Sciencemadness Discussion Board - Is this for Real? Mg + NaOH ==> Sodium?

Is this for Real? Mg + NaOH ==> Sodium?

aliced25 - 22-5-2013 at 22:14

I watched this video on youtube and I just had to wonder, is this really sodium (what he drops on the water looks like it)?

http://www.youtube.com/watch?v=seSg_GWj1b0

If so there are several ways of improving yields - mineral oil and then heat to melt the sodium and decant it off the slag/unreacted Mg/NaOH/etc.

Mildronate - 22-5-2013 at 22:41

Yes it is

chemcam - 22-5-2013 at 23:09

Can you elaborate on your ideas to improve the yield?

aliced25 - 23-5-2013 at 00:32

Shit, where to start - fused sodium hydroxide - out of the bottle it will contain water to some degree which will destroy yield. Inert atmosphere, even oxygen free atmosphere to stop oxidation (or get some argon and pump it in on top), rinse the magnesium powder as it is usually coated (thus reducing yield burning it off) and then adding in sufficient mineral oil/paraffin to allow for separation of the melted metal from the slag without water. Other people will have even better ideas, but those are some. You could also look into adding the mineral oil and melting the sodium (around 97C), then collect the balls of sodium that coalesce in the paraffin.

FUCK ME - CAVEMAN CHEMISTRY TO SODIUM

[Edited on 23-5-2013 by aliced25]

Bot0nist - 23-5-2013 at 03:57

You have read the potassium thread, yes?

blogfast25 - 23-5-2013 at 05:27

Forget about 'significantly improving yield', it's been tried HERE before (search for it before you waste more valuable time). This NaOH + Mg 'thermite' is a messy reaction, which works only to produce miniscule amounts of very impure sodium and for demo purposes. It is NOT a practical way to produce sodium of any appreciable quality in any appreciable quantity.

Sorry to rain on anyone's parade.

[Edited on 23-5-2013 by blogfast25]

chemcam - 23-5-2013 at 09:22

Quote: Originally posted by blogfast25

Forget about 'significantly improving yield', it's been tried HERE before (search for it before you waste more valuable time). This NaOH + Mg 'thermite' is a messy reaction, which works only to produce miniscule amounts of very impure sodium and for demo purposes. It is NOT a practical way to produce sodium of any appreciable quality in any appreciable quantity.

Sorry to rain on anyone's parade.

That's what I was thinking, I was hoping the OP had some novel way to do this better. I have tried many times but it's not worth it like you say. WAY too contaminated and small amount.

blogfast25 - 23-5-2013 at 10:06

Quote: Originally posted by chemcam

That's what I was thinking, I was hoping the OP had some novel way to do this better. I have tried many times but it's not worth it like you say. WAY too contaminated and small amount.

Not sure what you mean by OP.

The only magnesiothermic and aluminothermic reactions that yield good metal are those that fulfil the following conditions:

1) Must generate enough heat so both the metal and slag (MgO or Al2O3 respectively) form in the liquid phase, forming a melt that allows metal and slag to separate out.

2) End temperature of the reaction must not exceed the boiling point of the metal produced, as otherwise it will boil off (often leading to potentially dangerous flashing).

Reactions involving Al or Mg and NaOH, KOH or LiOH (never mind the other alkali metal hydroxides) do NOT satisfy these conditions and lead to messy, sintered masses from which decent metal recovery is basically impossible. A few small nuggets, yes. Anything more, no.

12AX7 - 23-5-2013 at 14:50

2) can be solved partially by performing the reaction in a bomb. I believe one member had ignited such a thermite mixture in a suitable steel bomb, and was rewarded with a buttery wad of metal.

Bombs suitable for high pressure and extremely high (thermite-grade) temperatures are a rather dubious proposition, however...

Tim

aliced25 - 23-5-2013 at 15:02

Not talking about anything quite so crude - but there is fuck all on the web about magnesiothermic reduction of sodium, which is what got me excited.

A propane furnace, a mild-steel pipe (low-carbon) and a boat - then a steel water-cooled condenser and a collection cup. The vacuum needed is fairly high compared to what people expect (according to the papers) and it would give high purity sodium.

One interesting question is whether vacuum would be needed at all... Magnesium burns at 3,100C (auto-ignition in air of 473C - http://en.wikipedia.org/wiki/Magnesium) which is well above the boiling point of sodium (883C - http://en.wikipedia.org/wiki/Sodium), so even a moderate vacuum - or flow of argon should push the vaporised Na onto the condenser (I'd personally go for the moderate vacuum), allowing for the collection of Na without the slag (see the 2nd & 3rd papers, one has a design of a pipe in a v-shape to collect Li the same way). If it worked, it could also be applied to Lithium (BP 1,342C -http://en.wikipedia.org/wiki/Lithium).

It all depends on how Magnesium burns in a modest vacuum (say 1/2 - 1/4 atm). Or use CO₂ as a sweep gas, Mg burns in iit, and it won't affect the metals (or their hydroxides/oxides) in the absence of water.

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[Edited on 23-5-2013 by aliced25]

blogfast25 - 24-5-2013 at 09:32

Quote: Originally posted by aliced25

Not talking about anything quite so crude - but there is fuck all on the web about magnesiothermic reduction of sodium, which is what got me excited.

There is 'f*ck all' on the web about this because it just isn't very promising at all. This is one of many SM's projects that probably won't even come off the ground or even the drawing boards.

Elsewhere a 'Zan Divine' posted some amazing stuff on reducing CsCl with Li in vacuo, with excellent results and fairly simple apparatus. I suggest you have a look at that re. reduction of NaCl with Li.

Merely for comparative purposes: Li, BP = 1342 C; Na, BP = 883 C; Cs, BP = 670 C; LiCl, BP = 1382 C.

Reduction of NaCl with Mg in vacuo could also be considered because the BP of MgCl2 is 1412 C. With a melting point of Mg at 650 C (BP = 1091 C), the 'sweet spot' mix of volatilities may allow [note caveat!] Na to be distilled off from a mixture of NaCl and Mg at > 700 C.

[Edited on 24-5-2013 by blogfast25]

blogfast25 - 24-5-2013 at 09:44

Quote: Originally posted by 12AX7

2) can be solved partially by performing the reaction in a bomb. I believe one member had ignited such a thermite mixture in a suitable steel bomb, and was rewarded with a buttery wad of metal.

Tim

I think you are remembering wrongly but I'll gladly acknowledge my mistake if you can dig it up.

In a bomb you have the additional problem that sodium hydride could be formed.

With a Standard Enthalpy of Formation of - 56 kJ/mol for NaH, the reaction:

NaOH + Mg === > NaH + MgO is thermodynamically favourable to:

NaOH + Mg === > Na + MgO + 1/2 H2

In open crucible conditions the second one is favoured because H2 leaves the reaction, in bomb conditions it cannot do so.

chemcam - 24-5-2013 at 09:49

To get NaCl to react with lithium wouldn't it need to be in solution? What happens to the Na? NaOH right?
I read though a thread about this before and you said reductions of chlorides with lithium is not possible. Have to changed your mind? Or am I misunderstanding the context?

http://www.sciencemadness.org/talk/viewthread.php?tid=15061&...

blogfast25 - 24-5-2013 at 10:04

Quote: Originally posted by chemcam

Or am I misunderstanding the context?

You are misunderstanding the context. Here we are exploiting the differences in volatitity so that, under vacuum, the desired species volatilises, thus leaves the reaction mix, thus pulling the equilibrium to one side. Take the example of:

CsCl(s) +Li(l) < === > Cs(l) + LiCl(s)

In the conditions relevant to the thread you linked to this equilibrium stays very much to the left and nothing much happens. But at high temperature and under vacuum, Cs metal is the most volatile of the four species and is distilled off. This pulls the equilibrium to the right because it reduces the concentration of the Cs in the mix ('Mass Effect').

This little 'trick' is exploited in numerous industrial processes, among others in blast furnaces where the volatile CO/CO2 reaction product's 'escape' pulls the reduction of iron oxide to the Fe side. In conditions where the carbon oxides could not leave the reaction, carbon has very little reducing capability.

[Edited on 24-5-2013 by blogfast25]

vmelkon - 24-5-2013 at 13:49

Quote: Originally posted by chemcam

To get NaCl to react with lithium wouldn't it need to be in solution? What happens to the Na? NaOH right?
I read though a thread about this before and you said reductions of chlorides with lithium is not possible. Have to changed your mind? Or am I misunderstanding the context?

http://www.sciencemadness.org/talk/viewthread.php?tid=15061&...

The reaction will be between a solid (NaCl) and a liquid (Li).
Because of the low pressure in the system, the liquid Na will boil off and you collect the vapors in a condenser.

The sodium won't be pure because some of the lithium boils off as well. Also, the solid NaCl will get covered by solid LiCl. There will be crystal defect because lithium ions are small compared to sodium ions.

Fantasma4500 - 24-5-2013 at 15:27

well you can make silicon metalloid by SiO2 + Al + S
the Al and S first reacts whereafter the SiO2 takes part in the reaction giving silicone metal..

in other words, a much slower burning thermite should be possible to do, perhaps with something to kick start it such as.. sulfur mixed in? and with aluminium
i might be wrong tho, not sure about reactivity and all of that (:

aliced25 - 24-5-2013 at 18:34

Quote: Originally posted by blogfast25

Merely for comparative purposes: Li, BP = 1342 C; Na, BP = 883 C; Cs, BP = 670 C; LiCl, BP = 1382 C.

Reduction of NaCl with Mg in vacuo could also be considered because the BP of MgCl2 is 1412 C. With a melting point of Mg at 650 C (BP = 1091 C), the 'sweet spot' mix of volatilities may allow [note caveat!] Na to be distilled off from a mixture of NaCl and Mg at > 700 C.

Sounds more like the Ames process (http://en.wikipedia.org/wiki/Ames_process), except using the Chloride instead of the Fluoride and Sodium instead of Uranium.

It would be an interesting procedure to work on, especially as NaCl is fairly easily acquired dry and a basic tube furnace (propane or electric) would get the temperatures high enough. Cs would be an interesting addition to the collection.

blogfast25 - 25-5-2013 at 04:21

The Ames Process is substantially different from methods that require distillation, in the sense that it relies on the very substantially exothermic reaction UF4 + 2 Mg == > U + 2 MgF2, with a Standard Heat of Reaction of about - 354 kJ/mol (of UF4). This enthalpy, combined with the preheat soak to about 600 C, ensures the reaction proceeds spontaneously (and quite quickly) and results in an end temperature well above the MPs of both MgF2 and U, which then separate out gravitationally (with U that really works a treat!). It's very much like a preheated Goldschmidt reaction.

Compare this to (for instance) CsCl + Li < === > Cs + Li, there the Standard Heat of Reaction is about + 35 kJ/mol (of CsCl), so actually endothermic. The reduction only works by removing the most volatile component (Cs) from the mix by distillation, thereby 'pulling' the equilibrium to the right by mass effect.

They really are very different separation techniques.

[Edited on 25-5-2013 by blogfast25]

blogfast25 - 25-5-2013 at 04:33

Quote: Originally posted by Antiswat

the Al and S first reacts whereafter the SiO2 takes part in the reaction giving silicone metal..

Nope. The reactions:

SiO2 + 4/3 Al === > Si + 2/3 Al2O3

And:

2 Al + 3 S ===> Al2S3

... proceed more or less consecutively. The first one simply doesn't generate enough heat to obtain a molten mixture of Si and Al2O3. To boost heat output, the second, highly exothermic reaction is used, with the required ingredients simply mixed in with the SiO2 and Al powders. Everything then just 'burns' together. It's called 'heat boosting'. The other advantage is that Al2S3 has a much lower MP than Al2O3, thereby reducing the viscosity of the melt and promoting separation between the Si and slag.

Another widely used [in industry] heat booster system is KClO3 + 2 Al === > KCl + Al2O3 which is extremely exothermic. Crude niobium metal is produced from pyrochlore, aluminium and potassium chlorate (or sodium chlorate) to ensure the insanely high MP of Nb is reached.

Quote: Originally posted by vmelkon

The sodium won't be pure because some of the lithium boils off as well.

I'm not convinced that the contamination will be significant if you get the conditions right. See the CsCl + Li example. Sure, Cs is more volatile than Na but Li is much less volatile than both.

[Edited on 25-5-2013 by blogfast25]

chornedsnorkack - 27-5-2013 at 11:56

Na boils at 890 C. K at 760 C.

What is the least active metal that can be used to reduce Na and K to metal vapour? (You need the metal to form a refractory compound, too).

Another relatively active but volatile metal is Zn. Can you similarly boil off Zn reduced by a less active but less volatile metal, like Fe, Sn or something similar?

blogfast25 - 27-5-2013 at 13:29

It's not really about 'activity'. The reducing agent must have volatility much below that of the target metal. In principle that works for Zn too.

aliced25 - 28-5-2013 at 04:24

The standard metals used in the Pidgeon Processes are silicon, aluminium, magnesium, calcium and sodium. All of which can also be made by the Pidgeon Process as well. I'm moving this to the unconventional sodium thread if the moderators would please help?

A basic Propane kiln/furnace will provide sufficient heat to allow the reaction to proceed, while I suspect a simple sliding vane (10pa/75mtorr) would suffice for most of these processes. I'd also like to look at Phosphorus by silicothermic reduction, a metaphosphate finely ground and briquetted with finely ground silicon should give the alkali silicate and P vapour, at comparatively low temperatures.

The best routes are through the respective oxides, in the case of Lithium & Sodium for example, these come from either decomposition of the Carbonate at high-temperatures or formation and decomposition of the peroxide. I'm not sure where one would even look for Cesium Oxide/Carbonate or whatever, or why I'd want to? Is there any real advantage in having it?

Apart from Element Collection?

There is a blast furnace design - lab scale - for P-Vapor from a preheat, note the temperatures for the Na/K Metaphosphates? Imagine using Si as the reductant and in a vacuum?

[Edited on 28-5-2013 by aliced25]

blogfast25 - 28-5-2013 at 05:03

Not sure what you mean by 'a simple sliding vane'...

watson.fawkes - 28-5-2013 at 08:35

Quote: Originally posted by blogfast25

Not sure what you mean by 'a simple sliding vane'...

I read that as "rotary vane vacuum pump". Though gas combustion kilns generally heat from the inside, which makes vacuum basically impossible. And if you were to use a vacuum muffle, you've got a sealing problem, since the seal has to be at kiln temperature. (Vacuum seals are usually not in the hot center of a kiln.) Easiest would be electrical heat, but even getting power feed-through at kiln temperatures that are proof against vacuum isn't trivial. All-in-all seems kind of half-baked to me.

blogfast25 - 28-5-2013 at 11:20

Ah, I see, a reference to the vacuum pump itself. But from the way I understand it the kiln doesn't have to be under vacuum: only the reactor placed in it.

watson.fawkes - 28-5-2013 at 12:14

Quote: Originally posted by blogfast25

But from the way I understand it the kiln doesn't have to be under vacuum: only the reactor placed in it.

That could work, say, if only a closed end were in the furnace proper and the vacuum seal was outside it.

blogfast25 - 28-5-2013 at 12:42

A *.pdf with some interesting illustrations of various Pidgeon process based reactors:

http://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s...

blogfast25 - 30-5-2013 at 04:49

Quote: Originally posted by aliced25

The best routes are through the respective oxides, in the case of Lithium & Sodium for example, these come from either decomposition of the Carbonate at high-temperatures or formation and decomposition of the peroxide.

Maybe but the oxides are hard to get/prepare.

Consider also NaF(s) + 1/2 Mg(l) === > Na(g) + 1/2 MgF2(s)

ΔH_R^{298 K} = +13.3 kJ/mol (NIST values)

For the equivalent reaction with KF, ΔH_R^{298 K} = + 6.5 kJ/mol

MgF2 is of course totally non-volatile: BP = 2260 C. NaF and KF also have high boiling points.

[Edited on 30-5-2013 by blogfast25]

aliced25 - 30-5-2013 at 05:29

The oxides are extremely hard to get/prepare, but that is what the people looking to make this work elsewhere are using. I'm happy to try it out with halides, but I suspect these people had some idea what they were doing.

You have read the preparation for BBr3 from AlBr3 and BF3 haven't you?

I also know the Pidgeon-type processes are used to make Titanium and pure Silicon from their halides, so I'm 50:50 on the idea. Let's work out how to build a vacuum-retort that will fit in a propane/air heater, then we can imagine all sorts of things to make with the sucker.

Look up aluminothermic/calciothermic/silicothermic reductions on Google Scholar, there are a shitload of things that can be done using vacuum metallurgy. Some use the halides, some the oxides. But there are limits, serious limits, on the materials that can be used with some of the compounds (like molten lithium for instance), that will place restrictions on how this can be done.

A bottle of BBQ Gas, a propane furnace and then something to put in it, with a condenser (air cooled in all probability) and then someway to get the reactive metals to the collection point and under paraffin so we can break the vacuum, to renew the charge or shut it down.

One major problem is that there will be reactive metals coating the inside of the entire system that have to be dealt with and removed, preferably without scraping them off, which would be an absolute bitch in my view, perhaps running a meker burner along the sides to move them down to the collection zone, or at least most of them?

The other part is the vacuum pump, the minute we start dealing with halides at high-temperature, shit can go wrong, as any stray halide/hydrohalide is unlikely to condense before the pump. Oxygen, Carbon dioxide and the like, no drama (provided it is cooled).

[Edited on 30-5-2013 by aliced25]

Endimion17 - 30-5-2013 at 05:33

Didn't we already have an identical thread?

aliced25 - 30-5-2013 at 05:42

Yeah, I want it to be merged with unconventional sodium if possible.

blogfast25 - 30-5-2013 at 12:24

Quote: Originally posted by aliced25

I think you're seeing obstacles where there are none. Have a good look at this thread (linked to from where it gets interesting):

http://www.sciencemadness.org/talk/viewthread.php?tid=6981&a...

None of this is easy but worrying about hot halides and vac pumps? Way before you get to the vac pump everything is at RT. I mean, why not worry about metal getting into the vac pump too, huh? It's really just as unlikely.

In the case of fluorides, despite the mental association with fluorine that they conjure up, liquid fluorides are among the most stable, least corrosive hot liquids known. See also their use in Molten Salts Nuclear Reactors.

[Edited on 30-5-2013 by blogfast25]

aliced25 - 30-5-2013 at 14:35

Might I suggest you read the Kroll and Schlectern Paper I uploaded in the Unconventional Sodium Thread? Magnesium cannot be used in some processes as it distills over at the temperatures needed for reaction (namely Lithium Fluoride), forming an alloy. Silicon doesn't, that is why they utilize it.

As to halides, halides at room temperature are still not something I particularly want in my vacuum oil, which will probably include a Diffusion Pump for some materials, and still be at rather high vacuum (so RT is not STP). The metals will condense as they will be well under their boiling point, even at high-vacuum. Halogens won't condense unless they are under positive pressure or we use a getter, or ultra-low temperature trap. Both are additional concerns that needn't be worried about IMHO.

As to making the oxides, most of the oxides can be made by heating the carbonate to around 800-1,000C in a vacuum. That equipment is precisely what we are making, more to the point, due to the fact that Calcium Oxide is needed to take up the Silica (if we use a silicon or if alumina if we use an aluminum reductant), the carbonates can be mixed and heated, which is much more effective according to the literature.

As to Nuclear Reactors, we aren't going to be using Tungsten, Zircalloy or Titanium, or even 300 series Stainless Steels, we'll probably be using mild steel (for ease of manipulation & welding - or cutting threads, etc., plus it copes better with high-temperatures than SS - have a look at SS Mufflers next time you see a Harley, they are discoloured from the temperatures).

Start thinking of how to build a simple reactor, preferably out of a straight section of pipe with a flange at the end so we can introduce the briquettes and vacuum seal it. Probably needs a flange at the other end too, so we can remove the product and disassemble it for cleaning. A propane kiln/furnace can be controlled to some extent, by reducing the introduction of forced air and the amount of propane (ie. mixture control). Only one part of the furnace has to be heated.

12AX7 - 30-5-2013 at 20:56

Stainless does up to 600C or so in air, while maintaining useful strength and corrosion resistance. Discoloration is superficial only, due to a thickening of the chrome oxide layer. Mild steel isn't rated for any temperatures and will turn to oxides rapidly at 600C and up. (Obviously, steel parts can handle some temperature, but this depends on environment, alloy and heat treating. Steel quickly tarnishes in air above 150C, and even with protective oil or whatever, metallurgical changes take place that may be undesirable. Car engine parts don't operate much over 100C, and the parts that get the hottest (valves, exhaust manifold, turbocharger impeller and housing) are made from alloy, stainless, cast iron, or aluminized steel.

Stainless may not be the most pleasant to cut ("three oh four is a whore") but if you need it, you need it.

Tim

blogfast25 - 31-5-2013 at 04:54

Aliced:

With LiF you’re picking an extreme example, as Li is the least volatile of Group I. Silicon wouldn’t work there either, as SiF4 would be formed.

Which thread are you referring to?

Re. nuclear reactors, you wouldn’t need fancy alloys for reducing NaF or KF with Mg in vacuo. For one, you’d react molten Mg with the solid fluoride. In MSRs the exposure of tubing to the eutectic fluorde is very prolonged and under mild pressure, quite different.

Any reason why copper couldn’t be used for the reactors?

aliced25 - 31-5-2013 at 16:19

Stainless is not fun to cut, I too am talking from experience here, it will puddle, splatter and if it gets down your welding gloves you'll do the dance of "ohfukithurts", where possible threads are your friend.

What we are talking about here is temperatures up to 1,300C from the high-temperature self-sustaining combustion synthesis (http://en.wikipedia.org/wiki/Self-propagating_high-temperatu...), initiated by the SiC heating the metal to ignition point - ie. MW ignited thermites buring in a solid-flame under vacuum. I don't know that SS or even MS will cut it, it might be worthwhile looking at putting a tungsten (formed by the same type of synthesis) or tungsten carbide, or silicon carbide end in the hot bit - it is just whether or not they'll hold a decent vacuum.

There is examples where commercial microwave ovens have been modified, but not to vacuum configuration. I'd remove the turntable entirely, put the refractory floor down on the base of the microwave, cut a hole in the top for the crucibles to come through (down to the base with the outer crucible - so it is supported) and have it so that only the metal container/crucible inside the susceptor (ie. not subject to MW Heating as such) is under vacuum, with a gas take-off at the top.

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blogfast25 - 1-6-2013 at 05:03

Quote: Originally posted by aliced25

What we are talking about here is temperatures up to 1,300C from the high-temperature self-sustaining combustion synthesis (http://en.wikipedia.org/wiki/Self-propagating_high-temperatu...), initiated by the SiC heating the metal to ignition point - ie. MW ignited thermites buring in a solid-flame under vacuum.

You’ve lost me now.

For (e.g.) Na2O + ½ Si → 2 Na + ½ SiO2 the Standard Heat of Enthalpy is a mere – 34.5 kJ/mol, barely exothermic. Assuming you have lime in there, then add the Enthalpy for CaO + SiO2 → CaSiO3, also quite pitiful I’d imagine. That’s not a lot of heat to keep this going and without constant removal of the Na vapour not too much is actually going to happen. I wouldn’t call that ‘self-sustaining’.

Also where does the SiC come into it?

You mention thermites in that context. Well, the heat-starved aluminothermic reduction of TiO2:

TiO2 + 4/3 Al → Ti + 2/3 Al2O3

... has a Standard Heat of Reaction of – 178 kJ/mol and could work in these MW ignited conditions. But – 178 kJ/mol is already worlds apart from – 35 kJ/mol.

As regards microwave heating, I think on a small scale temperature control isn't going to be easy. Contrast that with a 'static' propane or electrical furnace...

[Edited on 1-6-2013 by blogfast25]

aliced25 - 3-6-2013 at 06:28

Temperature control is going to be easy enough with a MW, on or off as needed.

Now, with the salts we are after, rather than Beryllium (Fluoride - reduction with Mg), Hafnium (Iodide process deposition off a Tungsten Alloy) or Potassium (the Chloride is reduced by Aluminumsilicon Alloy), the oxides look like a good place to start.

Now you mention the MW Ignited methods, the heat comes from the SiC, once it reaches a certain temperature, the thermite ignites. As to self-sustaining reactions, the only thing I've seen that will reduce Na is Mg and that is hellishly self-sustaining if it can be done in atmospheric oxygen. Various metallic/semi-metallic reductants are used for various products, silico/alumino/magnesiothermic reactions are utilized depending upon their reducing power. Might I suggest you actually read the literature, there is a shitload online for fuck all (dtic.mil has a lot).

http://www.sciencemadness.org/talk/viewthread.php?tid=2105&a... - is where the thread should be moved.

[Edited on 3-6-2013 by aliced25]