# Gold Refining with hypochlorite



## Rifkhan (Dec 28, 2021)

I have few doubts regarding refining with Na Hypochlorite.

1. May I know how much gram of industrial grade sodium hypochlorite powder is needed to make a 15% of sodium hypochlorite solution?
2. What proportion of sodium hypochlorite solution: HCl should be added for the refining process?

I tried with adding tiny pellets of gold with 35% Con HCl (100ml) and industrial grade sodium hypochlorite powders (5 grams)

I found a cloudy solution with a white precipitate. I felt chlorine gas is emitting. But the gold remained same without getting dissolved.

I have added three images of side, top, and bottom views.


Can anyone please guide me where I have gone wrong.


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## Yggdrasil (Dec 28, 2021)

When using hypochlorite, we use the liquid version.

Have what you need to dissolve in a beaker add HCl until it is covered and drip hypochlorite into solution and stir.
It is important to not add too much, it will neutralise the HCl.
Stir until no more dissolving happens.
Add i bit more and repeat. 
Again measuring the ph if possible to make sure the HCl are not neutralised.
It is not suited for lumps of gold only foils and powders.
To me it seems you have overdone the hypochlorite massively.


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## Rifkhan (Dec 28, 2021)

Yggdrasil said:


> When using hypochlorite, we use the liquid version.
> 
> Have what you need to dissolve in a beaker add HCl until it is covered and drip hypochlorite into solution and stir.
> It is important to not add too much, it will neutralise the HCl.
> ...


Thank you @Yggdrasil for the reply. I will try with reducing the hypochlorite solution.

Regarding producing a hypochlorite solution 
What I did was, I added 2 grams of Powder with 50 ml distilled water. And I checked for the PH & it indicates around 5.70. 
Added few powder and water with many trials but it was in the range of 5.9- to 6.9 approximately.
My question is also how can this be acidic? hypochlorite has to be base. Right?


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## Yggdrasil (Dec 28, 2021)

When you buy it ready mixed it is at least. 
Reading wikipedia it shows it is not basic at its own.
But as pure powder it decomposes fast if not cooled down.
So I expect it is already decomposed.
Better use liquid or even better Sodium chlorate.

Read here:








Sodium hypochlorite - Wikipedia







en.m.wikipedia.org


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## Rifkhan (Dec 28, 2021)

Yggdrasil said:


> When you buy it ready mixed it is at least.
> Reading wikipedia it shows it is not basic at its own.
> But as pure powder it decomposes fast if not cooled down.
> So I expect it is already decomposed.
> ...


As you said, I think I have added excess amount of Sodium Hypochlorite.
So I will try with adding dropwise of Sodium Hypochlorite. I am also planning to use Clorox instead of preparing a Sodium Hypochlorite solution from its powder.


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## Yggdrasil (Dec 28, 2021)

I'm suspecting your powder may have gone bad, depending on when you bought it and how you stored it.


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## MicheleM (Dec 28, 2021)

1- 15 % per cent concentration of a solute in a solvent : 150 g NaClO for 1000 g (1000 mL) of H20 ( 15 /100 moles proportion is different) but why ? It is a very high concentration
2- anhydrous NaOCl is potentially explosive, and the solid pentahydrate degrades quickly. usually i add small quantities of NaOCl (aq) ( bleach) to HCl (aq) in steps: 1) pour Hcl in the beaker with gold powder/foils 2) add small quantity of bleach and immediately cover your beaker and wait until all the chlorine reacts 3) check if gold /black powders are still in the beaker 4) if some gold still there then repeat from step 2)


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## Rifkhan (Dec 28, 2021)

Yggdrasil said:


> I'm suspecting your powder may have gone bad, depending on when you bought it and how you stored it.


It has time for the expiry. But never know when it comes to industrial grade.


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## Rifkhan (Dec 28, 2021)

MicheleM said:


> 1- 15 % per cent concentration of a solute in a solvent : 150 g NaClO for 1000 g (1000 mL) of H20 ( 15 /100 moles proportion is different) but why ? It is a very high concentration
> 2- anhydrous NaOCl is potentially explosive, and the solid pentahydrate degrades quickly. usually i add small quantities of NaOCl (aq) ( bleach) to HCl (aq) in steps: 1) pour Hcl in the beaker with gold powder/foils 2) add small quantity of bleach and immediately cover your beaker and wait until all the chlorine reacts 3) check if gold /black powders are still in the beaker 4) if some gold still there then repeat from step 2)


Thank you for the reply @MicheleM.
Yes. I realized it is too much concentration. 
And regarding covering the beaker as soon adding the bleach. I didn't do that before. 
So I will try that.


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## Geo (Dec 28, 2021)

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.


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## Geo (Dec 28, 2021)

Commercial bleach that is 8% sodium hypochlorite is 8% hypochlorite by weight and not volume. 100 grams of 8% bleach will contain 8 grams of hypochlorite. In theory, 100 grams of 8% sodium hypochlorite should dissolve 8 grams of gold foils or powders.


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## Rifkhan (Dec 29, 2021)

Geo said:


> 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.


Thank you @Geo for the reply.

This gives a good explanation of the steps. 
How long will it take to dissolve around 1 gram of gold using this method?


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## Rifkhan (Dec 29, 2021)

Geo said:


> Commercial bleach that is 8% sodium hypochlorite is 8% hypochlorite by weight and not volume. 100 grams of 8% bleach will contain 8 grams of hypochlorite. In theory, 100 grams of 8% sodium hypochlorite should dissolve 8 grams of gold foils or powders.


Therefore if I take 10 grams of bleach powder, that means it is 0.8 grams of hypochlorite. 
Anyhow I need 12.5 grams of commercial bleach to dissolve 1 gram of gold


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## dkbinco (Dec 29, 2021)

Rifkhan said:


> I have few doubts regarding refining with Na Hypochlorite.
> 
> 1. May I know how much gram of industrial grade sodium hypochlorite powder is needed to make a 15% of sodium hypochlorite solution?
> 2. What proportion of sodium hypochlorite solution: HCl should be added for the refining process?
> ...


Good luck dude, I am working with same stuff except with ore that people here are telling me is not smart because I don't know without an assay what all is in the ore, so Probably good I joined. I will check on your progress later, but I have read a lot about what I am trying to do, I use a 2 to 1 mix with HCI and one thing I found interesting is I have been told to use a ORP meter while oxidizeing is happening to keep above 400 and at 1000 was the best to get the most, by adding HCI a little at a time to keep it, then when the meter quits reacting when you add to it ...its done oxidizeing, no more left in solution, then adding some sodium metebisetate a little at a time to seperate it. Just FYI, and please tell me if I am out of line and or wrong, I am not a chemist and am learning so, best way to learn is ask.


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## Yggdrasil (Dec 29, 2021)

dkbinco said:


> Good luck dude, I am working with same stuff except with ore that people here are telling me is not smart because I don't know without an assay what all is in the ore, so Probably good I joined. I will check on your progress later, but I have read a lot about what I am trying to do, I use a 2 to 1 mix with HCI and one thing I found interesting is I have been told to use a ORP meter while oxidizeing is happening to keep above 400 and at 1000 was the best to get the most, by adding HCI a little at a time to keep it, then when the meter quits reacting when you add to it ...its done oxidizeing, no more left in solution, then adding some sodium metebisetate a little at a time to seperate it. Just FYI, and please tell me if I am out of line and or wrong, I am not a chemist and am learning so, best way to learn is ask.


Dkbinko:
You could start with following the advice you have been given.
Read the book of C.M Hoke, even though it is not about ore, it is about the chemistry we do here.
Search and read the forum.
Next, when dealing with chemistry it is very important to use correct denomination of chemicals.
There is nothing named:
"sodium metebisetate" at least that we use in our chemistry.
In stead of blowing frustration for not getting the answer you want.
Maybe be grateful for getting the answer you *need* to be still alive and healthy.


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## Yggdrasil (Dec 29, 2021)

Rifkhan said:


> Therefore if I take 10 grams of bleach powder, that means it is 0.8 grams of hypochlorite.
> Anyhow I need 12.5 grams of commercial bleach to dissolve 1 gram of gold


Can I suggest a slightly other approach.
Make a chlorine generator and bubble chlorine through the HCl.

Outside or in a fumehood of course.

Edit to add:
We expect you to do the research needed and take the neccessary precautions, so you do not injure yourself or others.


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## Rifkhan (Dec 29, 2021)

That will be little risky. 
But anyhow I wanted to make it happen 
I don't have a chlorine generator at the moment. 
And for now I have to follow the instructions you all gave me for any improvements.


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## butcher (Dec 29, 2021)

If the gold in an ore is free gold in the ore (not chemically bound in the mineral makeup of the ore), visible, even if you need a loop to see it at all, then crushing and gravity is your answer.

How much gold per ton, in the rich and nonrich portion of the mine, what mechanical and chemical processes will be needed, will attempts to be profitable, or will you spend more effort or time trying to find a dime. what equipment will be needed, what outside professional help and their costs will be needed to mine and process this ore...

If the ore is chemically bound with minerals (you normally will not see the gold with a loop or less powerful microscope, then you need tons and tons of this to make recovery worth the effort.
This will normally take a lot of experiments to get a working process set up.
is the mineral ore acidic or is it basic?

How will it react to a leaching process?

What is the chemical bond, bound up with? Sulfides, arsenic, tellurides, mercury, carbonates, asbestos,, magnetites, chlorates, micas shists, silicates, hematites, bauxites, dolomite, on and on... 
What preprocessing steps will be needed to prepare the material for a leaching process, like crushing grinding, roasting, floatation...

You can waste your time and put your health in danger for nothing, or you can spend a couple of dollars (to save you thousands and thousands of dollars or wasting your time for nothing ) to see what you have, assaying will be the first step to answering many of the questions we have before we even begin to look at this ore.


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## rickbb (Dec 29, 2021)

I use HCL and bleach on foils from plated electronic parts. It's a very simple, cheap and easy process. It's my go to process for foils.

As several have said, use it on small batches of powdered or thin gold only. It's just not efficient to use on solid gold objects like jewelry or even placer gold. For solid gold objects like jewelry I use "poor mans" AR, an equally simple, efficient process.

Do all this in a proper fume hood.

I start with a beaker of the foils, add enough HCL to cover the foils, then slowly add small amounts of common household bleach, (5% or 8% both work). Stir and wait until it seems the process stops, then add smaller amounts of bleach. Stop adding bleach when all the gold is dissolved. This keeps you from adding too much bleach. 

Put the beaker on a hot plate and set for low heat, no need to boil, just warm to the touch is enough. This will drive off any remaining chorine in an hour or so. You can then drop the gold or leave on the heat to reduce the volume and concentrate the solution, up to you. Then drop the gold using the method of your choice.

I don't know how ore was brought in to the topic, recovering gold from ore is a completely different process and you should never attempt to use any chemical digestion process on ore without knowing exactly what else is in the ore besides the gold. 

Ore, (actual ore and not free gold imbedded in quartz which is not really an ore per se), can and often does contain arsenic, cadmium, various other heavy metal compounds, etc. Which is why you should get a proper assay on any ore first before doing anything to it.


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## dkbinco (Dec 29, 2021)

Yggdrasil said:


> Dkbinko:
> You could start with following the advice you have been given.
> Read the book of C.M Hoke, even though it is not about ore, it is about the chemistry we do here.
> Search and read the forum.
> ...


Ok thanks I will check out the book, I found a place to get an assay, and I wont do nothing until, I am reading and learning thats why I am here. I will post assay and go from there.


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## orvi (Dec 29, 2021)

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.


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## Geo (Dec 29, 2021)

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.


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## dpgold (May 31, 2022)

Geo said:


> 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?


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## Geo (May 31, 2022)

dpgold said:


> 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.


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## Geo (May 31, 2022)

orvi said:


> 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.
> ...


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.


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## dpgold (May 31, 2022)

Geo said:


> 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?


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## orvi (May 31, 2022)

Geo said:


> 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.


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## Shark (May 31, 2022)

Geo said:


> 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?


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## Geo (May 31, 2022)

dpgold said:


> 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.


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## Geo (May 31, 2022)

Shark said:


> 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.


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## Shark (May 31, 2022)

Geo said:


> 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.


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## Geo (May 31, 2022)

Shark said:


> 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.


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## Shark (May 31, 2022)

dpgold said:


> 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.


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## orvi (May 31, 2022)

Shark said:


> 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.


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## Yggdrasil (Jun 1, 2022)

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.


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## orvi (Jun 1, 2022)

Yggdrasil said:


> 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.
> 
> ...


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


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## Yggdrasil (Jun 1, 2022)

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


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