37 replies to this topic

[robbstech]

Hi all,
I made a batch of black powder today using this ratio: 74.64% Potassium nitrate, 13.51% charcoal, and 11.85% sulfur by weight.

I placed in my ball mill anbd milled it for 4 hours, I took it out and I placed a small amount on the ground. The powder was extremely fine, anyway I lit it and it burned quite slowly, like 2 seconds for like 2 grams

Anyway I though it would better once I granulated it so I mix a very small amount of dextrin in, like 2% and then I added a small amount of 25/25 water/alcohol mix to it and mixed it until it was just forming into a ball.

I pushed it through a screen and got very nice sized particles.

Anyway i let it dry for about an hour and there was no difference in burn time

All the chemicals where sourced from friends and very pure.

What could be wrong here?

Let me know if you can,
Thanks
Rob

P.s Is there any use for the very fine powder left over when I screen the dried granulated BP?

[dr thrust]

try letting it dry for longer, an hour is not a long time in pyro , whats wrong with 75-15-10?
charcoal type?

[robbstech]

I should also add that the black powder is not as black as the name suggests it should be :s
It is a slight grey colour?

Can someone upload some pics of their BP? straight from mill and then when it has been granulated?

Thanks
Rob

[robbstech]

try letting it dry for longer, an hour is not a long time in pyro , whats wrong with 75-15-10?
charcoal type?

The charcoal is just pine airfloat. Also is that a nice ratio? 75-15-10?
Does it work well?

Also I would have thought that it would have burnt quicker than it did even straight from the mill?

[dr thrust]

yep its grey from the mill, 75 15 10 is the standard for hundreds of years now.
how efficient is your mill? is it rotating at the correct rpm for the jar size, have you got the correct amount and type of media?

[robbstech]

yep its grey from the mill, 75 15 10 is the standard for hundreds of years now.
how efficient is your mill? is it rotating at the correct rpm for the jar size, have you got the correct amount and type of media?

I od not know what RPM my mill is doing but at a guess i would say 80RPM...if the mill is inefficient will it be ok to run it for longer to counteract this?

Thanks

[Karl]

Put a mark on your drum, time how many times it goes round in 60 seconds and there's your RPM. I believe a good speed is 45rpm.

[dr thrust]

and your media is?..

Edited by chris m, 08 September 2010 - 07:23 PM.

[robbstech]

and your media is?..

Ceramic balls x 20 1/2"

[Potassium chlorate]

I make my black powder lift-specific, i.e. with the same ratio as Robbstech does. My mill makes about 80 RPM too, depending on how much I mill. My milling media is brass, 5-6 times the composition in weight. I mill for three hours and wet mill with +5% of a 25/75 alcohol/water solution for 20-45 minutes. Then I press it to 1.8 g/cc and dry it for three weeks before I smash the pucks and sort the different grades out. 1 gram of my fine granulated powder (passes through a spaghetti strainer but not through a tea strainer) burns within 0.16 seconds.

So keep on trying.

Edited by Pyroswede, 08 September 2010 - 08:17 PM.

[MDH]

What was the mesh size of each product before they entered the ball mill. What brands of potassium nitrate and sulfur are you using.

[robbstech]

What was the mesh size of each product before they entered the ball mill. What brands of potassium nitrate and sulfur are you using.

All the chems are unbranded and I have no idea what mesh size each chem was.....The potassium nitrate was kind of like suger grains and the charcoal is extremely fin (airfloat) along with the sulfur which was also extremely fine!

[dr thrust]

does the twenty number ceramic media fill the jar 1/2 to 2/3rds? thats whats needed

[MDH]

All the chems are unbranded and I have no idea what mesh size each chem was.....The potassium nitrate was kind of like suger grains and the charcoal is extremely fin (airfloat) along with the sulfur which was also extremely fine!

Mill, grind or blend each ingredient separately into extremely fine powders, and combine them in your ball mill. The problem is that most small sized hobbyist ball mills will make things fine only if they are already fine enough. They tend to do a very poor job at making coarser grades of potassium nitrate into a fine product, as well as charcoal. Dampening slightly after milling, and adding a small amount of red iron oxide (about 1-2% by weight) would not hurt.