AP solution case

[Ayham Hafez]

I soaked some plated gold connectors in AP solution as usual do, my materials divided in two buckets, after 3 days one of the buckets changed color to white green then start boiling for two days, all gold foils disappeared, second bucket also did the same after few days, I don't know what the reaction was, but most of the connectors dissolved partially, I didn't know what to do to get the gold so I used NaOH to precipitate everything, anyone knows what could this reaction was?

I attached two photos explaining the reaction.

 

[Yggdrasil]

I soaked some plated gold connectors in AP solution as usual do, my materials divided in two buckets, after 3 days one of the buckets changed color to white green then start boiling for two days, all gold foils disappeared, second bucket also did the same after few days, I don't know what the reaction was, but most of the connectors dissolved partially, I didn't know what to do to get the gold so I used NaOH to precipitate everything, anyone knows what could this reaction was?

I attached two photos explaining the reaction.

AP will not dissolve any Gold to speak of, so my guess is that those connectors was Brass and the boiling was the Zinc and Copper going into solution.
And if you suspected Gold to be in solution, why in the world did you drop everything as Hydroxides in stead of Cementing on Copper?

 

[Shark]

You could study the forum before doing these things. It is much easier to get it right than it is to fix it.

 

[Ayham Hafez]

AP will not dissolve any Gold to speak of, so my guess is that those connectors was Brass and the boiling was the Zinc and Copper going into solution.
And if you suspected Gold to be in solution, why in the world did you drop everything as Hydroxides in stead of Cementing on Copper?

Forgot to mention that when I tried to cement with copper a strong reaction start so I said to my self the solution is too much complicated to fix this is why I used NaOH

 

[Ayham Hafez]

Forgot to mention that when I tried to cement with copper a strong reaction start so I said to my self the solution is too much complicated to fix this is why I used NaOH

If zinc make this issue, what is the best practice to process brass connectors?

 

[Yggdrasil]

Forgot to mention that when I tried to cement with copper a strong reaction start so I said to my self the solution is too much complicated to fix this is why I used NaOH

If there is a strong reaction your Copper is not Copper.
So in stead you made a real mess.

 

[Yggdrasil]

If zinc make this issue, what is the best practice to process brass connectors?

If the brass connectors really are plated, just use HCl and if the foils are not loose go to AP.
Edit for spelling

 

[eaglekeeper]

I attached two photos explaining the reaction.

Those coax connectors are better to run in a striping cell..... Yes, removing them from the boards may seem time consuming.... but how much time/money will it take you to make your waste solutions safe for disposal.

 

[Ayham Hafez]

Those coax connectors are better to run in a striping cell..... Yes, removing them from the boards may seem time consuming.... but how much time/money will it take you to make your waste solutions safe for disposal.

In my case, chemicals much more cheaper than hiring some ones to dismantling, also save more time, regard solutions waste cementing with copper and iron do the job easily

 

[Yggdrasil]

In my case, chemicals much more cheaper than hiring some ones to dismantling, also save more time, regard solutions waste cementing with copper and iron do the job easily

Waste treatment wise that is far from enough.
Read dealing with waste:
https://goldrefiningforum.com/threads/dealing-with-waste.10539/

 

[Martijn]

The fact that leaching with acids is cheaper than labor like manually stripping, and in another post I asked how he deals with waste. now i see he cements on iron and then,...? local groundwater supplement? Fish food?

Lets get the environmental hygiene in order first before we advice any other chemistry!

@Ayham Hafez: Pictures and process description please!

 

[Ayham Hafez]

The fact that leaching with acids is cheaper than labor like manually stripping, and in another post I asked how he deals with waste. now i see he cements on iron and then,...? local groundwater supplement? Fish food?

Lets get the environmental hygiene in order first before we advice any other chemistry!

@Ayham Hafez: Pictures and process description please!

After last cementation with iron, I naturalize the waste barrel with NaOH, that's it I think this is the proper way, am I right?

 

[Martijn]

After last cementation with iron, I naturalize the waste barrel with NaOH, that's it I think this is the proper way, am I right?

Neutralizing is to pH 7. You need to bring it to pH 11 and filter off the hydroxides. The water can then be diposed in the sewage system.
Have you read the 'dealing with waste' link Yggdrasil gave you?

 

[Ayham Hafez]

Neutralizing is to pH 7. You need to bring it to pH 11 and filter off the hydroxides. The water can then be diposed in the sewage system.
Have you read the 'dealing with waste' link Yggdrasil gave you?

Yes I read it, I do the same but with NaOH rather than Sodium carbonate since NaOH much more basic but for sure sodium carbonate has lower price maybe in future I will use it, but still not have the cementing agitation tool I hope will make it soon since always PMs stuck on my copper bar while cementing.

 

[eaglekeeper]

After last cementation with iron, I naturalize the waste barrel with NaOH, that's it I think this is the proper way, am I right?

I think there is some metals that will go into solution in both high and low PH...but I could be wrong.

 

[Yggdrasil]

I think there is some metals that will go into solution in both high and low PH...but I could be wrong.

It is well described on the thread Dealing with waste.

 

[Martijn]

I think there is some metals that will go into solution in both high and low PH...but I could be wrong.

Almost all of the metals hydroxide curves have a 'tub bottom'; a lowest point from which solubility rises in both directions: acidic or basic.

that is why i filter at several pH levels, by sight. when there are other hydroxides forming (different color), i stop and filter to avoid redissolving any low pH hydroxides. See grahp. there are others, some do not have the line bending back up, some do. I guess it's where they stopped analyzing and assumed solubility further decreased.

 

[eaglekeeper]

that is why i filter at several pH levels, by sight. when there are other hydroxides forming (different color), i stop and filter to avoid redissolving any low pH hydroxides.

Thanks for the info,
I treat my waste a little differently, so I've never dug too deep into the Ph adjustment method.

What do you do with the hydroxides you recover?

 

[Martijn]

Thanks for the info,
I treat my waste a little differently, so I've never dug too deep into the Ph adjustment method.

What do you do with the hydroxides you recover?

Filter, and store in a bucket until full, drain excess water in a filter and offer it to the manucipal recycling facility labeled 'metal hydroxides'.
Private persons can bring it there for free. Companies have to pay.
The clear pH 11 water goes down the drain.

 

[eaglekeeper]

Filter, and store in a bucket until full, drain excess water in a filter and offer it to the manucipal recycling facility labeled 'metal hydroxides'.
Private persons can bring it there for free. Companies have to pay.
The clear pH 11 water goes down the drain.

We have something similar in my county..."Amnesty day", which is biannual and allows residents to drop off waste for free. Businesses will get charged a Tipping fee.