from cementing all values, which took longer to dissolve in warm AR, than the rest.


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## INDY864 (Sep 22, 2011)

GREAT STUFF, GENTLEMEN! THANKS!


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## Harold_V (Sep 23, 2011)

goldsilverpro said:


> Some thoughts on boiling.
> 
> In thinking back, there are certain things I boiled. Also, Harold has mentioned that he boiled certain things, although I can't remember what.


Virtually everything! But *NEVER* when evaporating. 
Heat is normally your friend where chemical reactions are concerned. I've commented I don't understand how some of these guys get anything done, relying on ambient temperatures for processing. You can't tell when acids are spent, and what should take 15 minutes takes a day to accomplish. I'd have gone broke immediately had I not used heat in refining. 

Some functions _demand _ boiling---such as processing polishing wastes after incineration. Without boiling, the material settles to the bottom and fuses to the beaker. Keep it boiling and it stays in suspension. 

Watch glasses. Always, except when evaporating. 

Harold


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