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Powder

27K views 146 replies 13 participants last post by  moose53 
#1 ·
I enjoyed Mike and Tracy when they visited in February, it was fun to show and tell. They suggested that it would be good to post my method of making powder on the Forum. I have held off working on my New Years Cannon for a few months to develop a new powder for my 40 mm. In the late 1800's before the development of smokeless powder Amide Powder was invented . It is said to be non corrosive, have a flatter pressure curve , 15% to 20% more power, less smoke, and no sulfur smell. One of the gasses produced is steam which makes it a very clean burning powder. The formulation is - 40% Potassium Nitrate - 38% Ammonium Nitrate - 22% Charcoal. The process for making amide power can be used for black powder as well. First step is making charcoal. I use a 55 gallon drum with a large propane tank with the bottom cut out and used as a lid. It makes 3 lb of charcoal per run. The flanged lid for the 55 gal drum has a 2 in gap for air and is supported by 3 bolts on the drum lid, the small air holes around the top of the drum are not necessary. In addition to the ring of air holes on the bottom of the drum I put a ring of larger holes in the bottom flat to let ash fall out. After loading the small tank with willow wood chips I fill the gap between the 55 gal drum and small tank with wood scraps and burn it. The next day its cool and ready to use.
 

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#2 ·
Moose53, Please describe the ingredients, purity, etc. and then the mixing equipment and method. This might spark some questions. Oh, sorry, bad choice of words, "This might prompt some questions." That's better! Mike and I had a great time with you at your shop. We learned lots and lots of stuff. Thank you!!

Tracy
 
#3 ·
So, that "Sparked" my interest! Moose53, please continue...like Tracy stated, can you please elaborate? And where would these ingredients be available? Local Hardware/Gardening center? On line, perhaps? Where do you get your materials?
Thanks, BoomLover
 
#4 ·
Just trying to understand. The willow wood chips inside the propane tank are heated by the burning wood scraps in the 55 gal drum. Instead of outright burning up, the willow wood chips char and become charcoal?
 
#5 ·
As the fire heats the willow chips the wood gas is forced out the bottom of the small tank and is fed up through the burning wood greatly increasing the heat output and minimizing smoke. The small tank is sealed except for the bottom gap so air can't get in when it's burning or cooling down. Seems to work very well. Before the small tank base warped a bit from use I found almost no white ash in the cooled charcoal . With the bigger gap now there is just a little bit. Waiting on more photos for next step.
 
#6 ·
Next is the ball mill , probably the most important part. I use a stainless steel milk can with 3 small paddles welded inside, with 51.5 lbs steel ball bearings sized from 1/2 in to 1-1/4 in. Normally steel on steel would be a disaster waiting to happen but with the powder in a slurry that problem is completely eliminated. I tested it with a mound of dry powder on a paper towel in a pan of slurry powder with no cross ignition at all. A friend of mine runs a ranch and is able to get agricultural fertilizer. I use potassium nitrate 05-06-00 , ammonium nitrate 34-0-0 and agricultural sulfur. The powder seems to level out in performance increase after 6-7 days of milling. It comes out of the ball mill like some of the finest mud you ever played in. ;D
 

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#7 ·
Moose53, I really like the safety aspect of the wet slurry mixing. Is there any particular reason why you use steel balls? Another thing I wondered was where did Amide powder lie with respect to all the other forms of black powder, and was Brown Powder among them? The link below brings you to a pretty complete chart of BP formulations. Brown Powder, I found, was a true early form of smokeless powder.

Tracy

http://www.privatedata.com/byb/pyro/pfp/BP.html#Ammonium-based
 
#8 ·
I began with 3/4 in lead balls as ball mill media, the wear rate was 3.5 lb in 48 hr. Ruined two batches of powder with lead contamination before I realized what was happening. Then I switched to ceramic balls, they sized from 1-1/4 in to 1-3/8 in. They worked better but still lost 4-1/4 lb in four runs totaling 24 days, and the larger size limited how fine the mill could grind. I am now running steel ball bearings sized from 1/2 in to 1-1/4 in. They are on their first run, so don't have wear data for them yet. The stainless steel milk can is starting to show signs of fatigue so I will eventually have to replace it with a heavier ball mill. The powder slurry is pretty forgiving concerning the amount of water used. It can be too wet and still work fine , just takes longer to dry. When drying, the slurry needs to be stirred as soon as it forms a light frosted crust. The salts will crystallize out a little but its tolerable.
 

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#11 ·
This graph will give a good idea of the performance capabilities of powder made by the slurry method in a ball mill and then dried. This batch was made with the large diameter ceramic balls , so the ball bearings I use now should be much more efficient. The large drop at the end was from adding 2 oz dextrin and milling for 2 more hours. It lost 1/3 of its burn rate from adding 2 oz of dextrin. As the graph shows there is room for more performance gain. The two entries per date are the burn rate for coarse and medium size powder grains, with the coarse powder grains being faster.
 

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#12 ·
I like the fact that you are sharing a performance chart with us. Mike and I studied hundreds of these in our 80 combined years of experience as machine shop inspectors. I understand what the various data points mean. This is merely a suggestion, but if you could add a "control" or known standard like 1Fg Goex BP and establish an inches per second or feet per second notation for all speed of burn data, it would help all those interested in understanding your performance chart, especially those who are not natural experimenters.

For those unfamiliar with dextrin, you can think of it as a type of glue or binder that holds the grains together. It is used primarily in model rocketry where in lots of cases, a slower, steady rate, burn is actually better.

Also surprising is your information that larger grains have a higher rate of burn. If he were still with us, I bet that would certainly startle Col. Rodman inventor of "Mammoth" powder, a larger grain, slower burning BP, designed for Seacoast Guns. Do you have a theory which could explain this phenomenon?

Thank you,

Tracy
 
#13 ·
Tracy thank you for your helpful suggestions . Yes I can use the inch system in the next chart for Amide powder. The two examples of control powder I had at the time were Goex 3F which tested at 66.3 in/sec (168.4 cm/sec ) it is too high for the graph and 1F cannon powder, forgot maker , it tested at 42 in/sec (106.4 cm/sec ), it is the red line on the graph. The larger grain burn rate difference looks like a result of surface treatment. I didn't polish the grains in a tumbler.
 
#15 ·
The bulk density of my black powder is , coarse .874 grams / ml , x fine .900 grams / ml , and for a control GOEX 3F is 1.03 grams / ml . After the powder has dried sufficiently to work , with out clumping up , I run it through a rubber roller press with a 1/8 in gap to break up the large chunks . Then I sieve it through a wire mesh with 1/8 in holes . This is my first powder size ( coarse ). The wire frame basket works very well and helps with the back strain by not having to bend over to sieve the powder. The powder is still damp at this step , so it burns very slow.
 

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#17 ·
Here is a report on my present test batch of amide powder. I stopped the ball mill tonight after 9 days of running with mixed ball bearings. The powder changed color to a nice olive drab, was not expecting that . I am very curious to see what effect that had on performance. Will try to get a photo tomorrow in the day light.
 
#21 ·
Here is the green powder. As I figure it can be because the charcoal is ground fine enough now to react differently with the other ingredients, or the steel bearings are interacting with the powder . If its the bearings reacting then it took over 7 days to start.

Maybe the same effect as the old paint formula for carriages producing OD from black and yellow pigments.
 
#25 ·
This is a update on my batch of green amide powder. It has different characteristics then the black amide powder made with the ceramic or lead mill balls. The green amide powder is as sticky as heavy clay , which makes it a little hard to keep mixed so it dries evenly. A good thing is when its dry enough to run through the sieves it is still damp enough not to burn at all. The fineness of grinding from the mixed steel balls has also made it difficult to dry, Monday will make three days drying in my drier. I am seriously looking at vacuum drying now. It now looks like I can store it after its run through the screens for size and still damp enough to not burn at all, then only dry what I need in a vacuum drier at the time I need it. Very safe.
 
#26 ·
I did more experimenting this afternoon to see just what it would take to light the damp green amide powder. I need to modify my previous post because I did get it to burn with extreme measures. If piled up with another almost equal amount of dry powder it will just barely burn.
 
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