Silver Chloride and Lead Sulphate mix

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Wingedcloud

Well-known member
Joined
Nov 6, 2014
Messages
96
Hello all,

Been recovering some gold from a large batch of ceramic cpus I got.

After leaching with AR, my usual method is to drop some ice cubes on my pregnant solution, to chill it and (presumably) remove any silver in the form of chloride, and add some sulfuric acid to it aswell, to drop any lead as lead sulpahte.

I usually dont pay much attention to the silver from ceramic cpus, but this time I fell like I should, because there is really alot of them :lol:
So, I've been pilling up paper filtes of the silver chloride and lead sulphate "mix" and was wandering if there is a method to redissolve it all again and get the silver isolated, either by chloride or through copper cementation.
I always think about AR'ing it all, but I would like insight from anyone before I do it and maybe create a big mess.

Anyone can chime in and give some advice on this ?

Thanks in advance !

Winged
 
With chilling you get both - Ag and Pb as insoluble chlorides. Then dissolve lead chloride in hot water - no need for sulphate
 
Another thing. Running a pregnant AR solution through silver chloride filled filters will lose you a reasonable amount of gold.

Based purely on the description of your process, you’re probably better recovering initially.

You can run your cpus in AP to recover the foils which will likely leave you with only gold and silver chloride.

Silver chloride can be converted easily into a soluble form which will eliminate losses through trapped gold solution.

But definitely think about a recovery process first. Makes life a lot easier and gold a lot purer.
 
Jmk88 said:
Silver chloride can be converted easily into a soluble form which will eliminate losses through trapped gold solution.
Click to expand...

You're going to have to help me out here please. How is Silver Chloride converted easily into a soluble form during the process of recovering gold from processors?

For the record over the ceramics I've done, Silver Chloride hasn't been an issue because there really isn't that much of it, and proper vacuum filtering to a clear liquid prevents the vast majority from even getting into your gold powder.
 
Jon,

Silver chloride is quite easily soluble in water and pentahydrates.

But I’m sure you already knew that.

Hope you’ve been well.
 
Sodium thiosulphate.

Hoke disusses it but mainly for an antidote to cyanide.

A 20% solution based on 1000 grams of water will dissolve approximately 90grams of silver chloride. Heated.

It’s a good option if you can’t get nitric to remove hard solder but I agree with you I’m not sure why you’d have much lead or silver on ceramic cpus. Possibly some minor lead but struggling with the silver.

Possibly hard soldering/brazing/welding I don’t know much about cpus they always strike me as a waste of time unless obtained free.
 
Yeah so it's Sodium Thiosulphate and water. I understand that, thanks.

The bit I will struggle with is why would I introduce that into the process thereby increasing my waste liquids, and in fact making a completely different additional waste stream.

My normal approach is to filter the AR to within an inch of its life using vacuum filtration, thereby making the drops incredibly clean and the HCl washes on the gold powder will take up small amounts of silver should any be there after correct filtration and precipitation.

All the filter papers are then collated for treatment in one batch at a later stage.
 
Yea I think we’re on the same page.

The issue is, we both understand and appreciate the recovery process.

I think butcher hits the nail on the head; the less rubbish in, the less rubbish out.

I think the answer for me, is recover using AP if just e scrap, dissolve the silver chloride and then you’ll have nearly a pure AR solution.

That’s probably where he’s going a bit wrong. I still think silver chloride is a problem if not removed prior to AR. It’s so easy to do so I don’t know why anyone wouldn’t. Silver chloride is, in my opinion, very hostile to the refining process. Recovery is 90% of the work I think. Any old fool can pour two liquids together and drop some gold and base in.

It also stops any flakes being trapped as well as pregnant AR. Thinking about it, cpus probably do have hard soldering.
 
I think a thorough explanation of the difference of solders somewhere by someone would be very helpful to people.

I notice that most the problems people are facing relate to solder issues; be it jewellery or e scrap.

I will draft something and send copies to the administrators to see their views.
 
Stick them up on here if you like. I'm pretty sure that the moderators would agree that there's a pretty good range of knowledge on GRF that doesn't depend upon the colour of your name.

I'd be interested in a look at what you've got to offer, but do be prepared for some reasoned disagreements from members as well as agreement.

Jon
 
I don’t mind that but I think something exclusively on solders would be helpful to people.

I see a lot of posts where people post pictures of what appears to me to be silver chloride thinking it’s lead.

People then offer advice on that basis.

It’s always identified as solder but soft solder as it was pointed out to me, is quite easily treated with hcl even with big batches. Hard solder is an entirely different beast, especially for someone starting out like me.

So my approach is to focus most of your energy on recovery. It’s where the real magic happens as it takes all of 20 mins to dissolve gold in AR. It’s how you prepare your gold prior to going in that influences quantity and quality.

Just having silver chloride in an AR solution based on my limited experience loses you gold. Agreed that funnelling would mitigate, but eliminating is the best option.

It’s so easy to do during recovery stage too that it doesn’t make sense. You are also able to collect more pure silver as it won’t be contaminated by gold. An ounce of silver would pay for 25kg of a salt that can dissolve silver chloride so it’s well worth doing.

I also cement my copper so it all adds up eventually.

But the silver removal prior to ar is a no brainier to me?
 
anachronism said:
Yeah so it's Sodium Thiosulphate and water. I understand that, thanks.

The bit I will struggle with is why would I introduce that into the process thereby increasing my waste liquids, and in fact making a completely different additional waste stream.

My normal approach is to filter the AR to within an inch of its life using vacuum filtration, thereby making the drops incredibly clean and the HCl washes on the gold powder will take up small amounts of silver should any be there after correct filtration and precipitation.

All the filter papers are then collated for treatment in one batch at a later stage.
Click to expand...

Found that kind of funny, but since I started working on that same principle I have had way better looking gold.
 
Lino,

Do you know how to effectively separate silver chloride from recovered gold?

I’m thinking thiosulphate will result in gold losses; however, based on basic chemistry, we know gold and silver do not like being in solution together.

Does this apply to thiosulphate? As in, if it reacts with the silver chloride, will it also react with the gold?

My understanding is a strong oxidiser is needed, however, I’m also reading study papers suggesting the intake of the atmospheric oxygen is sufficient. I can’t find anything that’s clear.

Kindest Regards,
 
Jmk88 said:
Lino,

Do you know how to effectively separate silver chloride from recovered gold?
Click to expand...

Whilst I'm not Lino I can answer that. You boil the powder in 50/50 HCl, and follow a wash process. It's fast and done correctly you have zero silver in your gold.
 
Jmk88 said:
Lino,

I’m thinking thiosulphate will result in gold losses; however, based on basic chemistry, we know gold and silver do not like being in solution together.
Click to expand...

That's not true. There is no aversion to them being in the same solution either acidic or alkaline. There are just different levels of loading, and different ways for them to precipitate which leads to the impression that they don't like being in there together.
 

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