Non-Chemical How to produce grains ?

[Noxx]

Hello!

I am not sure if this has been covered yet, but I am wondering how casting grains are produced...

We all saw Harold's shiny gold shots, but how are the refineries producing grains ?

Maybe pouring molten gold over a powerful water jet will break the gold droplets thus producing grains ?


Thanks a lot.

 

[machiavelli976]

Hi Noxx ! i think is about pouring in a very hot liquid like silicon oil for example. there must be some additives also to get the shiny finish

 

[leavemealone]

I am currently looking for a video that I saw on youtube(international) from a company overseas that was making silver shot.They melted what looked like 50+ pounds then poured it into a cauldren that had been riddled with holes in the bottom.The cauldren was about 6 inches above a huge vat of water.The idea is to not let the molten material get enough inertia that it "splats" or flattens out when it hits the water.The same result can be had from dropping the material very long distances as long as the tempurature of the material is just above its melting point,therefore causing it to solidify in mid air,prior to hitting the water.
The end result on the video I saw was absolutely awe inspiring.Just countless pounds of perfect silver BB's.
If I can locate the video I'll post it.
Johnny

 

[goldsilverpro]

NO oil!! NO additives!! Cool, clean water.

I'm thinking that, maybe, 4metals covered this on the forum. I think that Harold also had quite a bit of good stuff to say about the subject. I could very well be wrong on both counts. I know that it was covered in fair detail on the forum.

At one place I worked, we shotted large quantities of silver. There was a gas fired crucible furnace mounted on a platform. The bottom of the furnace (and the platform, of course) had a hole in it, in which a large (#70, I think) crucible was cradled. The crucible had about 4 holes drilled in the bottom of it. I'm thinking either a #54 or #56 drill bit was used for this. Under the furnace, sat a 300 series SS container, about 18" dia X 48" high, on wheels. The water was pumped from about a 500 gallon (at least) reservoir into 2 angled inlets (placed on opposite sides so the water would rotate) near the bottom of the SS container. The water flowed back into the reservoir from an overflow pipe near the top of the SS container. A SS basket, with holes in it, was suspended with heavy SS wire near the bottom of the SS container.

The water was circulated into the bottom and out the top of the SS container. The furnace was heated up and a 1000 oz (or, smaller) pure silver ingot was put into the crucible with no flux. As it melted, the molten silver dripped through the small holes in the crucible and fell into the circulating water. The silver shot fell into the basket, which was lifted out when all the silver had dripped through. The shot was placed in SS trays and dried in a gas fired oven. The result was shiny, almost spherical shot about 1/8" - 3/16" in diameter, with no discoloration.

Once the silver started melting, it didn't take but a few minutes for all the silver to drain through. It took a lot of water circulation to keep the water in the SS container from getting too hot. I would guess the water inlets were about 3/4" diameter.

There are some details that I can't remember. You get the idea. Gold is done similarly with a smaller setup, of course.

 

[Palladium]

http://www.scribd.com/doc/20406032/How-to-Make-Gold-Shot

 

[qst42know]

Near the end of this video at 1.12 they are pouring a huge quantity of shot.

http://in.reuters.com/news/video?videoId=112738&videoChannel=104

 

[Noxx]

Hmmm... I'm sorry, I wasn't clear enough.

I'm looking for a way to produce casting grains, not shots. They are like 10 times smaller than regular shots.

 

[Barren Realms 007]

Is this what you are looking for?

http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=39&t=6211&hilit=PSI

 

[nickvc]

I used to produce many kilos of mainly 9carat casting grain for the manufactures here in the UK,the main thing to get right is to produce a good alloy that the casters are happy to use.I spent hours and hours trying to get the grain to look pretty but the effort was wasted as the casters just want a good alloy that performs to their satisfaction.If your aim is to supply grain find out what alloy they want and copy it using only high grade elements,melt in a clean crucible and then pour the molten alloy into a deep stainless container so the shot doesnt stick to the bottom.I always aimed to make the grain to .376 so no problems with the assay would arise, some of the trade casters had a habit of allowing for a melting loss and throwing a small amount of brass into the melt :shock: The best way to make acceptable grain is to work hand in hand with the customer and give them a good alloy as the grain only ends up been melted again and if you can produce it cheaper than the bullion dealers they dont care how pretty it looks :lol:

 

[Noxx]

Is this what you are looking for?

http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=39&t=6211&hilit=PSI

Exactly ! Thanks.

 

[nickvc]

Noxx there are several ways to produce grain,the method shown in the video uses a crucible that has small holes drilled into the bottom through which the already molten metal pours into a vat of cold water,i would suggest heating the crucible as the metal soon cools if you dont.The height of drop to the water also has a bearing on the shape and size of the grain formed and be sure to have a large enough volume and depth of water to make sure the grain sets before hitting the bottom. A method i ended up using for a while was having an angled piece of graphite slightly submerged in the water and pouring directly in a thin constant stream onto it to form a pleasing looking grain.The one thing i do know is that you have to have reasonable quantities for the grain to look good due i think to the cooling,much under about 250 gms and it leaves you with very poor looking grain.Hope this helps.