Rookie's first run issues

[BaalAdvocate]

After doing some research on Youtube, I decided I finally had a use for the pile of old PCBs I had in the basement. During the course of my research of the vids, I noticed they only used the fingers for refining; I had full sticks that I wanted to process, and didn't think to depopulate the board since the etchant would dissolve the solder holding everything on the board.

Essentially, I had populated boards in the etchant solution, including the PCI slots (put in a trial MOBO) which are either (upon further research) ABS or PP plastic since they are susceptible to HCL; they dissolved into this gray-blue muck. Following advice on the PM refining Reddit, I took the muck and soaked it in an HCL bath, which helped but still contains the particulate. I set this batch aside in a second HCL bath until I can figure out how to separate it.

Since the first batch, I ran a second where I depopulated the plastics and capacitors, but left the ICCs on the sticks. As I expected, these more or less fell off into the solution with the gold foils and these tiny components which were not attacked by the HCL. During the decanting process, I noted that the same blue-gray muck was forming with the second plastic free batch. Is this the solder coming out of solution, and if so, how do I remove it from the gold foil (and fine gold particles which broke off the foils)?

I'm thinking either a soak in a greater quantity of HCL (maybe the HCL becomes saturated and loses capacity) then run it through consecutive baths in distilled water to remove the chlorine then soak in Nitric, or remove the material, dry it and incinerate. A third option that I had contemplated would be using different density media (layers of oil, water, and corn syrup or some such) then let it separate by gravity.

Any advice would be most appreciated; I don't want to lose gold yield through trial and error.

 

[kernels]

I'm a complete beginner, only having done 1 successful gold drop, but something that I read on the forum somewhere stuck with me, it went something like: Get to the point where you can drop 2 to 3 grams of gold from 600 grams of clean ram fingers reliably before chasing the higher-hanging fruit.

Tin is what is most likely causing you problems in your chemistry, have you read the relevant parts of the hoke book ?

 

[jason_recliner]

Hi Advocate, welcome to the forum.
(Note that I do not call you by your full name - at which I take slight umbrage.)

To your problem: I do think it is not just tin also the garbage you have collected. As you have discovered, HCl can turn junk to gunk. Particularly soft plastics, whereas hard plastics might be a little more resilient. Don't try to filter the muck. For your muck will become stuck. The best you can do is wash it with more HCl and 'decant' to clean it. That is, allow it to settle and gently pour the saturated dirty acid away from the valuable solids.

I've been there, done that, made the same mistakes.

Based on your description, where you have not mentioned any oxidiser (Peroxide, nitric, bleach, etc), I expect you have probably not yet dissolved any gold. And that would make it easier for you. Though at some point you will need stannous chloride SnCl2 testing solution, to be sure. Search amongst the gazillion posts about stannous chloride to avoid the repetition here.

Also. Swapping HCl/HNO3 acids cannot be done by merely rinsing in water. For some acid will remain and dissolve your gold. You need incineration. This is a fundamental rule. Get some reading under your belt and you will learn why.

 

[BaalAdvocate]

Sorry, the name is a hold over from highschool; just easier to remember one username. Thanks for the advice! I downloaded the e-book and have started reading it, but I'm slow.

With the reading I've done in the forum (particularly Harold's post on incineration), I think I should collect all the muck I have and dry it (was thinking of boiling it in an old crockpot to drive off the moisture), then just torch it in a stainless pan. From my understanding, this would destroy the plastics and drive off the acids, but how does one deal with the resultant ash and probable base metal contaminants? Soak in nitric?

 

[Phishin_ca]

Sorry, the name is a hold over from highschool; just easier to remember one username. Thanks for the advice! I downloaded the e-book and have started reading it, but I'm slow.

With the reading I've done in the forum (particularly Harold's post on incineration), I think I should collect all the muck I have and dry it (was thinking of boiling it in an old crockpot to drive off the moisture), then just torch it in a stainless pan. From my understanding, this would destroy the plastics and drive off the acids, but how does one deal with the resultant ash and probable base metal contaminants? Soak in nitric?

The incineration that Jason was referencing was a method of completely eliminating one acid from the material before adding another. Without that process, you will be putting gold in solution and filtering it as waste. It would be noticed of course with proper testing of your solutions, but if it can be avoided it will improve the immediate yield from your material.

Pictures are extremely helpful here as it allows the other members to see what is going on. Please try to post some!

Hoke's books are surprisingly easy reading for a beginner, and do cover almost every aspect of what you are attempting to do. If you have enough material to justify your work, the small investment in reading them will pay off(if not in yield, definitely in safety!)

Personally, I think you may have created a mess that will not be easily recovered from and that slowing down (stopping for now) is going to be your best bet. Sorry for sounding negative, but please don't just torch your material in the back yard in hopes of cleaning up and gaining a few dollars.

Shawn

 

[BaalAdvocate]

Yeah, I made a mess, lol. I have a crockpot full of everything that you'd find on a board; little capacitors, pins, rusted pins, silicon dust, partially dissolved PCI slots (ABS or PP plastic). I'm dealing with (comparatively) small amounts of material, since this is more of a pet project to occupy myself with than a money making venture (for now anyway). I will try to get some pictures up, assuming I can find a decent camera.

I had around a pound of these old RAM chips and 1 motherboard I broke in half that I put in a solution of CuCl with a bubbler. After a week, I checked the material in my tub, and found that the PCI slots had bloated and started to slough off into the solution which is where most of the mess came from. I have tried filtering this crap out, but as Jason pointed out, it's just clogging my filters. At the time i had been simply squeezing the filter papers into a rough poultice shaped blob and putting them in a jar for later processing. This later processing took the form of a bucket filled with a large excess of clean HCL, which did break up the tacky mess to some degree but didn't eliminate it. When I tried to filter the contents of this first clean HCL bath, the filters again were clogged, so I put it back in the bucket to sit.

While the first batch was sitting in the 'digester', my second batch which was again RAM chips with the ICs still on the board but without any plastic were completing their etch cycle. As I was spraying the gold foils off the fingers, I noticed that the water created a white cloudiness in the drain, which I am assuming is either dissolved plastics or as has been suggested, tin. At this point I came to the conclusion that I was using too many containers. I added the contents of the digester to the crockpot that I had washed the second batch into; both batches are now in the same crockpot with most of the same impurities (minus the ICs because they were easy enough to remove).

Where I am sitting at currently, is that all my my active source material (minus some HCL that I have removed from the system to free up crockpot space and neutralized with aluminum and sodium bicarb; abortive attempt to recover copper. It's not in a jug awaiting hazardous waste day) is currently in the crockpot. This is where I'm stuck.

I'm trying to figure out a way to remove the colloidal plastic and metals. I was thinking incineration because it would destroy the plastics, and drive off the chlorine and moisture, then use a magnet to remove the bigger bits of ferrous metals. The remainder I could then soak in nitric acid, dissolve everything but the gold, filter, then AR.

Some questions I would have, aside from how you guys would address the problem, are:

1. How do I remove the tin (haven't had much chance to read Hoke's book yet)?
2. How do I remove the plastic? As it's colloidal, it settles with the gold particles (the foils break apart under the spray bottle). I was considering a panning or sluicing attempt, but I have no experience with that, nor the equipment on hand. Am I just going to have to soak the muck in a large amount of HCL or nitric to dissolve it away, or can I burn it off?

 

[butcher]

I wish to learn how metals react chemically.
I wish to learn the chemistry of working with metals safely.

Where do I begin?

How about starting with study, the forum has the information, safety is a good place to begin.
Now that I have begun my study into safety, I will want to understand the basic principles.

Hokes Book will help me understand the principles. Here is also a great place to begin to learn the reactions of metals in chemistry, the book explains the chemistry in layman's terms, along with a guide of simple experiments to help you get acquainted with the reactions which give you a basic understanding. This book explains the basic principles and will be very helpful in beginning a study into this field of science.

Or

I can just watch a video, read a page or two and dump a bunch of dangerous acids into a pot of circuit boards full of many different kinds of metals many of which can be dangerous. that didn't work as planned may i can ask a few questions and clean up this mess? wondering what would happen if I just burnt everything and started over after asking the forum a couple of questions to answer what I think may happen), still without any idea of how I should deal with this toxic mess I have, and no idea of the dangers involved.

 

[BaalAdvocate]

At this point I feel the need to point out that I'm not just slopping chemicals around in buckets in my back yard with no PPE or thought into safety or process. I'm following the lab protocols that I learned in school, using the PPE I have, outdoors. I am putting my waste into marked and labelled source jugs (contrary to my typo in my earlier post). I have the MSDS for the chemicals I'm working with printed off and stored in a binder. I am researching the steps that I'm attempting to take, and finding that there is a variable present that I had not noticed or failed to account for. Which at this particular step of the process, is an abundance of colloidal lead chloride. My research is not perfect, and I readily acknowledge that fact, which is why I ask. I am trying to follow what advice I've gotten, which is why I've started reading Hoke, though she appears to be using a different method than I was when I set out (for instance, I do not have electrolysis equipment, am not intending to recover silver or platinum group metals, etc).

I was hoping to, through Q&A, discover a method of separating gold particles out of whatever colloidal solution has formed (probably lead chloride from what my googling has shown). I don't mean to sound snarky or petulant; there is alot of information out there and it's somewhat difficult to parse out which forum posts are pertinent to what I am encountering. As this is a first production run, I am ironing out the kinks in my process. For example, I will probably soak the boards in HCL prior to CuCl etching to remove the solder since it's proving to be a hassle to do so post-facto.

Anyway, thanks for taking the time to read my posts, I appreciate it.

 

[jason_recliner]

PbCl2 is almost insoluble in cold water, but readily dissolves in hot water. When it crystallises, it tends to form needle-like crystals.

I very much doubt lead chloride will be a colloid. In fact I am not really sure you understand what a colloid is. Colloids are nano-sized particles that are too small to see (without some expensive gear). They will not "settle" and is one reason you need to keep tin out of your gold.

You may have a suspension of plastic parts. Without some photos it's a bit hard to guess what you're looking at.

 

[Anonymous]

BA, do us all a favour and throw some pictures up please, then we can be of more help.

Jon

 

[BaalAdvocate]

I apologize for a lack of pictures; took me a while to find the camera, and the weather has been less than cooperative, but I did get some today. I dunked a beaker into my crockpot to pull some of the crap up then let it separate.

 

[jason_recliner]

Can you confirm that the only chemical used on this so far is HCl?
You have proposed adding nitric, several times, but have not yet said you've used any.

 

[BaalAdvocate]

Yep, the only acid so far I've used is HCL.

 

[kernels]

It just occurred to me that if you put whole boards into HCl, then there was probably a lot of aluminium from electrolytic capacitors, that gives a grey-ish result with HCl and reacts very happily.

 

[jason_recliner]

Since it has only seen hydrochloric, if this were mine I would investigate further by taking a very small sample (of either known weight or volume) and adding some more HCl to it. I would see whether it then dissolves completely, and if it does so, how much HCl is required. Then I would calculate how much acid is required to dissolve the lot.

For with so much junk in it, you may find yourself at a point where the cost of HCl exceeds the cost of recoverable values.

 

[BaalAdvocate]

As a hunch, I saturated the crockpot with tap water and heated it; the mix took on a milky white consistency. I started carefully removing the water from the top (which ranged from a light grey to an almost milky color) and poured it into jugs. I think I'm going to take your advice Jason and collect a sample or two. See what happens with additional HCL, and then dry out the other and heat (see if it's plastic, aluminum, or PbCl).

Thanks for the help guys, feels nice to be making some progress again.

 

[jason_recliner]

See what happens with additional HCL, and then dry out the other and heat (see if it's plastic, aluminum, or PbCl).

Don't put the cart before the horse. Do your test on the sediment first. Hunches are what got you into this mess.

 

[BaalAdvocate]

Alright, I took 800 ml of my mystery solution and boiled off the moisture. This left some dark deposits, which when I scraped them up with a spatula, turned into a dark brown powder. There didn't appear to be any crystal growth, though whether they would grow under heat I don't know (if they did, they'd be small crystals). So, I'm not going to jump to any conclusions as to what this is.

 

[FrugalRefiner]

Take a look at this thread. I hope it will help. Simple Answers

Dave

 

[BaalAdvocate]

Excellent post! I try to be as safe as I can with the PPE I have, but so far I've only had to deal with Cl fumes. Nitric is still a ways off for me. If PAPR or SCBA weren't so expensive, I'd love to have them, but for the moment I've got an M17 mask with new filters (and hood), neoprene gloves, leather apron, and long sleeves. Not ideal I know, but it's what I've got.

I do my work outside since I don't own real estate (being a broke recent graduate of 27) of my own and have no fume hood. Aside from sudden changes in wind direction (as mentioned in one of the links) are there any major downsides to working open air?

I did see mention in a couple of the posts you linked of some forum handbooks? I didn't see links to them, unlike the Hoke book. Was wondering if they're still a thing.

As for my experiment today; didn't do much aside from heating a sample to try and determine what it is. I spoke to my friend's mom (chemist at 3M for something like 15 years) to see if she'd help me figure this out. Hopefully I can get some help.