Recovery of silver from waste solutions.

[xms95]

Hello everyone. I need some help with this. So, i have waste solutions containing Ag - 100 mg/l. Ni ~ 700 mg/l. Zn ~ 800 mg/l. Co ~ 1 mg/l. Cu ~ 300 mg/l. Its sulphate solutions btw. The volume of solutions is very big so i dropped all of these metals by increasing its pH by adding NaOH solution. Now i think i have Ag2O and a lot of Me(OH)2. Is there anyway of extracting silver from this hydrate?

 

[Lino1406]

Instead of caustic add simple salt, to get silver chloride

 

[xms95]

Instead of caustic add simple salt, to get silver chloride

There is very big volume of solution. 20 m^3. I added NaOH to separate water for increasing concentrations. I tried to dissolve hydrate in nitric acid and drop AgCl with NaCl and HCl, no result. May be i added not enough salt..

 

[Lino1406]

Make experiment on 10 liters = 1g silver

 

[xms95]

Make experiment on 10 liters = 1g silver

This solution is from regeneration process of ion exchange resin.
2R-Ag(CN) + 2CS(NH2)2 + 2H2SO4 -> R2SO4 + 2Ag[CS(NH2)2]SO4 +4HCN

So this Silver complex will dropped by NaCl?

 

[Lino1406]

At least partially

 

[xms95]

At least partially

Hello. I've read a lot in this forum. And i found DMG for my self. So the problem was Ni in Ag ThiO solution. And i couldn't separate Ni from this and we had to drop this solution. Today i found in lab DMG and tried to drop Ni from solution. And its concentration was 210 mg/dm3 and after adding DMG concentration of Ni decreased to 58 mg/dm3.
I have some questions. pH of solution was ~1.85. i added some NaOH for getting pH 4. Then i dissolved DMG in Ethanol, heat it and when its cooled i mixed two solutions. The solution become light pink, almost red. That was Ni-DMG2.
How can i drop all Ni from solution? Without losing Ag. If i could do this, i would use this ready product solution for extracting Ag with electrolysis.

 

[Lino1406]

1stly try to remove Ag. The rest can be precipitated as before. I do not see any economics in Ni recovery

 

[xms95]

1stly try to remove Ag. The rest can be precipitated as before. I do not see any economics in Ni recovery

Yes, we dont need to recovery Ni. First of all im working in Hydrometallurgical Plant. In Elution manufactory. And i have some volume of solution that is ready for electrolysis but there is a lot of Ni and this solution cant be sent to the Electrolysis. All i need to remove Ni from that solution. This will solve all of my problems with Ag.

 

[Lino1406]

Unfortunately Ni is so much concentrated vs. Ag that Ag will be dragged together with Ni by your ideas

 

[xms95]

Unfortunately Ni is so much concentrated vs. Ag that Ag will be dragged together with Ni by your ideas

Concentration of Ag was 129 and after adding DMG it became 98 mg/dm3. I think part of Ag droped from solutions when i was adjusting pH.

 

[xms95]

Unfortunately Ni is so much concentrated vs. Ag that Ag will be dragged together with Ni by your ideas

Hello. I did the same today and tried not to lose Ag while adjusting pH. I didn't noticed any drop. Start pH was 1.39, Ag 75 mg/dm3, Ni 144 mg/dm3. i added some NaOH and it became 4.00. After adjusting pH concentrations were little lower. But i think because the volume of solution increased. Then i prepared DMG solution 50 ml of Ethanol and 1 g DMG. I mixed 20 ml of dmg with NiAg solution, then about 50% of Ni dropped. Ag become 54 mg/dm3. And i think thats because the volume of solution increased and concentration become lower, again. So i got Red drop. I can get these drops and dissolve it in aqua regia and check Ag in it. But i still cant drop all of Ni with DMG.

 

[Lino1406]

Ni better drops at pH over 8

 

[xms95]

Ni better drops at pH over 8

Yes, but at pH 8 all the metals will be dropped...