Lesson 23 The Air Classifying Impact Mill
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- Опубліковано 25 лис 2016
- I show how to make an impact mill sort by particle size without any other moving parts. This reduces wear and over grind while delivering a consistently fine product. It can also be used as a convevor system with no moving parts.
You are welcome. Many people don't realize how helpful fluid transport and classification can be. For example, gold and rock particle that settle at the same speed are very different in size. Therefore combining a settling operation with a screening operation can get high concentrations.
Keith
thanks - love the vids.
WOW! 5STARZ! A MUSTWATCH!
Thank you. There are times when fluid classification is much better than screening. It doesn't do the exact same thing though. Fluid classification sorts by settling velocity which is heavily dependent on density and shape as well as size, while screening works only by size. Imagine what happens when you first sort by one method and then the other- that is why gravity separations work best when dealing with particles all the same size.
Keith
good video gives me a vary good idea on my system , Thank you.
I just had another idea last weekend on this concept. You'll have to wait for the video, but it should be fairly soon.
Keith
Cool! Can I use this to grind up circuit boards? I would be soaking the boards in liquid nitrogen before i feed them in so they are very brittle
I doubt you would need to embrittle them. A mill like this turns half inch hard rock to sand and dust. The one in the video at about 50-100 lbs per hour, the one I am working with now 100-200 lbs per hour. You might need to shred them a little first as the input opening needs to be relatively small for safety.
@@hardrockuniversity7283 thanks for quick reply! I would like to feed boards so that I can recover the plated part being the easiest goal or mil the boards fine enough that the gold separates and I can pan, shaker table, or sluice the gold out of the concentrates I can cut them up and make the pieces smaller before feeding thanks!
@@nolanfoster6782 Good luck. Let me know how it turns out.
@@hardrockuniversity7283 thanks I will
i watched mbmmllc say you have to be careful of overgrinding the gold, will this not do that??
It is possible, but coarse gold will tend to settle in the bottom of the mill and micro fine gold will get blown out. There is NO one size fits all mill design as all ores are different. However this is one component you can 'plug in' to you flow sheet if it fills the appropriate need.
In general an air classification system would be most useful if you were going to leach the product since, in that case, the smaller the gold the better as it would dissolve faster.
You might also use it to re-grind tailings after a gravity separation has recovered the free gold; or, to fine grind a heavy mineral concentrate to either leach or gravity recover bound gold.
As with all milling processes- testing is imperative to determine a good process for your ore, or to maximize profitability. That is why I am so fond of hand panning micro fine gold. You can get useful results in real time with almost no cost at all. Using it you can quickly determine what works and what does not for your ore.
Also, gravity separation systems have different capabilities. All will recover coarser gold- say 100 mesh or larger. Smaller than that some systems start to lose efficiency very rapidly. A grinding process that works fine with one recovery technique may be disastrous with another.
In general, I would always try recovery first after only my RC-46 jaw over rolls as that is easiest and most economical. Only if I needed a finer grind for some reason would I go impact, and in that case, air classification might be very useful since physical classification (screens0 has a number of undesirable constraints. OTOH, screening might be the way to go. No way to tell without testing.
Did that clarify the situation?
Keith
thanks Keith
yes, i just mentioned it because mb was saying that if the gold is over ground it makes it like slimes and harder to capture on wet gravity. but your right, test, test.
"Over grind' basically just means grinding more than necessary for the extraction process and since that is highly variable and ore dependent- so is the definition of over grind on a case by case basis. More grinding than necessary will almost always mean more difficulties with slimes and usually higher costs.
However, sometimes a trade off happens which makes sense.
A fully stocked tool box has a number of tools that are rarely used, but very valuable when they are.
Keith
Thankyou
You're welcome
ld always put the 1st bolt in from the feeder side then it can't drop in ?
So the nut can't drop in later after the other bolts have been inserted requiring me to take them out in order to retrieve it.
@@hardrockuniversity7283 Ahh. Seen a few hard rocks there then I take it :)
@@iainwoodhead4440 Yep. Especially the hard quartz at Montana B. We named it 'kryptonite' for a reason :-)
YeeeeeeeeHaaaaaaa
Thats a good point there Keith.. fabbo ..😁
Thank you.
This video is much more fun to watch when you set the speed to 1.5x
:)
You're right!
Thank you.
Keith