first run and depopulating mem sticks help!

[justme2]

finished my first run of closely trimmed fingers from ram and pci cards.

used the AP method total weight 1200 grams. end result 4.3 g foils.

from reading the forum, it seems like my yield should have been a little higher.
I probably lost half a gram through inexperience, sticking to the filter spilled and little finger foils scattered here and there.

I used a bubblier. It has been cold here.

I am going to do a more controlled sample of 200 grams to check results.

Second: I tried to depopulate some ram in plain HCL 35%. I left it in the dish for 2 weeks, it finally did depopulate some of the flat chips but not all and, along with that it dissolved half the foils. When I poured off the HCL it was a purple/violet color.
any input would be very much appreciated.

 

[bmgold2]

I couldn't find the post I just read about AP dissolving gold but what I did find states that too much peroxide can oxidize gold and allow it to go into solution. The message I was looking for was debating about the cold temperature allowing more oxygen (from the bubbler) in the solution and dissolving gold. The only other thing I can think of is IF you might be using chlorinated tap water instead of distilled water. As everyone here is fond of saying, use the google custom search on this forum and you should find your answer or at least how to recover your gold from the AP or HCl. At least you tested with stannous chloride and now know where your gold (or some of it) is.

 

[dannlee]

On your second question:

I just cleaned 120 SDRAM to bare board - using 1200 watt hot-air heat gun my times for half of the pile averaged a minute thirty seconds each, heat from gripped end up and tapping off components, holding putty knife in same hand as hot air gun to scrape the micro SMD's off at the 50% point then flipping the board to get the still-hot other side quicker. Doable but a lot of busy work.

Then I placed ten sticks at a time in a pan w/ wire rack to keep them upright, so the needle-nose vice-grips could latch on easy - and preheating the boards to 350/400°F reduced the time per each to about 25 seconds. Going hotter, about 415°F, loosened 80% of the components but had the OEM no-clean wax flux starting to smoke like a candle just snuffed out... a little hot unless you can exchange a lot of air in your shop or really like the smell of burning crayons. Anyhow, with preheating a careful grab & loft to the chip bin and a square smack almost cleaned the boards except the smallest SMD's, so a run-over with heat gun was still required and it still took 15 to 30 seconds each.

A quick wipe with terry cloth towel while the solder is still liquid removed about 95% of the remaining solder too, gets involved trying to do it in one step with the heat gun - maybe boards back onto rack at 420°F and grabbing them hot to wipe solder would be more streamlined when you have hundreds of sticks to process, then go HCL to lift the remaining solder.

I could not, but would've liked to, been able to slip the still hot PCBs into a solder-mask removing solution to keep the production line going...

 

[justme2]

Is it possible to put too much air through the bubblier, causing gold to dissolve in the AP.

 

[JHS]

As soon as the ap is saturated with copper
it can not hold gold.
it will be forced out as black powder.
piictures are of my 20 gallon ap tank .the pump on the shelf puts out 50 times the air that an aquarium pump does
i have run as much as 12 lbs of pins and 7 wire wrap boards at a time.
john

 

[butcher]

The acid can only absorb so much oxygen, temperature will play a role on how much oxygen the solution will hold as well as other factors.

Basically you will not have any trouble with gold dissolving, so I would not worry too much about how much air you are adding, it normally takes quit a bit of air to rejuvenate the copper II chloride.

Now with that said it is possible to dissolve a tiny bit of gold with Air and Heating, but you will not be adding this much heat, just like a tiny bit of gold may dissolve even when first adding 3% H2O2 to a solution, it normally does not attack gold that bad and the gold quickly plates back out of solution onto the copper you are dissolving, so it is basically like no gold goes into solution.
The copper saturates solution and displaces any gold that may go into solution.

This is a bit hard to explain, just like when we say something is insoluble, when in truth a tiny bit of the salt may go into solution, but it is such as small amount we call it insoluble.

Simple answer, no you will not dissolve gold to any extent with air.

 

[moose7802]

I like your set up John, that very cool.

Tyler

 

[bswartzwelder]

John,
I, too, like your setup. I am assuming (possibly incorrectly so), that the white pipe is where the air is supplied to the AP solution. If so, do you have an exhaust pipe leaving the solution and venting somewhere out of doors? Thanks for the pictures.

Bert

 

[JHS]

Bert,
on the left bottom of the tank you can almost see the air supply fiting.it is about 3"
above the bottom.there is another at the other end..
the pipe at the top is a vent pipe through the wall.
because there is so much air moving the solution most of the foils collect in the pipe.
the trash can is there for safety.when i an ready to get the foils,i close the the valve,
put a 3 gallon bucket under the pipe and open the bottom valve.
it works good for me as i don't have to deal with 5 gallon buckets.
just 1 qt.of ap.
john
p.s.this was a water supply tank that came from a pop up camper i junked.
i also got a 3 burner propane stove top,which i mounted in my work bench.

 

[justme2]

thanks Butcher: 4.3g of foils seems a little low for 1200g of fingers. These were all from server boards some of them military specs. I am currently running a test batch of 250 grams of fingers using precise measurements of AP,, air, temp ect. I want to get this down pat for maximum yield before I move to the next step.

 

[niteliteone]

Can you post a picture of the fingers you are ready to run so we can see if we have the same view of closely trimmed fingers :?:

 

[justme2]

I'm a little dim on posting pictures. I'm going to get my son to set me up with the process. will post photos soon. Thanks for the help.

Can't do any thing here right now but sit in front of the fire. water froze last night. it got down to 39 in my house, thank god for electric blankets.

 

[moose7802]

That's awesome! Thanks for the info John, I have the opportunity to scrap a camper right now if I want. I know what i will be looking for now. Thanks again

Tyler

 

[justme2]

second run: 250 g fingers. More care taken and the first experience behind me. the yield on 250g was 2.2g of foils. According to those results I should have gotten near 10.1g out of the first batch of 1200g. To refresh your memories these are fingers from Military contractor servers. any thoughts?

 

[gold4mike]

Keep in mind that the 2.22 grams of foils will be significantly less when dissolved, precipitated, cleaned, dried and melted.

 

[rich_2137]

I personally think that you have done very well to get 2.22g of foils from 250g of edges!
My yield from 487g of memory mixed with a few PCI edges was 2.78g of foils, I was very happy with this as I expect around 2 grams per pound! That said I thought your first yield was sort of spot on as you said you lost around half a gram due to inexperience!
I think you should save your good stuff until your 100% with the AP process
Can you post pics of your material?

Rich

 

[justme2]

Up date and another question or two: first of all thanks for all the help!

Had another pallet of servers in this week so been busy, but did do another 150g of fingers and added 1.4 g of foils to my stash. Each batch seem to improve with experience.
first run1200 g fingers = 4.5g foils

second run 250g fingers =2.3 g foils

third run 150 g fingers = 1.4 g foils

total 1600g fingers = 8.2 g foils
I am also beginning to accumulate black powder,, in still yet, small ammounts in my AP solution. I take it this could be gold also.

Now I'm out of fingers trying to negotiate for more. got a call for 6-7000 lbs of boards in the Midwest and ,3500 lbs here. Not a finger card ram or cpu in the whole 10,000 lbs. but I digress.

I'm trying to get my son to post some pics, he can't seem to find the time.
On to the questions.
I want to use the HLC/cl method but I'm not ready or comfortable with it yet The problem is I would like to clean the foils as much as possible. I trimmed the fingers close, the problem that caused is minute bits of green fiber board in the foils they are too small to pick out, is there a way to either dissolve or otherwise remove them with out harming the fingers.

2. I tried to depopulate ram using straight HCL (no heat) let them set for a week some chips came off but most I still had to remove by hand, all be it they did come off easier. I also tried a batch in Lye, again no heat with no success.
How ever my batch turned a translucent blue with a white cloud floating in it. can someone elaborate on this.

I have now started stripping MMLCs from boards have 130 g.I am using a sharp chisel, is this the best and fastest way or am I leaving valuable traces on the board.

Thanks in advance for your patience and help. Olddude.

 

[g_axelsson]

How ever my batch turned a translucent blue with a white cloud floating in it. can someone elaborate on this.

Hi Olddude!

I think the white cloud is made up of more or less of three compounds, tin oxide, lead chloride and silver chloride.
Filter off some of the cloud, pour some hot water through the filter as a last wash, this will remove any lead chloride. Then if there is some white powder left put the filter paper in a sunny spot to see if it turns purple. If it does then it is silver chloride.

There could also be some colloidal gold in your solution. Any golden solder pad is dissolved in the solder when soldered and when you dissolve the solder the gold is liberated. It will collect in the mud and as colloidal particles. It's not much but it is there for the taking if you feel it is worth it.

Göran

 

[justme2]

thanks much. will do.

 

[rich_2137]

I just clean my foils with HCL a few times then dissolve with HCL-CL then filter the solution to remove the green fibers, drop with SMB, clean powders with HCL and a few water washes (one boiling)
Re dissolve again if you like, carry out the washes the same way then melt into a button that's what I do and it works fine for me!

Rich