Advice Appreciated - Gold Plated w/steel & hollow

I have a couple pounds of test pins that will be a mix of gold plated steel and gold plated copper. Supposedly plated on the interior, but I'm not quite sure how they'd do this. They also have a small amount of solder on them, so tin and lead as well.

I also have a couple pounds of pins from amphenol connectors....these definitely are plated on the interior, as it's required to meet spec. 30 mill at the contact points. (I assume they are plated then formed) These also have a small steel spring retainer on them. Then there is also the crimp, where it meets the copper.

These are just a start on my collection...but I'd like to start determining yields, as I have a constant supply of this, just not sure if it's worth collecting.

Option 1)

So, I could just process the whole thing in a tumbling sulfuric cell after cleaning with HCl to get rid of the solder. Downfall is that I don't believe I'm getting the interior of the pins, nor am I getting the plating where the crimp is.

Option 2)

Digest copper in Nitric, filter, digest in AR, then drop...not a fan of this, since it uses a huge amount of nitric, creates a lot of waste. Advantages are that I can test the waste with stannous to determine if I got everything. Disadvantage - I have to clean all the little pieces of steel.

Option 3)

Wait until I have a hammer mill and a small smelting setup. Grind everything down, flux, smelt, refine copper and further refine sludge.

Preferences:

Option 3) This is where I'm heading. My reading suggests that it's the most efficient and most versatile. I still need to be competent at the other two methods though.

Not sure about the steel plated parts.

Questions:

Either way, the steel presents a problem. And it has been stated for any refining process, garbage in garbage out.

In the smelt option, should the steel be removed prior to grind? Can I grind to 40, then remove via magnetic conveyor? Seems like I'd lose a lot to frictions.

Even if I were to just melt them down to do an assay, how is the steel best handled?

Let's have some pics of your pins then!

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So if you would allow, lets redefine the objective a little...I'll try to eat the cake a piece at a time instead of getting my face dirty.

If a customer asked you to process a representative sample of these, how would you perform an assay on this product, in two scenarios.

Scenario one - Chemical methods only

Scenario two - With your full capability (full on fire assay?)

Goal...least amount of waste and most accurate assay. If cyanide is #1 choice for chemical, please list first non-cyanide method.

I use those pins to make nitric acid, copper sulfate, useful byproducts, and recover the gold, killing a couple of birds with one rock.

butcher said:

I use those pins to make nitric acid, copper sulfate, useful byproducts, and recover the gold, killing a couple of birds with one rock.

Click to expand...

Copper sulfate:

With steel still attached? Concentrated sulfuric so that the steel passivates?





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http://goldrefiningforum.com/~goldrefi/phpBB3/viewtopic.php?t=6199
That ^^^^ is the brilliant post by butcher elaborating on his method.

Edit to add: i dont see why those pins wouldnt work in a tumbler style sulfuric cell.

For assaying a component I usually go for nitric acid, easy to work with and fast. Dissolve the base metals, wash by decanting, add HCl and dissolve the gold. Filter, precipitate, wash, dry, melt, weigh (or calculate the weight).

Being careful you can do an assay that way on a single IC or circuit board. The larger the lot the better the precision of the numbers.
This is an example http://goldrefiningforum.com/phpBB3/viewtopic.php?f=52&t=23737

I would never use cyanide for an assay, except for a rolling bottle assay of ore. Never done that but Dean wrote about it.

Those pins are made of a plated sheet rolled into a pin form or a receptacle. There will be gold in the crimped area that is impossible to recover with cyanide or sulfuric cell since the crimped connection makes a gas tight seal. If it motivates to dissolve the base metal just to get to that extra gold instead of deplating it depends on your refining situation and price of chemicals.
So if an assay tells you that you have 10 grams of gold in a lot, then you might select to only recover 8 grams as the last two grams might cost more to recover than the gold value of it.

Göran

Well, I am currently soaking 50 grams of them in dilute nitric. That's after spending forever peeling all the steel off, then trimming away any connector with solder on it. I'll add more nitric throughout the day as I don't really want to boil over. It's outside, so it's slow going because it's so cold.

Need to order SMB off Amazon. Better than driving all over creation to find it. Love amazon prime.

Google search a local brew your own beer store. they sell smb or kmb, either will work.

I know...but it would be at least two hours in the car, plus gas. There's really not much around here.

$6 from Amazon, delivered to my door....and it forced me to walk to my office in the garage, and that's like exercise. I probably burned off the calories I absorbed while smelling dinner.

Ok, I produced a 0.2g button of copper/gold mix by incinerating my foil filter papers in flux then melting. My flux was unknown "brazing flux", and I wish I hadn't used it, but it's done. I did produce the button, but I still have purpleish flux in the crucible, so I'll save that for later.

I then dissolved the button in to a solution of AR overnight...however, after getting antsy because I didn't see a reaction taking place, I used waay too much nitric. Likely eqaul to the amount of HCl.

So now I have a clear greenish yellow solution. SMB is due in later today.

For this first one just ignore the excessive nitric and drop the gold with excess SMB?

Oh no.

Cutting 2 corners doesnt make a circle of gold.
It makes a much longer path to get what you want..
Flux should have only been borax, lightly glazed on the crucible.

And your solution needs denoxed, not overdosed.

Sno- you should have just dissolved the foils but I'm sure you already realise you've made yourself a boatload of unnecessary work that you won't be doing again

We all make these mistakes. No harm no foul, we just don't make them twice.

snoman701 said:

For this first one just ignore the excessive nitric and drop the gold with excess SMB?

Click to expand...

If you have a LOT of excess nitric (& it sounds like you do) using an excess of SMB is not going to do it :!:

you will need to "rid" the nitric by ether the old evaporation method - or - with sulfamic acid - or - use copper to cement the gold

if you want the gold back as pure gold then ether the evaporation method - or - sulfamic

If you just want to recover the gold - then cement with copper - personally this is what I would do

Kurt

Alternatively - leave it on your hotplate overnight at 80 degrees C and wait until the fumes come off white instead of brown. No additives needed and that that point you're de-noxxed.

I second what Kurt just wrote.

Do NOT fight the nitric with SMB, you will end up with a mess of sodium sulfate and a little bit of gold, maybe still in solution. I would evaporate as that doesn't add anything to the solution and you can keep the volumes down.

Göran

My initial reaction was to cement with gold, but will this reaction stop? ie, if I cement with copper, will I end up with just gold precipitate (assuming solution is only containing gold and copper)...and if that's the case, why use SMB? Just to selectively drop gold out of a mix of possible nobles?

On edit...and thank you!

snoman701 said:

My initial reaction was to cement with gold, but will this reaction stop? ie, if I cement with copper, will I end up with just gold precipitate (assuming solution is only containing gold and copper)...and if that's the case, why use SMB? Just to selectively drop gold out of a mix of possible nobles?

On edit...and thank you!

Click to expand...

Gold and just a little bit of copper in the mix, as well as any pgms that may have been in solution. Mercury will also cement onto copper.

Look at the reactivity series of metals.

We use smb or another precipitant to selectively precipitate the gold out of solution, leaving pgms and other impurities in the mother liquor.

Some do choose to simply cement on copper, melt, and sell. As it can run around 98% pure(or so) and they dont see the point in trying to purify it more (they dont get more $ for any more purity...but, some do. I sell to a jeweler and wouldnt ever be able to cement, melt, sell)

Got the SMB, have had a small piece of copper in there for a few hours...still bubbling, so I'll let it go. It's cold outside, and I'm not dragging out a hotplate. And I don't have good enough ventilation in the shop as of yet. It's one thing for preparing reagents, it's another when you are actively producing NOx

g_axelsson said:

For assaying a component I usually go for nitric acid, easy to work with and fast. Dissolve the base metals, wash by decanting, add HCl and dissolve the gold. Filter, precipitate, wash, dry, melt, weigh (or calculate the weight).

Click to expand...

I started a small assay like this today. But I did it backwards....somewhat. I crushed the chip, soaked in HCl until it stopped bubbling. Then filtered. Once I filtered, I then added Nitric & HCl to dissolve base metals and PM's.

Goal with the HCl wash initially was to get the tin, prior to using Nitric so as to avoid tin oxide. In the end, I was just trying to skip the roast, as I can't seem to find my roasting dish.

For small amounts, such as the amount to be found in say, 20 grams of chips, is the inability to filter Tin Oxide not as worriesome?