YT2095 - 25-1-2007 at 07:47
my Monazite arrived this morning, this rock is Really HOT! 1200+ counts per minute!
I`ve crushed up 7 grams of it (I have 24g total) and have that in conc NaOH soln, it`s forming a reasonable ppt, although some parts a bit large.
I`m wondering if heating this mixture up would assist in the process at all, just on the off chance that the larger bits form and insoluble hydroxide
layer and prevent further reaction.
Monazite is a Phosphate, so the plan it make Sodium phosphate, pour this off as it`s water soluble, wash my "sludge" and then HCl it to make soluble
chlorides.
re-crystalize them and heat up to drive away the chlorine and leave the oxide.
(I may alter the last part though, as I`m sure there is a more elegant way to do this).
so heat or no heat is the question really...
I`ve also put it in here, as this stuff is a little more than just Chemicly dangerous (toxic), and requires special handling.
I`de like to keep the waste down to a bare minimum!
[Edited on 25-1-2007 by YT2095]
Sauron - 25-1-2007 at 08:26
Just how much thoria (thorium oxide) do you hope to isolate from 24 g of this mineral?
Waffles - 25-1-2007 at 08:36
You would be very lucky if the Th content of this is even 8%, since monazite also contains several lanthanide phosphates
As soon as it's out of aqueous solution, just remember to wear gloves and stop breathing.
YT2095 - 25-1-2007 at 08:43
the quantity is immaterial, I`m interested in the process.
unionised - 25-1-2007 at 11:16
"As soon as it's out of aqueous solution, just remember to wear gloves and stop breathing. "
A bit late I fear
"I`ve crushed up 7 grams of it"
Sooner or later we all stop breathing.
Don't forget to worry about all the daughter products too- some of them are nastier than the thorium.
YT2095 - 25-1-2007 at 12:09
NBC Gas mask Outdoors, and then screened with GM counter, no dust inhaled/present.
and Daughter products are a B!tch, I already know to Gamma emitters in there 
not_important - 7-2-2007 at 02:54
Have you read http://www-pub.iaea.org/MTCD/publications/PDF/TE_1450_web.pd...
50% to 70% aq NaOH at 140 C
The raw monazite is 1/4 cerium oxide and 1/3 to 1/2 other REE oxides, plus a fraction of a percent uranium and titanium, several percent iron.
Unless reduced to the trivalent state, cerium will follow thorium in most simple chemical processes. In acid solution H2O2 can be used to reduce the
cerium, in alkaline solutions it oxidises it to the 4+ state.
Thorium chloride tends to hydrolyze, if the solution isn't too strongly acid. You might be able to take up the solids from the hydroxide treatment in
HCl, use H2O2 to get the cerium to th trivalent state, and dilute or otherwise decrease the pH to get most of the thorium to drop out as hydroxide
while most of the REE stay in solution as the chlorides. However, that will not be a clean separation, you'll likely have to repeat the process on
both the thorium rich ppt and the REE filtrate taken to hydroxides.
Note that the hydroxides tend to be gelantinous precipitates which are #$%^&* hard to filter, a centrifuge is handy.
The best way to the oxide is through the oxalate, the chloride can form oxychlorides and really isn't that unstable as a solid unless you're passing
steam over it.
[Edited on 7-2-2007 by not_important]
olmpiad - 10-2-2007 at 16:44
"The raw monazite is 1/4 cerium oxide and 1/3 to 1/2 other REE oxides, plus a fraction of a percent uranium and titanium, several percent iron."
This really depends on the locality of the monazite. It not unheard og to find it over 75% Cerium Phosphate. Or, on the other hand, up to 35% Thorium
(as an impurity). the locality is very important here. I live in Texas, and I have a 13.038g sample of Monazite that was recently discovered here that
registers over 25kCPM. I also have Monazite from Florida, in the form of small granules, and when the same amount is measured for its radioactivity,
it only registers at 1-2kCPM.
"my Monazite arrived this morning, this rock is Really HOT! 1200+ counts per minute!"
I am just curious as to what you are comparing the radioactivity to to consider your monazite really hot. Are you comparing it to other monazites, or
to other minerals. If you are comparing it to other minerals, I must say that 1-2kCPM is not even something that I would put in my radioactive
collection (for a comparison, I have over 2,000 different mineral specimens, and my "hottest" mineral is around 250kCPM. If you are comparing your
sample to other minerals where U or Th only occurs as an impurity, then I would agree, your monazite may be slightly elevated than others, but most
certainly nothing to be afraid of.
[Edited on 2/11/07 by olmpiad]
YT2095 - 11-2-2007 at 01:51
because I`m still getting a good 400 counts through 5mm of lead, That to me is a concern.
edit: my Am241 and Ra226 is blocked entirely by 5mm and gives nothing above background.
[Edited on 11-2-2007 by YT2095]
not_important - 11-2-2007 at 02:53
Am241 and Ra226 are both alpha emitters, the decay chain for thorium spits out betas at several energy levels, 2.something anf 5 MeV stick in my head.
For energetic betas lead may actually less effective than lighter elements, due to bremsstrahlung radiation.
From my foggy memory 5 mm lead is marginal for 5 MeV betas. Try thick aluminium, or a cm thickness of water.
YT2095 - 11-2-2007 at 03:15
wouldn`t Lighter materials start spewing out Neutrons instead though?
I bought a 16Kg roll of lead last week, I`m just waiting for a reasonable day outdoors so I can cast this into a pot, I`ll feel much happier then 
not_important - 11-2-2007 at 03:28
No, you'd have to slap a low A atom pretty hard to kick a neotron out of it, very hard to do with a beta which are interacting with the electron
clouds.
Try it - use about 5 mm of plastic, aluminium, copper, lead, and compare the counts.
I've seen shields where the side facing the source is aluminium and the other side is lead, Al to slow down the betas without a lot of bremsstrahlung,
Pb to soak up the bremsstrahlung and finish off the betas.
Waffles - 11-2-2007 at 14:59
I just picked up a great book,"Materials For Nuclear Reactors", and they go through several pages of isolating, purifying etc both thorium and uranium
from their ores, including monazite. Would you like me to attempt to learn how to scan pages, since I've never done it before, and post it up for
everyone?