" Help ! Have a deplating set up but cant get good yeild"

[4metals]

i have attached a picture of the set up i have.

could you recommend a different deplating chemical or that i can use in this machine with a different precipitator?

In theory its all there just the precipitation phase isn't working as good as it should i dont think

It is difficult to shoot from the hip and assume the process the manufacturer is proposing, so maybe if we dissect the equipment you have and figure out what each piece does we can come up with a different more user/environment friendly method for your equipment to process the material you wish to process.

To me the closed head tanks look like some sort of connected by transfer plumbing pressurized reactors and there is some sort of electrolytic recovery based on what appears to be a rectifier. The 4 connected square tanks look like either cascading rinse tanks or a tumbling barrel that progresses through 4 tanks to strip the parts.

Knowing what sequence you progress through the system and what of their chemistry is used at each step maybe we can figure this out. If they have instructions (ideally in English) you could post that would help.

 

[Shunter421]

It is difficult to shoot from the hip and assume the process the manufacturer is proposing, so maybe if we dissect the equipment you have and figure out what each piece does we can come up with a different more user/environment friendly method for your equipment to process the material you wish to process.

To me the closed head tanks look like some sort of connected by transfer plumbing pressurized reactors and there is some sort of electrolytic recovery based on what appears to be a rectifier. The 4 connected square tanks look like either cascading rinse tanks or a tumbling barrel that progresses through 4 tanks to strip the parts.

Knowing what sequence you progress through the system and what of their chemistry is used at each step maybe we can figure this out. If they have instructions (ideally in English) you could post that would help.

i have attached a picture with the items lettered on each part of the machine

"A" is the stripping tanks

it has an automated bucket that you load apporx 100kg of ram into the bucket with fine holes in it which soaks in the first tank for 5 mins approx. then goes to the next tank and rinses off all the way down to tank 4 then empty's out after wards and start the process again i did 300kg as that all i had at the time. the solution still stripped the gold plating off pretty quickly..

from there the solution travels via pump to a large vaccum filter and sucks through into the first holding tank on ground level behind the mixing tank "b"

"B" is a mixing tank that you mix up the stripping solution and then its pumped to the first tank "a"

onced throught the filter the solution is then pumped into the holding tank behind b on ground level then goes in to the tank "c" this is where the precipitation goes
they say it takes 5 -6 hours it has a mixing blades inside " C" solution with NaOH is added which i belive to be sulphur from the tests i had done by xrp.

"The liquid in the "C" reduction tank is about 700L. Add 7kg NaOH and 8kg C chemical, stir for more than 6 hours, turn off the stirring motor, let the liquid stand for 1-2 hours, and then filter"

after the precipitation the solution filters through a vaccum in which all going well there is meant to be a black dust which is the gold.


After filtering, transport the liquid to the "D" enrichment tank. After the transportation is complete, add zinc powder or zinc wire. Zinc wire is cheaper and easier to buy. The amount of zinc powder added is 0.2-0.3g/L, or zinc wire is 0.3-0.4g/L. React for 5-6 hours after adding, stand for 1-2 hours after reaction, and then filter. The filtrate is put into a vacuum storage tank to observe whether the liquid level gauge is clear.

Then can disgard the waste solution

This is the process they have told me to follow

 

[haveagojoe]

I think the process may be Alkaline Sulfide leaching. However if so, the cementation with Zinc may be producing highly toxic gases.

The approach was developed as an alternative to cyanide leeching of mineral ores. It is not well known in conventional refining and has several variants; some of the processes are patented.

The leading professional researcher of this process is Corby G. Anderson. He is the director of the Kroll Institute for Extractive Metallurgy at the Coloado School of Mines, and is a visiting professor of Mineral Engineering at Central South University in China.

 

[Yggdrasil]

I think the process may be Alkaline Sulfide leeching. However if so, the cementation with Zinc may be producing highly toxic gases.

The approach was developed as an alternative to cyanide leeching of mineral ores. It is not well known in conventional refining and has several variants; some of the processes are patented.

The leading professional researcher of this process is Corby G. Anderson. He is the director of the Kroll Institute for Extractive Metallurgy at the Coloado School of Mines, and is a visiting professor of Mineral Engineering at Central South University in China.

There is many things it can be, but until we get some tangible information it is pure guessing.

 

[Yggdrasil]

i have attached a picture with the items lettered on each part of the machine

"A" is the stripping tanks

it has an automated bucket that you load apporx 100kg of ram into the bucket with fine holes in it which soaks in the first tank for 5 mins approx. then goes to the next tank and rinses off all the way down to tank 4 then empty's out after wards and start the process again i did 300kg as that all i had at the time. the solution still stripped the gold plating off pretty quickly..

from there the solution travels via pump to a large vaccum filter and sucks through into the first holding tank on ground level behind the mixing tank "b"

"B" is a mixing tank that you mix up the stripping solution and then its pumped to the first tank "a"

onced throught the filter the solution is then pumped into the holding tank behind b on ground level then goes in to the tank "c" this is where the precipitation goes
they say it takes 5 -6 hours it has a mixing blades inside " C" solution with NaOH is added which i belive to be sulphur from the tests i had done by xrp.

"The liquid in the "C" reduction tank is about 700L. Add 7kg NaOH and 8kg C chemical, stir for more than 6 hours, turn off the stirring motor, let the liquid stand for 1-2 hours, and then filter"

after the precipitation the solution filters through a vaccum in which all going well there is meant to be a black dust which is the gold.


After filtering, transport the liquid to the "D" enrichment tank. After the transportation is complete, add zinc powder or zinc wire. Zinc wire is cheaper and easier to buy. The amount of zinc powder added is 0.2-0.3g/L, or zinc wire is 0.3-0.4g/L. React for 5-6 hours after adding, stand for 1-2 hours after reaction, and then filter. The filtrate is put into a vacuum storage tank to observe whether the liquid level gauge is clear.

Then can disgard the waste solution

This is the process they have told me to follow

Just a couple of questions.
Do you have the full procedure of dropping the Gold?
If so, can you disclose it here?
What does the precipitating agent look like?
Is it a powder, what color, is it heavy and so on?

 

[haveagojoe]

There is many things it can be, but until we get some tangible information it is pure guessing.

Certainly. But I think since we can rule out the conventional processes, ASL would be my best guess.

 

[Yggdrasil]

Certainly. But I think since we can rule out the conventional processes, ASL would be my best guess.

Since we have no information, how can we rule out the convential processes?

 

[haveagojoe]

Since we have no information, how can we rule out the convential processes?

Well it doesn't seem like any of our common processes such as Copper Chloride leaching or a Sulfuric cell, or even direct AR. You are right that this is pure speculation and concrete information is an absolute neccessity.

I'm making some fairly wild assumptions and just guessing based mainly on the presence of sulfur in the XRF. It would potentially seem consistant with the formula for the lixiviation of gold by sulfides and polysulfides:
2Au + S₂^2- + 2S^2- => 2AuS- +2S^2-

It seems to me that the precipitant is Zinc but this would be quite dangerous according to Anderson.

https://www.saimm.co.za/Conferences/PbZn2008/121-132_Anderson.pdf

 

[haveagojoe]

A simple litmus test of the solution would be a good idea, if it's strongly akaline then that could be an indicator of ASL. I'm guessing it will be alkaline since OP says he added 7kg of Sodium Hydroxide.

 

[Yggdrasil]

A simple litmus test of the solution would be a good idea, if it's strongly akaline then that could be an indicator of ASL. I'm guessing it will be alkaline since OP says he added 7kg of Sodium Hydroxide.

The 7 kg of NaOH is added during precipitation, which is puzzling.
That indicates dropping it as a hydrolytic process as Hydroxides, not as Gold.
And then Add Zinc in the next tank to deplete the solution completely.

Maybe one can change the chemistry to a known process using the same equipment?

 

[haveagojoe]

I wonder if it could be thiourea? There are some hybrid bioleaching methods described here which look vaguely possible:

https://link.springer.com/article/10.1007/s40831-022-00499-8

There's some clever stuff going on out there, it really is pure speculation as to what it could be.

Edit to add: There's a precipitation method described in the link above which uses
"a solution containing 40% sodium hydroxide and 12% sodium borohydride balanced with water (VenMet solution)" (Awadalla and Ritcey). The referenced paper is here:

https://www.tandfonline.com/doi/abs/10.1080/01496399108050525

 

[haveagojoe]

This is also interesting:
https://www.mdpi.com/2297-8739/10/7/384

Looking at the XRF of B, Sulfur 15.9 and Sodium 11.1,


"Other suitable replacements could be leaching with sulfide, bisulfite, and hydrogen
sulfide. Sulfur-based reagents other than thiosulfate and thiourea are sulfides, bisulfides,
hydrogen sulfide (or sulfur dioxide), and polysulfides. Of these reagents, only bisulfite
and hydrogen sulfide have practical application"
- Ibid

 

[g_axelsson]

It seems to me that the precipitant is Zinc but this would be quite dangerous according to Anderson.

https://www.saimm.co.za/Conferences/PbZn2008/121-132_Anderson.pdf

I skimmed through that paper and it looked like there are no big risks unless you have arsenic, antimony or mercury in the material you leach.

It didn't seem like the the gold leaching effect was so good as it only dissolved a minor part of the gold in the ore. Enough to be worthwhile to recover but the majority went along with the copper concentrate to the smelter.

For ram memory sticks, most of the gold is contained in the thin bond wires embedded in the plastic capsule. To expose the gold you need either to grind the material down to a fine powder or incinerate the chips. There are no other way to get to the gold.

Göran

 

[haveagojoe]

I wonder if it possible to test chemical B to see if it's Sodium Bisulfite Bisulfate? It looks like it could be from the XRF. That would be a clue if it was.

 

[haveagojoe]

it looked like there are no big risks unless you have arsenic, antimony or mercury in the material you leach.

I was just going from what Andersen says about cementing with Zinc:
"Conventional methods of gold recovery such as zinc or aluminum cementation are not applicable to this type of solution because of the dangers associated with stibine or arsine gas generation"

 

[haveagojoe]

I think identifying chemical B will be the first step.
It looks a bit like it could be Sodium Bisulfate which when reacted with Sodium Hydroxide forms Sodium Sulfate, then the addition of Sulfur forms Sodium Thiosulfate.

Here is the synthesis of Sodium Thiosulfate: video
Here are some tests to identify if it is Sodium Thiosulfate: video

Here is the manufacturer's website which has some vague decription of the process and a video:
https://www.sunygroup.cn/products/E-waste-Recycling-Equipment/Gold-Deplating-System.html

 

[haveagojoe]

Some more light reading:

Patent

Paper

from this old thread: https://goldrefiningforum.com/threads/a-new-plan.19973/

 

[Shunter421]

I think the process may be Alkaline Sulfide leaching. However if so, the cementation with Zinc may be producing highly toxic gases.

The approach was developed as an alternative to cyanide leeching of mineral ores. It is not well known in conventional refining and has several variants; some of the processes are patented.

The leading professional researcher of this process is Corby G. Anderson. He is the director of the Kroll Institute for Extractive Metallurgy at the Coloado School of Mines, and is a visiting professor of Mineral Engineering at Central South University in China.

that would make sense it seems to be an unreliable method of recovering the gold i think my best option is to scrap that and go for a more easier conventional method.

Aqua regia would be the best option out the cost of the nitric acid and the 1 use of it would out weigh the recovery. any other ideas for a more cost effective option?

many thanks

 

[Shunter421]

Just a couple of questions.
Do you have the full procedure of dropping the Gold?
If so, can you disclose it here?
What does the precipitating agent look like?
Is it a powder, what color, is it heavy and so on?

when the solution is put into the tank "c" it precipitates over 5-6 hours of stirring with no heat.
im wondering of the no heat is the issue?
then the black gold dust is filtered out of the tank

then the waste solution is transferred to the next tank "d" where the zinc and vitamin c is added to neutralize the waster solution and then is discarded.

i think that their way of stripping the gold is ok but the precipitation is not working. My best option i think is to scrap all the mystery powders and potions and start from scratch with proven conventional methods

Aqua regia is going to be to expensive for the nitric acid it will out weigh the recovery because mixing up 300l of the solution per time will be far to costly.

What do you recommend as a cost effective alternative that would be more reliable ?

Absolutely blown away by hoe many people have reached out to assist i thought it was going to be a long shot but everyone has been so helpful !!

Many thanks

 

[Shunter421]

The 7 kg of NaOH is added during precipitation, which is puzzling.
That indicates dropping it as a hydrolytic process as Hydroxides, not as Gold.
And then Add Zinc in the next tank to deplete the solution completely.

Maybe one can change the chemistry to a known process using the same equipment?

absolutely agree with changing the chemistry with the equipment it must work surely.

Any thoughts on what to use chemistry wise?