BP clumping while milling

[nesc39]

I'm having a pain in the ass problem where everytime I mill BP it's sticking together and to the edges of the mill and therefor doing nothing. I'm using the double rock polisher from harbor freight. Filling it halfway with material and lead antimony balls. I assumed it was because it was damp so I tried drying the nitrate in the oven first and that didn't help either. I used the same exact process before and never had this problem. What do I do?

[Col]

The charcoal will absorb more moisture than the kno3, its the prime suspect. BP can still clump with bone dry chems, a lot depends on efficiency of the mill but generally when it clumps its done.

[nesc39]

I wish that were the case. It clumps within minutes of milling. I have to take apart and scrape sides. It's basically useless. The only fix I can think of is a larger drum so everything falls further and breaks up better? I shouldn't have to though because lots of other use same set up and it worked for me before. I never tried drying the charcoal first though but it was taken from an unopened heat sealed bag? It's so aggregating

[Bobosan]

This isn't the main reason for your clumping problem but helpful to determine the correct media and chem charge for the HF mill.

 

Here is an excerpt from this Skylighter tutorial;

 

The ratios: This is the most important factor for ball milling success. Your mill jar should be 1/2 full of milling media, and ¼ filled with chemical(s), with ¼ of the mill jar left empty. Here's an easy way to get it right: first fill an empty mill jar one-quarter full of your chemical(s). With this mill jar, approximately 4.4 ounces (125 grams) of black powder chemical mixture will be an optimal charge. Approximately 6 ounces (170 grams) of a single chemical such as potassium nitrate or strontium nitrate will also be an optimal material charge. Then simply load the jar with your 200 1/2-inch lead balls (5 lbs.).

[eb11]

I switched to prilled potassium nitrate all my clumping went away

[pyroMIKE]

Also do not add dextrin.Screen in the dextrin after the other ingredients mill.

[dynomike1]

I forget what you call it, but i keep a drying bag in my charcoal bucket and P.N. bucket. Cured my problem.

[dagabu]

I'm having a pain in the ass problem where everytime I mill BP it's sticking together and to the edges of the mill and therefor doing nothing. I'm using the double rock polisher from harbor freight. Filling it halfway with material and lead antimony balls. I assumed it was because it was damp so I tried drying the nitrate in the oven first and that didn't help either. I used the same exact process before and never had this problem. What do I do?

 

Universally it is high water content that causes clumping. Dry the chems first and then try it. A desiccant (new) in a bucket will eat up your moisture in your BP that has already been milled.

[marks265]

Do you keep your mill jar well sealed after each use? Your dirty media will pick up moisture if not sealed from the elements while idle. In the summer months we set a sample of our chems out in the sun when sealed in a plastic baggie. The moisture culprit shows up pretty quick when the moisture condenses to the clear baggie. Winter months for us that live in the cold I would dry each batch of chems one at a time and mill to find which one is the problem. If you dry them all and make a batch you won't know which is the problem. Conversely, you could have a couple of wet chems. Usually a new lot of chemical is introduced and usually the source. This isn't to say it is always the problem either especially when storage practices are suspect to moisture. I've used many different batches of chems and never had a problem. I always add dextrin in varying amounts and still never had a problem.

 

Mark

[enanthate]

Im sure you have moisture in some of your chems.

My kno3 got moisture as hell, but does not clump. My last charcoal had some humidity however, and that was clumping like hell.

 

Cook your chems individually in the oven at 50C for an hour or do, stirr it a couple of times during this process. Your problem WILL dissappear.

 

I assume you are using real dextrin (bought or cooked to a brownish color).

Mike, I allways mill with dextrin, never had a problem with it. Its specially good when using the powder as prime, for rolling, etc. as the dextrin needs to be evenly distributed.

My experience anyway.

[LambentPyro]

I usually get clumping when I over-mill, it's 50% or greater humidity outside, or add Dextrin or some other binder within the mix.

 

I never got clumping when I used the old harbor freight jar, but when I upgraded to the hobfir mill with the PVC jar, clumping became a frequent issue I ran into.

 

To prevent clumping, I take the jar out and tap it with a piece of hickory and put it back on the mill every hour and then a good 10 minutes before I turn it off so it separates easier in the bucket screen.

 

FYI, when BP clumps, it's actually not milling, so your wearing your media away for nothing.

[marks265]

When he said, "It clumps within minutes of milling." I figured something has to pretty damp or really not a good scenario. It'll be fun to see what he has found out.

[Col]

Easiest thing is to take a known weight of chemical including container weight and oven dry it. After an hour or two, reweigh it (container and all) and whatever went missing was moisture.

[enanthate]

LP, how long are milling for? Sounds like "too much". Bp does clump when overmilling.

Anyway if this is the case, get your hands on some better charcoal (im using harbor freight 3lb with alumina, and got very hot bp after 2 hours.)

Just a suggestion

[zakmaster524]

Honestly, I wouldn't worry about it too much but if its a real problem for you i would suggest a smaller size and higher quantity of media. Youre using brass, right?

[dagabu]

Honestly, I wouldn't worry about it too much but if its a real problem for you i would suggest a smaller size and higher quantity of media. Youre using brass, right?

 

Uh... No. "I'm using the double rock polisher from harbor freight. Filling it halfway with material and lead antimony balls" He has the right idea.