Best way to process tiny flatpacks?

[lazersteve]

Sam,

The key to getting all the values out is crushing/shredding to the proper size. Too small and, as you stated, filtering is a pain and values are trapped in the sludge; too large and values are left behind in the plastic/epoxy matrix.

The best size to get at the internal wires is 1/4 to 1/2 the package's lead spacing distance. Now you can't control every particle's size, but you can crush so that all will pass a given sieve size. Think about this: The legs of the component must be isolated and connected to the die inside the component. From this we can deduce that the gold wires must be spaced within the package matirix at even intervals around the die where the bonding wires connect. As long as we crush to a particle size that is 1/4 to 1/2 the distance between the legs we will expose a portion of the bonding wire in the matrix in all probablity. Once the wire is exposed the acids will dissolve it completely from the plastic/epoxy matrix if proper dissolving techniques are used (eg: dissolve all base metals and run AR reaction to completion).

Determining the end point of the reaction can be tricky, but a little secret I learned is:

1). Remove a small sample of the pulp and vaccum it until the rinse water runs clear.
2). Place the small sample in a test tube and add enough AR to cover the sample.
3). Heat the test tube to a gentle boil and cool.
4). Test the solution for values using stannous chloride.
5). If negative the pulp leach is complete, if positive more leaching is required.

One last thing I noticed is that you stated that you started you leach directly with AR, bypassing the use of nitric to remove the base metals. This choice of processes may be why you are finding so much additional value in your pulp. Going straight to AR with silver and ample base metals present in the pulp will likely ensure incomplete dissolution on the first pass. These base metals must be removed first or they will certainly inhibit the AR's ability to dissolve the gold. Any base metals present must be fully dissolved first or they will cement your values back out of the AR prolonging the digestion cycle.

Steve

 

[samuel-a]

I don't know Steve...

This sounds too laborious to me and i think the potential for losses is quite big when going this route.
Perhaps couple of lb's is not such a great truble as you say, but bear in mind the quantities Scott is talking about, i just can't see it not ending with a tragedy...
In my mind, i would like to know that i get the job done currectly at the first shot rather then doing guess work for each and every batch and maybe having to re-work it, this is money down the drain...
Now don't get me wrong, i know 100% recovery is rearly achaived, I can live with process losses, as long as they are acceptable (compared to other recovery methode) but more important, that i can put a price on it.

Btw, my one lb test was a little more involved, i have only summerized the preocess and results in three sentences for the sake of keeping my post short and to the point. I can write if you want me to. Unfortunately i'm still struggling my bad habit of not logging my process and procedures in my lab note... I mean, the note is there, i just don't write in it... But i can describe the test based on my memory.

Another thing, I have yet to test it though. I have a theory about absorption of liquids by the plastic.
As you well know, when you break the chips, you can see the porous structure, i can only imagine it acts like a sponge to a certain degree, thus holding some solution back. What do you think about it?

 

[lazersteve]

The porosity has always been a big question mark for me too Sam. I do feel the epoxy/plastic that has been crushed may well be less porous than it's ash after incineration.

Regarding the batch size, after crushing to the 'optimum size' chemical costs can be greatly reduced by using cyanide to recover the Ag and Au.

Incineration would surely save the labor involved with crushing, but let's face it; if the values are going to be recovered, eventually someone has to do the hard work one way or another. I think it was Irons that said it best, "eat the elephant one bite at a time", or something to that effect.

Steve

 

[samuel-a]

using cyanide to recover the Ag and Au.

lol, that's cheating :mrgreen:

Siriusly though, this idea actually did crossed my mind in the past, we have a 17 gal SS centrifuge destined for our silver cells crystals... That could be one hack of a solution for working with such sludge and cyanide, assuming we will decide to recover gold from chips at this scale (and for some odd reason, decide not to smelt).

 

[lazersteve]

Sam,

You would be better served by saving the 17 gallon SS vessel for another purpose in my opinion.

Invest in a large plastic cement mixer for your cyanide processing. A standard harware store variety will strip an average 40 pound batch of plated material in one shot. Mine cost $300 here in the states and comes with it's own motor and mixing blades. You'll need to coat the blades and insides with a protective spray on coating before using and also fabricate a wooden lid with a handle to cover the opening while the -CN and parts mix. GSP has covered all of this in one of his older posts.

Before CN treatment:

and after CN treatment (5 minutes later):

A safety note is in order. Working with cyanide is extremely dangerous for the untrained. Do not attempt unless you have an experienced mentor on site to walk you through the process from beginning to end. One wrong move and you can kill yourself and others in the vicinity. Cyanide is also dangerous to animals, plants, and the environment. You must be certified to properly dispose of the wastes or you will be fined by the authorities when you are caught. There are many online safety courses dealing with cyanide safety which you should be 100% familiar with before even attempting to use cyanide. It is also advisable to have a cyanide antidote kit for each worker on hand before you begin processing and training on how to administer the antidote. Most local water treament facilities monitor the incoming effluent for cyanide. If they detect it they generally track it's source.
Steve

 

[texan]

Have you disected all of the different flatpacks to see if they all have the same interior design? I have found many to be quite unique. I have found some used in cell phones to have a small AuSn brazed crystal package burried inside the rectangular flat pack rezin that was not at all observable from the exterior...many have more than one silicon wafer housed in one package. The interior design could be a factor in how you go about processing them if you choose that route. The choice is between a brute force method and something more sophisiticated.

Texan

 

[samuel-a]

Nice Steve.

I agree, i should probably not use it for anything else.

 

[NobleMetalWorks]

I wanted to update this in case someone else came behind and read it.

I ended up shreading the flatpacks and processing them. It worked out perfectly.

After I processed the shreaded flatpacks, I took a few ounces of the left over shreaded material, washed and then incinerated, dissolved in a test tube with a little AR then tested with stannous to make sure I had no gold in solution. Nothing. I was able to shread the material small enough that the solution was able to attack and dissolve whatever gold was inside the chips.

I want to thank everyone who posted on this thread, all of what was discussed helped me find an excellent way to process this type of material without incinerating or wet ashing. I want to stay away from both whenever possible.

Thank you

Scott

 

[maynman1751]

Scott! How much did you process and what were the results? John.

 

[NobleMetalWorks]

I'll post my results after I drop and refine. PMs are still in solution at this point. I'll be dropping the Au tonight, so I'll post tomorrow or the next day on yields. I started out with 50lbs and I'm hoping for good results because I have access to a lot of this type material.

Just a side note: I think I-Waste is overlooked as a possible source of material, and I think this because most of the time manufacturing companies are not going to talk with small refiners. These and a few other manufacturers I have access to, through an asset remarketing company I have partnered with. The owner has connections and contacts with all of the major manufacturers in Silicon Valley. My only problem now seems to be having a place big enough so that I can purchase equipment large enough, to process the amounts of I-Waste I have access to. And that takes money, which I never have enough of. I don't mind being in this situation, but I hate turning away potential clients just because I'm not large enough to handle it yet.

It's a catch 22.

So if you have a remarketer close to you, make them your best friend. Not only can you get some of the equipment you need, but they have contacts with places that will have I-Waste you can process, more likely than not. And give you access to customers you otherwise would not be able to land on your own.

Anyway, once I have yields, I'll post for others.

Scott

 

[glondor]

Hey Scott. Any more info on yield ? My guess is they were pretty darned good.

 

[NobleMetalWorks]

I ended up processing a total of 58 lbs of this type of material thus far, with an average of 3.1 g per lb.

I figured another way to process that would be sort of like wet ashing, but not with sulfuric. Instead of processing with HCl/Cl, if you go straight to AR and put it on heat, it creates a jelly like substance. This retains the Au even after filtering and washing. You can dry this material in a filter, I used strainers with restaurant coffee filters (the huge ones) over a 5 gallon bucket. I retained the solution, it has Au in it. I dried out the gel substance in the filter. I sprayed down the filter to insure all the Au bearing solution made it into the bucket. I took the resulting dried gel substance, which by this point turned into a rubbery solid that was stratified with light green on the top, then several layers of other colors. It acted very strange, it was puffy, but also heavy.

I then took this material and roasted it, it shrunk about 80% by doing this. The resulting dried and roasted gel then easily crumbled into a powder, which I then ground in a mortar and pestle. I then did an HCl wash to remove whatever base metals I could, then washed, then went to AR again.

Using this method, I was able to get the same yield as I did by shredding and processing with Nitric first, then wash and go to HCl/Cl. My concern when I first tried AR was the gel substance that was created, HCl/Cl doesn't see to do the same, and it doesn't see to create the gel using only Nitric, only when HCl and Nitric are used together. I ran a couple lbs this way. It works, but it takes much longer to process than it does using the other method. I thought I would post it here as another way to wet ash, it seems to have worked really well even though it took so much time to do so.

I also want to note that 95% or more, of the material, were the tiny rectangle chips and not the tiny flatpacks in the second picture, and very little of the silicon material in the third picture. I am going to process 50+ more lbs of only the tiny rectangle chips this next time, they will not be mixed.

I also want to note that if the tiny rectangle chips are not shredded, and put directly into AR, the layers come apart so that you end up with 3 different pieces of plastic, before it ends up getting totally dissolved by AR. The next time I test these, I am going to see if I can get the different layers to come apart without shredding, and process with HCl/Cl after to see if I get the same numbers compared to shredding/processing or shredding/AR/roasting/AR Digestion. If anyone is interested, I'll post my results here, along with pictures this next time. I should have thought to post pictures this time.

Again, thanks for all the help, it's greatly appreciated. I learned a lot processing this material, and I feel fairly confident that even when I run into a situation where I create gel substances, I can still recover the values by the method I outlined above. I am kind of curious now how much plastic material could be wet ashed using AR instead of Sulfuric. Anyone have any experiences similar?

Scott

 

[glondor]

Thanks Scott. Sounds like you hit a little gold mine there!

 

[Palladium]

Hey Scott i've talked to Chris several time about recruiting manufactures. Or should i say he has talked to me about it. That's what Chris use to do. If you need some good advice he's your man!

 

[AUJack]

I run an impact mill to crush gold ore. I've tested it on RAM sticks. The difference I will note in my mill is that I have changed up my pulley's in order to double the rpm. Mine is running in the order of 7k rpm at full throttle. It turns quartz to an average of 30 mesh minus to 200 mesh minus(In seconds). Because it is an impact there is a percentage that doesn't go below 30 mesh. 30 mesh being the size of the exit screen. In my own opinion its a great machine for efficiency prior to a ball mill. I'll take a pic of my machine and post later.

 

[AUJack]

Impact mill.

 

[AUJack]

Inside the action of the impact mill. Chains spin by gas powered motor in my set up approx 7k rpm counter clock wise. As material it dropped in through the feed chimmney it is pulled in and turned to smaller fragments. In some cases depending on material ...dust.

 

[AUJack]

In the photo above of the inside of the machine there is no 30 mesh screen as I had been using it minus the screen while doing some recent field testing of hard pack pay layer samples while gold prospecting.