could you use NaOH to help get rid of AgCl

[solar_plasma]

Correct equation for precipitation of silver sulfide:
2 [Ag(S₂O₃)₂]^3- + S^2- ==> Ag₂S + 4 S₂O₃^2-

If the S^2- would be added by a solution of alkali sulfide like K₂S, would we be left with a solution of alkali, chloride and thiosulfate ions, so we could reuse this solution for the same purpose?

edit: if so, the silver sulfide could be used as SO₂ source for the precipitation of gold... :?: :idea:

 

[butcher]

I have not tried to dissolve the silver chloride from gold powders, it sounds like a good plan, I would like to say a few things I see here, it looks like one of the products is the chemical we stated with:


Let say we used sodium thiosulfate (Na2S2O3) to dissolve the silver Chloride AgCl.
this gives us a sodium silver thiosulfate compound and mixed in salt water.

2 Na2S2O3 + AgCl --> NaCl (aq) + Na3[Ag(S2O3)2] (aq)

This silver thoisulfate compound (Na3[Ag(S2O3)2 would be called sodium bis(thiosulfato)argentate.

Then we used sodium sulfide Na2S to convert the silver thiosulfate compound to silver sulfide.
Our product is sodium thiosulfate and silver sulfide.

Na3[Ag(S2O3)2] +Na2S --> Na2S2O3 + Ag2S

Looks to me like we might find a use for the sodium thiosulfate byproduct, but I would want to look more into separating sodium thiosulfate from the salt water through crystallization, and solubility, but at a glance it looks like we can crystallize the NaCl out of solution).
sodium thiosulfate solubility 231g/100ml@ 100 deg C, and 70g/100ml@ 20 deg C.
NaCl solubility not affected too much by temperature about 35g/100ml @ 20 deg C


Then we convert the silver sulfide to silver metal using zinc metal, to get silver metal and negligible soluble zinc sulfide.

Ag2S + Zn --> 2Ag + ZnS

(zinc sulfide which we can dry and disposed of as waste).

 

[Platdigger]

Solar, If you tried to use silver sulfide to drop gold from a chloride solute, wouldn't you end up with silver chloride again?

 

[NeMonstr]

Gold dissolves in the thiosulphate in the presence of oxygen.

4Au+O₂+8S₂O₃^2-+4H⁺→ 4[Au(S₂O₃)₂]^3-+2H₂O

 

[butcher]

NeMonstr,

Notice you not only have added oxygen in the equation, you also have acid (H+) with the thiosulfate and gold.
With Ore many times they use copper II as a catalyst, and pH is fairly critical, ammoniacal solutions are also normally involved.

 

[NeMonstr]

Yes, not attentive.

 

[NeMonstr]

Notice you not only have added oxygen in the equation

Oxygen may be present in solution. Dissolution copper in ammonia as an example.

Silver chloride is dissolved in sodium sulfite. AgCl+2Na2SO3 =Na3[Ag(SO3)2]+NaCl
http://www.findpatent.ru/patent/217/2170277.html Sulfite complex is decomposed with acid. Sulfuric or hydrochloric acid, for example. (SO2↑)

 

[solar_plasma]

Solar, If you tried to use silver sulfide to drop gold from a chloride solute, wouldn't you end up with silver chloride again?

No, I meant to use the silver sulfide as a source for SO₂ by roasting it first then, when we want to drop gold.The SO₂ gas could be filtered and drawn or pumped through the gold solution.

 

[solar_plasma]

Yes, not attentive.

...could be stirred and heated in a stream of inert gas...

 

[solar_plasma]

Notice you not only have added oxygen in the equation

Oxygen may be present in solution. Dissolution copper in ammonia as an example.

Silver chloride is dissolved in sodium sulfite. AgCl+2Na2SO3 =Na3[Ag(SO3)2]+NaCl
http://www.findpatent.ru/patent/217/2170277.html Sulfite complex is decomposed with acid. Sulfuric or hydrochloric acid, for example. (SO2↑)

Could the silver be cemented from this complex, too?

 

[NeMonstr]

]Could the silver be cemented from this complex, too?

Data exist, but I have not tried. All at an experiment at the moment. I think that need zinc dust, as well as possible and alkalis.
I know exactly what complex is decomposed with sulfuric or hydrochloric acid.

Bottle stands with dissolved chloride in sodium sulfite. I learn it when time permits.

 

[butcher]

solar_plasma

The idea of heating silver sulfide to make SO2 gas, I believe it would be hard to roast it back to silver and drive off the sulfur gases, adding iron metal to the sulfide would help to take the sulfide from the silver, and then release it as gas, also I do not think glass would be the best choice to work well, the temperatures needed are very high in the roasting process, luckily silver does not amalgam with iron.

Actually I do not think I would want to deal with sulfides if I did not have to.

I just see there are much easier methods to generate SO2 gas.

 

[Mudville9]

]Could the silver be cemented from this complex, too?

Data exist, but I have not tried. All at an experiment at the moment. I think that need zinc dust, as well as possible and alkalis.
I know exactly what complex is decomposed with sulfuric or hydrochloric acid.

Bottle stands with dissolved chloride in sodium sulfite. I learn it when time permits.

Sodium sulfite/silver chloride reactions are quite interesting. The sulfitoargentate solution can be filtered and the silver recovered in various ways.
1) Acidification results in a fairly pure silver chloride which can then be worked up to a purified silver powder.
2) Heating the solution to 90 C and keeping the pH at 12 throughout will decompose the sulfitoargentate directly to silver powder. After cooling, this solution can be reused to dissolve more silver chloride, at least until the chloride content builds and interferes with the reaction.

Alternatively, silver chloride can be directly reduced to silver powder by vigorously agitating the silver chloride/sodium sulfite solution, heating to 90 C while maintaining the pH at 12. ORP can be used to determine end points. A near saturated solution of sodium sulfite is preferred and care must be taken to allow sufficient headspace in the event of foaming.

 

[METLMASHER]

Though I struggled with the chemical signatures, I understood all the written processes. I thank you, all who added here, you've made it understandable.