Ball mill costruction - ideas

[pyrosailor99]

Anyway i just made 2 calculation and a little 3d simulation (to prove my calculations)...

for my ideal jar i need only 200 media (half than before).

 

with 200 i can fill half jar if they are put in the jar in ordered manner.

it is a big cost anyway!

 

can i ask you why SST is better for oxidizer and why BRASS is better for others and mixes?

[pyrosailor99]

NEW IDEA!

as 16kg of brass is too expensive for my project...

what do you think of this idea:

 

i could buy the same volume of BRASS PIPE, make small pieces 36mm long - and fill it with Fishing Lead and Cement... so i could have highweight brass medias without buy the same weight of expensive brass.

 

what do you think? could it work?

cement can react with other chemicals? lead can produce electrostaci energy or sparks while blocked in the cement/brass pipe?

 

i know i'm a desperade mad... but i have few money for my hobby and i have to optimize all "spark" ;-)

 

thanks!

[Gunzway]

Yes, pouring molten lead into the brass pipe will work and is safe for ball mill media. I advise against cement as I think it would wear out from the inside too fast(crumble and crack possibly). Purely an assumption, I'm sure there's a reason for why people aren't using it otherwise they would take advantage of it. There's a little small tutorial on the brass/lead hybrid media on Passfire.

[Bonny]

Anyway i just made 2 calculation and a little 3d simulation (to prove my calculations)...

for my ideal jar i need only 200 media (half than before).

 

with 200 i can fill half jar if they are put in the jar in ordered manner.

it is a big cost anyway!

 

can i ask you why SST is better for oxidizer and why BRASS is better for others and mixes?

 

 

I just use the SS (balls) for oxidizers:

1) It's what I have, but not enough to charge a 4-6" mill jar (small batches only)

2) They are the easiest to clean. Also IIRC, in the case of chlorates (which I'm NOT using ATM) the copper from the brass is a no-no, sensitizes the comp I think (?).

 

The brass media I have is a mess of different shapes and sizes, but works fine for me.

 

As Gunzway suggested though, leave out the cement. Brass or copper filled with lead will be fine and is commonly used by members here.

[pyrosailor99]

Thank you all for your replies! unfortunately i'm not able to mold lead.... in my idea there was cement because i can easily build it!

 

Anyway i just received a quotation for ceramic balls of 1inch diameter. wow! they are enough cheap to fill more than 1/2 of my jar with about 80usd (25kg of balls) shippingg included.

 

i wonder what is the difference of performance against brass/lead (that have a higher specific weight or density)...

each 1 inch ball weight 27,5 grams and in my jar i need about 700 balls (about 20kg)

 

i think in my jar i can do batch job of 1kg, what do you think?

 

do you think a washer motor (osually 0,16hp) will be enough to mill 20kg of media + about 1kg of chemicals?

[Updup]

Thank you all for your replies! unfortunately i'm not able to mold lead.... in my idea there was cement because i can easily build it!

 

Anyway i just received a quotation for ceramic balls of 1inch diameter. wow! they are enough cheap to fill more than 1/2 of my jar with about 80usd (25kg of balls) shippingg included.

 

i wonder what is the difference of performance against brass/lead (that have a higher specific weight or density)...

each 1 inch ball weight 27,5 grams and in my jar i need about 700 balls (about 20kg)

 

i think in my jar i can do batch job of 1kg, what do you think?

 

do you think a washer motor (osually 0,16hp) will be enough to mill 20kg of media + about 1kg of chemicals?

 

Just to let you know, people have said ceramic has a chace to spark... Be careful.

[pyrosailor99]

Just to let you know, people have said ceramic has a chace to spark... Be careful.

 

yes, i read it that someon said that in dark room ceramic emit some light and that anyway the energy produced by this spark is not enough to start any fire in the jer...

really i'm a bit scared of this because... we don't know what could happen with MANY (As 700) sparks in the jar....

 

but... I can't afford 27 kg of brass... i'm desperade!

[Mumbles]

Given the size of the mill you mentioned, you can exceed 1kg with ease. A 1kg jar is around 15cm x 20cm. The size you describe you can probably make 2kg or so. It's important to find out the optimal charge, as an undercharged mill is hard on the media.

[dagabu]

... as an undercharged mill is hard on the media.

 

And, as I recall, it can also lead to detonation, as was quipped by one of the PF guys. Don't know if its true or not but I try really hard to balance the load every time.

[pyrosailor99]

i've just read this:

http://www.amateurpyro.com/forums/topic/4605-ball-mill-explosion/ :o:o

 

ceramic media!! someone says probably the jar wasn't perfect as was closed with mask tape... and is supposed of some losing powder during the batch job...

i'm very scared!

 

anyway thank you for the info, now i know that i can reduce my jar project! i want to do batches of 1kg at time. so i can save some money...

(not too much as today i asked for the price of a pvc tube of 15cm ID and it was about 12USD for 50cm long)

 

another bad notice for me today... i cannot find KNO3 in my city in big bags... farm shop said me it's not used anymore and was replaced by another fertilize potassium oxide based...

another said me it have 25kg bags... but it's only 63% pure...

last time i bought kno3 in a pharmacy with no few question about its use...finalyy pharmacist gave it to me, but i cannot remember the price... i remember about 12usd for 1kg (99,99% pure)...

 

i think i will order it on ebay and will have to pay much shipping!!

[dagabu]

eBay has 50# bags for $25.00 US LINK

[Updup]

My mill has a 4" PVC jar, with 300 lead balls, cost me about $50. It will make 200 grams of great lift powder in 3 hours.

 

It sounds like your not really in the situation to make big shells anyway, why do you need to make such a large mill?

 

 

[pyrosailor99]

eBay has 50# bags for $25.00 US LINK

 

Yes, but i don't live in USA... i'm in Europe and the nearest country that sell this materials are UK... and from UK the shipping cost to me will cost enough to descourage me...

 

My mill has a 4" PVC jar, with 300 lead balls, cost me about $50. It will make 200 grams of great lift powder in 3 hours.

 

It sounds like your not really in the situation to make big shells anyway, why do you need to make such a large mill?

 

 

 

You are completely right...

i don't know why but from my last experience with mini jar of chic**o instruments i ever felt that the problem was also the little *amount* i was trying to do... i ever felt that making the things bigger the error margin was less respect to the total works so the things would result better... this could be a wrong thought... but as i'm thinking the things in the better serious way to obtain what i want (that's primarily a HIHG GRADE BP to make hq blackmatch and liftcharge) i think that if all will result in a good job, then is better that *before* i done it for not too small quantities... otherway i have to remake all the job to increment batchs...

 

for me 200g of liftcharge in 3 hours is a real DREAM! you are very good! i hope to obtain your results! really! i'm moved to tears!

 

again, thanks for all info

[pyrosailor99]

 

There is a man named Lloyd Sponenburg that wrote the book (literally) on the PVC ball mill jar and he has a list of proper media sizes for each jar size, as I remember, he has 7/8" to 1" media in the 8" jar. Since you are using a 20cm jar (8") the 20-24mm media will work fine since he was looking for media 1/10 the diameter of the jar for the best cascading effect.

 

 

I have that book but i read (page 8) that he suggest 1'' ball size also for 6'' jar diameter (thats*not 1/10 of jar ID)...

So what ball size should i have in a 15cm (about 6'') jar?

and what cylindical media size i should have (i think i may buy brass rod and cut it)?

 

thanks!

[dagabu]

I have that book but i read (page 8) that he suggest 1'' ball size also for 6'' jar diameter (thats*not 1/10 of jar ID)...

So what ball size should i have in a 15cm (about 6'') jar?

and what cylindical media size i should have (i think i may buy brass rod and cut it)?

 

thanks!

 

My bad, I was at work and didn't have the book in-front of me. 8" then. I use 3/4" media in mine and have no issues. 4 hour BP, 20 minutes to grind most chems.

[pyrosailor99]

My bad, I was at work and didn't have the book in-front of me. 8" then. I use 3/4" media in mine and have no issues. 4 hour BP, 20 minutes to grind most chems.

 

Perfect, thank you.

can someone tell me if brass grind faster/slower than lead fishing or riffle lead?

 

(or, better....)

 

Can we all make a point (also for future readers) of what is the best solution for ball milling?

 

I read so many things i really don't know what way i should prefer.

 

we could write a page with PRO and CONS for each element/variable

 

Medias material:

 

Ceramic:

Cons: could make sparks (but someone use it without problem)

lighter than other metals

Time to grind: ?

Incompatible with chemicals: ?

more faster to grind than: ?

medium cost (lower higher than): ?

Where to buy: ?

 

Lead (riffle):

Cons: wear easly (but someone says not)

Time to grind: ?

Incompatible with chemicals: ?

more faster to grind than: ?

medium cost (lower higher than): ?

 

Lead (fishing):

Cons: wear easly (but someone says not)

Time to grind: ?

Incompatible with chemicals: ?

more faster to grind than: ?

medium cost (lower higher than): ?

Where to buy: ?

 

Lead (riffle):

wear easly (but someone says not)

Time to grind: ?

Incompatible with chemicals: ?

more faster to grind than: ?

medium cost (lower higher than): ?

Where to buy: ?

 

SST (=stainless steel):

Cons: ?

Time to grind: ?

Incompatible with chemicals: ?

more faster to grind than: ?

medium cost (lower higher than): ?

Where to buy: ?

 

Brass:

Cons: ? (maybe "is lighter than lead")

Time to grind: ?

Incompatible with chemicals: ?

more faster to grind than: ?

medium cost (lower higher than): ?

Where to buy: ?

 

 

 

Medias shape:

 

Balls:

Cons: ?

Time to grind: ?

more faster to grind than: ?

 

Cylinders (length= 1,5 x Diameter):

Cons: ?

Time to grind: ?

more faster to grind than: ?

 

 

thanks to all writer - from this we could make a sticky beginner post

[dagabu]

Perfect, thank you.

can someone tell me if brass grind faster/slower than lead fishing or riffle lead?

 

(or, better....)

 

Can we all make a point (also for future readers) of what is the best solution for ball milling?

 

I read so many things i really don't know what way i should prefer.

 

we could write a page with PRO and CONS for each element/variable

 

Medias material:

 

Ceramic:

Cons: could make sparks (but someone use it without problem) Completely bogus, no such evidence exists that ceramic media commonly used to grind chems and the like causes anything but photonic sparks, non-heat producing.

lighter than other metals Yes

Time to grind: ? Yes, it takes longer

Incompatible with chemicals: ? No incompatibilities

more faster to grind than: ? No

medium cost (lower higher than): ? Lower cost then everything but hand made media.

Where to buy: ? eBay

 

Lead (riffle):

Cons: wear easly (but someone says not)

Time to grind: ?

Incompatible with chemicals: ?

more faster to grind than: ?

medium cost (lower higher than): ?

 

Lead (fishing):

Cons: wear easly (but someone says not)

Time to grind: ?

Incompatible with chemicals: ?

more faster to grind than: ?

medium cost (lower higher than): ?

Where to buy: ?

 

Lead (wheel weights):

wear easly (but someone says not)

Time to grind: ?

Incompatible with chemicals: ?

more faster to grind than: ?

medium cost (lower higher than): ?

Where to buy: ?

 

All lead wears, hardened lead looses its hardness over time and becomes soft. Linotype is best but can fracture. Grinds very fast.

 

SST (=stainless steel):

Cons: ? Highest

Time to grind: ? Lowest

Incompatible with chemicals: ? Yes, it still has steel in it and will rust and pit under certain circumstances.

more faster to grind than: ? All others

medium cost (lower higher than): ? Highest

Where to buy: ? McMaster Carr, Smallparts.com

 

Brass:

Cons: ? (maybe "is lighter than lead") Yes

Time to grind: ? Better then all but SST

Incompatible with chemicals: ? Yes

more faster to grind than: ? Lead and ceramic

medium cost (lower higher than): ? Second most expensive

Where to buy: ? McMaster Carr, Smallparts.com

 

 

 

Medias shape:

 

Balls:

Cons: ? Has less weight them cylinders

Time to grind: ?

more faster to grind than: ?

 

Cylinders (length= 1,5 x Diameter):

Cons: ? Has less fewer points to crush chems.

Time to grind: ?

more faster to grind than: ?

 

 

thanks to all writer - from this we could make a sticky beginner post

 

These are my opinions only, please provide counterpoints

[pyrosailor99]

with which chemicals is brass INcompatible?

[AdmiralDonSnider]

Why would hardened lead become soft over time?

[dagabu]

with which chemicals is brass INcompatible?

 

Ammonium Perchlorate, it will also pit SST balls.

[dagabu]

Why would hardened lead become soft over time?

 

Two things happen with heat treated lead (hardened lead), first, when lead is worked, it becomes softer, not harder. The second is the way lead is heat treated, "In most lead alloys, heat treating and rapid cooling (quenching) result in a breakdown of the supersaturated solution during storage (aging). Although this breakdown produces coarse structures in certain alloys (lead-tin alloys, for example), it produces fine structures in others (such as lead-antimony alloys). In alloys of the lead-tin system, the initial hardening produced by alloying is quickly followed by softening as the coarse structure is formed."

- Heat Treating Lead/Antimony/Arsenic Alloys By: Rick Kelter-

Interestingly enough, it takes time for the cast lead to harden, in fact, it can take a full two weeks for the heat treated lead to reach its hardest state and non-alloys cannot be hardened at all.

 

This issue is beyond the scope of the discussion here, I would have to break out my textbooks on metallurgy for more information.

[AdmiralDonSnider]

Ok, thanks dag. So the PbSb variety seems to be less affected by softening - did I get this right? Better discuss this by PM.

[Updup]

I might try and make some brass tube with a lead core media, seems to me as if it just wouldn't work as well as ball media... thoughts?

[dagabu]

Ok, thanks dag. So the PbSb variety seems to be less affected by softening - did I get this right? Better discuss this by PM.

 

Yes, Sb stays at a constant hardness and is less likely to foul your comp.

[dagabu]

I might try and make some brass tube with a lead core media, seems to me as if it just wouldn't work as well as ball media... thoughts?

 

This is what I make to crush charcoal. They are made from 1/2" copper pipe, slightly over-filled with wheel weight lead, pressed to 1000PSI to seal the lead to the walls. I use an electric pipe cutter to make the cuts every 3/4".

 

http://www.pyrobin.com/files/dsc_9566.jpg