A golden edge on the end of the year

Hi all!

It's been a long journey to get to this point... I'm sitting and playing with my 52 g gold button. 8)

It started so many years ago, long before I found GRF, almost 30 years ago. I was a teenager and scrapped relays and switches for silver when I discovered something golden in a TV. It was also the time when a schoolkid could buy acids in the nearest paint shop. Soon after I had some nice golden foils and water in a small flask.
Fast forward 25 years. I still got the bug, collecting both silver and gold scrap. processing fingers with nitric and melting into quite dirty gold. I had some ideas about how to refine it but I hadn't put any plan into work, and it was a good thing. Because in 2007 I discovered GRF and joined as member #1059. GRF wasn't as big then as it is today but there were already a lot of information. Not soon after I got my first brown powder of refined gold in an erlenmeyer flask and I was all :mrgreen:

Since then I have learned a lot, tested different techniques and materials. Sometimes made a mistake but always recovered. Every time adding to my pot in the flask, gram by gram. At first I told myself that I would stop at an ounce, but when I got there I had several batches going so I just continued. Finally this summer I felt ready to re-refine my gold and make that big button.

I started with 53.9g gold, calculated the amount of acid I needed for approximately 4:1 ratio ( 205 ml HCl and 51.2 ml HNO³), then measured up even more HCl (125 ml) as it doesn't hurt and 25 ml HNO³, thinking half a batch of acids is a safe starting point. After a while and some heating the reaction seemed to come to a stop. I poured off the auric chloride via a filter into a flask. Realizing that almost all gold had been dissolved I only added a bit of HCl and only 3 ml HNO³ and it was enough. 54g gold took only 150 ml HCl and 28 ml HNO³! 8)

Two months ago I brought the gold chloride, beakers, SMB, some sulphuric acid and filters to my parents, showing them how to drop the gold from solution to metallic powder.
The powder I brought back home for final wash (HCL, ammonia and water, never saw any discoloration of the washing liquids) and drying.
I went to my parents over the holidays and I brought the gold, a beaker from Steve and some borax and finally on Christmas day I melted the gold while my dad watched. We managed to melt it using only LPG and air but it took a while.
Sadly, there seemed to be some scrap falling off the fire bricks when melting since I got a bit of discoloration of the borax in one spot and a slight oxide discoloration of the gold button.
I guess I'll re-refine it again when I got another 50g of gold to add to it.

So... here are the pictures from start to finish. Ok, I start with the button. 8)

52.5 g final button. My red gold 18k ring looks like copper in comparision.


This is where I started, 53.9 g gold powder dropped with SMB.


Dissolving gold in aqua regia.


HAuCl₄ 250g/liter. I just love that orange color!


Dropped a second time and dried.


Continued below...

Starting the melt.


Almost there...


I made it! I wasn't sure it would be enough heat.


The melting dish afterwards. Only discoloration of the borax in one spot.


Fernlike crystal pattern on the bottom, up to a cm in size. Some small patches of borax still hanging on even after pickling in diluted sulphuric acid.


Ok, let's bring on the comments! I can take it!

Happy new golden year!

Göran

Göran,

Well done!

A point to ponder.

Hard to say what has contributed to the appearance in the first picture, but the frosty surface is an indicator that there may be a contaminant of sorts. When your gold is quite pure, it should yield a shiny surface.

I refined for more than 20 years. I never got tired of watching gold precipitate. It was often a spectacular display, as I used SO2 from a cylinder, and did my precipitation in large, tall vessels (when re-refining). Imagine watching a solution quickly flash to what could best be described as bronze paint, with millions of tiny gold particles in suspension and quickly moving about.

Harold

Cool art work in that button, I see lots of pine trees.

30 years in the making, great story and well done. Looks like I have another 28 1/2 to go. I'll tell you one thing though, if I ever do tackle that art it will be well worth the wait. Looks awesome!

Thanks!

I'm suspecting that a small piece of iron dropped down from the top brick at the end of the melt. If the contamination was there from the beginning I would expect it to discolor the borax all over the dish. I should have brushed the fire bricks with a wire brush, my dad uses them for support when he welds.
I was quite disappointed when I didn't get that mirror surface. But part of the disappointment is offset by the cool crystal forms, triangles of crystal surfaces. You can actually see the cubic structure of the gold crystal. 8)

I'm already started on the next batch... 1.1g in the flask already. 8)

Harold, once I got SMB down (dissolved in water) to the bottom of the gold chloride, creating small SO₂ bubbles that left tracks of precipitated gold going up towards the surface. It must have been something like that when you used SO₂ gas. It sure is a "magical" feeling to drop the gold.

Göran

What great way to end the old year, and begin the new year.
Thanks for sharing, and for the pictures, I know this was exciting for you doing it, but I kind of get excited just seeing the pictures of what you have done.

The characteristic pipe is also missing from your button. Your explanation of iron contamination may explain why.

I've seen a pipe pulled so deep it looks like a cliff--and the color within the pipe is breathtaking. Happens only with very clean gold.

When working with refined gold, everything must be clean---even the torch. The slightest thing can ruin a lot of hard work.

Harold

Well ruined or not that is a darn pretty 52.5 g gold button, any one should be proud of, besides with about 8 grams more, we can watch Göran change it into a beautiful pure 2 troy ounce gold button.

In my experience, the presence of a small amount of Pt group metals can produce that fern-like crystal pattern.

Mykert bra Goren!
What a feeling of accomplishment ,eh! Gold powder sitting there for 30years. I could never do that. I get so affraid that it might get broke and the powder would get lost. Plus, I love seeing it in the melting dish turning into a button.
If you already have another 1.1grams, then we should be seeing your 2 oz button before long!

You can melt without the fire brick. Get a handfull of the insulation that they use around the ductwork for restaurant exhaust hoods or in boilers. just lay it in the surface set your melting dish on it and then pack the insulation around the outside af the dish. you can melt two ounces with a map-gas torch and no air or oxygen. that way the heat stays in the dish and you don't have anything over it that can fall in.
Beautiful work! I like the pattern it has.
artart47

The crystal pattern was explained before by Lou, if I remember right he said it was a sign of very high purity, meaning .9999+. Every bit of gold I have refined has had this same pattern when melted. The only time I have achieved a pipe in any of my gold, or silver, has been when allowing it to cool under a flame lacking oxygen. This bar was refined twice today from gold filled material and weighs just over 26 grams.

Oxygen has nothing to do with a pipe forming. It's the result of very pure gold shrinking as it cools (in the process of solidification). The final freezing creates the deep pipe as the center solidifies and shrinks. In the process, the pipe is formed. It can be avoided by continually heating the entire surface of the gold, so it cools from the bottom up, and shrinks uniformly, cooling very last at the center, at the surface. In such a case, the surface ends up concave, but with no pipe.

I strongly disagree with the notion that the crystal formation shown is the result of very pure gold. When gold is extremely pure, it forms a huge crystal structure, with the surfaces within the crystal boundaries being very shiny. I witnessed that routinely. In all my years of casting ingots, I never once managed to achieve a surface such as that which was shown. If pure gold was the reason, I'd have experienced that surface routinely, and commercial ingots would be fraught with the pattern. They NEVER are.

I defy anyone being able to create that pattern with pure gold. It just doesn't happen. And, I tend to agree with GSP---I had a small ingot submitted to me to be included with a lot I refined. It was obvious by the color and surface condition that the submitted bar was not pure, in spite of the fact that it was marked as such (anyone can stamp an ingot). The small ingot (about a half ounce) was re-processed, resulting in a solution that tested positive for platinum. It takes very little of the wrong contaminant to cause gold to form that small crystal pattern, which also accounts for the lack of a pipe. The material freezes before it can form, as it has a narrow liquidus state, due to the contamination.

Harold

Thanks for all the comments!

That could explain my crystal patterns and lack of pipe.
Firstly I let the button cool slowly by just backing off the flame. Secondly, some of the gold came from dental materials, I dropped a couple of grams of gold from a solution that looked like amber afterwards. I also processed my stock pot and it had some PGM:s in it. So there is a high probability of PGM contamination.

But there is some base metals in it too, as the unprotected surface got an oxide cover when I removed the torch. Unless palladium can oxidize a bit even when mixed up in a lot of gold.

Anyhow, this gives me a perfect opportunity to try out a small Wohlwill gold cell. I just need to extract gold for the electrolyte and then I'm in business. :mrgreen:

Göran

When I had my last refinery, most all the gold was torch melted with acetylene/O2 and cast into 10 oz bars in a preheated graphite mold. I never kept the flame on the bar after pouring. The purer the gold, the deeper the pipe and the larger the squarish crystals (sometimes as large as 1/4"). When really pure, there was a slight separation between the large crystals, especially those nearest the pipe. I reworked any gold that was discolored (usually reddish), exhibited a fernlike crystal pattern like the photos above, or that with no pipe or squarish crystals. I probably ended up reworking about 5% - 10% of the bars. If the gold wasn't too much off-purity, I remelted with small alternating pinches of niter and borax in an attempt to make it acceptable. This usually worked.

Inside the "pipe"

Glondor, that one is just extreme! 8)

I guess that the niter and borax trick doesn't work when dealing with PGM contamination.
Anyhow, I think I will try to remelt it next time I get back home to my parents.
Thanks for the tip, Chris.

Göran

Looks like glondor picked that gold out of the dish before it completely solidified and squeezed it a little to hard. I have had the same thing happen, I just re melted it. But that does look pretty cool glondor!

Tyler

Glondor's pictures are a perfect example of what I've been talking about. Note the large crystal pattern on the surface, and how shiny the gold is within the boundaries. Also, I had commented on the extreme beauty of the gold within the pipe. This one is an exceptional display of the enriched color.


Harold

Harold_V said:

Glondor's pictures are a perfect example of what I've been talking about. Note the large crystal pattern on the surface, and how shiny the gold is within the boundaries. Also, I had commented on the extreme beauty of the gold within the pipe. This one is an exceptional display of the enriched color.


Harold

Click to expand...

how would you rate this Harold ?

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=61&t=20404&p=209000#p208960