Borax in waste treatment?

[Gsracer]

Hello grf

I have ready 4 metals post on the subject and have read numerous posts on the subject but I need some help with the end process. ’ve been trying to process a 5 gallon bucket or waste solution from refining silver for better part of a week.

I had 5 gallons of dilute nitric and distilled rinse water from silver cementation. About 1500 ml of nitric the rest is the distilled rinse waters.

I let it sit in copper for a week stirring a few times a day.

After this I siphoned off the liquid to a separate bucket filled with iron and raised the ph to about 2 using lime.

After another week of stirring the copper dropped and the solution changed to tea green. I then moved it to its final bucket. To drop the iron.

This is where I’m stuck. I’ve added 8 Dixie cups of lime over the course of 5 days but the ph will not go above 3. I know I need to get it to 11 at least to drop everything so I can bring it back to neutral and dispose of the waste properly.

I took a sample of 50 ml and added a couple of pinches of borax and it the ph shot up right away.

Can I safely add borax to the rest to raise the ph as I have about 15 lbs of borax just sitting I’m not using or should I pony up and order some lye. Don’t want to blow myself up or make it worse.


Thanks in advance.

 

[Gsracer]

Well, my sample of iron waste solution with some borax sat over night and it did indeed drop everything out of solution. There is clear liquid sitting on top of fine sediment. The solution was previously a rust color but the sediment is now yellow. Pic of now below, ph is sitting between 9 and 10 of the clear liquid.

I would still like to know if this is safe before i give the full 5 gallons the borax treatment.

 

[Martijn]

Don't know about borax. But you can use soda ash.

 

[4metals]

Iron comes out of solution at a pH between 3 and 4. Sodium hydroxide will get you there quickly.

 

[Gsracer]

Thank you both for the reply, i was able to find some lye locally for a good price and i just used that. I did consult a colleague at work who consulted with his old chemistry professor who stated you could create copper tetroborate if you added borax to to copper nitrate. Off topic but interesting.