Gold Refining with hypochlorite

[orvi]

if you opt to use some solid hypochlorite, i will choose tech grade calcium hypochlorite. Here, it is accessible as shock pool chlorine, and it is roughly 70% stuff, nicely granulated. Calcium chloride formed has very good solubility.
But this method on solid gold give you poor results, as the chlorine evaporates very quickly, making the whole process very inefficient.
In your place i will try to obtain some nitrate or nitric acid. Also poor´s man AR work better than plain bleach/HCl.
Try to hammer the gold very thin, or pulverize the material to increase surface area.
I was using this method to extract native gold from quartz ore (just quartz with gold) one time. I poured the HCl and crushed ore to the PE bottle, add one small spoon of hypochlorite to the bottle, cap it and shake it well. You can see decrease of the pressure inside the bottle as chlorine dissolves in the liquid. After some time/shaking, open the bottle, add more hypochlorite (just tiny additions) till you dissolve the stuff - saturation with chlorine can be roughly seen as no shrinking of the bottle after shaking is observed. With this method, chlorine loss is minimized (if you dont want to use suitable pressure vessel). Be careful with additions, not to overpressurize the bottle.
Stay safe.

 

[Geo]

You can heap leach in almost any container, even a 5 gallon bucket. First, make the ore leachable. Roach, quench, mill, repeat as necessary. Add this to a 5gallon bucket. Make sure that you secure a length of 1/4 tubing to the bottom of the bucket and add a small filter to keep the sand out. Add a gallon of HCl. Add bleach in doses. Use a peristaltic pump (an old IV pump will work) to move the solution to the top and let it drip on the top of the ore. The solution has to pass through the ore back to the bottom of the bucket. Lightly cover the bucket to keep the chlorine gas down or seal it and vent the gas into a container of basic solution or away from any thing of concern. It is not fast and may take several doses of bleach. Wear a respirator or plan ahead and have good fume control. This can scale up to the mountainous heap leach mining operations that covers square miles.

 

[dpgold]

Sodium hypochlorite does not work well with gold solids. It is best used for foils and powders. When NaOCl is added to HCl, three major things happens. Chlorine gas is produced and NaCl is produced and HCl is neutralized. Chlorine gas in solution is very short lived unless it's under pressure. The chlorine gasses off too quickly to dissolve anything more solid than foils and powders. Chlorine gas is lost to the atmosphere as soon as the two chemicals are mixed. Much like nitric acid, it takes roughly 1.2 grams of trichloro to dissolve 1 gram of gold. An excess of HCl is recommended as the hypochlorite is basic and will neutralize some of the acid when the two are combined. It is recommended that an excess of hypochlorite is used. The excess, after dissolution of the gold is complete, can be removed by gently boiling the solution. Hypochlorite is destroyed at temps above 112°F. The solution should be brought to a low boil for a couple of hours and allowed to cool. Expect a white precipitate of sodium chloride to form when cooled. If the solution is evaporated to concentrate gold in solution, more salt will form in the solution.

Nice explanation, many people do not explain that is the gas which does the job. I have seen only one video in which Streetips explains that you have to contain the gas to act. Now it seems that nitric acid for aqua regia is better. Is there other thing beside nitric acid which would be easier to find and cost effective? Also does the neutralization and precipitation would be different?

 

[Geo]

Nice explanation, many people do not explain that is the gas which does the job. I have seen only one video in which Streetips explains that you have to contain the gas to act. Now it seems that nitric acid for aqua regia is better. Is there other thing beside nitric acid which would be easier to find and cost effective? Also does the neutralization and precipitation would be different?

Any of the "ides" will dissolve gold (iodide, bromide, chloride, fluoride). These are called ionic halides. Together with HCl will dissolve gold and hold it in solution. Each has it's own process and dangers involved. Some are more dangerous than others by the nature of the reactions it has with organics. Availability varies for each due to dangers posed by exposure.
Hypochlorite is destroyed by heat. Sodium hypochlorite boils (decomposes) at 214°F. Removing chlorine from solution will not work as long as there is dissolved sodium hypochlorite in solution. The hypochlorite must be destroyed to remove chlorine from solution. Heat the solution to 214° for a couple of hours and then let it cool completely, or alternatively, heat to 120°F all day. Lower heat will destroy it but much more slowly. Sodium thiosulfate is a chlorine scavenger and will destroy the gaseous chlorine instantly when added to the solution. The byproducts of significance is a small amount of sulfuric acid in solution.
As far as my experiments have proven, none of this effects the precipitation or quality of gold dropped.

 

[Geo]

if you opt to use some solid hypochlorite, i will choose tech grade calcium hypochlorite. Here, it is accessible as shock pool chlorine, and it is roughly 70% stuff, nicely granulated. Calcium chloride formed has very good solubility.
But this method on solid gold give you poor results, as the chlorine evaporates very quickly, making the whole process very inefficient.
In your place i will try to obtain some nitrate or nitric acid. Also poor´s man AR work better than plain bleach/HCl.
Try to hammer the gold very thin, or pulverize the material to increase surface area.
I was using this method to extract native gold from quartz ore (just quartz with gold) one time. I poured the HCl and crushed ore to the PE bottle, add one small spoon of hypochlorite to the bottle, cap it and shake it well. You can see decrease of the pressure inside the bottle as chlorine dissolves in the liquid. After some time/shaking, open the bottle, add more hypochlorite (just tiny additions) till you dissolve the stuff - saturation with chlorine can be roughly seen as no shrinking of the bottle after shaking is observed. With this method, chlorine loss is minimized (if you dont want to use suitable pressure vessel). Be careful with additions, not to overpressurize the bottle.
Stay safe.

Do not use calcium. Calcium has an adverse effect on the gold drop. Dissolved calcium in solution will precipitate solid, insoluble calcium sulfate (gypsum) as soon as a sulfide/sulfite is added to the solution. It will rob the SO2 from additions of sodium metabisulfite. Instead a gold drop, you will get a fluffy, white, pearlescent powder that settles quickly. If any gold does drop, it will be mixed with this mass and will have to be dissolved back out to separate it again. Seriously, avoid calcium when dissolving gold. This also goes for calcium nitrate.

 

[dpgold]

Any of the "ides" will dissolve gold (iodide, bromide, chloride, fluoride). These are called ionic halides. Together with HCl will dissolve gold and hold it in solution. Each has it's own process and dangers involved. Some are more dangerous than others by the nature of the reactions it has with organics. Availability varies for each due to dangers posed by exposure.
Hypochlorite is destroyed by heat. Sodium hypochlorite boils (decomposes) at 214°F. Removing chlorine from solution will not work as long as there is dissolved sodium hypochlorite in solution. The hypochlorite must be destroyed to remove chlorine from solution. Heat the solution to 214° for a couple of hours and then let it cool completely, or alternatively, heat to 120°F all day. Lower heat will destroy it but much more slowly. Sodium thiosulfate is a chlorine scavenger and will destroy the gaseous chlorine instantly when added to the solution. The byproducts of significance is a small amount of sulfuric acid in solution.
As far as my experiments have proven, none of this effects the precipitation or quality of gold dropped.

Is nitrate good to dissolve gold, would it be neutralized and precipitated like AR? It seems like I could find some nitrate at reasonable prices over here.
EDIT: it seems that there are many kinds of nitrate with 17 percent N and 17 percent something else, what kind should I use if it the case?

 

[orvi]

Do not use calcium. Calcium has an adverse effect on the gold drop. Dissolved calcium in solution will precipitate solid, insoluble calcium sulfate (gypsum) as soon as a sulfide/sulfite is added to the solution. It will rob the SO2 from additions of sodium metabisulfite. Instead a gold drop, you will get a fluffy, white, pearlescent powder that settles quickly. If any gold does drop, it will be mixed with this mass and will have to be dissolved back out to separate it again. Seriously, avoid calcium when dissolving gold. This also goes for calcium nitrate.

Very good point which I never realized. If I used the Ca(ClO)2/HCL, it was only for test leaching the non-sulfidic ore. Gold was cemented using copper wire or powder. Never continued with classic SMB or ferrous sulfate drop.

Thank you for correcting me.

 

[Shark]

Do not use calcium. Calcium has an adverse effect on the gold drop. Dissolved calcium in solution will precipitate solid, insoluble calcium sulfate (gypsum) as soon as a sulfide/sulfite is added to the solution. It will rob the SO2 from additions of sodium metabisulfite. Instead a gold drop, you will get a fluffy, white, pearlescent powder that settles quickly. If any gold does drop, it will be mixed with this mass and will have to be dissolved back out to separate it again. Seriously, avoid calcium when dissolving gold. This also goes for calcium nitrate.

Geo, have you tried other precipitants such as ascorbic acid or sodium nitrite?

 

[Geo]

Is nitrate good to dissolve gold, would it be neutralized and precipitated like AR? It seems like I could find some nitrate at reasonable prices over here.
EDIT: it seems that there are many kinds of nitrate with 17 percent N and 17 percent something else, what kind should I use if it the case?

This my video of using poor man's nitric acid to process gold fingers. Poor man's AR is HCl and a solid nitrate. PM's nitric acid will work on any material you would use nitric acid on, even silver, just used distilled water instead of tap water.

 

[Geo]

Geo, have you tried other precipitants such as ascorbic acid or sodium nitrite?

Ascorbic acid (vitamin C) or oxalic acid (wood bleach) is for purifying gold past .999 for what ever reason. I have performed the process when someone want's gold back from a refine instead of payout. I don't routinely use it as .99+ is good enough to keep my percentage high enough to get the good prices.

 

[Shark]

Ascorbic acid (vitamin C) or oxalic acid (wood bleach) is for purifying gold past .999 for what ever reason. I have performed the process when someone want's gold back from a refine instead of payout. I don't routinely use it as .99+ is good enough to keep my percentage high enough to get the good prices.

I am curious if the nitrites or Ascorbic acid would stop the calcium from dropping allowing the use of calcium nitrate for poor man’s AR? Mostly thinking out loud, but could give another useful thing for those with more limited access to some chemicals.

 

[Geo]

I am curious if the nitrites or Ascorbic acid would stop the calcium from dropping allowing the use of calcium nitrate for poor man’s AR? Mostly thinking out loud, but could give another useful thing for those with more limited access to some chemicals.

A sulfite or sulfide or sulfuric acid would have to be added to precipitate calcium sulfate.

 

[Shark]

Is nitrate good to dissolve gold, would it be neutralized and precipitated like AR? It seems like I could find some nitrate at reasonable prices over here.
EDIT: it seems that there are many kinds of nitrate with 17 percent N and 17 percent something else, what kind should I use if it the case?

Yes. Geo’s video shows poor man’s AR using sodium nitrate, a fertilizer that is described as 16-0-0. Ammonia nitrate is 33-0-0. Potassium nitrate is typically used as a stump remover in that the nitrates breaks down the pulp in the wood. Sodium and potassium is my usual two choices based on availability.

 

[orvi]

I am curious if the nitrites or Ascorbic acid would stop the calcium from dropping allowing the use of calcium nitrate for poor man’s AR? Mostly thinking out loud, but could give another useful thing for those with more limited access to some chemicals.

If it doesn´t sound complicated to you, use copper powder to cement gold out of calcium containing solution. I was doing this multiple times. Altough I have never used calcium nitrate but calcium hypochlorite. Nitric would be hard to destroy with calcium in solution - sulfamic acid is out of a game... Maybe urea will serve this time, as it will decompose to CO2 and nitrogen - possibly no precipitate (but I didn´t test this). Aside of this, evaporating the solution will be the option of choice for me.

If you have calcium nitrate, there are few ways how to convert it to nitric acid using sulfuric acid - to get rid of calcium. I must say it´s tedious process, but it kinda works. You need to test it on a small scale to observe how the precipitate is formed and if you can manage filtration of the formed gypsum.

I add a paper issuing similar systems and solubilities of CaSO4 in nitric. Some will stay in the acid formed. But not very much.

 

[Yggdrasil]

When talking about Hypochlorite leaches, Deano’s NeutralSalineHypochlorite leach came into mind.
For small scale leaching as this would be compared to mining, could prove easy.
The whole issue of Chlorine evolution is avoided since it is run in close to neutral conditions.

Just a thought..
But here as anywhere else one has to be observant for cementing on undissolved metals, I guess.

 

[orvi]

When talking about Hypochlorite leaches, Deano’s NeutralSalineHypochlorite leach came into mind.
For small scale leaching as this would be compared to mining, could prove easy.
The whole issue of Chlorine evolution is avoided since it is run in close to neutral conditions.

Just a thought..
But here as anywhere else one has to be observant for cementing on undissolved metals, I guess.

Chlorine isn´t that much problematic, if you evolve it continously and carefully. And work in good fume hood of course. It has relatively OK solubility in aqueous solutions, but only when cold or room temperature. If mixture heats up, it start to escape. Not only you are losing the oxidant and you must use excess, you also evolving toxic gas with tendency to corrode everything around. But neutral hypochlorite leach sounds really good, if you got the reference or link to the thread in hand, I would like to read it.

Slow addition as solution (bleach or calcium hypochlorite) under the level of acidic mixture (via small diameter PVC, glass or better FEP/PTFE tube) of material what you intend to dissolve may be a way. Regulating the flow can be easily done with some DIY screw "press" that press the tubing in one place - how hard you screw the tubing = approximate regulation of flow from bigger stock container above. Similar to medical IV kits. After the dissolution, heat the solution to liberate excess chlorine, then filter the solution and stirr with copper powder or shavings for at least one hour. Let the cemented PMs settle, decant calcium/base metals solution and then refine the solids as usual. Or you can use cementation rig as described in the thread When in doubt, cement it out

 

[Yggdrasil]

I know, but as a neutral leach you get more bang for the bucks so to speak.
No free chlorine are evolved.

 

[MicheleM]

I think we are OP

 

[MicheleM]

Is that for me? Thank you so much for responding. But I'm kinda confused, plus let me tell you where my situation stands now.
100 grams gold filled incinerated and put into poor man's nitric ( sulfuric acid and potassium nitrate and distilled water). Heated and until after reaction stops, I'd put in a little more water and a spoon full of nitrates. Second and 3rd time reaction stops I decant solution through coffee filter. Had to do two funnels because I no longer have the right beaker to vacuum filter. So I used two funnels to try and expedite filtering. This resulted in lots of solution. I haven't noticed any silver chloride. So I thought maybe it was in solution? But there were sediment. Which is now mostly in the filters and the breaker. I thought it was either tin or metastannic acid, so I was planning on taking all the sediment and foils along with the filters and incinerating it. Because that's how you deal with that dreaded metastannic acid isn't it? Turning it into tin oxide? But if it's silver, which it doesn't look like silver chloride then it would be somehow regular silver right? And if I were to incinerate it then wouldn't I be turning it into silver oxide? Which is not what I want. Or do I have the chemistry all backwards?

Perhaps you should open a new thread...

 

[Yggdrasil]

I think we are OP

No Rifkhan is OP