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Any Sensor that can Differentiate Between a Stone and Metal?

10/11/2017 7:05 AM

Hi all,

Please help me find a sensor or any mechanism I can use to separate stones from sugar cane. NB: Cane washing/cleaning was considered and I cannot use it in my case...

Thanks

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#1

Re: Any sensor that can differentiate between a stone and metal?

10/11/2017 7:15 AM

Sugar cane should float in water (I think). Stones should sink in water.

Alternately, if there is need to do this without water, if you are dealing with decent sizes of cane and know the stones won't be too large, separation would be with grates/mesh using blowers to separate the various pieces into large canes and smaller stones.

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#18
In reply to #1

Re: Any sensor that can differentiate between a stone and metal?

10/12/2017 7:58 AM

thanks,

but the sugar washing method was considered and it was discovered to have a lot of disadvantages...

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#21
In reply to #18

Re: Any sensor that can differentiate between a stone and metal?

10/12/2017 10:46 AM

Then, to save readers a lot of time, it would only be fair to list the other non-starters that have been considered as well. Next time, please do this in the original posting.

Readers here don't like never-ending rabbit holes, games of "20 Questions", and other time-wasting nonsense, as they have day jobs to do as well.

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#29
In reply to #18

Re: Any sensor that can differentiate between a stone and metal?

10/12/2017 6:54 PM

Such as? (1of20)

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#2

Re: Any sensor that can differentiate between a stone and metal?

10/11/2017 7:17 AM

I suspect this will be one of those rabbit-hole threads where, as people reply with suggestions, the OP will keep adding more info he left out of the original post.

I think a perforated conveyor belt that vibrates, allowing the stones to fall through the perforations, might work... but there's that part about stones and metal. (Metal sugar cane?) Something isn't right.

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#3
In reply to #2

Re: Any sensor that can differentiate between a stone and metal?

10/11/2017 9:13 AM

Or the OP never returns with any information at all.

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#16
In reply to #2

Re: Any sensor that can differentiate between a stone and metal?

10/12/2017 7:46 AM

thanks for the constructive comment,

Just to clarify on the "metal and sugar cane" concern; I want to detect the presence of stones that come in with sugar cane in a large metallic spiller-table....

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#4

Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/11/2017 9:23 AM

Well since money is no concern...

Sugar cane has a considerably different x-ray density than any rock or bit of metal. An x-ray imaging system will easily identify the debris. An AI program and robotic arm could first identify the location and then remove the debris.

That should quickly deplete your engineering budget.

(That's a joke, son.)

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#17
In reply to #4

Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/12/2017 7:49 AM

I like...

But it looks complicated...

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#22
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Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/12/2017 10:47 AM

The definition of a pessimist is someone who finds a problem for every solution.

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#23
In reply to #22

Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/12/2017 11:06 AM

Correction: A pessimist is one who has problems that he needs to find a solution to apply them to.

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#25
In reply to #23

Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/12/2017 12:52 PM

I thought a pessimist is someone with all manner of solutions to problems that don't exist...

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#26
In reply to #25

Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/12/2017 1:14 PM

Nope, that's a marketer. "I have a woozle trap. Could somebody please genetically create and clone some woozles?"

Or the political equivalent, "Nitrosamine poisoning is a problem. Nitrogen must be bad stuff. Can we pass a law to ban it?" (From a real honest to goodness senate committee hearing)

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#27
In reply to #26

Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/12/2017 4:08 PM

Searched-til-I-dropped. Who was that lamebrained senator anyway!?!

Closest I got was:

http://www.practicalmachinist.com/vb/archive/index.php/t-73283.html

[Find-on-page]: jpfalt 03-19-2004, 12:56 AM [near BOTTOM]

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#31
In reply to #26

Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/13/2017 12:41 PM

The testimony was before a senate committee investigating fish kills at Niagara Falls prior to 1994. The witness was Nick Fish PhD (for real) and the senator was as I recall Nick relating the story from New Mexico.

Nick was explaining that during high flow the water going over the falls would go over 40 feet below the surface at the foot of the falls. Nitrogen would dissolve in the water under the pressure, be absorbed by fish and cause their swim bladder to either distend, forcing them to float upside down at the water surface or rupture the bladder. Either killed the fish. The senator asked about nitrosamine poisoning which he had heard was a problem in his state. Nick agreed that nitrogen from fertilizer getting into the ground water was responsible for blue baby syndrome. The senator was then reported to observe that this nitrogen sounds like bad stuff and should we consider banning it.

This was related during a class Nick was teaching in contaminant hydrology at Oregon Graduate Institute.

Nick considered that being informed should not be assumed for the government in general and legislators in particular.

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#33
In reply to #31

Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/13/2017 1:37 PM

"....The senator asked about nitrosamine poisoning which he had heard was a problem in his state. Nick agreed that nitrogen from fertilizer getting into the ground water was responsible for blue baby syndrome. ..."

That's a doozie of a misleading nonsequitur. Why stop there? Why not get people flipping out about thalidamide while we are at it.

Nitrosamines are not an example of a nitrogen based fertilizer.

I do like thus reference though, mainly for the moral of the story, and also because it is oddly similar to part of the OP's original inquiry about a sensors distinguishing between metal and stone.... A senator unable to distinguish between something meaningful and acting stoned.

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#34
In reply to #33

Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/13/2017 2:32 PM

Nitrate based fertilizers convert to nitrosamines when the nitrates get into anoxic, acidic ground water under the right conditions. In low oxygen content water, the nitrate converts to a nitrite which reforms to nitrosamine under acidic aqueous conditions. Usually the issue was when agricultural fertilizer reached an aquifer, decomposed and came up with local well water.

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#35
In reply to #34

Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/13/2017 3:13 PM

Is that really how it gets in my hot dog.

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#36
In reply to #35

Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/13/2017 5:05 PM

You're not supposed to drink it.

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#37
In reply to #34

Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/13/2017 6:22 PM

Any reference to that? Not trying to be a prick (just comes naturally) just interested.

It would be surprising to me for aquifers or ground water to be sufficiently acidic (except in rare occassions) to yield nitroso- group or nitrosating agent with amines available to produce toxicologically significant amounts....

...but it sounds like I am wrong about this, so please point me in the right direction.

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#38
In reply to #37

Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/13/2017 6:59 PM

Normally I'd pull out the textbook for Aquatic Chemistry, but instead I'll use on-line references.

Start with Wikipedia under nitrosamine formation discussing conversion of nitrites to nitrosamines.

www.dhss.delaware.gov/dph/files/nitratefaq.pdf is a nice pub on acidic conversion of nitrates to nitrites

Groundwater acidification usually results from a couple of sources. Normal surface water goes to a pH 5.6 due to normal contact with CO2 forming carbonic acid. Sulfur dioxide and nitrous oxides also cause acid rain. That soaks into the ground and biological oxygen demand from microbe consumption of organic materials depletes oxygen and increases the acidity. Contact with volcanic or igneous origin soils typically add phosphates that also increase soil acidity. Sulfur or pyrite contact also works to form sulfuric acid.

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#39
In reply to #38

Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/15/2017 5:04 AM

I'm still not following conversion of nitrates/nitrites to nitrosamines in groundwater.

I do see reference to conversion of nitrates/nitrites to nitrosamines in the far more acidic condition of stomach acid. This wasn't what I had in mind when first reading this blurb, but does satisfy the original conditions of fertilizers being responsible for nitrosamines exposure via drinking water....even if not in drinking water at the time of consumption.

Thank you for your persistence.

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#40
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Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/16/2017 11:42 AM

Groundwater can become highly acidic. In acidic groundwater, nitrates convert to nitrites and nitrites convert to nitrosamines. The nitrosamines come in the well water as a courtesy feature.

If it helps, when high on acid, The Groundwater Fairy waves her magical wand and turns all the manure and urea that soaks into the ground to nitrosamines for all the good little boys and girls.

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#41
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Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/16/2017 12:16 PM

Look at what I found as the very first listing when I did a Google search on "nitrosamines in ground water", a short paper published by the American Chemical Society about nitrosamines in China.

What I want to know is how this has any bearing on a sensor that can detect the difference between a stone and metal? Metallic ore stones will certainly be difficult to differentiate.

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#42
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Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/16/2017 12:36 PM

None whatsoever.

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#43
In reply to #42

Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/16/2017 12:38 PM

However, if you believe in a holistic approach, all things are interconnected.

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#44
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Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/16/2017 1:37 PM

Don't mind me. Sometimes I get on a high horse about marking things off-topic. This usually happens when AGW deniers mark my AGW replies on an AGW thread as off-topic just to spite me.

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#45
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Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/16/2017 1:41 PM

Heck, you mark everything I say as "off-topic".

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#46
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Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/16/2017 1:44 PM

Not everything but I have noticed that your mind wanders quite a bit.

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#47
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Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/16/2017 2:26 PM

Oh, my attention span is about as long as my index finger, and I even have still all parts of all digits.

My mind was born under a wandering star. Dad used to tell me, I never finished anything I started, but maybe he was talking about fights between me and my older sisters.

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#48
In reply to #44

Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/16/2017 2:46 PM

So what is there about All-Glass-Wheels that needs denying?

Let he who's street has no potholes drive the first all-glass wheel.

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#49
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Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/16/2017 3:25 PM

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#50
In reply to #41

Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/16/2017 10:03 PM

Have you considered that if you found a difinitive answer so easily, yet there was already more than a cursory discussion, perhaps you don't correctly understand what is being discussed?

Yes, there are nitrosamines in groundwater. Reread carefully and you should be able to decern that is not what is being discussed.

Nitrosamines can leach into ground water from domestic and industrial run off. Nitrosamines are a waste product of many industrial processes. Nitrosamines are also used as pesticides. All routes to ending up in drinking water....but none are what the discussion is about.

The discussion is about fertilizer runoff resulting in nitrosamines in ground water. While I can understand how nitrates can yield nitirites and these can be converted into nitrosamines in the highly acidic conditions in the stomach, I still am uneasy about the idea that groundwater might commonly be acidic enough to result in that conversion.

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#51
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Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/17/2017 9:56 AM

...and here I sit, thinking the discussion was about stones and metal in bagasse, and being able to detect and remove said objects from the fuel.

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#54
In reply to #51

Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/17/2017 11:22 AM

Leave it to some senator to take the discussion off in some really weird direction.

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#58
In reply to #51

Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/18/2017 11:56 AM

Yes, indeed, there is the original discussion about raising cane concerning included undesireable foreign material.

Still, it is very common for other pines of discussion to branch off from there. Many of these lines are interesting or intertaining as well, yet wouldn't often work as stand alone questions/discussions.

Even your last comment about the effects of your body position/location on your opinions/misgivings of the main topic, isn't actually strictly pertaining to just the OP.

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#52
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Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/17/2017 9:59 AM

My apologies. I forgot that my work based internet access grants me direct access to a variety of articles. When I looked at the link posted from home only the introduction was available. Part of that article does discuss the finer details on how nitrosamines are formed from runoff fertilizers. The Google book, "Medical Importance of Normal Microflora", contains this simple description:

Bacteria are obviously found in soil.

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#55
In reply to #52

Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/17/2017 11:40 AM

So now, we have to ban all those pesky bacteria. Nitrogen OK, bacteria illegal.

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#57
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Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/18/2017 11:42 AM

I appreciate your persistence. Thank you.

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#59
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Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/18/2017 11:59 AM

"Bacteria are obviously found in soil."

I am willing to bet that was well known, when it was written:

"when you sit down outside, you shall dig with it and turn and cover your refuse"

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#28
In reply to #25

Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/12/2017 6:51 PM

I have it on good authority a pessimist is a microhydrologist fixated on drought.

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#30
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Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/13/2017 9:02 AM

No, boyo, that would be a pissamist.

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#32
In reply to #30

Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/13/2017 1:18 PM

Arg!

I'm ah pissed-I-missed.

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#53
In reply to #32

Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/17/2017 10:37 AM

I knew of a bar where they glued a small plastic fly inside the bowl. I greatly reduced the occurrence of erratic aim. You might try that if you have an issue of aim.

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#19
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Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/12/2017 9:08 AM

So if you have enough of these roosters needing to fill their craws with stones, all he would have to do is open the cage and let the peckers out?

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#5

Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/11/2017 10:09 AM

Just hire a cane sorter, and he will sort it all out for ye.

The larger question here: knowing how cane is harvested, why in the green earth's name of leadership, are you getting stones, or metal mixed in with the canes (that grow above ground).

Did your cane get knocked down by a storm? Your best bet is screening, and air separation.

The direct answer to your question: Yes! Microwave emitter/sensor. Metal should drive it wild, stones not a bother, but the cane will get hot, maybe.

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#6

Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/11/2017 10:47 AM

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#7

Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/11/2017 10:54 AM

A sensor that can differentiate between a stone and metal?

I'm not sure if, in this instance, a magnet would qualify as a sensor. As well, it would only sense ferrous metals.

Stones I could see in the product stream, picked up in harvest. Metal from... process or harvest equipment shedding?

Optical sorter, maybe?

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#8

Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/11/2017 11:22 AM
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#9

Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/11/2017 12:51 PM

Put a microphone on the harvester chute, or the processing feeder chute, and make sure to drop the product on the thing from some height, so that metal or stones would make a sharp ping while the cane would go thud, then apply some sort of diverter of the product stream to help with process safety, and damage minimization.

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#10
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Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/11/2017 1:11 PM

Not even close....

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#11
In reply to #10

Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/11/2017 1:29 PM

Real funny! Yeah, screens and air separation are the state of the art.

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#12

Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/11/2017 3:43 PM

Just Google "metal detectors".

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#13

Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/11/2017 8:40 PM

You need a tumbler

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#14

Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/11/2017 8:54 PM

You need a high temp furnace, 800 f, or better. Run your sugar cane, stone mix through the furnace. The cane will burn off, the stones will come out clean, you can then through out the stones as you wish.

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#15

Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/12/2017 7:11 AM

If the stones or metal are large enough to be a concern in the crusher-mill, then they will be "heavy" enough to not adhere to the sticky juice on the canes. The previously suggested rotary bar sorters or screens would be adequate.

Anything small enough to stick would just run through the mill and end up in the "straw" that is either directed to mulch or diverted to co-generation and thus would accumulate in the ash.

Any that are even smaller would settle in the juice collection. Maybe you need a settling tank for that. Design is based on terminal sinking rate of stone/metal, cross flow velocity and flow depth to provide minimum length so that the debris will reach the floor before removal to the next process. (Look up water treatment clarifiers for details.)

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#20

Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/12/2017 10:40 AM

Lucky M,

Perhaps you could win by thinking more out of the box. Why do you believe that you need to remove stones early ? Is it because you intend to use sharp cutters to subdivide the cane into small fragments so that water can remove the sugar from the cellulose of the cane ? Maybe you should not do that cutting step and thus sidestep removing stones. Consider *adding river rock* (cheap smooth grapefruit sized stones) to feed a "ball mill" to grind up the cane. There will be no worries about dulling your sharps since there just are no sharps. After thorough dry maceration of your cane by means of the river rock pulverizing the cellulose of the cane in some kind of rotating bin or cylinder, pass the water through everything and you easily capture your sugar. If you want to burn the cellulose for fuel on site, just use high volume and high pressure compressed air underneath to run the stone/cellulose mash as input for a gigantic kind of fluidized bed furnace. If instead, you want to sell the cellulose, use any of the crude(do them crudely so they can be robust and cheap) but efficient techniques the other posters have ably and amply described in other posts. Just be sure to ask yourself critically, exactly why you believe you cannot tolerate the stones when you propose to remove them and choose some alternative technique at that point which lacks that requirement. Before actually designing any of this process, read some literature from a few decades back on saving money(initial cost and more importantly, continuing cost) by using appropriate technology(as opposed to high technology.) You should visit a library(virtual is fine) and retrieve old issues of the magazine, Mother Earth News) to find a winning point of view as described for other inherently crude processes. Sugar cane and rocks fall into that category of stuff that you do not want to have to super-refine(are there bugs in there, too ? Of course there are !) in order to operate your process or you will go broke. Any super-refining should, at the very least, be deferred until you simply must do it. The last step of dissolving the sugar (from the macerated mash and stones) in water and fine filtering of that water to get your sugar pure to a level appropriate for digestion(for whomever or whatever will digest it) is a great example of a final process that ultimately gets to the actually required purity. Trying to get there early will unnecessarily cost you money. Think of it as "just-in-time appropriate technology".

All of this is just an example to create the atmosphere for out of the box thinking. You might alternatively investigate the large scale disruptor approach to not needing sharp edges to break cellulose cell walls in the cane. In this approach a large pressure vessel contains the cane(and whatever stones are present) under high pressure. You allow the sugar cane cells to internally reach the high pressure and you abruptly decompress the vessel. The cellulose walls of the sugar cane still have high pressure inside so the cell walls explode blasting the internal juices(and pretty much all of the sugar) out so thoroughly that no amount of just macerating and/or cutting can touch it. This approach is more elegant, more perfect, and inevitably more costly than the ball mill above but, just like the ball mill, cleverly sidesteps the difficult(to the point of absurdity) and oppressively expensive "we want to refine this impure, crude, huge volume of stuff we get from the farmer's field ahead of the real process" red herring.

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#24
In reply to #20

Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/12/2017 12:50 PM

nice out of box style thinking. I like it!

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#56

Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/17/2017 6:25 PM

Cyclone separator, maybe 2-3 stages if too much cane lost in first stage. Otherwise called centrifugal cleaners for liquid phase separation of materials with very different specific gravities.

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#60

Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/19/2017 12:15 PM

I once heard of a method used for sorting peanuts. They shot them out of a device that looked like a baseball pitching machine and kept the peanuts that went through a specific target hole. It meant that the air resistance, shape and density met specific parameters. Similar practice applies to separating wheat from chaff.

Would there be a possibility to make a sugar cane thrower where rocks would take a trajectory different from the cane and thus separate?

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#61
In reply to #60

Re: Any Sensor that can Differentiate Between a Stone and Metal?

10/19/2017 12:45 PM

Pure genius. Of course it would. The denser stuff flies through the hole in this case, the bagasse simply drops below the hole to another chute.

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