Solder, tin and base metals removal from IC's

[Albai]

Hello everyone
I have gathered some different types of e-waste and planning to start experimenting with it. I have done my home work and written some notes so that i develop the most beneficial, economical and safest way to process them But still there are some points that im not certain about and kindly seeking your help with them.

After sorting my e-waste i ended up with:
Connecter pins ( from RAM's, GPU's and modem cards)
Flatpacks 2S thin ( RAM and GPU )
Flatpacks 4S thin ( modem and motherboards)
Large BGA chips from motherbords

For the IC's:
Well wet ashing is not even an option as it is extremely dangerous and hazardous ( I dont know why some people do it with no regard to there own heath ! ). So I am planing to incinerate them and crushing them ( in a gashood as the fiber powder is highly corrosive to the lungs)
After that i will proceed to dissolving the base metals in HNO3 solution ( which in a later step i will recover silver from it )
The third step will be AR ( HCL/HNO3 )
Then precipitating the gold with SMB
In the end refining the gold to the finnest state i can

Same steps will be applied for the gold fingers ( without incinerateing them)

Note: all process are done in a filtered gashood

My method of separating the IC'S is by using a knife and im planing in the future to buy a heatgun but not yet because i dont have enough space in the gashood and im aware that heating the solder also produces toxic fumes that am not happy dealing with now


My questions that i kindly ask for help with are:
1- after dissolving the base metals if i used a copper rod to precipitate silver im expecting to precipitate all the metals that are lower in the reactivity series which are by order ( tungesten, mercury, silver, gold, and platinum )
And knowing that AP does not dissolve gold or lower im expecting high purity of silver. My question is what are the contaminates that i should expect and what methods should i use to eliminate them ?
2- what changes are introduced when i use a heatgun instead of a knife as a method to removing IC's
3- by not removing the whole solder and the IC's legs im expecting to use more HNO3 as there are more base metals present. Is that the only thing i should expect?

My greetings to moderators, members and everyone here
Please excuse my English and i happy for any corrections to be made

Abdulkader

 

[goldenchild]

I would start with the "fingers" from the memory as they are the easiest and will help you learn more about reactions and what to expect. If you'll be using nitric to process them I assume you have a good supply for a good price? If not then I would look into the "AP method" to process them. Also, it would help to have a substantial quantity of each type of scrap so that you can see your product during precipitation. Especially with ICs. If you have too small of a quantity it will seem that you got nothing for you're work. For fingers I would say to have at least half a pound to start with. I would put all the other scrap away until you master the fingers.

 

[butcher]

Albai,

Although the chemistry may sound simple to discuss, it is not as easy as it sounds.

Goldenchild's advice to start off simple, and beginning on simpler processes is very sound advice, memory fingers will not give you as many problems, to begin with, making recovery and refining of gold easier to learn. instead of learning from mistakes, spend the time studying the processes, and study all of the problems people have with the process, gain an understanding on simpler materials.

getting acquainted as Hoke teaches in her book with the small experiments, you will learn very important details, doing those experiments in her book, and doing similar experiments on your own of what methods she may not have had in her day ( such as the cupric chloride leach) will teach you much about how the different metals react and how they can also become troublesome in some solutions...

From the details in your question, I can see you have not spent enough time studying the processes yet to begin, jumping in now without that understanding will only lead to many problems.

Beginning with memory fingers will give you some basics to build upon, while you learn about the more complicated processes or have to deal with the more troublesome metals...

 

[Albai]

Goldenchild,

Thank you for your advice i will try first with the finger's as they are the least complicated and easier to control their solution's. I have about one pound of finger's but i will wait until i get a full grasp on what i expect to go wrong as I am more concerned about the safety aspect than getting the PM's
Nitric acid is relatively cheap were i buy it from.
Thank you again for your advice.

Abdulkader

 

[Albai]

butcher,

I respect The refining chemistry and its danger's if it was not handled with expert hands and a full understanding of it.
Sorry for not being clear on my intention's and over simplifying the chemistry. what i was seeking help for are the contaminants that could mess up the chemical reaction's and results in toxic ingredients that im not expecting and im more concerned about my safety than the PM's
For nitric acid. Well it is not the cheapest way, but I chose it because im more familiar with dealing with it from my experiments at college refining silver from amalgam filling's with the supervision of the doctor.
my concerns rely on that when i refine amalgam filling's im completely aware of the metals present and their quantities and able to control the reaction with ease. But in the case of e- waste im completely blind on what im dealing with.
After that i think im going to take a step back until im entirly in control of what to expect going wrong as im not processing any thing that is not worth my health.
Thank you for your advice. The e-waste can have a break now until i gain a full grasp on the chemistry.

Abdulkader

 

[patnor1011]

You omitted an important step from your IC processing plan. Washing incinerated and crushed material to reduce its volume.
After incineration and crushing to powder while sieving multiple times using different size sieves you will end up with a lot of metal. There is no point to dissolve it as it contains very little value anyway. If it goes through crushing and sieving several times then over 95% perhaps even more of the gold bonding wires will break loose from pins so to dissolve them chasing for minuscule values may be unnecessary.
You can always store them and perhaps go after what is left on them when prices will double few times. Or you can use magnet and separate them to magnetic and non magnetic. Non magnetic can go to your stock pot and magnetic - let them rust in saltwater for a year or few and save time and chemicals you spend trying to dissolve them.

When you incinerate your first few IC you will be surprised at the amount of metal which is in them. Even if you are using knife harvesting IC the visible metal legs you cut off is less than 10% of metal which is inside of them. Most of the pins run all the way into the centre.