Stars on Gold bar

[Gold.refinery]

I wold guess the steel container.

Probably true, but
I used steel in previous operations, but it was not an impurity.

 

[Yggdrasil]

With a wooden spoon

I still think the Iron came from the steel container, maybe use borosilicate glass or some ceramic dish.

 

[PeterM]

last operation, we washed the gold powder with ammonia. We dried the powder in a steel container by heat. But finally you see the final level of the ingot below. Not good.
The white layer on the second photo was shown on the XRF , more Fe and less Cu.
Where does the problem come from?

Sir, what did you drop the gold out with? This contamination is terrible.

 

[4metals]

In the end, when the melting pool formed,
I looked at the melting pool, there was some white surface and the surface of pool was not shiny.

These impurities can often be removed by a process called toughening. When you notice the discolored surface on the molten gold add just a pinch of borax and a few prills of potassium nitrate. These will oxidize the metals into a slag which will cling to the small quantity of borax on the crucible wall.

You can see the nitrate collecting and oxidizing the surface and sticking to the borax on the wall. Biggest mistake is too much borax and over adding nitrate. Just a few prills at a time.

 

[Gold.refinery]

You can see the nitrate collecting and oxidizing the surface and sticking to the borax on the wall. Biggest mistake is too much borax and over adding nitrate. Just a few prills at a time.

What do you mean by a few grains of potassium nitrate and borax in an induction 5 kg crucible?
Also, after adding these two, the impurity along with borax sticks to the wall of the crucible.
Can this crucible be used for the next time to melt pure gold powder?

 

[4metals]

Can this crucible be used for the next time to melt pure gold powder?

If you use it sparingly enough you will see either the ring of shiny borax just where the surface of the gold interfaced with the air, or just a spot of borax if you didn't over do the borax. When the crucible is cold it is easy to scrape off this deposit to get at least a few fine gold melts out of a crucible, then the crucible still has a life melting fluxed melts or pouring shot for digestion.

 

[silver1]

You probably have a exhaust over your furnace, but did you notice any weird smells when you melted it? Did it smell like sulfur or ammonium? I think this may be a washing problem more than a refining/chemistry problem.

 

[Gold.refinery]

You probably have a exhaust over your furnace, but did you notice any weird smells when you melted it? Did it smell like sulfur or ammonium? I think this may be a washing problem more than a refining/chemistry problem.

I melt the gold with vacuums furnace ,without any exhaust, but when I dry powder with heat, it smell ammonium.

 

[silver1]

I think this this is a manifestation of you not being able to suck all the water because of your filtering problem. Might be some iron in there from you drying it on stainless after refining. Since it wasn't washed properly chemicals remained in the powder. When you place that powder on metal, raised the temp to dry it, the reaction occurred. It's a fail point to me in two areas. one. I never let my metals once pure ever contact a metal surface again before i melt them, especially when moisture is around. It's glass all the way. I can dry a lotttttt of gold in a kitchen cooking oven. Shit! I don't have to have a nothing more that some high grade cook ware. Ask Betty Crocker!

The second and most problematic issue and what lead to the discussion that's happening on the other thread is your filtering issues. We will finish that over there. One step at a time. We will have you making that shiny stuff you are looking for. Refining is an art and once you get all these little issues work out you will be set to teach others. What should be observed here is that a failure in the system showed itself in the result. There is so many ways from Sunday something can can go wrong from a-z, and will....trust me! Once you learn from it your see and catch those mistakes, hopefully early. It's a science and an art. 4metals and the rest of these gentlemen will hook you up right.

 

[4metals]

If you are melting in a vacuum furnace and the gold is not absolutely dry it is near impossible to get an accurate weight. A potential solution could be to melt the refined gold (of course rinsed clean of the solution it was precipitated from) into smaller lots in your induction furnace and toughen the gold, if needed, to clean it up as much as possible. Then pour this gold through a preheated crucible drilled to produce shot and make small BB sized shot.


The shot can be dried in a glass tray and accurately weighed into your molds for the vacuum furnace.

This gives you both the opportunity to clean up the molten gold by toughening and moisture free shot that can be accurately weighed into the molds.

It also gives you the ability to hold your gold as shot until you know what size bars you have orders for, because we all know when all you have are kilo bars, all of your buyers want half kilo's!

 

[silver1]

That's exactly how i run silver. I don't do bars. Everything is shot or powder. Bars if i pour them are a premium. I'm not a mint! lol Bars are always make from shot not powder.


Doing high purity gold the only thing i do different is after i pour the shot i place it in a stainless pot with a weak solution of water and nitric. I'll bring that up to a boil to take care of any borax or minor surface contaminates that may have risen to the surface. Couple of water rinses. After that it really shines. Measure and pour bars after that.

Remember this. It doesn't matter if you have a million dollar operation or a 100 dollars operation. That doesn't dictate the quality of your gold, your skills do! Chris taught me that.

 

[goldshark]

I have heard of beads "sprouting" during cupellation. Usually caused by several circumstances, including contamination. I will research the cause more fully, unless someone else beats me to the punch.

 

[Lou]

That's exactly how i run silver. I don't do bars. Everything is shot or powder. Bars if i pour them are a premium. I'm not a mint! lol Bars are always make from shot not powder.


Doing high purity gold the only thing i do different is after i pour the shot i place it in a stainless pot with a weak solution of water and nitric. I'll bring that up to a boil to take care of any borax or minor surface contaminates that may have risen to the surface. Couple of water rinses. After that it really shines. Measure and pour bars after that.

Remember this. It doesn't matter if you have a million dollar operation or a 100 dollars operation. That doesn't dictate the quality of your gold, your skills do! Chris taught me that.

I sure do miss him. He was the real deal and I wish he could see how things have developed.

 

[silver1]

I miss him every time i open this forum on my computer. To tell you the truth i have PTSD. I kick myself in the ass everyday for not picking the phone up and talking to him those last few months. That's on me though. He's still here. His spirit lives on in the words and memories shared here in his post. Wonder why i get defensive about the forum and it's existence? There's a lot of wisdom, history, and shared experiences here. One day even i shall cease to exist, but i hope my spirit to live on with those i can help.....even in death.

 

[goldshark]

I personally like W.C. Fields, I inherited a million dollars, half of it I spent on wine, women, and song. The other half I wasted.

 

[goldshark]

I did a little research into to sprouting of Au + Ag. Silver at 1020 C., can hold up to 19.5 volumes of O ( at 760 mm., and 0 degrees C. ). Since Silver oxide is not readily soluble in molten Silver, it can be expelled with much violence. Also slow cooling is preferential to a good clean ingot.The longer you can keep the metal insulated at an elevated temperature, the nicer your product will look.So my question to Gold.refinery is, was the Silver you used oxidized at all? I don't mean sulfidized, but oxygen introduced somehow into the Silver at the time it was in its molten state?

 

[silver1]

I did a little research into to sprouting of Au + Ag. Silver at 1020 C., can hold up to 19.5 volumes of O ( at 760 mm., and 0 degrees C. ). Since Silver oxide is not readily soluble in molten Silver, it can be expelled with much violence. Also slow cooling is preferential to a good clean ingot.The longer you can keep the metal insulated at an elevated temperature, the nicer your product will look.So my question to Gold.refinery is, was the Silver you used oxidized at all? I don't mean sulfidized, but oxygen introduced somehow into the Silver at the time it was in its molten state?

This discussion is about gold.

 

[Gold.refinery]

hold up to 19.5 volumes of O ( at 760 mm., and 0 degrees C. ).

Explain more clearly please.

was the Silver you used oxidized at all?

I melted the granular silver with 999 gold and the carat to 995. Then, in the end, I casting the 995 gold into a ingot by a vacuum casting furnace. According to the submitted photos.

 

[Lou]

Appears to me that there was not enough time spent mixing the gold in the induction furnace. I know people who make 23 K gold for leaf and they always superheat the melt to 1175-1200 C because they claim the alloying is better. Try hotter for longer, perhaps?

 

[silver1]

This discussion is about gold.

Ok now i see!I was confused. I'm still confused though. I understand alloying for manufacturing purposes, but am i to assume he added silver to get it from .999 down to .995..... Why? For more profit?