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Posted

I have been having problems granulating my BP. It seems, for the most part, all I can get is big chunks or fine powder. Any tips or suggestions? I have been LIGHTLY dampening my mill dust and pressing it into 2" pucks that run in the neighborhood of 1/4" thick. After drying they are quite hard and solid. I then crush them in a SS metal bowl with a large diameter wooden dowel (on end, not rolling). The BP I've been making turns out dam hot! I would just like to get some decent size grains.

Posted

My 2 cents....

 

Use 3% water by weight. Press to a density of at least 1.5 g/cc, and preferably 1.7 g/cc. ( a puck 2" in diameter and .25" thick would weigh about 21-22 grams). Corn the powder before you dry the pucks. Recycle fines back to new pucks and corn them. I use a heavy wooden mallet on a thick aluminum plate for corning. I break up the pucks as they come out of the press, then put several chunks in a heavy plastic bag. Whack! Whack! until you don't find any more big chunks. Screen and repeat. Light to moderate blows are adequate for the task.

 

I've gotten better than 90% 2FA this way.

 

If you can't press to that density, you might want to consider just granulating the powder with alcohol using a 1/4" screen. I add 3% red gum for really hard grains. It will be as hot or hotter than corned powder, but will take up more volume.

 

Kevin

  • Like 1
Posted (edited)

Thinking about it, I load around 25g of mill dust into my press at a time, so minus the water, I figure I'm in the density range you describe. Off the top of my head I figure its probably around 3% water that I add; I just go by feel, add water with a spray bottle until the dust get a little lumpy and won't raise up dust when stirred. I don't know about the light to moderate blows though, these pucks are pretty dam hard. Therein lies the problem, by the time I use enough force to break them, I'm crushing the crap out of them :( But, just maybe, impact instead of pressure type force might be better. Also, corning before drying..hmm sounds like something worth trying thanks

Edited by MadMat
Posted (edited)

Are you breaking them up before drying?

 

Ummmm. It's important to measure things. Accurately. Too much water and KNO3 will leach out. Too little and your pucks won't hold together.

 

Kevin

Edited by Nessalco
Posted (edited)

Haven't tried that yet. I always dry them first. I not worried about leaching out any KNO3, I never get it that wet, plus I use 80/20% water/denatured alcohol. I have measured the water in the past; now I go by feel since I've seen what the mill dust looks and feels like many times.

Edited by MadMat
Posted
As mentioned, break it before it's dry and you will be happy. If you let it dry, especially with a binder like dextrin, and they will be as hard and tough as porcelain. Which as you found, likes to either breaks into big pieces or small grains.
Posted

I have a batch of BP in the mill as I'm typing this. I'm going to try that out this time; thanks guys

Posted
Either wet the meal and screen 4 mesh or continue the way you are and get a set of screens and sieve your crushed pucks into various mesh sizes. You can get screens on amazon just like skylights sells for much much less.
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