Odd reaction in AR process

[RicXX]

Hi all I don't post much but that doesn't mean I dont follow other posts and processes. Yes read Hokes book, twice and refer to it when I forget or make a mistake. This I do not have an answer for.

Situation, Stripped several pounds of gold plated pins (new old stock) with sulfuric acid process. Cleaned out the powder and washed with distilled water and HCL. Filtered the black powder and added to pot. Fresh HCL added and brought to a boil, Nitric added drop by drop till mixture turns that nice yellowy clear color. Let it cool, filtered any left over debris, washed down the filter with distilled water, then added an equal volume of distilled water to the liquid. (Note, I have done this several times in the past) This is where it goes odd...

The liquid turns milky yellow, and a white powder starts forming on the bottom of the beaker. Attempt to filter again same result but white powder also in the filter. Testing shows gold in solution still, but not sure what this white chloride looking stuff is. I thought maybe silver chloride? but why would it only show up after I added distilled water? Yes I checked twice that it is distilled water in my container, I am careful about cross mixing containers and even spray bottles.

Question is then what could this white powder be?
Am I safe to add SMB or should I wait and try and filter all the powder out?
Should I try another process?

This is my final lot from this batch of pins, the rest went smoothly and yielded good results. I clean everything between batches, All chemicals and distilled are fresh, no more than 6 months old.

Any assistance and thoughts are welcome.

Thank you

 

[RicXX]

I dont post much... wow that was my first post...

 

[FrugalRefiner]

A small amount of silver chloride can dissolve in a concentrated AR solution. When you dilute the solution, the silver chloride can precipitate. Other possibilities would be copper, lead, tin or mercury chlorides.

Filter the solution till it's clear before your precipitate the gold.

Dave

 

[RicXX]

Thank you FrugalRefiner,

I have not encountered it before with the other pins I have done, half of this batch were only half gold plated so possibly the other portion were silver plated.

The golden liquid is now a pale lime green, I will filter it out a few times to be sure there are no chlorides or particles left before adding SMB.

Note for others reading this, I have been doing silver for the better part of the year, and collecting what gold I get into a bin. The pins came from someone else who wanted to find out the yield per pound. So far I have been averaging about 1.1g per pound of pins processed and I will post my final results once this batch is done (and include pictures).

Ken

 

[Palladium]

Being as how this is the first drop and coming from a sulfuric cell it should only take one drop to get 995 this is an alternative method. When I do gold filled it takes 2 ar drops to get it all cleaned up because of how trashy gold filled can be. You want to experience every metal under the sun run you a good large batch of gold filled. On the first drop if I have chlorides or anything for that matter that keeps coming through the filter I just drop it all any. On the 2nd ar drop it will all be cleaned up. I say drop it and run it again instead of chasing your tail with filtering. I've dropped many of solutions with junk floating around on top of the beaker including bugs. It all gets redissolved anyway.

 

[RicXX]

It was only 1.8 liters, so filtering only took half an hour (Gravity feed). Im only doing this for hobby sake and not income, its fun as hell! I have a good full time career and though it would be good fun and profitable to do this full time I couldent trust a viable supply of PM's to support myself. After it was clear, once through the filters, I added some more distilled and no reaction, so I dropped it with SMB. Looking good so far, tomorrow after work I will filter what I have. I also am running concurrently the entire batch of filters I have used for gold processing, it didnt have the reaction with the "silver chlorides", that could be cause its all trapped in the pulped filters. It took more SMB to get it to drop, probably cause I had added more nitric to dissolve the filters than was needed, but looking good so far.

Thank you for all your help, I do plan on making a couple posts about my set up, results and pass along some helpful hints for Canadians.

 

[RicXX]

Well that was a little bit ago, but I am finally back home, work had me out of the country and very busy right up till Dec 24. A couple days rest to visit with family over the holidays and right back to work.

I ran the process again if I remember correctly and came out with some nice gold in the end, attaching some pictures...









As you can see the original material was probably about 4 lbs (I thought I took a picture of it guess not doh) and the results were 5.8g after double processing and washing. That works out to 1.45g per pound! The odd part was the difference in color between the solutions, they came from the same batch! both in new clean beakers, I just split the original solution between the two and before dropping it (starting beaker would not fit under my protection box outside, and fume hood was in use) From what I gather my results were uncommon and it was real good material to work with. I got intouch with the guy who provided the pins to get more when I got back as he had said there was about 200lbs of this stuff but sadly he says that they are unassailable any more. Ah well back to searching for material to play with... Almost out of silver now too, only a couple of KG left.....

 

[beav3r316]

Hi all I don't post much but that doesn't mean I dont follow other posts and processes. Yes read Hokes book, twice and refer to it when I forget or make a mistake. This I do not have an answer for.

Situation, Stripped several pounds of gold plated pins (new old stock) with sulfuric acid process. Cleaned out the powder and washed with distilled water and HCL. Filtered the black powder and added to pot. Fresh HCL added and brought to a boil, Nitric added drop by drop till mixture turns that nice yellowy clear color. Let it cool, filtered any left over debris, washed down the filter with distilled water, then added an equal volume of distilled water to the liquid. (Note, I have done this several times in the past) This is where it goes odd...

The liquid turns milky yellow, and a white powder starts forming on the bottom of the beaker. Attempt to filter again same result but white powder also in the filter. Testing shows gold in solution still, but not sure what this white chloride looking stuff is. I thought maybe silver chloride? but why would it only show up after I added distilled water? Yes I checked twice that it is distilled water in my container, I am careful about cross mixing containers and even spray bottles.

Question is then what could this white powder be?
Am I safe to add SMB or should I wait and try and filter all the powder out?
Should I try another process?

This is my final lot from this batch of pins, the rest went smoothly and yielded good results. I clean everything between batches, All chemicals and distilled are fresh, no more than 6 months old.

Any assistance and thoughts are welcome.

Thank you

Silver Chloride tends to settle out of solutions better when they are cold and dilute, as silver chloride is only readily soluble in ammonia solutions (don't do it, read steve's post about his flaming filter)

One solution tests positive with stannous? one not? ...going to guess that the greenish tint one is the one that is negative..?

Have you added any sulfuric acid to your pregnant AR solution to drop lead as lead sulfate before precipitation?


EDIT:

last question:
Are those pins in your picture already ran? I am assuming yes, since they are labeled "tailings"

How did you rinse those off? or did you only rinse the black powder from the cell itself?

They look to me (I don't know jack though, in the grand scheme of things..) that they are still presently holding gold on them...in its original plate, and in black crud.

 

[RicXX]

I do believe that the photos of the 2 beakers was the day after the drop, though I dont 100% remember. That was the same batch, just odd how they came out 2 different colors, both tested negative after letting them settle for a few days (but the color stayed the same) I added them to my "gold" stock bottle and added some more SMB, that sat the entire time I was away and a nice powder was formed on the bottom, filter it all out, (use this as a carboy wash fluid and got another gram out of all that I had processed... I did eventually get all the white out into a dense wine filter, that is in my filter bucket...

Yes I still have the pins, yes they look like that and I too think there is still more to be reclaimed from them. Im thinking they might be heavy on the copper side of things so was thinking of dropping a batch into some nitric and see what happens, then another batch in HCL and watch what happens... see if I can squeeze another gram out of whats left!

Wish I could get enough material to do this full time, I really enjoy it! Alas my FT Career I enjoy too, and there is the added benefits that come with it... Maybe when I retire... Thats a lot of time to study and get a second education... (ok 5th or 6th in my case lol but who is counting)

 

[beav3r316]

Ive read another thread where this was the case...

They had a large ar reaction, then split it up into two (new and clean) beakers. Then began their precipitation.

Just another question or two.

Before you began to reduce the gold in solution, did you happen to denox the solution?

Just my thought, (waiting on my coffee to percolate...yeah, I'm old school...use the recalled corningware and all...its beautiful to me)... What if- when you poured the solution into 2 beakers one of them happened to get very little left over HNO3 and the other got the majority of it? ...
**I'm not sure if this is possible** but, could it have allowed the leftover nitric to go to one beaker only, possibly through separation from its specific gravity difference from the HCL?... Again, just a thought..

I'll look to find that thread, and I'll look up a couple things in my CRC reference book just to satisfy the curiousity... Maybe one of our professional science guys can shed light before i can put it together piece by piece.

I only thought extra nitric because after another addition of precipitant the solution reduced another gram of gold... ...and that yellow solution... It looked oh so pretty (color means nothing though unless its the purple of cassius in a stannous test)

 

[Barren Realms 007]

Ive read another thread where this was the case...

They had a large ar reaction, then split it up into two (new and clean) beakers. Then began their precipitation.

Just another question or two.

Before you began to reduce the gold in solution, did you happen to denox the solution?

Just my thought, (waiting on my coffee to percolate...yeah, I'm old school...use the recalled corningware and all...its beautiful to me)... What if- when you poured the solution into 2 beakers one of them happened to get very little left over HNO3 and the other got the majority of it? ...
**I'm not sure if this is possible** but, could it have allowed the leftover nitric to go to one beaker only, possibly through separation from its specific gravity difference from the HCL?... Again, just a thought..

I'll look to find that thread, and I'll look up a couple things in my CRC reference book just to satisfy the curiousity... Maybe one of our professional science guys can shed light before i can put it together piece by piece.

I only thought extra nitric because after another addition of precipitant the solution reduced another gram of gold... ...and that yellow solution... It looked oh so pretty (color means nothing though unless its the purple of cassius in a stannous test)

Not very likely that there would be any separation as you are suspecting. It would be equal to taking some blue food coloring solution and putting it into a container putting water in the container and then adding some yellow food coloring and expecting them not to mix. Heating and cooling of the solution even from the sun causes minor turbulance in the solution causing it to mix. But that is not to say that the ratio will not change in the solution from the top to the bottom if there are metals that are being processed in the solution.

 

[beav3r316]

Not very likely that there would be any separation as you are suspecting. It would be equal to taking some blue food coloring solution and putting it into a container putting water in the container and then adding some yellow food coloring and expecting them not to mix. Heating and cooling of the solution even from the sun causes minor turbulance in the solution causing it to mix. But that is not to say that the ratio will not change in the solution from the top to the bottom if there are metals that are being processed in the solution.

I agree, that it would be VERY unlikely that it could happen. But, in your analogy of the colored dyes, they would be the same gravity (I assume)...and while the SG of HCL and HNO3 is only slightly different, different they are, none the less.

I only brought it up, because it is the only rational explanation that I could even begin to conjure up.

Once the acids are mixed and are each doing their part to dissolve gold, I would consider them to be homogeneously mixed.. After the gold is done dissolving, the solution has been filtered, and it begins to cool. Would the percentage of water contribute to the dilution of the HCL first? or the HNO3 first?... or would it be an equal split?

The differences in the SG of acids would only be about .4 at most (that is just a ball park, depending on concentration, and temperature) Seems to be VERY small, but the difference in oil and water can be even smaller than that.
http://www.engineeringtoolbox.com/specific-gravity-liquid-fluids-d_294.html

I am very curious as to why this is really happening... I do not know the answer, and I was just throwing out ideas as to why this could have happened.

My ideas are also going under the assumption that the same amount of precipitant was added to each beaker, and the same amount of distilled water was in each one also.

I also have no idea on what % difference in specific gravity can lead to a separation of constituent compounds, and how much of a role it plays in separation in addition to the viscosity of the chemicals involved

http://www.handymath.com/cgi-bin/nitrictble2.cgi?submit=Entry

Just wanting to spur some thought, and maybe get this gentleman some answers...
and of course, satisfaction of my own curiousity

 

[Barren Realms 007]

Not very likely that there would be any separation as you are suspecting. It would be equal to taking some blue food coloring solution and putting it into a container putting water in the container and then adding some yellow food coloring and expecting them not to mix. Heating and cooling of the solution even from the sun causes minor turbulance in the solution causing it to mix. But that is not to say that the ratio will not change in the solution from the top to the bottom if there are metals that are being processed in the solution.

I agree, that it would be VERY unlikely that it could happen. But, in your analogy of the colored dyes, they would be the same gravity (I assume)...and while the SG of HCL and HNO3 is only slightly different, different they are, none the less.

I only brought it up, because it is the only rational explanation that I could even begin to conjure up.

Once the acids are mixed and are each doing their part to dissolve gold, I would consider them to be homogeneously mixed.. After the gold is done dissolving, the solution has been filtered, and it begins to cool. Would the percentage of water contribute to the dilution of the HCL first? or the HNO3 first?... or would it be an equal split?

The differences in the SG of acids would only be about .4 at most (that is just a ball park, depending on concentration, and temperature) Seems to be VERY small, but the difference in oil and water can be even smaller than that.
http://www.engineeringtoolbox.com/specific-gravity-liquid-fluids-d_294.html

I am very curious as to why this is really happening... I do not know the answer, and I was just throwing out ideas as to why this could have happened.

My ideas are also going under the assumption that the same amount of precipitant was added to each beaker, and the same amount of distilled water was in each one also.

I also have no idea on what % difference in specific gravity can lead to a separation of constituent compounds, and how much of a role it plays in separation in addition to the viscosity of the chemicals involved

http://www.handymath.com/cgi-bin/nitrictble2.cgi?submit=Entry

Just wanting to spur some thought, and maybe get this gentleman some answers...
and of course, satisfaction of my own curiousity

Unless he has done this in a analytical lab with precise measurements of ml and g used in each container it is just a guess like throwing a horse shoe.

Do try to over think things. just learn from the experience in what you might need to do.

 

[beav3r316]

Unless he has done this in a analytical lab with precise measurements of ml and g used in each container it is just a guess like throwing a horse shoe.

Do try to over think things. just learn from the experience in what you might need to do.

Yea, not very likely that THAT amount of precision is in this case, but my over-thinking is a very bad, or good habit (depending on who you ask).

Just trying to engage others in productive discussion to find the source, or cause, of why this may have happened.

I have read about others having the same problem on the forum once or twice, but i have yet to find the right bookmark on my phone, tablet, or desktop...still have my laptop to look through.

I wasn't trying to give the implication that without an incredible level of precision that his question is null and void, I was just trying to share my thoughts as to what may be happening, so that others may do the same. And, possibly together, we could give him his resolution as to "why?"

Sorry if i unwittingly derailed this thread, it was not my intent.

 

[Barren Realms 007]

Unless he has done this in a analytical lab with precise measurements of ml and g used in each container it is just a guess like throwing a horse shoe.

Do try to over think things. just learn from the experience in what you might need to do.

Yea, not very likely that THAT amount of precision is in this case, but my over-thinking is a very bad, or good habit (depending on who you ask).

Just trying to engage others in productive discussion to find the source, or cause, of why this may have happened.

I have read about others having the same problem on the forum once or twice, but i have yet to find the right bookmark on my phone, tablet, or desktop...still have my laptop to look through.

I wasn't trying to give the implication that without an incredible level of precision that his question is null and void, I was just trying to share my thoughts as to what may be happening, so that others may do the same. And, possibly together, we could give him his resolution as to "why?"

Sorry if i unwittingly derailed this thread, it was not my intent.

You are fine, no harm done.

 

[RicXX]

Wow, Im happy to give people an idea that spurs the imagination of thought! When I talked about this thread with my girlfriend she reminded me that I used the last of my SMB into one beaker and fresher SMB into the other... Would probably explain the difference in colour.

Gold still dropped and the second time through there was only one beaker and it was that awesome crystal clean orange!

I love this stuff, my father was a chemical engineer and I never thought the stuff I learned sitting on his knee would excite me so! Im sure though that if I did this type of stuff for work I would get bored... As it is I love the travel of my job, I get to see all sorts of places, and see all sorts of things!

 

[Harold_V]

When I do gold filled it takes 2 ar drops to get it all cleaned up because of how trashy gold filled can be.

That was my experience, too, but I developed a work-around that eliminated the problem. I've talked about it before, but I'm going to make mention again.

Once the base metals have been eliminated, the solids ended up in a filter, which I incinerated. After incineration, I gave the resulting solids a wash in hot HCl (boiling, with a watch glass covering). This removes all manner of troublesome constituents, and results in a nice, clean gold chloride solution when dissolved after rinsing well. The nice part is, any traces of tin that may have been present (not uncommon with gold filled material) is eliminated, so the resulting gold chloride solution filters exceedingly well.

One more thing. After the hot HCl wash, the solution settles quite well, and rapidly. In the long haul, this operation saves more time and effort than it costs.

Harold

 

[kurtak]

When I do gold filled it takes 2 ar drops to get it all cleaned up because of how trashy gold filled can be.

That was my experience, too, but I developed a work-around that eliminated the problem. I've talked about it before, but I'm going to make mention again.

Once the base metals have been eliminated, the solids ended up in a filter, which I incinerated. After incineration, I gave the resulting solids a wash in hot HCl (boiling, with a watch glass covering). This removes all manner of troublesome constituents, and results in a nice, clean gold chloride solution when dissolved after rinsing well. The nice part is, any traces of tin that may have been present (not uncommon with gold filled material) is eliminated, so the resulting gold chloride solution filters exceedingly well.

One more thing. After the hot HCl wash, the solution settles quite well, and rapidly. In the long haul, this operation saves more time and effort than it costs.

Harold

Harold - you are so spot on with this advice that I really don't understand why in the world anyone with any real experience refining would ever skip this step --- this is one of the first things I learned (from you) after I joined the forum 5 years ago - I NEVER skip this step & do it EVERY time I am working with foils "of any kind" --- the result is "almost" with out exception a clean & heavy (settles in an hour or less) gold drop on the "first" AR run - if there should be a "slight" contamination it is normally so slight that it can be eliminated with a "small" pinch of potassium nitrate on the molten gold during the melt

The only thing I can add to your words of wisdom is that if you are dealing with "heavy" foils - the kind that retain the shape of the original object as a shell & float because they trap air - is to before incineration - crush them to break them up so base metals &/or there salts (like stannic tin) that are trapped in the shells get fully exposed to both the heat & air to effect complete oxidation --- in other words - complete incineration (or oxidation roasting)

I have only skipped this step a couple (few) times thinking I could take a short cut &/or thinking these foils look clean enough I don't need to incinerate & HCL treat & I regretted it each time - it resulted in ultra fine &/or colloids that took a day or more to settle which in turn lead to a washing/filtering nightmare of the first drop & even had to go to a third refine to truly clean it up

I think there was like three time back when I was first starting out that I thought I could short cut skip this step - that was enough to convince me to NEVER ever skip this step again - because as you say --- "In the long haul, this operation saves more time and effort than it costs." (there is a period at the end of that sentence)

Kurt

 

[thepickerexchange]

Hi all I don't post much but that doesn't mean I dont follow other posts and processes. Yes read Hokes book, twice and refer to it when I forget or make a mistake. This I do not have an answer for.

Situation, Stripped several pounds of gold plated pins (new old stock) with sulfuric acid process. Cleaned out the powder and washed with distilled water and HCL. Filtered the black powder and added to pot. Fresh HCL added and brought to a boil, Nitric added drop by drop till mixture turns that nice yellowy clear color. Let it cool, filtered any left over debris, washed down the filter with distilled water, then added an equal volume of distilled water to the liquid. (Note, I have done this several times in the past) This is where it goes odd...

The liquid turns milky yellow, and a white powder starts forming on the bottom of the beaker. Attempt to filter again same result but white powder also in the filter. Testing shows gold in solution still, but not sure what this white chloride looking stuff is. I thought maybe silver chloride? but why would it only show up after I added distilled water? Yes I checked twice that it is distilled water in my container, I am careful about cross mixing containers and even spray bottles.

Question is then what could this white powder be?
Am I safe to add SMB or should I wait and try and filter all the powder out?
Should I try another process?

Thank you

This is an old post but resembles my experience today. I knew something went wrong when my solution was fluorescent colored and milky. After searching through the pages of Hokes to find this reaction, then the forum, I’m so glad to find a post regarding it.

I just want to say thanks to everyone’s who shares their support as to how to move forward when something goes sideways.

Mar




Sent from my iPhone using Tapatalk