Preparing Metal for Digestion

There seemed to be some interest in the methods we use to "shot" our metal before digestion.

When we first began wet refining we would make cornflake shot by simply pouring molten metal from our induction furnace crucible into a large stainless pot full of water. That material works fine for karat scrap and even for alloy batches containing <10% Ag. But in order to quickly and completely digest by inquartation methods smaller shot is better; no greater than 3mm to be exact.

So our solution was to construct a spray nozzle aray in the shape of a doughnut. It is constructed of steel, is about 2.5 inches thick, hollow, and about 12 inches in diameter. It sits nicely in a hole cut in the middle of the top to the pot mentioned above. There is a water inlet on the outside of the doughnut and there are four fan spray nozzles located on the bottom pointing towards an imaginary spot below the middle of the center of the hole in the doughnut. Our water is pumped by a pump similar to the kind in the self serve car wash places. It provides 750 psi of water pressure per nozzle. When the molten metal is poured into the converging streams of water it is cut into sand size particles. Some particles are so small that they remain suspended in the water for quite some time.

Once the batch is completly shot all water is filtered and containers are rinsed into the same filter.

Below is a link to a few pictures of a batch we will begin to refine on Monday. This was a starting weight or 177 troy ounces of assorted karat scrap. I'll get a picture of it when it's dry next week.

http://dl.dropbox.com/u/3358180/Our Shot 1.jpg

http://dl.dropbox.com/u/3358180/Our Shot 2.jpg

http://dl.dropbox.com/u/3358180/Our Shot 3.jpg

this is awsome. ive done something similar to this before but it was by grinding the scrap with a dremel. i guess it would take much longer to grind down 12 pounds though. :mrgreen:

Hi Scrapper
I was wondering how this looked

So our solution was to construct a spray nozzle aray in the shape of a doughnut. It is constructed of steel, is about 2.5 inches thick, hollow, and about 12 inches in diameter. It sits nicely in a hole cut in the middle of the top to the pot mentioned above. There is a water inlet on the outside of the doughnut and there are four fan spray nozzles located on the bottom pointing towards an imaginary spot below the middle of the center of the hole in the doughnut. Our water is pumped by a pump similar to the kind in the self serve car wash places. It provides 750 psi of water pressure per nozzle

Click to expand...

It looks kind of like a little innertube made of steel with four nozzles on the bottom of the inside of the innertube aiming at the center. I don't have a picture of it. Sorry.

The difference between what you described and a full fledged water atomizer is how the molten metal is delivered to the spray pattern. To get smaller particle size you need a constant delivery of molten metal. I've seen it done using a crucible with a critical orifice in it positioned over the center of something similar to the donut you've described. The molten metal flows out of a single hole about 1/4 inch in diameter or less and is shattered by the water pressure. I'd bet by experimenting with orifice diameter and pressure you could atomize with your setup. Nice job!

I am thinking about making an atomizer with plumbing pipes and drilling it and them soldering it
What do you folks think
These pipes are galvanized steel and coated with zinc if I am not wrong

I will re-paint the pipe or is it not neccesary.
After it it welded and drilled will this be a problem like rust from the pipes contaminating the batch of gold

Because this is before the gold is digested I don't think it will be a problem.

The gold can NOT contact any of the metal. It should only touch refractory materials (i.e. ceramics and graphite) which are not wetted.

Otherwise it'll braze so quick your head'll spin!

I've mentioned this several times and have never even gotten a comment. Has anyone ever tried pouring the metal directly into a stirrer propeller that is submerged a few inches under water in a stainless vessel? I have and it works great. I once carved about a 4" propeller out of hardwood, drilled a hole in it, and attached it to a threaded rod chucked it into a drill. Very simple. I got super small shot. I don't know if it would stick to a stainless prop, but I would doubt it.

An ancient metal of fine shotting is to put a board a few inches under the water, at an angle, and pour the metal directly onto the board. I have never tried this but I've read about it in about 50 different places.

goldsilverpro said:

I've mentioned this several times and have never even gotten a comment. Has anyone ever tried pouring the metal directly into a stirrer propeller that is submerged a few inches under water in a stainless vessel? I have and it works great. I once carved about a 4" propeller out of hardwood, drilled a hole in it, and attached it to a threaded rod chucked it into a drill. Very simple. I got super small shot. I don't know if it would stick to a stainless prop, but I would doubt it.

An ancient metal of fine shotting is to put a board a few inches under the water, at an angle, and pour the metal directly onto the board. I have never tried this but I've read about it in about 50 different places.

Click to expand...

It's funny you mention that about the board under the water. I have had the same thought only with a SS sheet angled into the water with an ice cold water flow down the face of it to the water. Would this not give you flatter shot when you poured it? I don't think the metals will stick to the surface of it is polished.

I suspect wood being porous and full of water would create localized steam explosions further shattering any drops of metal that contacted it. Wood may be a better choice than stainless.

Years ago, when I was first making shot I used the submerged board trick, worked very well and the board barely charred. It lasted a long time. I figured if wood is good, stainless is better. Wrong! What a mess, the gold stuck to the submerged stainless, angled just like the wood, and made a mess. Needless to say that refining lot had some stainless in it as well.

Lou is right, stay away from metal, stick with the wood.

I would like to Preparing my Metals for Digestion
I must admit that the term atomizer is something I never heard before
Anyhow I want to have powder like gold for digestion like Scrapper-aw-

I made a picture with photoshop and it should have been done with a 3D software
but this was easier and I think you can get my idea across

In this picture I start with an empty garbage can with maybe few inches of water in the bottom
The water for the atomizer(dougnut shaped metal) is turned on and I start pouring
I was thinkg that this idea would work

I cant understand what Lou means here

The gold can NOT contact any of the metal. It should only touch refractory materials (i.e. ceramics and graphite) which are not wetted.

Otherwise it'll braze so quick your head'll spin!

Click to expand...

I would like more on Gsps idea

I just got a comment from 4metals
He says stay away from metal


I already bought the plumbing pipes but I can always return them back
It was only 20 dollars

So I need a new plan
Back to the drawing board

I forgot this
http://img41.imageshack.us/img41/6973/atomizerz.jpg

I wouldn't use a galvanized (or bare steel or plastic) garbage can. A pin hole in the zinc or a place where the zinc didn't cover well (like where the bottom meets the sides) and you will end up with rust mixed with your metal. The best, of course, is stainless. I've seen people use such things as SS beer kegs with the top cut out, but they're not quite deep enough for my likes. The best I've ever used is a 55 gal SS nitric drum with the top cut out. To buy one of these drums new is prohibitively expensive, but sometimes you can scrounge one, maybe in a scrap yard. Also, you could try to find a scrap dealer that specializes in used SS restaurant equipment - they'll usually have something that will work. No matter what you use, make sure it is deep enough so the metal is not molten when it hits the bottom. If it is molten, like Lou said, you will get instant brazing of the metal to the SS (or, most any other metal). Once the metal sticks to the stainless, things cease to be fun. In most cases, your tank will end up ruined. For standard shot, you can attach 4 long SS wires to a SS colander (pick one with small holes) nearly as wide as the tank, sitting on the bottom, to catch the shot. Makes it a lot easier to remove the shot.

Hi Cris
Then it would be a bad idea to use plumbing pipes to make the doughnut shaped object

Hi Chris
Maybe I can build something like this

http://images.google.com/imgres?imgurl=http://imghost.indiamart.com/data/3/J/MY-145126/Barrel-Stirrer_250x250.jpg&imgrefurl=http://www.indiamart.com/company/145126/other-products.html&usg=__ja0kQBm48H__IGLqA1DiNk7BQCc=&h=240&w=240&sz=18&hl=en&start=5&tbnid=CYEOXz-RMZUI2M:&tbnh=110&tbnw=110&prev=/images%3Fq%3Dstirrer%2Bpropeller%26gbv%3D2%26hl%3Den%26sa%3DG

A plastic barrel and cut a hole in the center and pour with the stirrer working

So our solution was to construct a spray nozzle aray in the shape of a doughnut. It is constructed of steel, is about 2.5 inches thick, hollow, and about 12 inches in diameter. It sits nicely in a hole cut in the middle of the top to the pot mentioned above. There is a water inlet on the outside of the doughnut and there are four fan spray nozzles located on the bottom pointing towards an imaginary spot below the middle of the center of the hole in the doughnut. Our water is pumped by a pump similar to the kind in the self serve car wash places. It provides 750 psi of water pressure per nozzle. When the molten metal is poured into the converging streams of water it is cut into sand size particles. Some particles are so small that they remain suspended in the water for quite some time.

Click to expand...

I am wondering how Scrapper-aw-
made his

Then it would be a bad idea to use plumbing pipes to make the doughnut shaped object

Click to expand...

If there is any chance of molten metal coming in contact with any other metal, it's a bad idea.

So our solution was to construct a spray nozzle aray in the shape of a doughnut. It is constructed of steel, is about 2.5 inches thick, hollow, and about 12 inches in diameter. It sits nicely in a hole cut in the middle of the top to the pot mentioned above. There is a water inlet on the outside of the doughnut and there are four fan spray nozzles located on the bottom pointing towards an imaginary spot below the middle of the center of the hole in the doughnut. Our water is pumped by a pump similar to the kind in the self serve car wash places. It provides 750 psi of water pressure per nozzle. When the molten metal is poured into the converging streams of water it is cut into sand size particles. Some particles are so small that they remain suspended in the water for quite some time.

Click to expand...

How about making the doughnut shaped object from galvanized pipes and drill holes and cove it with plastic and use a plastic garbage can

A plastic barrel and cut a hole in the center and pour with the stirrer working

Click to expand...

Similarly, if there is any chance of molten metal coming in contact with the plastic, it's a bad idea.

Also, after thinking about it, if you use a propeller, I wouldn't take a chance and use a metal one. You could carve a prop out of hardwood. Or, you could probably just drill a fairly tight hole for the threaded rod in a piece of hardwood about 3/4" x 3/4" (or, 1" x 1") by 4" or 5" long. You could use a nut and washer (SS would be best) on each side of the wood to keep it from slipping. You might have to trim it a bit to balance it and keep the shaft from wobbling. The threaded rod should probably be at least 3/8". Here again. SS would be best, if you can find it. A smooth SS rod with threads on one end would work well also.