Lesson 10 Crushing and Grinding: Technical Level Intermediate

[@bryantlock]

Keith, thank you so much for sharing your knowledge and experience. I have learned so much from watching your videos and other similar channels.

[@hardrockuniversity7283]

Thank you very much. If you have any specific questions, you can also just ask. keith

[@quantumrim3805]

Great information. thanks and keep good staff

[@hardrockuniversity7283]

Thank you

[@garyssprinklerrepair]

Wish I would have seen this before buying my impact mill, without replaceable inner drum liner. Good info

[@hardrockuniversity7283]

I think it is rather reprehensible when manufacturers: A. Make representations about what their equipment will do that are dramatically different from normal experience or.. B. Market something as a piece of production equipment that will not last long under continuous use. When I build something, I build it for ME first. Then, if it works well I will see about marketing it. Got a number under development, but not set up for production yet. Keith

[@selvakumarjayaraman6199]

Well explained, thank you.

[@hardrockuniversity7283]

You are most welcome.

[@maranti34b]

An impact mill will destroy quartz and make powder of it in one pass. I sell them/use them. It is very easy to replace the hammers in our mills, about 5 minutes. We have liners for the mill and impact rods, too and an attachment for a hose to a centrifuge and vacuum. Almost no dust.

[@sams7967]

Great info. Thanks

[@eduardodaquiljr9637]

How do you calculate the power needed to crush limestone to ultrafine powder of an output of say 1ton per hour?

[@hardrockuniversity7283]

First you would need to DEFINE "ultra fine powder" and with what equipment. For example, ball mills are more energy efficient than impact mills. However, they are also larger and depending on the source, possibly more expensive. In my personal experience with impact mills I would expect a 15-30 hp requirement to grind 1/2" minus to about 60-100 mesh minus if fully classified at one ton per hour. Limestone would be good as the wear rate would be low.

[@eduardodaquiljr9637]

@@hardrockuniversity7283 can you share the formula to get the power needed either in Kw or HP?

[@hardrockuniversity7283]

Again, you would need to determine particle size and type of grinding. If you know that you may be able to find a formula by an internet search. If the ore is wet or dry, you will need need to be take that into account in the mill design. I would caution that when looking up processing equipment suppliers, the throughput claims are often maximum possible under ideal conditions. Thus the manufacturer's rating will need to be down rated. I have used a 2 TPH nominal rate impact mill that will only get me about 1/4 TPH actual production. I have yet to see a small scale mill that fulfilled the manufacturer's estimates. Again, for 1TPH I would guess 15 to 30 Hp (12-26 Kw as a rough estimate. Better to have to big a motor than too small also.

[@eduardodaquiljr9637]

@@hardrockuniversity7283 thank you so much engr. Based on internet search,911 metallurgist I have arrived a 20hp for 1TPH mesh 325 limestone with input size of 2 to 3 mm grits.Thank you for the information you have shared.

[@hardrockuniversity7283]

I am glad I was helpful. Good luck!

[@diegocastromonte]

Great information and a very didactic method to explain the processes of crushing and grinding minerals. I work in the industry of composite liners, mainly for ball mills and sag mills, and it would be interesting to explain how this kind of liners impact positively in the performance of grinding process. Congratulations for the video and thanks for share this info.

[@hardrockuniversity7283]

You're welcome. Unfortunately I have no direct experience with ball or SAG mills, or floatation. I would love to learn more sometime, but those darn bills kinda hinder going back to school. Grrrr... They are usually not the most apropos for micro scale mining anyway though-so for now it's jaw before impact with possibly a rolls thrown in the middle. Thank you for the kind words. It makes it worthwhile. Keith

[@peterheylen8640]

Great info, by pure luck (no planning involved) Ive got a jaw crusher, roller crusher, impact mill then sieve. More luck than good management. Thanks

[@hardrockuniversity7283]

Excellent! Combined with the hand panning you are practically set up to run a gravity ore. For a non-toxic leach you are in good shape also, but ore grade determination would be more difficult.

[@peterheylen8640]

@@hardrockuniversity7283 Yes ive been sieving to 25 mesh which is 710 micron but my big bits of gold are only 150 micron, (ive measured then under a microscope with a micron marked slide) maybe 200 but with also fine and ultra fine gold. So I think Im going to have to sieve with 100 mesh so my quartz ore and gold bits are the same size so I can gravity sort on my M7 Wave table

[@hardrockuniversity7283]

@@peterheylen8640 It's worth a try, but a standard wave table seems to be slow because too much feed packs the beds. Make sure you keep good fluidization.

[@peterheylen8640]

@@hardrockuniversity7283 You are 100% correct. The packing under the first riffle bar and keeping it fluid are the issues. Ive been thinking about other options

[@hardrockuniversity7283]

@@peterheylen8640 I have been working on some options......

[@jdeluisa]

Hello. Great videos! Keep 'em coming

[@hardrockuniversity7283]

+jdeluisa I'm trying. Have some more days off so I am working on the next video. Hopefully it should be up soon. The programmer also expects the new web site to be up next week. May be able to go for a prospecting trip the weekend of 2-13 and 14. Keith

[@khalifasambo7408]

I really enjoyed ur video is very helpful to me but there are some calculations under crushing and grinding i don’t know if u can help me out with it thank u

[@hardrockuniversity7283]

What do you need to know?

[@carlosreynoso8303]

Thank you!

[@hardrockuniversity7283]

You're welcome.

[@nikolal6085]

Hello everyone. I have production line for vibro pressed concrete pavers. I'm using crushed river rock (very hard) for my main material, sizes 0-2 mm , 2-4mm and 4-8mm in diameter. I want to buy crusher for that river stone, input max 45 mm in diameter, output 0-8mm, but i need that 0-1 mm in output too. Which type of crusher is best solution for me?

[@DeliciousDeBlair]

I find that high volumes of water can easily and cost effectively move materials through a mine and the processing equipment saving on the cost of more complex, costly and maintenance intensive conveyor equipment. ~( 'w')/ Luckily for me, the mines I am seeking to buy comes with a massive supply of water year-round, albeit, I can not [and WOULD not] dump contaminate water into the environment, so all it really is, is a source of water to tap off into a closed loop system and replaces water lost to evaporation.

[@vitorandazzo6326]

I would like to come to your location and meet you have some questions is this possible? Please let me know. We are about 5 hours away.

[@hardrockuniversity7283]

Sure. We would have to set up a time, but that shouldn't be too hard. Why don't you email me at [e-mail]?

[@vitorandazzo6326]

@@hardrockuniversity7283 awesome will do

[@DeliciousDeBlair]

Since the ores I am working with are mostly sulfides, and soft, if I can get it fine without wasting energy on the gangue, it is more profitable for me. ~( 'w')/

[@DeliciousDeBlair]

I have a design for an ultrasonic crusher. ~( 'w')/ [yes, I'm a full on nerd]

[@hardrockuniversity7283]

Nothing wrong with nerdity. It has become quite popular in some circles.

[@hardrockuniversity7283]

I have seen an 'ultrasonic' ball mill once. Seemed to work OK. I've just built a prototype of an impact mill that seems to do well. It is air classifying, so the output is much more consistent than a standard impact mill.

[@DeliciousDeBlair]

@@hardrockuniversity7283 I definitely see merits in air classification as well, especially when it comes to fines which would want to float on top of water and be carried away, I also figure one can build an inertial staircase inside of a ball mill specifically for lifting the heavies from the bottom and depositing them separately from the bulk of the grind, it just has to be such a stair case that blocks out larger, lighter particles. Between those 2 [air and inertia] one should be able to readily and rapidly sort their heavies at all mesh sizes. Then, of course, comes in the question of efficient air moving equipment for high volume, but with precision air flow control so that neither too much air or too little air is delivered to the sorting areas. I have a small roots type blower [ 2" inlet and outlet] (can be mounted to gas or electric, or even water wheel input) and a gas operated leaf blower as well as some old vacuum cleaner motors, so I can work with either an electrically or engine driven air supply. With the large volume of water the land is offering, I do hope to be able to employ a water wheel to do a lot of my work because it would be cheaper in the long run than fuel or electricity, assuming I can make a cost effective flume down the valley. My thoughts on the flume is to cut it as much as possible from the hillside as a contouring canal, and then use chert stone and concrete for the balance of the outer walls where trenching can not be economically performed. It may prove financially unrealistic I admit. Will just have to play that one by ear.

[@DeliciousDeBlair]

@@hardrockuniversity7283 I come from a family of engineers, machinists, and other nerdlike professions, so it would be a stain on my family's good nerdy name to do things in some rudimentary way. [HOP HOP HOP!]

[@hardrockuniversity7283]

@@DeliciousDeBlair I wouldn't call engineering and machining 'nerdlike' personally. One can actually get icky hands and might even BLEED!