How to make consistent shot - drilled crucible? Slanted wood?

[snoman701]

I'd like to set myself up so that I can make really consistent cornflake, not necessarily shot. The alloy to be melted / shotted is karat gold inquarted with silver.

In practice, if I'm trying to pour cornflakes, I end up long strings, or big chunks. Obviously some of this is practice, but I was never all that coordinated. The practice of mixing the water while trying to pour the molten metal at a uniform speed leaves might as well be ball room dancing on a greased floor.

I need nice uniform cornflakes.

So, I need to invest in building something that will help me. I'm open to suggestions. I can put an overhead stirring motor on the tank I'm shotting in to, no problem. I can also create a second heated crucible that's drilled, again, no problem. My biggest concern is that all of the metal that I melt in the first crucible end up shotted out as cornflake.

Suggestions?

 

[4metals]

A simple and very old method is to place a pre soaked hardwood plank in the cold water of the shot tank and when you pour aim for the water line. The shot hits the board and spreads out breaking up the solid stream and preventing the re-solidified alloy blob from forming on the bottom.

Pouring as slow as possible to assure a thin stream helps. But that is often akin to ballroom dancing on a greased floor too.

Of course a certain depth of water also helps. In many large refineries they have a deep tank built into the floor which allows the cornflakes to cool before getting to the bottom. They then pull up a bucket which somehow collects all of the shot. I assume the bottom slopes into this bucket but the water is never clear enough to see down past the first inch.

 

[snoman701]

So if I pour into a heated drilled crucible first, then let it dose out the stream, will it reduce the likelyhood of getting the giant blob? Let it do the work for me. Or will I end up with metal held up in the crucible?

 

[FrugalRefiner]

I have read in several places about having a stream of water spraying over the top of the water vessel. I believe 4metals has shown an atomizing system that uses a circular ring with holes pointing toward the center, and pouring into this spot. I believe Loewen described a simpler variation that used a lower pressure water stream aimed right across the surface of the water. I've never tried either, but in theory, they both sounds like they would work.

Dave

 

[snoman701]

I'm not ready to invest in pumps and filters and such at this time.

Right now I'm simply trying to run a mass balance over a series of lots. I'm buying karat scrap, then pin sampling, fire assay of the pin, with follow through inquartation and lot treatment to 999 fine so that I can make sure that my assay is spot on.

Have to prove out my fire assay before I can really feel comfortable buying karat.

 

[4metals]

I've done the drilled crucible thing in the past, it's a fine line. Sometimes it all dribbles out but more often some freezes in the holes.

I believe 4metals has shown an atomizing system that uses a circular ring with holes pointing toward the center, and pouring into this spot.

Atomizing is a different thing, it produces a fine micron sized powder, great for quick digestions. This is a shotting tank, more for making uniform shot than cornflakes.
This is an atomizing setup which successfully can atomize up to 500 oz lots for a small shop.

This is what to does to metal poured through it.

And this is me testing it in the parking lot just to see the spray.

 

[snoman701]

How many PSI do you have to feed that? 3600? I believe we are beyond the simple 1750 PSI harbor freight pressure washers.

 

[snoman701]

I've done the drilled crucible thing in the past, it's a fine line. Sometimes it all dribbles out but more often some freezes in the holes.

So I'm better off just making a surface I can lean my crucible tongs on so I'm not trying to balance.

Probably a tad bit easier tech as well.

I've got an intention tremor, and it's amplified when I'm holding $10k in molten metal on the end of a stick.

 

[4metals]

I've got an intention tremor, and it's amplified when I'm holding $10k in molten metal on the end of a stick.

These days that isn't so much metal, $10K is only 12ish ounces of a 10-14 carat mix averaging 50%.

For that size, by hand should be fine, for larger melts, over 100 ounces, a tipping cradle may be better. The trouble is freezing up of the melt while you get the crucible into the pouring cradle.

 

[4metals]

How many PSI do you have to feed that? 3600? I believe we are beyond the simple 1750 PSI harbor freight pressure washers.

It depends on how small a particle size you are after. The cheapie harbor Freight 1750 psi pressure washer will work and give you sand sized particles. For really fine dust you need more pressure, which involves better welds for safety.

Once you have processed powders you will never go back. And the chemistry changes so there are advantages. It excels for cleaning up dental alloys to. make higher purity bars to get better rates.

 

[snoman701]

I used to be able to do a 100 oz pour with a pair of channel locks just grabbing the crucible...both when it was someone else's money, and I had someone else's induction furnace and pouring area.

90% of it is practice and routine, which is what I'm genuinely trying to develop. But my two left feet don't help me much either.

 

[Palladium]

Maybe it's just the way my mind thinks...... but is that a Torque converter?

 

[snoman701]

It depends on how small a particle size you are after. The cheapie harbor Freight 1750 psi pressure washer will work and give you sand sized particles. For really fine dust you need more pressure, which involves better welds for safety.

At that pressure I'd probably cut it out of a solid piece of stainless. You drill straight holes all the way through on all four edges, then just tap and plug . Then drill out your center and drill your nozzle holes at an angle to hit the straight holes on the edge and tap them for the nozzles.

When I first was put on to atomized metal, I designed exactly what you show out of readily available stainless pipe fittings that were rated for the appropriate pressures. I never used to have the money to put it together.

Maybe it's just the way my mind thinks...... but is that a Torque converter?

lol...no, they are 90 degree weld elbows.

 

[Palladium]

 

[4metals]

they are 90 degree weld elbows

Stainless steel butt weld long style elbows welded and X-rayed for weld integrity.

 

[Palladium]

Now i can see it!
Quality welding can get expensive real quick.

 

[4metals]

Quality welding can get expensive real quick.

And faulty welds can cause a pressure explosion even quicker. I choose the safer and alive option when possible.

 

[Shark]

In the last picture, does the metal pour through from the bottom side, then into the sprayers?

 

[4metals]

I

In the last picture, does the metal pour through from the bottom side, then into the sprayers?

Yes the metal pours through the donut and is contacted by the high pressure spray which is what does the work of breaking up the alloy into small particles.

In the top photo of the atomizer mounted onto a 55 gallon drum, you can see it set up to pour. The large hose exiting the lid is from a wet shop vac because a fine mist of the spray made it up through the donut without it. So the way it works is melt the metal and when you are ready to pour turn on the power washer and the shop vac and pour through the center hole of the donut into a drum about 3/4 full of cold water.

 

[Palladium]

And faulty welds can cause a pressure explosion even quicker. I choose the safer and alive option when possible.

Yep! Same here. An ounce of prevention is worth a pound of cure. In a previous life i was a industrial coating technician. You can call it a painter. I had a spray gun blow up in my hand with about 3500 psi running through it. Split my palm open and blew paint almost through the other side of my hand. Took me years to finally not be able to see what looked like a dark tattoo under my skin ( battle ship Grey). The doctors flushed it out, sewed me up, and away i went!