gold powder

[chemistrycoach]

hello again butcher !
no the earing did not dissolve, but the color of the solution turns to yellow after the first 30 minutes of heating, there is a lot of brown smoke fumes coming out ( i suspect nitric fumes ) and have a realy unpleasent odor. im prepared about this so i wear a mask and ventilated well the area
, after an hour or so the brown fume is no longer seen and the fumes are gone , it only gives out white evaporated smoke and i noticed that the AR is drying..so i added another 30ml of HCL... the solution is slowly turning to deep yellow ..but still no metal dissolve.. i test drop the solution in a cavity plate and drop freshly made stannous chloride .. but no reaction at all.. after which the solution in the beaker turned red orange..total hours digesting 3 HOURS.
i stop at this point thingking i might go no where..
i saw lazer steves video about platinum refining .. he mentioned there that he dissolve ( complete dissulution ) the platinum for 12 hours?

thank you very much butcher

ps
i bought the pair of earing from a jewelry shop longtime ago 2 grams each earing... and it is platinum according to the jewelry shop owner ( kinda reputable shop)
but i realy dont know if it had silver or gold in it. i plucked out the little diamond stone prior to this...

 

[butcher]

From reading your post it sounds like you did not eliminate nitric acid before the test, this can be done with a small amount of solution few drops in test tube, over a candle flame, a pipette is handy to add a drop of HCl to re-wet solution as it concentrates and fumes off NOx gas, the last evaporation I would leave some what concentrated and put q-tip in the tube to wet it then retest with stannous chloride.

You need to know if you have value in your solution.

If I only had small earrings, and was not sure if they had silver (you can test for silver with schwerters solution in a filed notch), I would just process them with my dental scrap in-quarter with silver and the gold and dissolve in nitric before proceeding to aqua regia, or I could mix them in the next big silver melt and get the Platinum when I built that silver cell I have in my dreams (getting an accumulation of silver it hopefully will not be long till that dream comes true).

 

[qst42know]

there is a lot of brown smoke fumes coming out ( i suspect nitric fumes ) and have a realy unpleasent odor. im prepared about this so i wear a mask and ventilated well the area

You do know no mask is truly effective against nitric fumes except an air supplied mask.

You also know Platinum salts are highly toxic and once you have become sensitized to these compounds you cannot be around them ever again. The unpleasant odor is telling you something and you aren't listening.

i saw lazer steves video about platinum refining .. he mentioned there that he dissolve ( complete dissulution ) the platinum for 12 hours?

Platinum in a catalytic converter are very small molecules already, the time to dissolve jewelery is going to be vastly different.

 

[chemistrycoach]

thanks for the precious advices qst42know and butcher.
i will do it with best safety precautions.

may i ask these questions for my practicing

what is an oxidizer? i heard that oxidizers prevent stannous detection and precipitation if there are values in a solution?
if so, how can we get rid of it?

why does my jewerly materials cause the HCL to turn yellow? ( because i wash my materials first with hcl heated for 10 mins , decant and replace AR )

how will i know when mild boiling that if nitric is already gone in my AR solution with the material in it?

i would like to know if i already have some values of my jewelry in the solution so....

after 3 hours of boiling i test to put a little drop of the solution in a cotton ( with no stannous ) the result is deep yellow

then i put another drop of it in cotton ( now with stannous chloride ) stiill no color change but the same deep yellow solution

i drop a second drop of the solution again in the same cotton with the stannous in it and it turns out an s dark orange color in the middle.

is it already ripe for precipiating? or i might be going no where

i realy would like to be a refiner and im bent on learning and read hokes every night but still some scenario presents problems that was not tackeld in the book.

thanks a lot guys!

ps
the solution when i left is dark orange and the jewelry is still in there i think unharmed..in AR ( 3 parts HCL 1part nitric ) cp pure

 

[butcher]

Oxidizer in your case is the nitric acid in your aqua regia, it sound's as if you still have some free nitric acid (oxidizer) in solution (and several additions of stannous to test), evaporate solution down to a concentrate solution (this is to gas off the NOx fumes from the nitric in solution, add just a little HCl, repeat two times, last evaporation leave solution concentrated but do not get it so concentrated (when hot) that it forms salts when cooled, you will usually notice brown fume when HCl added.


The free nitric re-dissolves your metal in the stannous chloride test, it will also do the same when trying to precipitate the metal from solution, depending on how much platinum you have in solution would determine whether to try and precipitate or to just pour it into stock pot ang collect it when you have more(two small ear rings and not much dissolved you may not have much in solution).

If only working with small amounts this would not be my choice of processing, to easy to lose values from small lots.

 

[chemistrycoach]

thanks again butcher your a big help!

 

[chemistrycoach]

howdy ! what material has alkaline? ........ what connectection does alkali or alkaline have in dissolving gold in AR?......i read hokes but cannot fully absorb the literature, does alakaline in AR cause problems in refining? a liitle knowledge is very much appreciated!

 

[butcher]

Alkali or alkaline is the opposite of acid.

pH is a (logarithm) scale we use to measure acidity or alkalinity (opposite of acid), this scale is numbered 0 to 14
An alkaline has a high pH on the scale (example pH 12), water is neutral about pH 7, a acid will be low on the pH scale (example pH 2).

To dissolve gold we use acids. I am not sure what you are referring to in Hokes book, but if we added alkaline substance to gold in solution we could precipitate gold (depending on conditions), actually if gold was precipitated and added to a very strong excess of an alkaline hydroxide we could actually make a solution of gold hydroxide.

Normally we would not want an alkaline in our acidic gold solution, I am not exactly sure if this answers your question as it is a bit unclear to me what you are asking.

some alkaline things, sodium hydroxide, baking soda, soda ash, wood ash, sodium carbonate.

 

[chemistrycoach]

hi butcher ! im just collecting knowledge on hand or by the book for future references, but that is realy a great explanation even for a non chemsit or refinist to understand , so easily explained, thank you very much i realy appreciate it !

 

[Oz]

In reading about your digestion of the pair of ear rings totaling 4 grams and your solution going from clear –> yellow -> orange -> red, and you are not getting a stannous chloride result when testing, I’m betting your stannous is no good. Make a gold standard test solution out of some card edge fingers so you can test your stannous. Your reaction sounds as I would expect for a platinum digestion with your color changes.