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Specialty Chemistry Forums => Citizen Chemist => Topic started by: BlueTheCow on May 16, 2008, 02:10:40 AM

Title: Need help in miniaturizing the Bayer Process
Post by: BlueTheCow on May 16, 2008, 02:10:40 AM
I'm fairly new to chemistry (I'm at the high school level of chemistry education and just started reading General Chemistry by Linus Pauling), and I want to implement the Bayer Process (for extracting alumina from ore) on a small scale (not for production or anything - more for my entertainment than anything else).

Of course I don't expect a step-by-step guide on how to do this, but I'm wondering if there is some set of books that I can read to give me some basic knowledge to work from. My main problem is that I cannot find enough information about the type of equipment used, and so I cannot figure out what kind of makeshift equipment I should use.
Furthermore, I do not really know which field this concerns, so I'm not really sure which books might help.

I would really appreciate it if someone could point me in the right direction. Thanks.
Title: Re: Need help in miniaturizing the Bayer Process
Post by: BlueTheCow on May 17, 2008, 07:39:07 PM
Hmm. If nobody has any answers to that, I'll edit the question to something a bit more specific.
I'm working on the part where I mix the ore with a sodium hydroxide solution and heat it to 175-200ºC and then filter out the solution from the mud.

My first attempt at a reaction chamber is a stainless steel teakettle with a sealed lid (which can be removed to add reactants), and a spout which is connected to galvanized steel pipe. A coffee filter is placed in the pipe such that after digestion, the kettle may be lifted and angled such that the spout is vertical and the solution pours through the spout, through the pipe, and through the coffee filter, and then gets trapped in a long portion of pipe which holds the solution while it cools (I'm considering instead using another teakettle for the cooling part).

Anyway, to test the idea I hooked up the teakettle to the pipe and put a cap on the end instead of a cooling chamber and did not insert a filter (so it's basically a teakettle with a galvanized steel spout, with a cap fitting on the end). After playing with this setup for a few minutes, I realized that at each connection between fittings there were leaks. I expected this, but I did not expect the amount of leakage that occured. At that rate, I will not be able to sustain enough pressure on the water to keep it in liquid state at the high temperatures required, due to the fact that the steam will escape through these leaks and reduce the pressure.
There are sealants specifically for these galvanized steel pipe fittings, but they are not rated for the temperatures and pressures I expect (150ºC-210ºC and around 35 atm, which is about 500 psi).

So is there some other way to seal them properly?

Also, I'm having a bit of trouble visualizing how I can monitor the internal temperature of the teakett- I mean reaction chamber ;)
I have a digital food thermometer that says it goes up to 200ºC/392ºF and has a long pointy probe that looks like it could be used to stab meat or something. I'm not entirely sure that just touching it to the side of the teakettle will get an accurate temperature (I plan on testing this tonight). Is there some more standard method I could use? Or do I need to invest in some better equipment?
Title: Re: Need help in miniaturizing the Bayer Process
Post by: Borek on May 18, 2008, 05:26:33 AM
A coffee filter is placed in the pipe such that after digestion, the kettle may be lifted and angled such that the spout is vertical and the solution pours through the spout, through the pipe, and through the coffee filter

Solution will be so alkaline that it will probably easily eat through your coffee filter. But that's the least of your problems.

Quote
At that rate, I will not be able to sustain enough pressure on the water to keep it in liquid state at the high temperatures required, due to the fact that the steam will escape through these leaks and reduce the pressure.
There are sealants specifically for these galvanized steel pipe fittings, but they are not rated for the temperatures and pressures I expect (150ºC-210ºC and around 35 atm, which is about 500 psi).

Your teakettle is not rated for 35 atm. What you are basically planning to do is a homemade bomb, that will explode splashing everything around with hot caustic solution of NaOH. This is an interesting, but painfull aproach to suicide.

Sorry to say that, but looks like your enthusiasm pushes you outside of the boundaries of your knowledge, thats very dangerous combination.

AFAICT you don't need high pressures for that process, but even then playing with hot, concentrated NaOH is a very dangerous idea.
Title: Re: Need help in miniaturizing the Bayer Process
Post by: BlueTheCow on May 18, 2008, 01:52:30 PM
Thank you for your reply!
Before I comment on each part, I'd just like to say that I found and acquired a tube of sealant that says it works on gases up to 3000 PSI (about 200 atm), 400ºF (around 200ºC), and higher for liquids. So aside from the probability of explosion, the setup might work.

Solution will be so alkaline that it will probably easily eat through your coffee filter. But that's the least of your problems.
Hm... any suggestions for a more stable filter?

Quote
AFAICT you don't need high pressures for that process, but even then playing with hot, concentrated NaOH is a very dangerous idea.
Well, water boils at 100ºC, and since higher temperatures are required, at atmospheric pressure it would all boil away before the reactions could take place. I figured if I heated up the solution in a sealed container, some of the water would boil, turning into steam that would expand as the temperature increases, increasing pressure. I figured the increased pressure would allow me to retain some of the water as a liquid, giving me my hot NaOH solution. I don't think it would really reach 35 atm, that was more of a max figure that I found searching through industry websites (the specific source said this approximate pressure occurred around 240ºC, and due to various limitations I only intended to reach around 200ºC).

Quote
Sorry to say that, but looks like your enthusiasm pushes you outside of the boundaries of your knowledge, thats very dangerous combination.
Exactly! That's why I came here asking for pointers on how to acquire the necessary knowledge.  ;D

Quote
Your teakettle is not rated for 35 atm. What you are basically planning to do is a homemade bomb, that will explode splashing everything around with hot caustic solution of NaOH. This is an interesting, but painfull aproach to suicide.
Oh dear.
Well, I did expect the explosion of the setup as a possibility, so I had planned on testing it with just water (no NaOH, no ore) to see if it would explode (and also to see if I could actually keep liquid water at that temperature, and for how long, given the possibility of leaks). So at worst I would have been scarred for life with ugly burns all over, damning me to a life of pathetic virginity (or, I suppose I could die from the burns...).

In any case, I thank you for the warnings and I would like to know if there's something you can suggest (other than just giving up).
From where can I acquire a digestion chamber (to replace the kettle) that can take the temperature and pressure without blowing up?

Thank you.
Title: Re: Need help in miniaturizing the Bayer Process
Post by: Borek on May 18, 2008, 03:55:03 PM
Google boiling point eleveation. What will be the concentration of your NaOH?
Title: Re: Need help in miniaturizing the Bayer Process
Post by: BlueTheCow on May 18, 2008, 07:55:24 PM
Google boiling point eleveation. What will be the concentration of your NaOH?

Hm. I was thinking somewhere around 12.5mol NaOH/kg H2O (500g NaOH/kg H2O).

I took a look at the equation on the wikipedia article about boiling point elevation, and even though I'm not sure what the van 't Hoff factor for NaOH is, I don't think it would be high enough to stop the water from boiling off at 175ºC. If the van 't Hoff factor is 1, the elevation would be 6.40 K. For the elevation to be high enough (40 K-100 K, to increase the boiling point to 140ºC-200ºC), the factor would have to be around 6 to 15, or I would have to increase the molality by that same amount. Due to the finite solubility of NaOH in water (111 g/100 ml at 20°C according to wikipedia), I don't think I can increase the molality by a factor more than about 2 (it might be a bit higher as I think the solubility increases with temperature). [Edit - I think the van 't Hoff factor is 2, so the elevation would be 12.8 K, and so I would need to increase the molality by around 3-8, which doesn't seem likely].

In any case, it doesn't seem likely that the boiling point elevation of the solution by the dissolved NaOH will be sufficient to allow me to reach the necessary temperatures in an open container without the water boiling off... so... what were you suggesting? Perhaps that I should use another solute to increase the boiling point? Or... what am I missing?
Title: Re: Need help in miniaturizing the Bayer Process
Post by: Borek on May 19, 2008, 03:09:17 AM
Solubility goes up with temperature and boiling point elevation is not linear for high concentrations. Unfortunaltely I don't have data for NaOH at hand, but KOH at 500g/100g H2O boils over 300 deg C.

Note: this is still dangerous as hell. Even if there is no pressure and no chances of explosion, just temp makes the solution of NaOH dangerous - and it is additionally corrosive as hell, it will eat through flesh at the light speed. Well, almost light speed.
Title: About the filter...
Post by: BlueTheCow on May 28, 2008, 06:45:36 PM
Sorry for taking so long to reply; I wanted to test a few things on my own before I asked for more help. As to the dangers, they are still present, but I ask you not to worry about that part as I am being extremely careful.

I've been working on much smaller batches than I originally hinted to with the teakettle (my largest batch was 17.0g ore), and I have found that everything so far works as planned except the filter: the mixture eats through it before the first drop goes though, just as you said.

So what other filter type could replace the coffee filters? I've been looking around, and I've found hints to the existence of such filters, but I never come up with anything substantial.

Thanks again.
Title: Re: Need help in miniaturizing the Bayer Process
Post by: Borek on May 28, 2008, 07:18:30 PM
This is not the answer, but it may push you in the right direction:

http://www.google.com/search?rls=en&q=alkaline+resistant+filetr&num=25&ie=utf-8&oe=utf-8
Title: Cannot find a cheap alkaline resistant filter for testing
Post by: BlueTheCow on May 29, 2008, 04:55:49 PM
Thanks, it did help me find some further information.

However, I am still a bit stumped on how to acquire the type of filter I need. All the suppliers I've found so far seem directed towards higher scale applications (industrial production, large laboratory testing etc), and sell either high qualities or high quantities, increasing cost (e.g. sterlitech.com's 0.22 micron pore size ptfe membrane disc filters cost $263.89 for the cheapest pack, which is qty 100). My budget allows the expense, but it does not allow such expenses when I'm not sure if the product will work (that is, I'm not prepared to order $200 worth of filters to find out I can't use them for whatever reason).

Is there some cheaper, smaller quantity source I can use? Perhaps something that is meant for something else that I can use for this (similar to how I can use coffee filters for other filtration needs)?

Am I missing something important? Or do I have to just bite the bullet (very hard) and shovel out the cash in the name of science?
Title: Re: Need help in miniaturizing the Bayer Process
Post by: HighTek on May 30, 2008, 09:30:48 AM
This could very well be the worst idea that I've given, but how about a pressure cooker?
Title: Re: Need help in miniaturizing the Bayer Process
Post by: BlueTheCow on May 30, 2008, 02:43:19 PM
Thanks for your reply.
I did think of using a pressure cooker, but as I explored this idea, I realized that a) most pressure cookers were rated for pressures much lower than the pressures experienced in the industry, and that b) a pressure cooker is essentially a container in which water and some food is heated, and as steam develops the pressure increases, increasing the temperature at which the remaining water can sustain a liquid state, until the pressure passes the desired pressure, at which point a valve is opened and steam is released, decreasing the pressure until the valve closes.

When I thought about this, I realized that all I needed was some sealed container which could remain structurally stable in the presence of such pressure (that is, a container that would not explode at the high pressures I thought would be necessary) - the valve to relieve pressure was not necessary, and thus the expense of a pressure cooker was not necessary (the presence of such a pressure-sensitive valve makes a pressure cooker a pressure cooker instead of just a pot; so if I don't need the valve, I don't really need the pressure cooker).

In fact, as I was browsing the kitchen appliances, I stumbled upon the idea that I could use a teakettle as such a container - it would allow me to fill with ore, NaOH, and water through the top, heat from the bottom, then pour through the spout into the settling chamber. The main problem with this was that I needed to seal the spout to the settling chamber somehow; I decided to use galvanized iron pipe with teflon sealant. Shortly after this, Borek informed me that the teakettle was unlikely to remain structurally stable with the pressures I described (that is, he told me it would explode, as seen above). Furthermore, he informed me that the higher pressures were not entirely necessary to the process; rather, that I could sustain the liquid state of the water using the boiling point elevation that occurs with high concentrations of solute.

Taking his advice, I increased the concentration of my NaOH solution to 4g NaOH/g water (=4kg NaOH/kg water = 100mol NaOH/kg water = 100m). I believe that this solution, heated to around 180ºC, successfully digested my ore. Granted, of course, I then poured it through the coffee filter which was eaten away by the extremely alkaline solution, and the trial failed.

In any case, as I stated in my last post, my current problem is the difficulty in acquisition of a suitable filter (capable of filtering a 100m NaOH solution at 180ºC; I expect red mud minimum particle sizes to be around 0.5 microns). At present, I'm debating with myself as to whether I should just spend the $122 and get the 0.1 micron pore size, 47 mm diameter GE Polypropylene Membrane pack of 100 (http://www.osmolabstore.com/OsmoLabPage.dll?BuildPage&1&1&402 (http://www.osmolabstore.com/OsmoLabPage.dll?BuildPage&1&1&402)). I know, I know, it's just $122... I don't want to sound like I'm whining, but I really don't want to spend $122, figure out it doesn't work, spend another $122, and so on, until I spend a few thousand, etc.

Anyway, that's the basic summary of this thread.

[Edit- btw, your avatar is entertaining.]
Title: Re: Need help in miniaturizing the Bayer Process
Post by: nj_bartel on May 30, 2008, 07:23:40 PM
I highly advise you find something safer to entertain yourself with before you kill yourself in an excruciatingly painful way.  I don't think you understand.  Hot, concentrated NaOH solution will rape your tissue to the bone.  I'd be less worried about ever having sex and more worried about lucking out and living if that tea kettle explodes.
Title: Re: Need help in miniaturizing the Bayer Process
Post by: BlueTheCow on May 30, 2008, 08:19:41 PM
I highly advise you find something safer to entertain yourself with before you kill yourself in an excruciatingly painful way.  I don't think you understand.  Hot, concentrated NaOH solution will rape your tissue to the bone.  I'd be less worried about ever having sex and more worried about lucking out and living if that tea kettle explodes.

While I do thank you for your concern about someone you've never met, I must say that it is a bit unfounded.

Firstly, I would like to say that I am taking every precaution feasible (gloves, etc.), and that even though I know there is obviously a limit to the protection allowed by such precautions, they do at least allow me extra time to evacuate any valuables (hands, etc.) from areas of danger.

Secondly, the explosion of the teakettle is extremely unlikely, for two main reasons: a) I no longer need such a high pressure in the reaction chamber, due to the boiling point elevation of the solution caused by the increase in molality suggested by Borek, and b) due to the even smaller experimental batch size, I'm now using open-topped stainless steel measuring cups as reaction chambers instead of teakettles (at least for now); so nothing could explode and if it did for some reason it wouldn't be a teakettle. Also, the smaller batch size reduces the danger somewhat, just because there's less dangerous stuff.

The biggest danger I face are bubbles of steam popping out from under chunks of dirt, sending hot mud into the air at the observer (I thought this would happen due to my experience with frying food in cooking oil), which becomes less of a problem using a lid to cover the measuring cup as it is heated (interestingly enough, the lid on one of my teakettles fits one of the measuring cups pretty nicely, allowing space for steam to escape to keep the pressure around the atmospheric pressure). The chunks of dirt hit the top (which makes for constant small *thud*ing sounds around lower temperatures) and fall back down until enough water escapes as steam to increase the molality (with NaOH) enough to bring the boiling point above the reacting temperature.

The other danger I face is the possibilty that the mixture spills over the sides of the measuring cups. This would happen for two reasons: first, when pouring through the filter, it is possible (though unlikely) that I might spill it. This hasn't happened yet, but if it does, I wear gloves and have towels nearby to contain the hot mess. The other way this could happen didn't occur to me until it actually happened. I used too much of the reactants and increased the temperature past what I expected (I didn't have much experience with my electric burner before now, so my temperature controlling was flawed), and the material overflowed out of the container while it was on the burner. I quickly removed the container from the heat and killed power to the burner, which stopped the overflow, and used the towel to clean up the mess. If I had not reacted quickly, the worst that could have happened would have been damage to equipment. Luckily, everything was fine. In any case, I prevent this now by controlling the digestion more carefully, but if it did happen again I would still be able to react in a similar way.

So you see, it really isn't all that dangerous, because I take my time and take necessary precautions. I'd be more worried about the youngins that have a fascination with explosives.

And no, I'm not worried about having sex.   ;)


Post Note:
Also, even though I know it's an extremely long thread (that's my bad, by the way - I tend to ramble), and it would take a while to read it fully... I think it would prevent further lengthening of the thread to do so - I would not have to restate things so much and so my posts would be shorter and thus the thread would be shorter and thus the next person that replies would not have to skip reading, and so on. It's a vicious cycle. I don't mean to be rude, of course, just trying to help out  ;D
Title: Re: Need help in miniaturizing the Bayer Process
Post by: eugenedakin on May 30, 2008, 10:11:27 PM
Hello BlueTheCow,

My first comment is ... WOW .. quite unsafe. I need to start this comment with a legal statement: this mechanism and reaction in the manner you are planning is extremely unsafe. Do not perform the test or reactions, please, for your own safety.

From a theoretical perspective, a really inexpensive filter can be created from various cloths ...yep, the kind that you use to clean dishes. Folding the cloth on top of itself, along with putting it on the bottom of an old soup can can form a very good filter. If the material passes through the filter with particles, add a little sand in the bottom of the filter can before pouring your ingredients into it. Finer sand = finer filter.

Here is a little information that I was able to find on the alumina process:

Quote
Aluminium oxide, also known as alumina, is the main component of bauxite, the principal ore of aluminium. The largest manufacturers in the world of alumina are Alcoa, Alcan and Rusal.[citation needed] Companies which specialise in the production of speciality aluminium oxides and aluminium hydroxides include Alcan and Almatis. The bauxite ore is made up of impure Al2O3, Fe2O3, and SiO2. Bauxite is purified by the Bayer process:

Al2O3 + 3 H2O + 2 NaOH → 2NaAl(OH)4
The Fe2O3 does not dissolve in the base. The SiO2 dissolves as silicate Si(OH)62-. Upon filtering, Fe2O3 is removed. When the Bayer liquor is cooled, Al(OH)3 precipitates, leaving the silicates in solution. The mixture is then calcined (heated strongly) to give aluminium oxide:[3]

2Al(OH)3 + heat → Al2O3 + 3H2O

The formed Al2O3 is alumina.

More details about the process can be found here:

http://en.wikipedia.org/wiki/Bayer_process (http://en.wikipedia.org/wiki/Bayer_process)

I wish you the best on understanding the theory behind your question.

Sincerely,

Eugene



Title: Re: Need help in miniaturizing the Bayer Process
Post by: constant thinker on May 30, 2008, 11:03:11 PM
I'm sorry to be blunt but you are naive. I know this because I was the same way at one point but I learnt quickly and thankfully before I ever seriously hurt myself.

I know people keep warning you this and that, and you think you have everything good, but you've only been lucky so far. I'm shocked you haven't received chemical burns yet.  :o

Strong bases HURT... A LOTTTT. And the pain isn't always instantaneous so quite a bit of damage can be done before you realize it.
I know this from experience making soap the old fashioned way.

I'm glad you said you're using gloves but you missed 4 other important things for safety.

1. Lab coats aren't just for good looks. If someone wearing a lab coat spilled chemicals on themselves, odds are it'd wind up on their lab coat. They can quickly yank of the lab coat and separate it from themselves preventing chemical burns. I guess an apron that covers your full front may act as a stand in.

2. Maybe I missed something, but something like this REALLY REALLY needs goggles at the very least. You won't be able to do too much chemistry if your blind or your vision is really blurry. Eye damage is permanent.
     You actually should have a face shield on along with the goggles.

3. You said nothing about having any weak acids nearby in the even you manage to spill it on yourself or anywhere else. I always make sure I have baking soda and vinegar nearby.

4. You've said nothing about having good ventilation. It doesn't take much to be overwhelmed by fumes. Also just throwing open a window and calling it good doesn't always work. Trust me I figured that one out when I through open my bathroom window and then poured bleach into my bathtub. Within a few minutes my eyes were very irritated and it was difficult to breathe.

5. (I know I said 4 things) I do hope you aren't using things that you use to cook with! Never mix labware and cookware. Do yourself and family a favor and invest in some Pyrex beakers, flasks, test tubes, etc. [u=http://www.unitednuclear.com/]United Nuclear[/u] has a lot of good and in my opinion fairly priced lab equipment and glassware for the lab.

And no I'm not just some adult that is telling you what to do, I'm only 17, a teenager like you. So please just take the safety precautions we've all told you. Not just for you, but for everyone you live with, and trust people when they say what you're doing is dangerous. Just because you haven't had an accident yet, doesn't mean what you're doing is safe.

Good luck with experiment. Maybe I'll do the same one you're doing now sometime over the summer.
Title: Re: Need help in miniaturizing the Bayer Process
Post by: macman104 on May 30, 2008, 11:32:26 PM
3. You said nothing about having any weak acids nearby in the even you manage to spill it on yourself or anywhere else. I always make sure I have baking soda and vinegar nearby.
That caught my attention too.  He said that he had towels, and I was trying to figure out what exactly he was hoping the towels would do against the hot caustic base...
Title: Re: Need help in miniaturizing the Bayer Process
Post by: BlueTheCow on May 30, 2008, 11:46:51 PM
In reviewing this post, I just realized it was giant... BEAR(sp? originally I had bear, then bare, now bear... lets not bare  :P) WITH ME:

Hello BlueTheCow,

My first comment is ... WOW .. quite unsafe. I need to start this comment with a legal statement: this mechanism and reaction in the manner you are planning is extremely unsafe. Do not perform the test or reactions, please, for your own safety.
Ah, right. Well, ignore the bayer process part of it. I take full responsibility and am completely self-liable for my actions and so on. Any information I acquire here could be acquired on my own in other ways, etc.

But in any case, lets just talk about filters. Nothing dangerous about theorizing about filters, right?

Quote
From a theoretical perspective, a really inexpensive filter can be created from various cloths ...yep, the kind that you use to clean dishes. Folding the cloth on top of itself, along with putting it on the bottom of an old soup can can form a very good filter. If the material passes through the filter with particles, add a little sand in the bottom of the filter can before pouring your ingredients into it. Finer sand = finer filter.

Hm... I'm not entirely sure what you're talking about. Would you cut a hole in the bottom of the can and flow water through? Or what? Are you talking about a sand filter as described here http://en.wikipedia.org/wiki/Sand_filter (http://en.wikipedia.org/wiki/Sand_filter)? As I said, I'm not entirely sure I understand this (it's not described very well on wikipedia at the moment).

Also, a NaOH solution dissolves SiO2/silica/sand, especially in my case. Would there perhaps be some alternative to using sand? Or is the sand not entirely necessary for what you described?

Lastly, do you have an idea of what sizes of particles would be filtered out? As far as I know, I need most of the particles size 0.5-1.0 microns (diameter I believe) and up filtered out. It might still work with less fine filtering, but I'm not entirely sure.







As to the next post that was posted while I was typing this one:   ;)


Quote from: constant thinker
I'm sorry to be blunt but you are naive. I know this because I was the same way at one point but I learnt quickly and thankfully before I ever seriously hurt myself.
I tend to appreciate bluntness for its efficiency (though I tend to not use it much myself because most people are not as understanding as I am). And good for you, not hurting yourself seriously and all!
Quote
I know people keep warning you this and that, and you think you have everything good, but you've only been lucky so far. I'm shocked you haven't received chemical burns yet.
Well... I've been really careful and such. Even with my shakey hands. Looking at your post though, I really have to say thank you for finally giving some constructive safety arguments (that is, stuff not meant to deter as the others posted, more meant to help; that's nice of you).

Quote
Strong bases HURT... A LOTTTT. And the pain isn't always instantaneous so quite a bit of damage can be done before you realize it.
I know this from experience making soap the old fashioned way.
Yeah, I heard about that soapmaking stuff when I was searching for a supply of NaOH (I finally settled on using Roebic "Crystal Drain Opener" from Home Depot/Lowes, but I'm not sure it's the best solution; I only bought one 908g/2lb bottle, and I won't need more for a while).
Quote
I'm glad you said you're using gloves but you missed 4 other important things for safety.

1. Lab coats aren't just for good looks. If someone wearing a lab coat spilled chemicals on themselves, odds are it'd wind up on their lab coat. They can quickly yank of the lab coat and separate it from themselves preventing chemical burns. I guess an apron that covers your full front may act as a stand in.
I it sounds kinda silly, but I bought a pair of welding gloves to handle the hot reaction chamber (the teakettle, or for now the measuring cup). Whenever I'm near the solution, I guard myself by putting my hands up. They are very large.
But yes, I do think I'll get a lab coat before I do any more experiments. Stylish and protective; I don't know how I forgot about those.

Quote
2. Maybe I missed something, but something like this REALLY REALLY needs goggles at the very least. You won't be able to do too much chemistry if your blind or your vision is really blurry. Eye damage is permanent.
     You actually should have a face shield on along with the goggles.
Yeppers, definitely. That's one thing I was extremely concerned about. I have a pair of impact and chemical protecting goggles. I don't have a faceshield yet, but I'll make sure I get one before I increase the size of my experiments from the measuring cup reaction chamber to the teakettle.

Quote
3. You said nothing about having any weak acids nearby in the even you manage to spill it on yourself or anywhere else. I always make sure I have baking soda and vinegar nearby.
Does HCl count? No...?  :o Oh dear. I'll get some baking soda before I do another trial as well. I'm not sure about the vinegar; if you have baking soda, why do you need the vinegar as well?

Recently posted while I was typing (it happened again, sheesh):
Quote from: macman104
That caught my attention too.  He said that he had towels, and I was trying to figure out what exactly he was hoping the towels would do against the hot caustic base...
Well, basically, I'm using such small amounts at the moment, that a big towel absorbed and contained everything (when it spilled over as I mentioned in a previous post). It had some (what looked like) temperature burns, and of course I am not reusing that towel for anything as it contains the mixture, but it didn't ignite or get eaten through by the hot caustic mixture... not exactly a standard solution, but it took care of the mess (and further cleaning of the table took care of the residue, as far as I can tell). So... I'm for keeping the towels nearby, just in case.


Quote
4. You've said nothing about having good ventilation. It doesn't take much to be overwhelmed by fumes. Also just throwing open a window and calling it good doesn't always work. Trust me I figured that one out when I through open my bathroom window and then poured bleach into my bathtub. Within a few minutes my eyes were very irritated and it was difficult to breathe.
Hm... well, it is right next to a wide open window; the table is literally sitting along the window...  And along with the goggles I wear one of those 3M respirator masks. Further than that, I'm not sure what I would do... place a fan on one side of the experiment and the window on the other, and have the fan blow across the experiment and out the window? Or what?

Quote
5. (I know I said 4 things) I do hope you aren't using things that you use to cook with! Never mix labware and cookware. Do yourself and family a favor and invest in some Pyrex beakers, flasks, test tubes, etc. [u=http://www.unitednuclear.com/]United Nuclear[/u] has a lot of good and in my opinion fairly priced lab equipment and glassware for the lab.
Heh, of course not. All the cookware that I hijacked from my mum, I told her I would keep (I only took 1 steel measuring cup and a plastic teaspoon, which she has plenty more of; I'm planning on replacing them anyway, of course). All the rest of the stuff, I've either bought from Wal-mart, Home Depot, Lowes, or acquired from my (old) high school chemistry lab kit (it had some test tubes, a graduated cylinder, a spring scale and some other stuff).
At the moment, I'm not really interested in beakers, test tubes, etc, as all that is glass and most of my experiments currently involve NaOH, for which glass is a bad container.
In any case, no, I'm not eating out of the chemistry equipment.

Quote
And no I'm not just some adult that is telling you what to do, I'm only 17, a teenager like you.
I don't remember mentioning I was a teenager... Is it that obvious? Maybe it was the really old posts from when I was distraught (my first thread etc).

Quote
So please just take the safety precautions we've all told you. Not just for you, but for everyone you live with, and trust people when they say what you're doing is dangerous. Just because you haven't had an accident yet, doesn't mean what you're doing is safe.
Right, it's not safe. And I have had accidents, I've just managed them properly. I will take the safety precautions, but I will not, of course, desist (that would be against my values).

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Good luck with experiment. Maybe I'll do the same one you're doing now sometime over the summer.
Hehe, cool. If you need any information about the specifics, lemme know (I went through a lot of information finding the specifics I needed; then again, as my experiments are part of a larger project, you may not need to go through as much stuff). Or just ask on the forums and if I'm there, I'll reply.

Post Note:
By the way, do you have any suggestions for sources of a full face chemical shield and a labcoat?

Also, if there are typos, errors, etc. in this post... gimme a break. It's giant, and hard to review.
Title: Re: Need help in miniaturizing the Bayer Process
Post by: macman104 on May 31, 2008, 12:28:37 AM
Just wanted to say until you get the faceshield, the goggles you are talking about are they "glasses" or "goggles", the ones that have a elastic band around the back of the head.  I would recommend those if you have the glasses instead.
Title: Re: Need help in miniaturizing the Bayer Process
Post by: BlueTheCow on May 31, 2008, 12:32:18 AM
Just wanted to say until you get the faceshield, the goggles you are talking about are they "glasses" or "goggles", the ones that have a elastic band around the back of the head.  I would recommend those if you have the glasses instead.
They are goggles with the elastic band around the head. Sides, top, bottom, and frontal coverage of the eyes (basically, fully covering my eyes).
Title: Re: Need help in miniaturizing the Bayer Process
Post by: eugenedakin on May 31, 2008, 07:56:40 AM
Hello BlueTheCow,

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Hm... I'm not entirely sure what you're talking about. Would you cut a hole in the bottom of the can and flow water through? Or what? Are you talking about a sand filter as described here http://en.wikipedia.org/wiki/Sand_filter? As I said, I'm not entirely sure I understand this (it's not described very well on wikipedia at the moment).

Also, a NaOH solution dissolves SiO2/silica/sand, especially in my case. Would there perhaps be some alternative to using sand? Or is the sand not entirely necessary for what you described?

Lastly, do you have an idea of what sizes of particles would be filtered out? As far as I know, I need most of the particles size 0.5-1.0 microns (diameter I believe) and up filtered out. It might still work with less fine filtering, but I'm not entirely sure.

My apologies about the instructions, I will try and clarify (pun intended) the instructions on the filter. Yes, the Sand filter works quite well, and can filter to below 40 microns. I doubt that a 1 micron filter would work without the need for pressure to force the fluid through the filter.

Instructions for a makeshift fine-filter:

Take a tomato can and cut both end off of the can, leaving a circular tube. Clean the tube with water and soap. Place a clean, folded cloth over one side of the empty tube and fasten it with rubber-bands. On the inside of the tube, place some fine-grain-sand (1 inch or 2.2 centimeters). Place a coarse cloth above the layer of sand. Take one last cloth and form it into a 2 inch loose ball with your hands and place it in the container. Pour the content that you need to filter on the 2 inch loose ball.

Functionality: The 2 inch loose ball slows down the speed of the fluid entering the filter, preventing dispersion of the sand in the filter. The coarse cloth directly above the layer of sand is your coarsest filter, to catch large particles. The sand catches most of the fine particles, and the last cloth (with the rubber band) just holds the filter together.

I hope this helps visualize a filter.

Sincerely,

Eugene
Title: Re: Need help in miniaturizing the Bayer Process
Post by: BlueTheCow on May 31, 2008, 09:37:31 AM
Hello BlueTheCow,
[snippet snipped]
I hope this helps visualize a filter.

Sincerely,

Eugene

It does, quite so. Thank you very much for clarifying (:P) it for me.

However, I do have a question about the actual sand. I won't be able to use sand in my specific process as it would dissolve and pass through the filter (leaving a can with a couple rags in it... could be a great archaeological mystery someday...).

So anyway, I was thinking that if I use some other particle instead of SiO2, it might work. Unless there are any suggestions/objections, I'll go ahead and test a few materials myself.
Title: Re: Need help in miniaturizing the Bayer Process
Post by: eugenedakin on May 31, 2008, 10:07:29 AM
Hello BlueTheCow,

Yes, you are correct. When you bring sand to a very high temperature, and then add caustic soda you can dissolve sand to make sodium silicate. It is very difficult to make sodium silicate under laboratory conditions, let alone the theoretical conditions both you and I are talking. 

Just for your own enjoyment, put sand in a jar, add water and caustic, mark the side of the glass jar with a felt marker and wait. If the sand dissolves, there should be a space in between the layer of sand and the mark you made on the outside of the glass. 

If you have sodium silicate already, then yes, sodium silicate dissolves relatively quickly with the addition of caustic soda. Sand is not sodium silicate  :) .

Sincerely,

Eugene
Title: Re: Need help in miniaturizing the Bayer Process
Post by: nj_bartel on May 31, 2008, 07:06:57 PM
Does HCl count? No...?  Shocked Oh dear. I'll get some baking soda before I do another trial as well. I'm not sure about the vinegar; if you have baking soda, why do you need the vinegar as well?
---------------------------------------------


Just got a wonderful image of some faceless person screaming with hot NaOH solution in his face grabbing for muriatic and pouring it in his eyes.

Oh, and there are more reasons to use Pyrex than you think, for example the fact that it's heat/shatter resistant.  BUY PYREX.
Title: Re: Need help in miniaturizing the Bayer Process
Post by: billnotgatez on May 31, 2008, 08:10:55 PM
I would think that a good metal container that is not effected by the corrosive nature of sodium hydroxide is a reasonable choice.

As to safety

A standard lab has several setups to help with this

A fume hood
A special shower that you just pull the handle down and it does the rest
Eye washing station

After that the experimenter uses
Face shields
Lab coats
Gloves
Maybe even special boots


I for one support citizen science especially when it is done on a very small scale.


Title: Re: Need help in miniaturizing the Bayer Process
Post by: BlueTheCow on June 03, 2008, 05:46:15 PM
Whew! The forum monster ate my post (my login cookie expired while I was typing, and then when I tried to go back, the text box for the message body was empty, and reposting was giving me the Already Posted error....), but LUCKILY I was able to cut him open and recover my post using Wireshark (a packet sniffer). That was a close one. Here's the post:

Alright, I'm back, and I think I've come up with a solution to my coffee filter problem. Essentially, I'll buy a pack of "0.22 micron Pore Size, 13mm diameter, 50 micron thick Sterlitech PTFE (Teflon) Unlaminated Membrane" (which is shaped like a circle) from http://www.sterlitech.com/products/membranes/PTFE/ptfeunlaminated.htm (http://www.sterlitech.com/products/membranes/PTFE/ptfeunlaminated.htm).

I'll take one of these PTFE membrane filters, stick it in-between two 3/8 inch galvanized steel pipe flange fittings, making essentially a steel pipe coupling with a filter squished in between (the diameter of the flow is 9.525mm, but the flange itself is about 4 times this diameter, allowing the filter to fit in nicely), and then seal it with pipe thread sealant (which also contains PTFE).

So I'll have my own little filter frame, which I can connect to any reactor contraption I come up with. It will require me to wet the filter with Isopropyl Alcohol before use, due to the hydrophobic property of PTFE. Also, I'll have to come up with some way to push the mixture through at 40 PSI. (I'm not actually sure if I need both the pre-wetting with alcohol and the pressure, or if either one would work; I'll test this myself, as it seems a trivial thing to consider at the moment: if both are needed, then I'll buy the supplies for both; there won't be much wasted if only one is needed, as I would prefer the more expensive pressure method, which excludes alcohol; the only wasted supply could be the Isopropyl Alcohol, which is inexpensive.)

In actuality, I'll probably need 2 or more of such filter frame contraptions, as I'll most likely need to filter in a step down manner in order to not clog the pores too quickly. That is, I'll most likely need to use similar 5.0 micron and/or 10 micron pore size membranes and filter through these before I filter with the fine 0.22 micron pore size membrane.
(This part where I have to use multiple filter sizes scares me, as I can already see the hundreds of membrane filters stacking up in cost... I think I'll email one of the suppliers to see if they can split packages for "sampling"...)



In any case, the next problem I'm working to solve is creating the pressure necessary to push the mixture through the filter (>=40 PSI). If anyone has any ideas, feel free to share (keep in mind that the mixture is extremely caustic and at around 170-210C, and may have fair sized particles, perhaps up to a few mm in diameter). Currently, I'm trying to figure out a way to build my own pump that will work in this situation.
Title: Re: Need help in miniaturizing the Bayer Process
Post by: Borek on June 03, 2008, 05:51:11 PM
In most cases pump just speeds the filtration. No pump - it still goes, just slowly. Remember that pressure can accidentally squeeze your liquid into any direction, that's not what you want.
Title: Re: Need help in miniaturizing the Bayer Process
Post by: BlueTheCow on June 03, 2008, 06:00:27 PM
In most cases pump just speeds the filtration. No pump - it still goes, just slowly. Remember that pressure can accidentally squeeze your liquid into any direction, that's not what you want.

Are you sure I won't need a pump? While that will make it much easier to design, the following is from the manufacturer's FAQ section:

EDIT2: SKIP THIS PART, as I made a mistake. I'm leaving it here so there's no confuzzling of anyone who already read it.

Quote from: http://www.sterlitech.com/membranefaq.htm#noflow
Q. Why is my flow rate low?  Little or no liquid is seen to pass through the membrane, what could be the problem?
A. There could be a number of things going on to restrict the flow through the membrane.

[first part removed to condense post]
Another thing to consider is if the liquid is being properly prefiltered.  With such small pore sizes, 0.05-0.01, you need to filter in a step down manner so as not to plug the pores.  Step down means a series of filters with decreasing pore sizes.  This can even happen with DI water, bacteria or other particles can be introduced to the process and cause problems with blinding or plugging the filter.

So... would I just have to wait longer? Or clean the filter more often? Or...?

Edit: Re-reading my post, is it possible that this information does not apply to the pore size I will be using (0.22 microns)?

EDIT2: This is the end of the skippable part.
Edit2: I'm going bonkers; this quote doesn't even concern the pump...

This one does:
Quote from: http://www.sterlitech.com/generalfaq.htm#airpassage
Q. What membrane has been used to prevent water vapor from passing, but would allow regular air to pass?

A.  The common membranes used for gas/air filtration are our hydrophobic Polypropylene and PTFE Membranes.  They both inhibit the flow of water vapors (hydrophilic) while allowing regular air molecules (such as oxygen) to pass.

For the PTFE membrane the water intrusion pressure (which is inversely related to pore size) is greatest with the smaller sizes:

Water Intrusion of PTFE 
Pore Size (um) Water Intrusion Pressure (psi)
0.240
0.4520
1.07
3.02
5.01

So what I meant to ask was: if I don't use a pump, where does the 40 PSI intrusion pressure come from?
Title: Re: Need help in miniaturizing the Bayer Process
Post by: Borek on June 04, 2008, 03:16:53 AM
OK, for such small pore size you may need external pressure just to wet the filter. But I still don't like the idea. OTOH - 40 psi you will get from tyre pump.
Title: Re: Need help in miniaturizing the Bayer Process
Post by: enahs on June 04, 2008, 08:50:00 AM
Do you really need super filtration? I mean, if this is just to see if you can do it, does it need to be super pure?

Insert obligatory safety warning, which you have gotten a lot, and should read carefully.

I would go to your local hardware store. Go to the window section. Look at the window screening. They make some out of metal. Find one with a metal that will not react with hot NaOH (they are not all pure metals, and some can be aluminum!) Buy a little. Cut a bunch of circles out, lay them on top of one another in alternating patterns so you make really tiny holes, and shape it like a funnel. You now have a metal screen that should filter pretty decently.

And while you are at the hardware store, get a face shield and really good gloves, pretty please. And maybe a cheap piece of plexi-glass to screw into a wood frame and put between you and the reaction.