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definitely an oxidation barrier. if you tested and no PM's showed up, i would focus on the recovery of the silver. its not uncommon for heavy copper parts to be coated with a thin coating of silver but its so little its not economical to recover it. im not saying thats what it is, just that if its not gold or a PGM, its not worth worrying about.
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I had the misfortune of splashing a drop of 68% nitric acid directly in my right eye, many years ago. Within seconds of the splash, the surface of my eye was yellow and was shedding. I was near water, so it was rinsed very quickly. I was alone, so I had to drive myself to an ophthalmologist. I was seen immediately.
The ophthalmologist told me how lucky I was that I was working with acid and not lye. I was told that the body can neutralize acid and recover, but had the drop of solution been lye, I would have been blinded in that eye. It can not be neutralized, unlike acid.
Treat lye with considerable respect.
Harold
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1) If you don't use up all the nitric in your AR prior to cementing, the excess nitric will first dissolve some of the metal you're using to cement, but will then progress into the replacement reaction. A small amount of nitric is desirable to get the cementation reaction going, but your goal should always be to use only enough nitric to dissolve your values.
2) heat increases the speed of most chemical reactions, so a warmer solution will generally react more quickly. More important is circulation of the solution. The precious metal ions in the solution you're trying to cement most come into contact with the metal you're using to cement the precious metal. Circulation is more important than heat.
3) In theory, any metal higher in the reactivity series will replace all metals lower in the series, so since silver is more reactive, it should cement gold and the PGMs. However, gold and the PGMs are usually found as chlorides in a solution of HCl. SIlver does not dissolve in HCL. It would likely form an impervious coating of silver chloride on the metallic silver and stop any possible replacement reaction.
I'll elaborate on #3 a bit: gold dissolved by AR means gold chloride is in the solution. silver will indeed 'cement' gold out of solution, but will form silver chloride, which is also a solid, thus not separate the gold and silver and will likely form, as FrugalRefiner said, a layer of silver chloride which will prevent further cementing. The same would happen to PGM in this solution.
Though I hear it is possible to dissolve PGM in nitric alone, and it should be possible to cement this using silver. (as it was explained: if there is a small amount of PGM in an alloy of a large amount of silver, say <5% PGM, then the PGM will get carried along into solution when the silver gets dissolved)
I hadn't considered using silver to cement PGMs from a nitric solution since chemistrycoach originally asked about AR and a "pregnant gold and pgm solution". Gold would not be in a nitric solution, so I only considered a chloride solution.
It seems that I've read a bit about progressive cementation on the forum and that it wasn't quite as clean as it might seem based only on the reactivity series. If I understand correctly, the PGMs get tricky, possibly existing in more than one state and those states can be more or less reactive.
I have had the ability to cement values from dental refining using 325 mesh copper as my source of copper. The reaction is very fast and complete leading to more complete recovery at speeds never imagined.
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with oxy/acet, you run the risk of blowing your gold powder out of the dish. dont attempt a melt without something large enough to catch any that blows out. cut the gas to its lowest possible pressure without the flame popping. you want a slightly reducing flame (more gas,less oxygen). a blue flame a couple of inches long will not hurt. when you melt the borax with a reducing flame, it will turn black from the carbon. dont worry. when the borax reaches a red hot state, it will turn as clear as glass. be sure theres enough borax to coat the entire inner surface but not so much it puddles up in the bottom. just a nice shiny wet look all over the inside surface. heat the dish to red hot, move the flame and dump in the powder gently. play the flame around the outside edge of the dish until the powder starts to bead up and gradually move the flame inward melting the powder as you go until its all molten. pick up the dish gently while you keep the gold melted and gently, gently swirl the button around the inside of the dish to pick up any stray beads. once all the beads have been picked up, move the flame away and continue to gently swirl so the button doesnt stick to the borax or keep the flame on the button until you pour it into a mold.
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there is a misconception about how much contamination can be removed by borax flux. the borax serves two purposes, its a lubricant to keep the gold from sticking to the dish and soak up the minute amount of impurities from the torch during melting.it will also trap a slight amount of salt if any made it through the washes and rinses but theres only so much it can do. dont rely on borax to clean your gold.
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If you did somehow dissolve metals with lye simply acidify it with HCL and drop out with copper. Zinc if you want to get everything. Lye is a very strong base so you might need a good amount of HCL depending on how much lye you used.
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the pins that the ribbon cable plugs into is brass base metal, the pins in the CPU sockets is iron base metal,all other like ram and pci are a bronze base metal and will contain tin in the base metal itself. only the bronze pins will add a substantial amount of tin to a solution if digested. the sulfuric stripping cell is probably your best bet. after the initial expense of material to build it, the electrolyte is re-usable.
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Poor Man's AR
Spoke,
You are using the poor mans AR recipe.
The document you posted is a variation of Steve Spevaks, using his photos and most of his verbiage. It's not the original and is missing some information.
Here's how I proceed with Poor man's AR:
Remove lids (top and bottom) from ceramic cpus using MAPP gas or a hammer and center punch applied from the top.
Add broken cpu's into large beaker or coffee pot.
Fill with tap water. Add just enough to cover the cpus.
Add and equal volume of HCl (31.45% approx 10 M) to the amount of water used above.
Place small ceramic saucer on top of pot to prevent vapor from escaping.
Heat to just below boiling.
Add in 1-2 teaspoons of sodium nitrate, use one if processing less than one pound.
Heat on low-medium for 30-45 minutes or until brown fumes and fizzing/tiny bubbles are no longer visible.
If salts form allow to cool completely and pour off dark acid through tight filter and start at step 3 above. Filter may contain gold foils or powder. Rinse any solids back into the reaction vessel. Test saturated acid for dissolved gold with stannous chloride.
Repeat steps 7 and 8 until all metals are dissolved.
Remove ceramic saucer and let the solution evaporate down to 25% of it's original volume, or until salts form. With very carefully controlled nitrate/nitric additions, steps 11-13 can be skipped.
Add fresh HCl to expel nitric as brown vapors.
Repeat steps 11 and 12 two more times.
Dilute with equal volume of tap water or add a 1/4 of the solution volume of ice cubes.
Filter cold through packed funnel under vacuum until 100% free of sediment and suspended particles.
Add Sodium Meta Bisulfite to precipitate gold as brown powder.
Let settle and siphon liquid off brown powder.
Add enough water to cover brown powder and stir throughly.
Repeat steps 17 and 18 two more times.
Add enough HCl (32% 10M muriatic acid) to cover brown powder.
Boil HCl with brown powder until color of HCl no longer darkens.
Pour off the dirty HCl and repeat steps 20 and 21 until HCl no longer discolors. Test HCl washes for dissolved gold with stannous chloride.
Slowly dry gold in beaker by shaking beaker over medium heat until the gold powder moves freely about the beaker it's was precipitated in.
Transfer brown powder melting dish and heat to red heat (incinerate) DO NOT MELT!!!
Transfer incinerated powder to beaker and repeat process steps 3 to 23 on the brown powder.
Prepare melting dish as shown on my website melting videos.
Melt dry gold powder in properly prepared melting dish.
The lids and ceramic housings will need to be processed to get the remaining gold from the cpus.
The lids strip very well using the sulfuric cell shown on my website.
The cores will need to be crushed to 1/8 mesh pieces and leached with hot AR or HCl-Cl to get to the final trace of gold trapped inside the ceramic.
I don't know of a way to get the gold without touching the base metals, perhaps a 1% sodium cyanide leech.
Steve
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Good luck with that. Everything I learned about evaporation dictates that you can do that endlessly and NEVER get rid of the nitric. So long as you keep adding water, all you're going to do is evaporate water. It's important that you get the solution down to a thick syrup. Can't do that when you add water.
Nitric is tenacious once in solution ----it often doesn't fully expel, even when you've done everything right---which is the very reason why I suggest readers use a button of gold in their solutions to eliminate excess nitric. It saves a huge amount of time and assures that the nitric is not a problem.
If you choose to not use a button, at least stop adding water.
Read Hoke. Read Hoke again. It's all there, in her book.
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Depends.
If you are certain that the silver was not fully removed because you jumped the gun and removed the gold prematurely, yeah, you can re-melt, using soda ash and borax (to recombine any silver that may be present as silver chloride, with the material). Pour to a cone mold, then separate the button from the flux, re-melt and pour shot again.
If you did NOT use heat in the initial process (dissolving the silver and base metals with nitric), you now see why that's not a good idea. If you have the ratio correct, all of the silver will be removed, making it dead easy to dissolve the remaining gold, which is now honeycombed because of the removal of silver and base metals. When it won't dissolve in AR, it's generally because you have not removed the silver, so when it hits a layer where silver remains, it quickly forms an impervious layer that can not be penetrated by AR, so action quickly comes to a halt. You can boil the material for days without further dissolution.
The other issue can be that you erred when you inquarted. If you got the ratio wrong, and the gold content is above 35%, removing the base metals and silver can be challenging, even impossible. If you boiled (or at least heated) the nitric solutions and added more than might have been required to dissolve all the silver, yet some remained, that may be an indicator that your calculations for inquartation were not correct. Only you can answer that one.
In any case, re-melting and adding a little more silver should solve the problem.
Harold
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tin oxidizes in nitric acid. thats what makes it insoluble. dry the sludge and incinerate it.you should be able to remove most of it with hcl bath. we use the name metastannic acid although in chemistry terms its sort of a mythical compound.stannic compounds is something we both need and hate. if you dissolve pins that are spring loaded (the connecting pin pushes back to the corresponding connection) it can be a bronze alloy specially made for electronics.the tin is part of the pin.no matter how you dissolve them, whether nitric or hcl, there will be tin in the solution. when dealing with tin oxide, when you bring the tin above the boiling point of tin, it will cast off an atom of oxygen converting from tin(II)oxide to tin(I)oxide. to be honest, i really am just learning what all this stuff means and i dont mean to come off like i really know what im talking about. im just copying most of this from wiki and the web. i do know that if you incinerate metastannic acid from dissolving tin in nitric acid, you can then dissolve it in hcl. metastannic acid is insoluble, so if you have a decent amount of gold in it, you can simply dissolve the foils using hcl/Cl and gravity filter the solution out. of course you will have to stir constantly to get all the foils to dissolve.
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I highly recommend a follow-up wash with HCl after the ammonium hydroxide wash and rinse. Combine that wash with the previous wash (ammonium hydroxide) to ensure that you don't end up with a basic (and therefore possibly explosive) solution when it dries. The follow-up HCl wash can prove very interesting if your gold wasn't quite pure. It's worth the effort. I did it routinely.
Harold
Ok, done with the ammonium wash, and i done a search on ammonium and found that the wash needs to be kept seperate from the other washs because of the silver content, it can possibily make a explosive compound, is this right and if so are there any need in keeping the wash and does it need to be neutralize before disposal.
Thanks
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when you cement using copper, you may have anything less reactive in that mud. i would rinse in boiling water and then boil in hcl. follow this with another boil in water and then a couple of cold water rinses. boil in ammonium hydroxide followed by boiling water.
this way you can remove as much base metal and impurities before you dissolve the values again. cementing on copper always leaves copper in your solids.
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if you incinerated and hcl didnt dissolve it, chances are its silver chloride. take a small sample and add to it some ammonium hydroxide (household ammonia) and see if it dissolves.heat it to be sure. filter out any solids and then add to the solution enough hcl to make it acidic. any silver will precipitate out as silver chloride. dont breath the smoke that comes off as you add the hcl.
this way you will know if it is silver chloride or something else.
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hcl reacts violently with aluminum. any of the soft, light metals can be mistaken for aluminum (zinc aka diecast and pot metal,titanium although it is very hard).a good chemical test to determine if a metal is aluminum or zinc is to scratch a spot and spray vinegar on it with a spray bottle.zinc will react violently while aluminum will react minimally and stainless will not react at all. aluminum is soft and can be cut easily with a knife blade while stainless steel is much harder and though it can be scratched, you cant cut off flakes like you can aluminum.titanium is light and resembles aluminum in almost every way except in hardness.titanium can not be cut with a knife blade.aluminum makes a dull ringing sound when struck while titanium has a rich clear long lasting ring when struck.
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a more reliable test for stainless steel is to hit it with a grinder. the sparks made will tell you what type of steel it is and if you get good enough you can just about tell how much nickel is in it by the spark it throws. a big spark stream with a lot of yellow and red is iron with less sparks and lighter colors the more nickel it contains. inconel and monel have their own unique spark, again it takes practice with known metals to get good at it.
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If there is much aluminum in your material let the reaction finish before you add heat. HCL + Aluminum + heat= violent reaction that will over flow your vessel.
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I realize it's hard for some folks to resist doing what they *think* will work, especially if they've spent much time cruising the net---but, for the most part, pretty much everything you're going to read out there is very misleading. Folks who know next to nothing quickly fancy themselves as gold refiners and begin to promote their miserable methods as acceptable. While they may achieve results of sorts, rarely will anyone disclose to you the risks involved. A classic example is the notion that one tosses everything in a vessel, subjects it to aqua regia, and, bingo, like magic, gold bars appear. No mention of the fact that tin is troublesome, no mention of the fact that traces of lead destroy gold's properties, and no mention of the fact that if not all base metal is dissolved, that some, if not all of the gold involved will be lost to the remaining solids. Because it no longer appears to be gold, in one's ignorance, it is discarded as trash.
There is no better advice that can be offered to you, or anyone who is not familiar with processes that are known to work, than to read Hoke's book. In it you can learn what works, and what does not. You can learn how to test properly, and how to make test and standard solutions. It is, for all practical purposes, the basics that one MUST understand in order to make decisions where recovery and refining are concerned. To approach these operations without that knowledge is akin to scheduling a piano recital when one has never seen a piano.
Read Hoke. Read her book again. Read it until you understand what she teaches. Only then should you attempt to refine precious metals.
Harold
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Pretty much what butcher said. The only place I may differ is that there are methods by which you can take advantage of the base metals, and process directly with aqua regia. It requires patience, and slow working, testing regularly along the way.
It works like this.
Start with a small amount of AR (far less than would be needed to dissolve everything), which should dissolve values along with base metals. The dissolution of values will expose base metals, so values can then be cemented on the exposed surfaces. That puts the values back with the solids, albeit finely divided. That's not a problem.
When all of the values are removed, they will have effectively dissolved traces more of the base metal. Water is added and the solution then allowed to settle well. It is siphoned off, then the process is repeated. This removes the dissolved base metals from the circuit. Each iteration removes more of the base metal, all the while leaving the values behind. When very little of the base metal remains, you then dissolve everything and handle the pregnant solution as one normally would. With good fortune, you will have removed the vast majority of the base metals.
As the base metal diminishes with each iteration, the cementing will take longer and longer (because of diminished surface area, and a greater amount of value in solution). I advise it be done with heat, and a covered vessel (use a watch glass). By heating, the reaction takes place faster, and the solution is constantly stirred.
Always test the solution after cementation, to ensure that all of the values have been recovered.
Harold
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Bamgold, if you check out the reactivity series, link below, any metal higher in the series will cement out metals lower in the series in a solution.
The way I remember it is this, the more reactive a metal is the less it wants to stay as a solid, prefering to go into solution, the less reactive the metal the more it wants to be a solid rather than a solution.
http://www.zephyrus.co.uk/thereactivityseries.html
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Ok, done with the ammonium wash, and i done a search on ammonium and found that the wash needs to be kept seperate from the other washs because of the silver content, it can possibily make a explosive compound, is this right and if so are there any need in keeping the wash and does it need to be neutralize before disposal.
acidify with hcl. any silver will drop as silver chloride.
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Yes, ammonium helps remove silver chlorides and any residual copper traces. Ammonium Hydroxide from family dollar That's what i use. Only one problem i have found is it has a little detergent in it. Don't worry it's just a little pain in the but to remove but here's the easy way to get it out. After your ammonium wash when you go to your hot water wash you will notice that their is some residual bubbles around the water level line on the beaker. As the water starts to boil the gold will attract bubbles as it boils. Next thing you know it will look like a thousand sea monkeys or frog eggs dancing around in the beaker. The gold will make you think it won't ever settle because of this, it will. Keep boiling and you will see the water go clear,the bubbles disappear, and the gold will just all the sudden fall out of the water. This usually happens in a matter of a few seconds once it starts. After the water boil when you pour the water off just add some more cold water to it and swirl it a couple of time and pour it off. The gold should settle in no time at all with this method making it easy to do.
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Heat from below to red hot in stainless, corning pyroceram, or vision ware dish. It will stick for a time as the salts melt, keep heating and the salts will give up as well and your material will begin to release from the surface. If you don't have oxygen stir gently to put all material in contact with the red hot bottom eventually virtually all carbon will be eliminated it just takes a bit longer without additional oxygen.
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For the HCl boiling, there is no set time. You boil it until the HCl doesn't get any darker. To give you a general idea, for the first HCl boil after a drop, it's usually around an hour, or maybe more. Boiling vigorously, gets it good and hot, and the bubbles keep the powder separated so the acid can get to all the surfaces.
When you boil household ammonia, it will evaporate almost immediately. I believe Harold said he did his cold, so that's what I do. The silver contamination should be minimal because much of it will turn to AgCl in the AR or A/Cl, and when you dilute it with water, and be filtered out before the drop.
Maybe when boiling the ammonia, the heat allows the silver to be taken up fast enough that it works before the ammonia evaporates, though. I don't know.
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After you decant the smb solution off wash it with water. I don't know what size beaker you are using but here's how i do mine. I use a 1000 ml beaker because it has enough room for me to put enough water on top of my powder without fear of the powder popping out the beaker. I usually use about 300ml in a 1000ml beaker. Why? because you will want to boil the powder hard in the water and when it starts to boil it will pop or bump the powder that settles on the bottom beaker at first and the depth of the water above the powder will stop it from jumping out the beaker. Use a watch glass to cover it also so you don't loose any if it does. When you boil the powder it will start to change colors (the powder). Boil hard for about 15 minutes after it starts boiling. It's better to add the water already hot ( nearly boiling ) to the beaker so you don't have to wait 15-20 minutes for it to start boiling. After the water wash the powder will look lighter. Then add hcl and repeat the process. The powder will get even lighter at this point. Then a water wash ( same as before ). Then ammonium wash. Then water wash. Then do the whole process one more time and you should notice how the gold is a light color and the powder sticks together real good and settles fast. It will stop changing colors at some point and this is when you will know it is clean. That's what Harold means.
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inert is a simple way of saying oxygen free. when we incinerate things of organic nature or carbon based, we want oxygen to reach the material to convert the carbon to carbon dioxide.when you want to remove an atom of oxygen the opposite is true. if you heat tin oxide to its boiling point, it will release the extra oxygen atom.what i used as a retort was a 6" threaded steel nipple with a cap on one end and a reducing cap on the other so i could reduce the size down to a manageable size and connect a copper tube to it with a compression fitting.any closed container that can withstand the heat will work, of coarse it has to have a vent so the gases can escape.
also, metastannic acid is a form of tin oxide. when you dissolve tin in nitric acid, metastannic acid is what you get. if i knew of an acid that would break it down, i would be using it.
actually, i was talking about tin oxide. tin chloride can be dealt with in a different way. when tin(II)chloride is formed in AP for instance, and is mixed with your foils, you can incinerate in the normal fashion and then hcl will dissolve it. tin(II)chloride is insoluble in hcl but when you incinerate it, it converts it to tin(I)chloride which is readily soluble in hcl.
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I don't know if what you say is a true truth. I would think that sending in your HOA dues is a ratification of their authority and accession to the terms of the implied contract. I'm not an attorney but I am also not thoroughly ignorant of legal issues. I WAS a realtor for a brief period. It could cost a serious boatload of money to assert the "right" to ignore the contract whether the OP signed it or not. And he must be sending in the dues or he would likely be in foreclosure from the HOA. While in the absolute sense, he may not have signed the contract; let me posit two additional principles: 1: he who gets their hands on money first has a massively more powerful claim to it in the purely practical and fully real sense than anyone subsequent. And 2: The law does not apply itself. You and or your actions may be in violation of the law as written or in compliance with the law as written. But there is a tremendous asymmetry in things legal; a violation of law is utterly nothing unless and until prosecuted; a right, if attacked, does not exist until it is defended, often at ruinous cost to the defender. I don't mean to sermonize, by the way. I just got done attempting to sue a caretaker who stole my uncle's estate, which was 80% willed to me. Talking $465K. I had to settle for $40K, with about $36K in legal fees. In other words, spit. This despite the overwhelming presumption in CA law that a caretaker who inherits all of an estate has stolen it. But the most important thing I can say is: The average person can NOT afford litigation. Simply can't. Thus they typically do not have access to it.
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I do not see the difference in Laser Steve’s advice and Harold’s, as they would both have worked if the situation was as you described (at that particular time when the questions were asked and with what details of the situation were given), several details I did not see in your description of the problem and more information added later after you tried Laser Steve’s solution to your problem as you described it to him, later you showed a picture and more details of the situation were revealed at this point Harold noticed from your picture and the formation of salts, color of solution, that this was just not your normal gold chloride solution loaded with gold, the color of the solution, it also looked very strange to me, I thought it looked more like HCl/Cl with salt in solution some copper and not much gold to me, nothing like concentrated evaporated aqua regia with 350 grams of gold in solution, it looked dilute but was forming salts, this was not normal for gold chloride solution made from aqua regia at this stage in refining, Harold is very sharp and noticed a problem, and gave great advice, as to what you had was not what the original description of where you were in the process described (at the point Laser Steve answered your questions), Both Laser Steve's and Harold's advice can be taken to the bank, but you also have to understand that they are not the one who has worked on your process, seeing or doing all of the reactions up until you had a problem, they are only answering on the details or clue's you give them, and have only a few clues as to what you have done so far and without being the one doing the process from beginning to ending they are only going by the few clues that you gave them as to what you have done so far and how, It is very hard to give advice when you do not know all of the little details, that can make a big difference as to what you actually have. I also did not notice any mention of using the poor-mans aqua regia and not pure acids until after everyone gave you advice, I suspect there are many details of where a problem could have been made in the process, that you have not revealed.
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As Harold suggested you may be best served at this point to cement with copper any remaining values in the solution that did not drop all your gold when you originaly tried to drop with SMB - doing this is going to give you a dirty "recovery" as you will get copper chloride with gold cement.
Another option I would consider would be to take the gold powder you have already droped - put it through the recomended washes for Karat gold (water/HCL/water/ammoina/water) melt a button - put the button in the free nitric solution - add low heat (same as evaporation) until there is no more reaction on the botton.
Because you already have SMB in the solution it will most likely precip gold as gold goes into solution (from the button) I don't know for sure if this will work - but it is what I would try first to avoid copper chloride contamination by cementing with copper.
I would also think you will want the solution rather dilute when you ad the button/heat to (1) allow for evaporation while reacting the button & (2) so the solution is dilute to allow SMB to precip gold as gold goes into solution.
Just an idea (open to comment)
Kurt
Here is something I posted in another thread about the evaporation process - hope it helps you understand it better -----
I am betting you have free nitric yet. The evaporation HCL addition method of getting rid of free nitric is a bit tricky. If you don't evaporate down far enough before adding the HCL the added HCL will not expel the free nitric & there is a fine line between evaporating far enough for the HCL to do it's job & evaporating to far to where your AuCl starts forming a crust.
You can tell if you evaporated far enough or not. When you ad the HCL you should get a strong fizz & a puff of brown smoke. If you only get a week sputter & white smoke you did not evaporate far enough. One is the chemical reaction of the nitric being expelled - the other is just the cold HCL hitting the hot AR.
If you don't evaporate far enough to get the chemical reaction to expell the nitric - it doesn't mater how many times you do it - you will still have free nitric. --- That is why it is important to calculate the amount of nitric just needed to dissolve your gold (so you don't get a lot of free nitric) & then go with Harolds method of adding a gold button with some heat to use up any possible free nitric. Then you don't need to evaporate.
Kurt
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You are wasting your time. To add water defeats the purpose of evaporation. Only when you have highly concentrated the solution will you expel any nitric, and then only if you add HCl, NOT WATER. Please refer to Hoke for a better understanding, as you clearly do not understand what you're trying to do. Also, ignore the admonition to repeat this process three times, as the number of times makes no difference if you aren't doing it correctly. You may achieve success with one iteration, or possibly not with six. I try to discourage all readers from doing these operations by count, as count is NOT reliable. Results will provide the required indicators of success, or the lack thereof.
The fact that a drop that was previously tested with stannous chloride was introduced to the main batch and yielded a reaction, which subsequently dissolved, is all the proof you need to understand that you have free nitric present.
Do NOT return drops of solution that have been tested. They should be sent to your stock pot, where they will be cemented by base metal and collected for future recovery. You should try to avoid adding tin to your solution at almost any cost, as it complicates filtration terribly.
You may have to drive your solution to the point of becoming almost dry before you'll succeed in removing the nitric. That's because you have it contaminated with substances you introduced previously. You may be best served by cementing the values with copper, then processing the small amount of powder that will be recovered. It will most likely be black in color, and not resemble gold in the least.
I say you have only a small amount present due to the color. It is too light in color and depth of color to suggest there's much gold present.
Evaporation. It makes no sense to attempt evaporation with a small surface area. The larger the area, the more tolerant will the solution be of heating, as the larger area dissipates heat at a greater rate, cutting the time it takes to evaporate, and making it much harder to make the solution boil. At no time should you see a boiling action, as that offers the risk of losing values.
Harold
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.....my dish (brand new and properly coated with borax ) Exploded!!!
If you use your melting dish irregularly, it most likely is absorbing moisture. Heating too rapidly, yeah, you risk cracking, maybe even exploding, as you described.
Play it safe. Place your melting dish on the hotplate at a low temperature for a prolonged period of time before placing it in service. Do this even after you've seasoned the dish if it has been unused for a period of time. That will drive off excessive moisture at a safe rate.
I used to preheat my melting dishes for quite some time before even seasoning. Once beyond the temperature of boiling water, I could then pour the heat to it without worry. So long as I used the white dishes that are now available, no problems with cracking. However, prior to the introduction of the white dishes, they used to market some made of brown clay. Even with proper preheating, they often would crack.
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Re-Irons. Can we get a picture of your kaowool furnace ? It would be great to melt with propane. so much cheaper than Mapp.
I'm in the process of rebuilding it at the moment. Too hot for a melt, but I will, as soon as it's ready.
Building one is pretty simple and actually cheaper than using Firebrick or refractory Cement. I used a 6 inch cylindrical form to wrap the insulation around. The first 2 layers are 1/2 inch Ceramic Blanket, rated at 2400*F. and the outer layer is 2" Kaowool. Moist Paper is wrapped around the form first. Being wet is important as it will shrink along with the ceramic slurry that is applied to the first layer. The paper allows the insulating cylinder to be easily removed from the form. I tried using a thick ceramic liner, applied as a paste, but it tended to crack due to expansion and contraction. Another problem with it was the increased time it took to heat all of that Mass. A thin liner works just as well. All it does is protect the Ceramic Blanket from effects of Flux. A thin wash, periodically applied with a foam brush will seal any cracks and reduce the amount of loose fibers being blown into the work area.
The bottom is made from a 2" wide strip of Ceramic Blanket wound around a ceramic cylinder to fit inside the outer insulating shell. I found that, unless Refractory Cement is applied to the strip, it will tend to sag over time. This go-round, I'm adding some re-enforcing wire as U-shaped pins of Kanthal 16 Ga. heating element wire. Nichrome or Stainless Steel would work as well, but I have the better part of a 5 Lb. spool of Kanthal-A1 handy.
The ceramic cylinder is made from refractory cement re-enforced with chopped Ceramic Blanket fibers applied to a cardboard tube from a roll of paper towels. The cardboard will burn away upon heating.
The lid is the same as the walls and sitting on fiber re-enforced Fireclay plate. Support for the plate is 3, 1/8 inch X 7" Ceramic coated Tungsten rods that began life as TIG welding electrodes. The Kaowool lid is separate from the Ceramic Plate. The weight of the plate is too much for the Kaowool to bear.
For A torch, I use an old Berz-o-Matic Mapp torch that is no longer in production. The new ones aren't worth the Money but I found a good substitute made by MagTorch, a dual use Mapp/Propane heavy duty one that puts out the heat when needed. I bought a couple since I plan to build at least one other furnace to hold a shotting crucible.
More later...
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How did you make up your stannous chloride test solution? What did you store it in? When did you make it?
If the solution was made and stored in a bottle with a lot of air in the bottle it will go bad faster than if it was in a small bottle full of solution. So storage is important, storage where it can freeze or bake in the sun will also shorten its life.
Also if it is just old it can go bad. Adding pure tin metal to a freshly made solution will add to its shelf life.
Stannous chloride is a powerful tool for refiners, lets get to the bottom of how you made it, when and how you stored it before we waste time speculating if it's in the solution or the foam. Your gold is there, and testing will tell us exactly where so lets approach this step by step.
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You could cut a couple of pieces of electrical copper wire and add it to your solution to cement your gold. Then take everything that cements out and run it again to get it right. I think that would be your safest bet at this point. If you decide to do this let us know and we can walk you through it.
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From your picture, your solution is only 1/2 cup, and yellow. Plus 1/2 cup or more of froth, about the same color.
If the whole ounce was in solution, I think it would be closer to a red color.
If the whole ounce was in metallic form in the froth, there would be so much weighty solid bulk, that I think at least a good part of it would fall to the bottom of the measuring cup.
A half cup of froth would have more air than solution, so if your ounce of gold was entirely in solution, including the froth, you would only have maybe 3/4 cup of solution---and I think it should still be a darker color, at least orange or red-orange. Maybe all the SMB and urea would account for the light color, I have never done that (among the many other mistakes I've made!) so I can't say for sure.
Maybe knowing what you should have done can put things into perspective, and help you sort this out. First, for practice, use a 1 gram bar instead of a full ounce. Put it into about 200 ml of HCl, and add a drop of nitric. Put it on heat to 150 to 160 degrees F (use a $25.00 IR "gun" thermometer). Watch the color change and bubbles (reaction) from the gold bar. When the reaction stops, add a little more nitric. Keep letting the reaction stop, and adding nitric, until you have an orange color, then take it off the heat when there are no more bubbles.
When there are no more bubbles, all the nitric will be gone. You should have a small chunk of the bar left on the bottom. (Whatever the color of the solution, stop adding nitric while there is still a small chunk of gold left, to be sure there is no more nitric in your gold solution.)
Pour this solution into three small bottles with lids. Make it so there is about 125 ml in one bottle, 50 ml in the second bottle, and 25 ml in the third. Cap and keep the 125 ml bottle as a reference. Fill the other two bottles up to 100 ml total each, with water. Use the two diluted solutions as your standard gold solutions for testing---one being weaker than the other will give you an idea of the sensitivity of your stannous chloride testing solution. You can even make another bottle of gold solution which is half the strength of the 25 ml bottle, to see how sensitive stannous is with solutions that are barely yellow. I've seen it indicate on filters which have been sprayed down with water until there is no yellow color at all, even.
Then make some stannous chloride solution for testing for gold in solution. There are several sources of material to make it with. Some people use tin solder (lead-free), some use the white powdered stannous chloride, and other methods. Then dissolve it in HCl. Some add water. Hoke lists her formula, and there are many mentions of various ways in the forum---just use the search feature at the top right of each page. Like the experts say, the most important thing is that you always make your testing solution of the same proportions, so you become accustomed to, and thus understand its indications with unknown solutions.
You said that you have some stannous solution that you bought, so you can test that with your standard gold solutions that you made. This will give you a certainty of what to expect when you test any unknown solutions.
If you are uncertain of your stannous solution, and you are uncertain of your gold solution, the only conclusions that you can possibly come to will always be uncertain when something unusual happens, like what you have now.
Just like in navigation, you absolutely must have some points of known positions. Testing solutions which you are sure about will provide those known points. Your standard gold solutions will provide certainty about your stannous solutions.
Understanding this will help you get out of your situation with your gold solution.
If you are new to the practice of precious metals recovery and refining, and you want to try it because you find it interesting, then you should read the Safety Section before attempting to perform any of the procedures or obtaining any of the chemicals involved.
Remember, neither the hospital nor the morgue are interesting.
Also read: Waste Treatment for the Small Refiner, by 4metals.
Be safe, and enjoy refining.
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If it were me, I would try heating the solution to see if the froth at the top would go back into the solution while hot. If it does, then I would continue heating the solution to steaming NOT BOILING and let it reduce to about half its volume, let it cool then add some hydrochloric acid and see if you get a puff of brown smoke. If it does off gas that brown smoke then you still have free nitric that needs taken care of.
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First check the stannous against a solution you know has gold to assure yourself the stannous chloride is good and working.
The stannous chloride works with or without free nitric, I can't count howmany hot reactions I've tested for gold with stannous and never had a problem.
If the gold is in the foam, it is likely in the metallic state and will not be detected by stannous chloride.
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You can substitute the word stannous for tin(II) - same thing.
I would probably get the first one (Technical, anhydrous) or the last one (98%, anhydrous)
-Stannous Chloride Anhydrous (Cryst. Powder or Flakes/Technical)
-Stannous Chloride Dihydrate (Cryst./Certified ACS)
-Stannous Chloride Dihydrate (Cryst./Technical)
-Stannous Chloride Dihydrate FSE
-Tin(II) Chloride Dihydrate 97%
-Tin(II) Chloride Dihydrate p.a.
-Tin(II) Chloride Dihydrate, Reagent ACS, Crystals
-Tin(II) Chloride, Anhydrous 98%
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Start by incinerating all of the solids. Follow that by a rinse with water, in the hopes that you might remove anything that is water soluble.
Follow that with a boil in HCl (to, hopefully, remove all traces of aluminum). Rinse well afterwards, until the rinse water is clear.
Incinerate once again..
You should now process the resulting solids with dilute nitric, to remove traces of base metals.
Rinse well, then dissolve the values with AR, or the solvent of your choosing. From there, it's routine.
Read Hoke. Read Hoke again. Read it once more, and do that until you understand what you should be doing.
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Hot sodium hydroxide will remove solder mask. Warm it slowly to boiling, put in your boards, boil for 5 mins, remove and wipe off the green goop. Wash well with fresh water. Job done. Wear gloves, eye protection and avoid breathing the steam
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Reguardless of your heat source - you need to keep an eye on your reaction. the heat is ment to "warm" the acid enough to get the reaction going - once you have a good reaction going you can turn the heat down &/or off as the reaction will generate its own heat - then when the reaction slows down you can turn the heat back on or up to finish the reaction.
With less reactive metals (like gold & PGMs) it may take several times of turning the heat up & down to get the complete reaction job done.
Be sure to keep a watch glass on top of your reaction vessel durring the reaction process.
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Take some of the white stuff out, wash it, and try and dissolve it in ammonium. If it dissolves add hcl,bleach, or table salt to it. If if come back as a white cloud then it's silver chloride. Or expose the silver chloride to sunlight for a day and if it turns purple then bingo!
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dont pay more than $0.20 a pound for complete computers unless its a truck load than pay a little more
from what i have read in here.. a complete computer if done well could yield for around 15-20$
nop, average today computer is more 6-10$ each ,when you go older you get better ,dont forget that old mobos are worth around 4.00$lbs and newer one 2.50$lbs,the power supply doesnt weight 4lbs anymore, now 2lbs is more realistic, metal is thinner, memory lighter,etc you understand what i mean...
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A reagent (play /ri'e?d??nt/) is a "substance or compound that is added to a system in order to bring about a chemical reaction, or added to see if a reaction occurs."[1] Although the terms reactant and reagent are often used interchangeably, a reactant is less specifically a "substance that is consumed in the course of a chemical reaction".[1] Solvents and catalysts, although they are involved in the reaction, are usually not referred to as reactants.
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Stump Out can be bought at Home Depot and at Ace Hardware. When you buy, ask for an MSDS and they will give you one.
It is sodium metabisulfite and it can be used to precipitate gold from Gold Chloride solutions.
Before use, dissolve in water to make a saturated solution and run it through a filter paper because it does have small amounts of dirt and other solids.
The filtered solution will work nicely to precipitate gold powder from AuCl2 solutions.
Also, make sure to do the precipitation outside or in a fume hood.
When the Stump out (in solution or powder form) is added to the AuCl, a poison gas is given off that will gag you.
I think it is sulfur dioxide gas. If you breath this gas then it will mix with the moisture in you lungs and form sulfuirc acid.
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http://www.youtube.com/watch?feature=player_embedded&v=HNq3Tp99XOE
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SMB (sodium metabisulfite) is selective when precipitating gold. the SMB, when dissolved in water decomposes into salt and SO2 gas. its the SO2 that precipitates the gold. it does not precipitate other noble metals to any extent that will effect refining bullion grade gold.
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vigorous stirring helps when using hcl/Cl.not sure what the mechanics of it is, but ive dissolved powder that seemed to take forever to dissolve and got impatient and started stirring. that seems to speed it up quite a bit.
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take a small sample of the brown mud and dissolve it in a few drops of hcl and a drop or two of bleach. test the resulting solution with stannous chloride. its really the only way to know for sure.
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When I get a mix of old material that contains gold & solder, I run the material thru 50/50 nitric. The white gunk forms. After no more reaction, I let the solution settle overnite. I decant the solution, rinse the material with hot water & proceed to dissolve in HCl/Cl. Then proceed as usual.
I think i would put it in something taller than wider and let settle for a day. Take a piece of hose and draw off as much solution as i could. Wash with water, let settle, decant, then put the residue in a pyroceram dish and evaporate slowly until dry. Then incentrate in a pyroceram dish. Pre wash with hcl to remove any tin, copper, or oxides and process with hcl/cl.
dealing with stannic acid is a pain no matter how you deal with it. if you incinerate it, it will lose an oxygen atom and turn back into elemental tin which then can be removed with hcl bath or you can dissolve the gold out of the material and spend time filtering solutions. in my opinion, if you dont remove the tin first, it will show up later.when you dissolve with hcl/Cl and let the solution sit undisturbed, does any white precipitate form? the tin will carry over and you may have to refine more than twice to clean it up.
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The silver nitrate will precipitate when your solution cools down. I feel that the white precipitant is Silver Nitrate, all you really have to do is put heat to the solution so that the silver nitrate dissolves back into solution, then filter it right away when the solution is warm, before the silver nitrate precipitates again.
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I would screen out what I could, I have a cheap plastic screen with a handle, I bought from the dollar store, the plastic holds up well to the acids, I put the screen into a plastic funnel and this funnels solution into a collection jar, after screening out the larger pieces, I would put a little wad of fiberglass insulation in the funnel (something like Laser Steve's Charmin plug, and filter out more of the finer stuff, then the liquid from this would go to my distilling rig (I may even add some gold plated pins to this with elemental copper that needed to be dissolved, this would give me some copper in the mix which would help drive off the nitric acid when distilled), a little sulfuric acid added, and I would distill off the nitric solution (which could then be reused), the results would end up copper sulfate, which the gold is not soluble in, and I could separate gold from, the copper sulfate solution can also be reused.http://goldrefiningforum.com/phpBB3/viewtopic.php?f=38&t=6199&hilit=killing+two+birds+one+rock
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You should not have lost gold at all if you had used the torch properly, I feel this is were any loss would have come from not the fact you had paper as a carbon source involved. next time try heating outside of the dish until paper forms an ash crush the paper ash with a carbon rod, play torch with just low flame tip barely lapping and heating the melting dish, not directly on the gold powder, keeping torched more focused on outer and around rim of dish (to keep torch from blowing away powder or ash), until gold powders begins to fuse together then you can bring torch in closer, and let the flame tips lap at the gold. after the gold starts melting turn up the torch and get that nice hot blue flame tin in there rolling the molten gold into one round button, roll it in the dish good using the torch to push it around some.
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Watch for boil overs and use a safety vessel.
Nitric is usually the animal when it comes to boil overs from surface reactions.
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for hcl/Cl, i would break the chunks into finer pieces so the dissolution will go faster.
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Gold will not dissolve in the copper chloride leach (called acid peroxide), the gold is too un-reactive, unless you oxidize the gold with the use of too much oxidizer in the copper chloride leach (such as too concentrated hydrogen peroxide solution), now the oxidized gold can form a gold chloride in solution, adding more copper to the copper chloride leach will dissolve more copper and solution will begin to change from a copper II chloride (green) to a copper I chloride solution (brown), once saturated the copper I chloride salt will begin precipitate (white powder), also if you did have any gold chloride in solution it would plate out to any copper that the copper II chloride leach was trying to dissolve (Gold would look like brown powder) or if the solution was converted to a copper I chloride (brown) the gold would precipitate as brown powder, most likely mixed with the white copper I chloride salts.
I see no need for the use of SMB in the copper chloride leach, control the amount of oxidizer used, and if you use too much just add more copper to the solution to push your gold out of solution.
Using SMB would make your copper chloride leach useless, if you do not use the SMB you can rejuvenate and reuse the solution as a leach.
Laser Steve Has an excellent document of this leach and treating the solution on his web site.
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-It Takes Approx 1mL of 70% HNO3 added to 4ml of 30% HCL to dissolve 1g of pure Gold
-It Takes 1.17 ml of 70% HNO3 and 1.17 ml of 100% H2O to dissolve 1g of pure Silver
