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people online in the last 1 minutes - 0 members, 0 anon and 0 guests. (Most ever was 29 at 13:36:32 Sat Aug 3 2002)

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geowizard
14:39:44 Sat
Mar 16 2013

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Re: The Next Frontier of Mining


Interesting notes on Cerium:

The layman prospector and probably a majority of geologists wouldn't recognize cerium or any other REE in nature. Cerium has isotopes ranging from 119Ce to 157Ce. 32 of them have half lives of less than 10 minutes. The natural occuring Cerium is not radioactive. It is a stable isotope.

http://en.wikipedia.org/wiki/Isotopes_of_cerium

Cerium is 100,000 times more abundant in the earths crust than gold.

- Geowizard

  
geowizard
15:20:36 Sat
Mar 16 2013

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Re: The Next Frontier of Mining


I think I understand where Baub was coming from so far as radioactive REE's...

A common source of REE is Monazite. Monazite is radioactive because of the element Thorium contained within it. An excellent paper is found online that discusses magnetic separation etc. with reference to Monazite sands.

Monazite sands represent a common "recognizable" source for some REE's.
http://www.archive.org/stream/monazitethoriumm00kithiala/monazitethoriumm00kithiala_djvu.txt

- Geowizard

  
jjedwab
16:51:37 Tue
Mar 19 2013

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Re: The Next Frontier of Mining

Bruker gives a PDF-presentation on REE prospecting with handheld X-ray elemental analysis instruments (under the blessing of Indiana Jones):

http://www.bruker.com/fileadmin/user_upload/8-PDF-Docs/X-rayDiffraction_ElementalAnalysis/XRD/Webinars/Bruker_AXS_Rare_Earth_Elements_Webinar_20110518.pdf

  
geowizard
18:31:49 Tue
Mar 19 2013

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Re: The Next Frontier of Mining


The link will work if you place a small "f" at the end. :smile:

- Geowizard

  
Jim_Alaska
19:22:50 Tue
Mar 19 2013

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Re: The Next Frontier of Mining

I fixed the link, no need to add anything.



---
Jim_Alaska
Administrator
jfoley@sisqtel.net
 
 
geowizard
23:56:17 Tue
Mar 19 2013

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Re: The Next Frontier of Mining

Thanks, Jim!

Ok, so, who is ready for some XRF intro?

I see a few hands are raised at the back of the room!

Most of us have heard the click-click of a geiger counter when the probe is held near a radioactive rock.

We have also probably heard of x-ray and more than likely have had an x-ray done for one reason or another.

X-rays are man made rays similar to the natural version called gamma rays.

It happens that when you x-ray a rock, it will produce gamma rays. It's called x-ray fluorescence. The principle is similar to when you use a black light to view a rock that fluoresces with a specific color.

Gamma rays are different sizes (energies). You can look at gamma rays using a cathode ray oscilloscope or a more modern digital o-scope. The gamma rays are viewed the best with a higher cost probe called a scintillation detector. A scintillation detector will output pulses that are different heights. The pulse height is directly related to the pulse energy.

So, now we can measure gamma radiation and we can tell the difference between low energy and high energy pulses!

An X-ray fluorescence Spectrometer measures the gamma ray pulses by height and counts the number of pulses at each height or energy level.

Every different mineral will generate a certain energy of gamma ray pulses when it is bombarded with x-rays. The XRF spectrometer counts the pulses for each of the different energy levels.

So, when you plot the energy levels, there are different numbers of counts . When the counts are higher for certain energy levels, the mineral element can be identified.

Look at page 24 and 25.

- Geowizard
[2 edits; Last edit by geowizard at 00:13:16 Wed Mar 20 2013]

  
dredger
02:26:10 Wed
Mar 20 2013

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Re: The Next Frontier of Mining

:smile:

  
baub
04:13:22 Thu
Mar 21 2013

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Re: The Next Frontier of Mining

I'll bite.

  
dredger
04:51:34 Thu
Mar 21 2013

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Re: The Next Frontier of Mining

baub,

:smile:

Where you been, ??. I have been waiting, :smile:

Have you any ideas, or relivant info, even a good joke,, ??.

phil.


  
baub
19:42:54 Fri
Mar 22 2013

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Re: The Next Frontier of Mining

I've exhausted my info.
However:

Many years ago I was riding as a passenger in a car driven by a young lady who claimed she was a specialty witch, that is, one who could change humans into things.
I asked her to prove it.
She did.


She turned into a motel.

  
BobAK
22:35:01 Fri
Mar 22 2013

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Re: The Next Frontier of Mining

Very good baub, I like that one.

Wish there was a reasonably priced spectrometer out there, 30-40 grand is not it

  
geowizard
23:34:20 Fri
Mar 22 2013

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Re: The Next Frontier of Mining


Unfortunately, the few companies that make XRF spectrometers operate in a niche, high price, scientific instrumentation marketplace.

The XRF spectrometers have limitations;

1. The handheld spectrometers are low power. They generate low power X-rays that have lower penetration and produce fewer gamma rays. That means the sample takes longer and is less reliable.

2. The XRF spectrometers have a small window. The sample window is less than half of a square inch. So, you might have sampled the wrong spot on a rock. Or, you have to take many samples of a given rock surface. The sample time can be as long as 5 to 10 minutes. So, you have to stand there and hold the "gun" up against the rock for long periods to collect one sample.

3. The depth of the sample is only a few microns into the rock. It depends on what the rock matrix is composed of. You might have a rock with high grade REE in the center and the spectrometer only reads the surface of the rock.

4. There are problems with interence from other elements that are more common than REE. When other elements interfere, it can completely mask the REE you are looking for.

5. The biggest problem is calibration. Nobody thinks about calibration. The expectation is that the spectrometer will provide an accurate readout in parts per million. No. It won't do that. The display might even say "PPM". But you cannot believe the display. The reason is that there are preferred conditions that cannot be obtained when you are out in the bush and up on a mossy rock face trying tp hold on to the gun, hold it steady and hold it perpendicular to the rock. It's not a perfect world to collect a sample. There are calibration samples available to compare the readings with. The calibration samples are expensive. The samples are crushed and uniform samples. The surface of every rock has different textures and you can "shoot" the same spot and get different readings.

What DOES work is an AA spectrometer.

I have bought several on ebay. You need to set up your own assay lab in a clean environment and learn how to use it.

- Geowizard

  
baub
13:19:21 Sat
Mar 23 2013

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Re: The Next Frontier of Mining

Geo,

What does a used AA spectrometer in funcional order cost?
Any brand name and models to consider?
Other than electricity, what else do they require to operate?
What info do they gather? What format?


  
geowizard
15:26:39 Sat
Mar 23 2013

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Re: The Next Frontier of Mining


An AA spectrometer is used to measure the quantity of certain elements in a sample. The spectrometer uses a flame to burn (ionize) the sample which has been prepared and dissolved into a liquid form.

Cost depends on how you buy. I used to watch auctions that were selling industrial electronic equipment. Depending on the crowd, you can get a good deal on an AA spectrometer. Buying at an auction doesn't include a warranty.

An AA spectrometer requires AC power and a tank of AA grade acetylene. Acetylene can be bought at most gas suppliers.

There's plenty of information on the internet to learn about how an AA spectrometer works and how to use them.

An AA spectrometer will provide an output usually on a digital display that measures the quantity of an element in parts per million. Like every other instrument that provides a quantitative measurement, it needs to be properly calibrated. You can buy calibration standards i.e.silver in solution of 1000 parts per million. There are also ways to make your own calibration standards by dissolving (for example) a known amount of silver into a known quantity of solution as a liquid having known concentration.

Usually when samples are processed, distilled water is ran to get a "zero" reading, then a calibration sample is ran and then a sample of the unknown is ran.

- Geowizard

  
baub
02:39:05 Sun
Mar 24 2013

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Re: The Next Frontier of Mining

Any recommended brands and models?
Personnel favorites?

  
geowizard
14:18:33 Sun
Mar 24 2013

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Re: The Next Frontier of Mining

baub.

Perkin-Elmer is a leading manufacturer. They publish documentation, provide parts support, service and training.

I have a PE-5000 which dates back to the 1980's It is micro-computer based, and it works great.

Thermo Jarrell Ash is another MFR. I found one on ebay buy-it-now for $675.

http://www.ebay.com/itm/Thermo-Jarrell-Ash-22E-aa-ae-Spectrophotometer-Gauges-/330402081964?pt=LH_DefaultDomain_0&hash=item4ced7facac

- Geowizard
[1 edits; Last edit by geowizard at 14:28:20 Sun Mar 24 2013]

  
jjedwab
14:41:56 Sun
Mar 24 2013

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Re: The Next Frontier of Mining

Speaking of meteoritic impacts: I just learned that there is a large impact crater recognized in AK, 12 km SE from Barrow: http://en.wikipedia.org/wiki/Avak_crater.

PGE/PGM do not seem to have been reported to date.

JJ

  
baub
20:19:30 Sun
Mar 24 2013

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Re: The Next Frontier of Mining

Thanks Geo. More good info to chew on.

  
dredger
03:49:03 Sun
Mar 31 2013

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Re: The Next Frontier of Mining

Hey Professor, :smile:

I found these,
http://en.wikipedia.org/wiki/List_of_volcanic_craters_in_Alaska

And closer to home,
http://en.wikipedia.org/wiki/List_of_impact_craters_in_Australia

Interesting that there are no reports on the East Coast of Australia, ???.

One question I do have is when big Meteorite hits Atmosphere, exactly what happens, ??. :smile:

  
jjedwab
09:08:01 Sun
Mar 31 2013

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Re: The Next Frontier of Mining

I have no ideas about these matters. I was once interested in the cause of very fragile samples (like carbonaceous meteorites) landing on earth without being pulverized or molten. I asked Ed Anders, and he told me that when exploding in the high atmosphere, some pieces happen to be shoot to the rear, and fall back to earth at "terrestrial" speed.

JJ

  
geowizard
14:25:03 Sun
Mar 31 2013

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Re: The Next Frontier of Mining

When I was a puppy, my father, a gold prospector, had a carbon arc spectrometer that he had constructed. The spectrometer used two carbon rods that were connected to a voltage source and when the voltage was turned on, an arc occurred, much like arc welders produce.

The spectrometer would burn a sample in the arc and you could see a noticeable discrete color associated with each different mineral. Copper, for example was blue.

Note: Never look at an electric arc without proper eye protection!

Anyway, the apparatus was not able to be calibrated and and was to a certain degree incomplete. A spectrometer needs to have a means of dispersing the color spectrum into the full range of colors. That is done with a prism or a diffraction grating.

The "solution" is an Atomic Absorption Spectrometer like the one posted above. All of these things cost money. Cheap solutions offer less information, are often not reliable and are prone to error.

Information about what is in a rock has to be given a degree of importance. If it isn't important, then the instrumentation can be chosen accordingly. If the information is important and has "value" then an equally valuable, reasonably high quality piece of instrumentation should be chosen.

Follow through:

Find an AA spectrometer. This is a "proactive" effort! It's like prospecting! You have to go out and look for one! Lately, I have found assay labs going out of business. There are other labs going out of business. They have a fire sale and sell lab equipment.

Lab equipment is required to prepare the samples for analytical analysis. The samples need to be weighed accurately. Then the samples need to be crushed and pulverized. Then the samples need to be digested into a solution.

- Geowizard
[1 edits; Last edit by geowizard at 14:27:52 Sun Mar 31 2013]

  
geowizard
16:20:02 Sun
Mar 31 2013

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Re: The Next Frontier of Mining

Let's shed some light on the subject::welcome:

So, copper produces a "blue" light. :confused:

Well, that's close, but what colors are emitted by other metals when they burn?

And... incidently, we are talking about "Atomic Emission" as opposed to "Atomic Absorption". :smile:

Light is a wave. It has wavelength. Cool!

So, here's the spectrum of light:




Blue is 450 to 495 Nano Meters (nm).

Copper is actually at 324.7 nm

Gadolinium is 407.9 nm

Dysprosium is 421.2 nm

Europium is 459.4 nm

Neodymium is 463.4 nm

Gold is 242.8 nm

Having provided illumination, you can see the importance of Atomic Emission Spectroscopy!

- Geowizard

  
baub
17:03:27 Mon
Apr 1 2013

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Re: The Next Frontier of Mining

Thanks Geo, good info.

b

  
jjedwab
13:53:47 Thu
Apr 4 2013

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Re: The Next Frontier of Mining

The problem is not so much in prospecting, but in the delays for getting mining permits :

"Faster project permitting times could reduce U.S. dependence on REE imports-NCPA"

http://www.mineweb.com/mineweb/content/en/mineweb-political-economy?oid=184732&sn=Detail

The quoted report considers also the case of AK

  
baub
14:23:48 Thu
Apr 4 2013

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Re: The Next Frontier of Mining

Thanks Dr. JJ.

  
dredger
01:27:45 Fri
Apr 5 2013

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Re: The Next Frontier of Mining

Hey Professer JJ.

Another good post, thanks,

phil.

  
dredger
03:05:59 Mon
May 20 2013

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Re: The Next Frontier of Mining

Hey, Professor, Guys,


I am trying to hook up with a miner involved in a new REE mine in Auss, also has a tailings deposit, he likes the excavator sucker concept for the tailings deposit,

Just waiting to see what developes,
:smile:

  
baub
16:01:38 Mon
May 20 2013

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Re: The Next Frontier of Mining

Dredger,

One big problem, among others, is there is no US buyers for small amounts that a little mining company would produce. Australians might be able to sell to China at terms favorable to both parties.
Perhaps there are beaches one could work that would produce enough REEs easily in Oz.
There's a lot to learn about REEs. Safe storage for both raw and refined products is one. Analysys of ores another. Getting paid by the buyer is another.

b

  
geowizard
19:51:47 Mon
May 20 2013

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Re: The Next Frontier of Mining


It's all a matter of marketing.

Maybe a Hotdog vendor in the Bronx could sell a hotdog in Ethiopia? :confused:

Marketing REE's is dependent on the buyers. The buyers represent the market and they write the checks. So, the buyer dictates whether that commodity is delivered in ounces, pounds, or by the rail car. Since REE's are used in industrial applications, it can be assumed that the consumers want capacity from their sources. The product has to meet the demand of the consumer. The product must also meet the specifications of purity within certain constraints of variability. Contracts for shipping REE's are long term - not short term. The producer has an obligation to produce a given quantity at a given purity for a certain minimum period of time.

The contractual obligations related to entering into the REE market or any market dictates that the seller is in a position to produce. A small scale producer doesn't fit into the REE market. A small scale producer probably cannot establish a business model that includes refining REE's to a marketable form. On a small scale, exploration, mining, and the costs related to developing a business selling REE's is simply not a practical venture.

- Geowizard

  

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