high yeald pins

[arthur kierski]

i have gold plated pins that have an iron spring inside them----
i took 1kilo of these pins and to it i added nitric+h2o ----3,6liters of nitric(70%) +3,6liters of water-------this dissolved the pins,leaving 64grams of gold foils with a lot of small iron springs-----i eliminated the iron springs(with a magnet) and was left with 40grams of gold foils------to this 40grams left,i dissolved in ar (by the usual way) and obtained 5grams of gold---very good yeald=2,27grams per pound----------
what bothers me and i asked for help many times is: the 40grams dissolved in ar became in the filter paper after the process 22grams.what may be these 22grams?still some gold?the powder left is yellowish---by my way of work,i thought that when dissolving the 40grams of foils in ar ,i would have no powder left in the filter paper
i thought that all the gold and other metals would be in the ar solution

this things repeat frequently in my work----is this normal? or am i making some gross mistake-----thanks for any help
Arthur

 

[Gold]

What was the source of the pins Arthur? Where they clean from solder?

 

[Geo]

dissolve some of the powder and test it with stannous chloride to see if it has PM's in it. if its metal it will dissolve in acid, you just have to find out which one.

 

[arthur kierski]

the pins have no solder-----the pins come from some modulus (boards) made of acrilic--- they do not come from e-scrap-----these modulus are used to manufacture cell phone boards before the components are added----they come from cellphones manufacturers--------

 

[arthur kierski]

Geo,how would you dissolve the powder left?
----i tried and tested with hcl and nothing happened
Arthur

 

[samuel-a]

5g per Kg is very good yield Arthur... i doubt you could pull any more gold out of them.

I can't possibly guess what is the powder you are left with, but if it won't dissolve in HCl/Ar, it's probably not precious...

 

[arthur kierski]

Samuel,i suppose that the powder left is not precious metal-----my doubt is that after the pins were dissolved in nitric and after the foils were dissolved in ar,----i deduced that should not be any powder left------but always there is powder left
regards
Arthur

 

[Sucho]

those are mid-grade pins for me.
if you ever seen pins that gives between 4-6 % w/w of gold it changes your attitude to yield 8)

 

[butcher]

Iron compounds strongly heated can be very hard to dissolve in acids, these can range from brown,black, yellow to red in color, I need more study on this subject as I still do not understand it completely, but we can form a magnetite substance which can also change into Hemitite and if overheated change back into magnetite, this is confusing to me, but apparantly we can possibly over roast an iron containing ore making recovery of gold harder than from properly roated ore, I have some red powder that came from hard boil of a waste chloride solution that I was trying to dissolve copper I chloride (it had iron chloride in solution) this red powder cooked hard to the bottom of the vessel with some gold powders, upon removing base metals from this red powder with nitric acid (re incenerating red powder) then leached out gold I still did not dissolve this red powder I believe to be an iron compound, that has lead me on a quest to try and understand the chemistry of iron, but since my study has just began it is still very confusing to me, maybe one of the chemists can help us to understand its wierd reactions.

http://en.wikipedia.org/wiki/Thiocyanate

If the powder you are left with is Iron (like my red powder) I have not found the answer of how to dissolve it. this has become a challenge for me even if it has no values I want to understand this red powder and be able to chemically change it and dissolve it.

 

[samuel-a]

I understand your logic Arthur.

In my mind, unless you subject it to analytical test in a lab, i doubt you will ever know...
I like to keep things simple, so if i eliminated the possibility of values, i usually lose interest.

I guess you could split this powder into few samples and run several reagents on it ti see what happens.
I would also add inciniration of one sample and test with different reagents.

 

[arthur kierski]

Sucho,i did not say it was high grade pins----i said that they were high gold yealds pins.
for me 5grams of gold per kilo is a very good number-----i never obtained pins with higher yealds

Butcher---after reading your thread and coments,i also think that these powders are insoluble iron compounds----i did many experiences on this powders and i only dissolved it in a hf-h2so4 solution---the powder left was dissolved in ar(hf dissolves oxides of insolubles metals) and sometimes gave some gold------
i read once that gold was found in the intertissues of haematites ores----also that these iron oxides have colored pigments used in many industries----
i read this in Ammen s book newer(but old) edition
regards, and i would like to follow your studies on this matter

 

[qst42know]

Silicon bronze pins may leave an insoluble silicon residue. Somewhere around 4% silicon is a hard stiff long wearing alloy.

Are your remains near 4% in weight?

 

[arthur kierski]

qst42know----my remains are 2% by weight-----1kilo,after nitric and then ar, gives 5grams of gold and remains 20grams of this material----it might be silicon
thanks for the reply and tip
Arthur