suspecting that not all gold dissolved

[arthur kierski]

i got some gold powder from many ways---10grams -when purifiyng with ar i obtained 4grams of gold and 5grams stayed in the filter paper anatacked----passed amonia over the filter paper and obtained some silver and the unatacked became 4grams------ i suspect that there is gold in this 4grams that remained anatacked by the ar---tried many ways with this 4grams that remained(hcl-cl,hcl-peroxide) and it still remains 4grams----could it be a agcl +gold, alloy formed?could this 4grams be not gold?how can i act to see if there is some gold in this 4grams? thanks for any help or sugestions-------Arthur kierski

 

[butcher]

some of this would depend on what the starting material this metal was recovered from, and the process used to recover,

I would incenerate, start with nitric, check it for silver and Pd,

insoluble to cold aqua regia, check for gold,

insoluble in boiling aqua regia, check for PGM,

if any still insoluble and valuble metal suspected it would go in my stock pot.

some types of PGM will not be disolved in these acids and need to be recovered through fusion processes.

 

[Harold_V]

You may have too much silver present to allow dissolution of the metal as it exists. A fast and easy way to eliminate the problem is to inquart and process with dilute nitric. Add three times the weight in silver, melt, stirring well, then pour in water. Make it a deep vessel, and not one made of plastic, since molten metal can hit the bottom.

By inquarting, you will permit dissolution of the resulting metal, leaving behind finely divided particles of values that will digest easily. They can then be dissolved in AR for purification. If there is palladium present, you will know by the dark nature of the nitric solution, or you can test with stannous chloride or DMG. Should you find palladium or platinum, it will be recovered along with the silver, assuming you use copper to cement the values. The platinum metals will be slow to cement, so allow time. Check with stannous to insure that any that may be present are fully recovered.

Harold

 

[butcher]

Thanks Harold, I did not think that he may have had been trying to dissolve a material with a high silver content, and your answer of adding more silver is this to get any platinum to follow the silver in the nitric dissolve?

 

[Harold_V]

Thanks Harold, I did not think that he may have had been trying to dissolve a material with a high silver content, and your answer of adding more silver is this to get any platinum to follow the silver in the nitric dissolve?

Frankly, I was somewhat confused by the description provided, so I presented a solution that will work, regardless of what he was dealing with.

Early in my refining years, long before I had started actually doing what Hoke advises (her advice seemed too hard, and unnecessary. That's how I know that newbies do stupid things), I had created a button that weighed about 3/4 troy ounce. It was obvious by the color that it wasn't pure. Thinking I'd dissolve it in AR, I boiled it for hours, resulting in the surface turning a rather unattractive green/gray color, at which time all action ceased. Prolonged boiling had no effect.

It was then that I decided that what I had read was right-----that there was too much silver present to permit the AR to dissolve the gold. The green/gray covering was a hard impervious shell of silver chloride. Inquartation solved the riddle. It will work under any and all conditions.

As far as the silver becoming a carrier for platinum, while that may not be one's objective, it's a very nice way to deal with platinum (and/or palladium), which is often found as nothing more than a trace, due in part to its ability to resist dissolution, or simply because there is very little present (often the case with dental alloys). Too much time can be wasted trying to recover small amounts; amounts that often fail to respond to conventional recovery methods. One is far better served to allow it to accumulate (stock pot, or by being carried with recovered silver), so that the concentration level is highly enriched.

Harold

 

[arthur kierski]

thanks Harold for the reply,it was very valuable an helpfull----it worked----------i have left behind 48grams of a similar batch(suposing it is the same problem)and tomorrow i will inquart with 150grams of silver and then tell you the result of gold obtained---really harold your experience is fantastic and is helping me very much----thanks once again
Arthur kierski

 

[Harold_V]

thanks Harold for the reply,it was very valuable an helpfull----it worked----------i have left behind 48grams of a similar batch(suposing it is the same problem)and tomorrow i will inquart with 150grams of silver and then tell you the result of gold obtained---really harold your experience is fantastic and is helping me very much----thanks once again
Arthur kierski

You're welcome, Arthur, but thanks goes to Hoke. That's where I learned almost everything I know.

It might be interesting to hear the results, so please do keep us advised.

Harold

 

[arthur kierski]

Harold, as i told you,i had 48grams of the material suspected as having gold -- with your magnificent help i inquarted with 3 times silver(144grams)---laminated the inquart and dissolved the laminate with nitric-----the result after the nitric dissolution was: 14,4grams of gold---and recuperated all the silver from the nitric dissolution(did not weighted yet because it is agcl)
once more thank you for yours and hokes experience-----
Arthur

 

[Harold_V]

Harold, as i told you,i had 48grams of the material suspected as having gold -- with your magnificent help i inquarted with 3 times silver(144grams)---laminated the inquart and dissolved the laminate with nitric-----the result after the nitric dissolution was: 14,4grams of gold---and recuperated all the silver from the nitric dissolution(did not weighted yet because it is agcl)
once more thank you for yours and hokes experience-----
Arthur

Welcome! 8)

Considering the recovered values were a small percentage of the parent metal, depending on what else was present, you may have achieved success by simply adding an equal amount of silver.

When inquarting, it was always my goal to create an alloy that, when processed with nitric, none of the values were reduced to fine powder. That way it was easy to pour off the spent nitric without fear of losing any gold. When the alloy content is proper, you end up with a piece that appears identical to that which you created in the inquartation process, but it is now a honeycombed configuration, having been leached free of silver and base metals. So then, in the future, is you are working with known substances, add only the amount of silver that is required to achieve a 25% gold content. It won't always be dead on, but will serve you perfectly well, without processing excessive silver.

By the way, recovering the silver with copper is a better choice, especially if you eventually part the silver in a silver cell. Any traces of platinum group metals that may be hitching a ride will be recovered, along with the silver, when you cement with copper.

Harold