Sciencemadness Discussion Board - Seperation of Lithium from ground salts

Seperation of Lithium from ground salts

bquirky - 22-9-2009 at 09:13

Gday Gents.
I have a friend who owns some land containing a salt lake. and hence have access to a practically unlimited supply of natural salts possibly containing lithium.

Im not trying to do anything outrageous like setup a pilot plant. just come up with a few grams of my very own Li salt

(im allso bipolar so the idea has particular appeal in making my own meds)

There are a few properties that i think i can take advantage of namely the varying solubility in alcohols.
then there is the diferent melting tempratures. allthough im not sure what benifit a thermal seperation scheam whould offer.

if left to my own devices id start a separation process based on the variing solubilitys of sodium chloride and lithium chloride probably with a few Kg or so of starting material.

but there are a few points im not sure of. namely natural processes may already have separated the different salts to some extent ie deeper 'ores' vs shallower 'ores' prehaps the center of the lake vs the edges etc..

anyhow as per usawal i figured id open the floor for comment and listen to ideas from others.

regards.

hissingnoise - 22-9-2009 at 09:56

Quote: Originally posted by bquirky

(im allso bipolar so the idea has particular appeal in making my own meds)

The only person qualified to prescribe meds for your bipolar disorder is your doctor.
Self-medicating this condition is fraught with danger. . .
Don't do it!

12AX7 - 22-9-2009 at 13:06

As I recall, lithium carbonate and sulfate are fairly low solubility. You might add extra sodium carbonate (which will also precipitate most of the calcium and magnesium) then evaporate. Fractional crystallization (in water, not in fire) is easiest.

What's in there? I'm guessing sodium, potassium, chloride and sulfate, and either lots of carbonate, bicarbonate and borate if it's an alkaline lake, or calcium and magnesium chlorides, sulfates and etc. if closer to acid. And probably a little lithium in there somewhere.

Tim

JohnWW - 22-9-2009 at 14:45

Quote: Originally posted by hissingnoise

Quote: Originally posted by bquirky

(im allso bipolar so the idea has particular appeal in making my own meds)

The only person qualified to prescribe meds for your bipolar disorder is your doctor. Self-medicating this condition is fraught with danger. . .Don't do it!

Lithium salts, including the chloride and carbonate which are the ones most likely to occur in natural salt pan deposits, are fairly non-toxic, anyway. It is absolutely disgusting that prescriptions are required in many places to buy them from pharmacies. I have uploaded the British and U$ Pharmacopoeias and posted links for downloading them in the References section, so you could find out the correct doses there. Besides, by getting a medical doctor (at significant expense) to prescribe you such a non-toxic but gro$$ly overpriced item as lithium salt pills, you would be merely helping to support the "$ick Industry", in which the big drug companies $uck billions of dollars annually out of economies world-wide by forcing victims to buy their overpriced wares on prescription.

JohnWW - 22-9-2009 at 15:26

I heard recently that there is a large salt pan in a desert area in Chile, formed by run-off from the Andes, which is particularly rich in lithium salts (probably mostly chloride, and to lesser extents carbonate, bicarbonate, nitrate, bromide, iodide, iodate, sulfate, borate), and which is set to become the world's largest source of lithium for lithium-ion storage batteries, for many portable appliances such as cameras and cell-phones, and now also plug-in rechargeable electric or hybrid vehicles. I would think that at least some of the many dried-up salt pans in the Australian outback, formed mostly during the Pleistocene ice ages when Australia (especially the southern seaboard and interior) had a more pluvial climate than today, are also likely also to contain significant and extractable amounts of Li salts, especially those formed by run-off from weathering rocky areas containing Li minerals like lepidolite and spodumene, which occur in granitic rocks.

Because Li salts are usually much less soluble in water than those of other alkali metals, they would tend to become concentrated in those salt pans the catchment areas of which have had sufficient historic rainfall to redissolve the Na, K, Rb, Cs salts, and wash these out to sea, leaving most of the Li salts behind. Have you had samples from your friend's salt pan analyzed?

Of course, separating the Li from other soluble alkali and alkaline earth metal salts present in the salt pans is the major problem. The alkaline earth metals, if present, could easily be separated out from aqueous solution as the very insoluble carbonates by adding ammonium carbonate. But this would have to be done carefully from a fairly dilute cold aqueous solution, because Li2CO3 is only sparingly soluble: 1.54 parts per 100 of water at 0ºC, decreasing to 0.72 per 100 of water at 100ºC. The other alkali metal carbonates are much more soluble, although Na2CO3 by not all that much of a margin, and the common-ion effect would still have to be taken into account. Alternatively, precipitation of Ca (mostly), Sr, and Ba sulfates (but not Mg) could be mostly achieved with ammonium sulfate or H2SO4.

But separating out the Na, K, Rb, Cs from the Li is more difficult; electrolysis of a molten halide mixture probably would not work. A large-partial separation could be achieved by adding fluoride (preferably ammonium fluoride), noting that LiF is soluble in water to the extent on only 0.27 parts per 100 parts water at 18ºC which decreases to 0.35 at 35ºC, while NaF (the largest and least soluble impurity fluoride) is several times more soluble, to the extent of between 4 and 5 parts per 100 of water in the entire range 0-100ºC. K, Rb, and Cs fluorides are much more soluble again. The precipitated LiF may be difficult to convert to the desired salts, but Li metal could be obtained by molten-salt electrolysis.

Another and more efficient method of separation of the Li from other alkali metals would be by elutriation of the aqueous mixture through a column of a suitable ion-exchange resin, if one exists, that retains either Li+ or the other alkali metal cations. Such a method may also be usable to obtain Li from sea-water, in which it occurs to the extent of about 1 ppm.

The use of Li in lithium-ion batteries, rather than Na, is the result of the small size of the Li+ cation giving it much more permeability or diffusivity in the battery media than Na+ cations. However, there is the possibility of battery media being developed in the future that would permit the use of Na instead of Li.

The cosmic rarity of Li, in spite of its low atomic weight, and compared to He and even Na, has to do with the fact that its stable nuclei, mass nos. 6 and 7, while among the first products of ongoing nuclear fusion in stars after He, tend to be subsequently destroyed in stars, particularly in supernova explosions.

[Edited on 23-9-09 by JohnWW]

chemoleo - 22-9-2009 at 15:38

LiCl can be electrolysed in pyridine.
How about trying to extract it from a concentrate of LiCl, using pyridine? Admittedly the latter being not exactly OTC - so better to use crystallisation methods based on the anion.

[Edited on 22-9-2009 by chemoleo]

JohnWW - 22-9-2009 at 15:43

That is, if it could firstly be efficiently separated from NaCl and other alkali metal halides.

hodges - 22-9-2009 at 17:01

Quote: Originally posted by JohnWW

The problem I have heard (don't know if its true or not since I don't personally know anyone who is bipolar) is that lithium has a fairly long half-life in the body, and different people metabolize it at different rates. Since the therapeutic dosage is supposedly a fair fraction of the harmful dose (to kidneys and other organs), blood tests have to be done regularly to determine lithium concentration in order to maintain the correct dose.

I agree you could make your own lithium carbonate and take it, but you would still need a way to monitor lithium levels.

I have a defective thyroid and have been taking synthetic thyroid hormone for 20 years. Initially I had to have blood thyroid hormone levels monitored every few months for similar reasons. Eventually, it was found that my levels did not vary much once the right dose was found, so now I only have it checked once a year unless I feel effects indicating a change. Maybe people could do this with lithium too but I'm sure initially it would have to be monitored closely.

As was mentioned previously, you can probably precipitate lithium as the carbonate. But there are other metals, which may be present in similar amounts, that will also precipitate (magnesium comes to mind). So you will need to do additional separations once you get rid of the alkali metals.

Hodges

chloric1 - 22-9-2009 at 17:55

Lithium carbonate has the funny property of being more insoluble in hot water than cool water

. If there is lots of magnesium or calcium I would not add carbonate just yet. Take a sample of your natural salt, dissolve completely in excess distilled or rain water, then boil it down until cloudy or a "skin" forms on the surface. Let it cool and save any crystals or powder. Your decanted solution could be concentrated further some of the moderately soluble salts like sodium chloride will begin to crystalize. You should be left with chlorides, bromides and iodides that are VERy soluble. You could evaporate to dryness and add anhydrous methanol. This will dissolve calcium, magnesium, and lithium chlorides.

I just remembered that lithium hydroxide is soluble to the extent of 12 grams in 100 grams of water. Adding potassium hydroxide to the solution after most of the sodium is gone would precipitate some of the lithium if high enough in concentration. Even with its limited solubility, lithium hydroxide is more water soluble that magnesium or calcium hydroxide.

Acetone also dissolves many lithium salts.

ketel-one - 22-9-2009 at 19:04

I agree with John, about how stupid healthcare/government is trying to make even a simple salt or element a prescription medicine. And bromide salts are also interesting. Similar mode of action from what I believe. Anyone up for some lithium bromide?

Lithium salts melt at lower temp than sodium or potassium or calcium or magnesium. So lets say if you have the NO3, Cl, and SO4 ions of Li, Na, K, Mg, Ca if you add excess KOH to it and then add excess nitric acid, you'll get K2SO4 and a bunch of nitrates of each of those elements, with LiNO3 being the only one that melts below 300 degrees celsius. Heat those salts till anhydrous, then to over 300 degrees with blowtorch or something to have lithium salt melt and flow off somewhere....

12AX7 - 22-9-2009 at 19:08

You'll melt off the eutectic, which may be rich in Li but will absolutely not be pure Li.

Tim

not_important - 22-9-2009 at 22:28

The amount of lithium in the salts will depend on the nature of the rocks the salts came from. If from igneous rocks, with granites being best, there will be more lithium than if the surrounding countryside is mostly sandstones or other sedimentary rocks; there are a few clays with reasonable lithium content but they are uncommon.

The lithium content of salt lakes is generally in the range of 50 to 200 ppm. As the lake transforms to a salt pan the lithium will concentrate in different regions depending on the chemistry of the water.

The first thing to do is determine if the salts are high in chlorides, sulphates, or carbonates (not very common). If high in chlorides and other halides the lithium will remain in solution as the lake drys, concentrating in the center of the pan. If high in sulphates or carbonates it will concentrate nearer the outer edges of the pan.

After that you need to get an estimate of the lithium content. As it is not likely more than 100 ppm, a kg of brine will yield maybe a tenth of a gram of lithium. Take a weighted amount, that kilogram or so, and treat it with CaCl2 solution to remove most of the sulphate as CaSO4. After that concentrate the solution until crystals of NaCL or KCl start to form. Sodium hydroxide solution can be added to remove magnesium as the hydroxide. After filtering add enough HCl to make the solution slightly acid, then evaporate to dryness. Extract the dry salts several times with hot MeOH, which is filtered and then evaporated to give mostly lithium and calcium chlorides with a small amount of sodium. Dissolve in water, add dilute H2SO4 dropwise until a drop does not give any milkiness from CaSO4 forming. Filter, then add some HCl to make it well acid, then H2O2 and boil to drive off bromine and iodine. After that evaporate to dryness, extract with MeOH or EtOH, evaporate that to get LiCl which is then weighted and the concentration of Li in the crude salts is calculated.

Actually extraction can be less complicated and reagent intensive. The exact process depends on the nature of the main anions.

If a halide pan the selected salts from near the center of the pan are dissolved in water, or if a lake the brine is used. It is concentrated until the lithium content would be about a half of a percent, then ammonium or potassium carbonate added to precipitate magnesium and calcium. Those are removed by filtration, which also removes any suspended solids in the original liquid. It then is made just acid with HCl, and concentrated to remove much of the potassium and some of the sodium as the chlorides. The remaining solution can then be evaporated to dryness, and if ammonium carbonate had been added earlier, heated hot enough to drive off NH4Cl. After cooling it is finely ground and extracted with MeOH or EtOH, which LiCl is quite soluble in.

The crude LiCl can be purified by repeated crystallising, or through the carbonate as described below. It can be converted to the the carbonate via the crude hydroxide, formed by electrolysing a solution of the chloride in a diaphragm cell such as a Gibbs cell. The crude hydroxide solution, which contains chloride, is saturated with CO2 and then brought to boiling for some minutes and filtered while hot to collect the Li2CO3; the filtrate can be returned to the next batch of LiCl to be converted. The precipitated Li2CO3 can be stirred in alcohol to remove LiCl adhering to it.

With a brine high in sulfate it is more difficult. Again it would be concentrated until nearing the saturation point of Li2SO4, which is similar to that of sodium sulfate; calcium sulfate may precipitate during the concentration. Al2(SO4)3 is then added and potassium alum crystallised out. Then remaining Ca and Mg are removed as carbonates, preferably using Li2CO3 but Na or NH4 may be used; this needs to be controlled so that not too much carbonate is added which would cause some lithium to precipitate. After filtering much of the lithium can be precipitated as the carbonate by adding Na2CO3.

The carbonate is best way to purify lithium. Add excess LiCO3 to ice cold water, then saturate the water with CO2 while stirring to convert the carbonate to the more soluble bicarbonate. There should be solid Li2CO3 remaining undissolved. Filter while cold, then bring the filtrate to a boil and hold it there for a number of minutes to drive off CO2 and reconvert LiHCO3 to Li2CO3. Allow the solution to cool just enough that it is not boiling, then quickly filter while hot to collect the Li2CO3. The filtrate can be used again to purify more Li2CO3, but impurities slowly build up and eventually it must be replaced with fresh water. A flame test can give an indication of how much Na and K are present. The waste filtrate can be used in the early processing of the crude salt, at the stage where Ca and Mg are removed as carbonates, thereby recycling the lithium.