Sciencemadness Discussion Board - extract chromium from 18/0 stainless

extract chromium from 18/0 stainless

plante1999 - 21-3-2011 at 15:33

recently i have make test on dollar store spoon witch is wrigthed 18/0 ss so i tried electrolisis of he spoon as an anode and a steel wire as a cathode in sodium hydrogen sulfate and a red incredibly corrosive solution is formed , this solution corrod glass(and stain it)! so i abandond this way. I make test and no nickel is present , vanadium also is not present. So im disolving it in HCl to make CrCl3 and FeCl3. how i can precipitate the chromium (as a coupound), extract the chromium(or precipitate the iron as a salt)?

thanks!

i know many post have been posted on this subject but no one correspond to my way.
.... and please dont post comment like: it is impossible, you cannot , or other same thing, this topic is for improuvement not for regress.

[Edited on 21-3-2011 by plante1999]

Jor - 21-3-2011 at 15:48

Add a large excess of NaOH-solution. All the iron will precitipate a hydrated oxides, while chromium will dissolve as CrO3(3-) (or a hydrated variant). Filter, and next, made the solution acidic again and add ammonia to precitipate Cr(OH)3, or just add enough ammonium chloride (or sulfate/nitrate) to the basic solution.

But why don't you buy pure chromium from eBay. It's pretty cheap and you avoid the messy seperation.

Polverone - 21-3-2011 at 15:51

If there is no nickel or vanadium present, I suggest using the spoon as an anode in a sodium or potassium carbonate solution. The chromium will go into solution as chromate and the iron will be left behind as insoluble basic compounds. I have done this myself, using toaster element wire rather than spoons. If you need pure, solid chromium compounds or metal you can convert the mixed carbonate/chromate solution later.

Much of the electrical energy goes to making oxygen at the anode rather than dissolving the metal, so it is inefficient, but electricity is available everywhere and leaves less waste to deal with than if you start out with dissolving stainless in hydrochloric acid.

plante1999 - 21-3-2011 at 16:09

in fact i will do chromium chemistery because i have used all my titanium and zirconium coumpound , and i will order some other compound in 1month , and i want to make chemistery , and the only chemistery that i like that it is redily avaible is chromium.

ive read this on wikipedia:For the production of pure chromium, the iron has to be separated from the chromium in a two step roasting and leaching process. The chromite ore is heated with a mixture of calcium carbonate and sodium carbonate in the presence of air. The chromium is oxidized to the hexavalent form, while the iron forms the stable Fe2O3. The subsequent leaching at higher elevated temperatures dissolves the chromates and leaves the insoluble iron oxide. The chromate is converted by sulfuric acid into the dichromate.[29]

4 FeCr2O4 + 8 Na2CO3 + 7 O2 → 8 Na2CrO4 + 2 Fe2O3 + 8 CO2 2

Na2CrO4 + H2SO4 → Na2Cr2O7 + Na2SO4 + H2O

The dichromate is converted to the chromium(III) oxide by reduction with carbon and then reduced in an aluminothermic reaction to chromium.[29]

Na2Cr2O7 + 2 C → Cr2O3 + Na2CO3 + CO

Cr2O3 + 2 Al → Al2O3 + 2 Cr

from wikipedia the online enciclopedia ,Chromium (element)

[Edited on 22-3-2011 by plante1999]

[Edited on 22-3-2011 by plante1999]

[Edited on 22-3-2011 by plante1999]

[Edited on 22-3-2011 by plante1999]

plante1999 - 22-3-2011 at 04:19

sorry for the double post but , after disolving the stainless for 12hour i filtered the solution and tested the presence of iron with naoh , it seam that no iron is present. also does anybody have an idee about the composition of the red solution.

the solution is realy dark green.

[Edited on 22-3-2011 by plante1999]

blogfast25 - 22-3-2011 at 06:47

Firstly, for your photos, try a whitish background and get close up: the black ruins everything.

Secondly, no stainless steel without an iron base. Are you sure you used enough alkali? But the ‘red solution’ may indicate the Fe(OH)3.nH2O has peptised, that is: gone into a colloidal state which runs right through the filter! Look up ‘colloid’ and ‘pertisation’, if needed. Fresh Fe(OH)3.nH2O is prone to peptisation when washing the precipitate because by washing the ionic strength of the washing water starts to drop a lot. A simple counter measure is not to wash too thoroughly (thereby losing small amounts of the target Cr…) or allowing the precipitate to mature somewhat. You may also simmer the slurry (obtained by adding the alkali to the solution of SS 18/0 in HCl) for a while. Washing the precipitate with strong NH4Cl (instead of water, thereby keeping the ionic strength high!) will also prevent peptisation.

After separation you then obtain a solution of sodium chromite [+III] (NaCr(OH)4), treat this with HCl, to about pH = 7 to obtain Cr(OH)3.nH2O, wash thoroughly and semi-calcine (>500 C) to dry to Cr2O3. At to low pH you’ll obviously redissolve to CrCl3.

Pure chromium is prepared industrially via aluminothermy from Cr2O3. I’ve done this myself and the metal forms as beautiful reguli of clean skinned metal You’ll need Al powder and fluorite (CaF2) for this reaction.

[Edited on 22-3-2011 by blogfast25]

plante1999 - 22-3-2011 at 08:41

Quote: Originally posted by blogfast25

Firstly, for your photos, try a whitish background and get close up: the black ruins everything.

Secondly, no stainless steel without an iron base. Are you sure you used enough alkali? But the ‘red solution’ may indicate the Fe(OH)3.nH2O has peptised, that is: gone into a colloidal state which runs right through the filter! Look up ‘colloid’ and ‘pertisation’, if needed. Fresh Fe(OH)3.nH2O is prone to peptisation when washing the precipitate because by washing the ionic strength of the washing water starts to drop a lot. A simple counter measure is not to wash too thoroughly (thereby losing small amounts of the target Cr…) or allowing the precipitate to mature somewhat. You may also simmer the slurry (obtained by adding the alkali to the solution of SS 18/0 in HCl) for a while. Washing the precipitate with strong NH4Cl (instead of water, thereby keeping the ionic strength high!) will also prevent peptisation.

After separation you then obtain a solution of sodium chromite [+III] (NaCr(OH)4), treat this with HCl, to about pH = 7 to obtain Cr(OH)3.nH2O, wash thoroughly and semi-calcine (>500 C) to dry to Cr2O3. At to low pH you’ll obviously redissolve to CrCl3.

Pure chromium is prepared industrially via aluminothermy from Cr2O3. I’ve done this myself and the metal forms as beautiful reguli of clean skinned metal You’ll need Al powder and fluorite (CaF2) for this reaction.

[Edited on 22-3-2011 by blogfast25]

1:in 2hour in half i will re made picture.
2:i think used enoug alkaly , but is this possible that this appen (take note that a precipitate of grayis powder have formed in the beaker).

FeCl3 + Cr -} CrCl3 + Fe

when i was talking about the red solution i was talking about the first experiment i made, with electrolisis in NaHSO4. The solution is clear dark red and corrod most metal including copper , iron, aluminium and it also corrod glass!!!! in fact if possible i wich to have 50g+ of solid green chromium trichloride hexahydrate. if i find a good way witch use cheap otc chemical i will made a prepublication , a video and a raport of my experimentation witch i will post on this topic.

and I know that the desk is really dirty but this is not my desk, I worked with my poratativ lab (which is in a steel suitcase) in my grandfather house.

@blogfast: for your question about ZrF4 i will send you in 1-2 day a complete report of all the experimentation with picture , at this time i have a lot of work.

[Edited on 22-3-2011 by plante1999]

[Edited on 22-3-2011 by plante1999]

blogfast25 - 22-3-2011 at 10:20

Cr (0) === > Cr3+ + 3e …. E = + 0.744 V
Fe3+ + 3e === > Fe(0) …. E = - 0.037 V

+ 0.744 + (- 0.037) = + 0.707 V, reaction is possible. But where would the elemental Cr come from??? Your gray stuff could be some magnetite: Fe3O4...

I’d forget about electrolytic dissolution, if I were you: Cr dissolves readily in strong HCl as does Fe. Then precipitate with excess NaOH, allow to stand so the Fe2+ oxidises to Fe3+ in air or add H2O2 or bleach. Proceed as above…

[Edited on 22-3-2011 by blogfast25]

plante1999 - 22-3-2011 at 13:44

wath apen if naocl is mixed with crcl3?

plante1999 - 22-3-2011 at 17:36

sorry for the double post. today i experienced the joy of the stiking iron II hydroxide , but befor explaning it i will start from the begining , ok i will start with my steel suitcase(portable lab). look to the yamaha phaser clutch (my father hoby).

here the suitcase

here the first batch of chemical i have all time with my.

a zoom of my favorite compound:

and the second batch (look to the realy dirthy acetone):

finnaly the third batch:

with this chemical wath can i do for precipitate the iron?

so i disolved the stainless spoon in the hydrochloric acid with reflux.

and after i filter (i take my young sister white board).

than i ad sodium hydroxide to 10 ml of it the realy stiky iron II hydroxide form and the chromium hydroxide is contained inthe iron hydroxide. so i need an other way for precipitate the iron (the picture of my portable chemical is for that).

i ave thinked of :
the solution + H2O2
the second solution + naocl , but i dont know if naocl afect the crcl3.

S.C. Wack - 22-3-2011 at 17:42

I would check the pH of that solution. IIRC everything should precipitate without drama though I may recall this with some nickel in there and perhaps heat. I suspect this subject has been covered pretty well before.

I would NOT count on NaOH in any quantity to dissolve much Cr in the presence of so much Fe. That blue-gray precipitate holds a lot of Cr, and NaOH. I dare anyone to find this used in the analytical lit. for the separation of Cr and Fe; naturally I say this without looking - let's see how that goes. Barring the use of an oxidizer with the alkali of course. I used H2O2 with the boiling well-stirred sludge and did obtain considerable quantities of Cr+6, but do not recommend this. For one thing among many is that excess NaOH seems necessary with makes isolation less simple.

You're on the right track with a chromite process, but I would target the immediate preciptitate as is.

blogfast25 - 23-3-2011 at 05:06

Quote: Originally posted by plante1999

wath apen if naocl is mixed with crcl3?

Hypochlorite cannot oxidise Cr3+ to chromate (Cr [+VI]) in alkaline conditions (see reduction potentials). H2O2 would oxidise it to Cr [+VI] but I don’t see the point here.

Quote: Originally posted by S.C. Wack

I would NOT count on NaOH in any quantity to dissolve much Cr in the presence of so much Fe. That blue-gray precipitate holds a lot of Cr, and NaOH. I dare anyone to find this used in the analytical lit. for the separation of Cr and Fe; naturally I say this without looking - let's see how that goes. Barring the use of an oxidizer with the alkali of course. I used H2O2 with the boiling well-stirred sludge and did obtain considerable quantities of Cr+6, but do not recommend this. For one thing among many is that excess NaOH seems necessary with makes isolation less simple.

You're on the right track with a chromite process, but I would target the immediate preciptitate as is.

Whether or not there are references to the separation of Fe and Cr in the anal. lit. (I’m pretty sure there are) is immaterial: Cr3+ IS amphoteric, Fe2+/Fe3+ IS NOT and that makes separation possible. My experience shows that 'fresh' Cr(OH)3.nH2O dissolves in NaOH solutions very readily, much like Al(OH)3.nH2O.

Firstly, complete dissolution of the metal in the acid has to be achieved of course, it’s not clear to me whether that’s the case or not in plante's effort. Then precipitate the whole lot with strong NaOH, using some excess to get the Cr3+ as Cr(OH)6(3-) (chromite). Filter and wash precipitate with strong NaOH to get all the chromite out.

Neutralise the filtrate carefully with HCl solution until Cr(OH)3.nH2O appears, filter and wash carefully. To ensure getting rid off all sodium, redissolve in medium HCl and reprecipitate with WEAK ammonia (avoiding Cr-NH3 complexes which would form with strong, excess ammonia solution) as Cr(OH)3. Filter and wash carefully. Drying and calcinating the hydrated chromium [+III] oxide will get rid of any ammonia/ammonium.

[Edited on 23-3-2011 by blogfast25]

blogfast25 - 23-3-2011 at 09:00

Chromium’s [III] amfoterism:

Below three identical test tubes with some K,Cr [III] alum solution:

After treatment with alkali:

1 = control

2 = after adding sufficient NaOH 1 M, Cr(OH)3.nH2O drops out as a greenish precipitate.

3 = after creating the same precipitate as in 2 and then adding a small amount of NaOH 4 M: the precipitate redissolves effortlessly to an emerald green solution of Na3Cr(OH)6.

The pix don’t really do it justices (too concentrated solutions, I think…)

[Edited on 23-3-2011 by blogfast25]

S.C. Wack - 23-3-2011 at 09:22

Quote: Originally posted by blogfast25

Whether or not there are references to the separation of Fe and Cr in the anal. lit. (I’m pretty sure there are) is immaterial

I thought said separation was the subject of this thread. Your reaction of the hydroxide without massive amounts of iron present is immaterial.

Since I am not completely inept and suspect you know nothing about this and have never done it you may want to read rather than disregard the literature. I'm pretty sure the iron prevented solution fairly well but not entirely. In fact I recall considerable iron being present (it's rather conspicuous after a time in air) in the alkali, and chrome in the precipitate. Indeed the precipitate was soaked and washed many times with NaOH, and it still contained Cr. However I probably did add solid NaOH in my larger experiments with the acid solution that I still remember some, which is likely a no-no. I expect many books at Google Books to have available full text detailing separation of the two; as a rule not involving extraction with alkali, since my efforts were not drawn out of thin air.

Oxidizers are used in the literature. You say hypochlorite is no good yet there are many references to alkali and chlorine.

But if the green solution really is strongly basic, and precipitates the hydroxide on boiling, you've got chromite. If the solution turns chromate yellow on adding H2O2, and dichromate orange on addition of acid, well that's what it is.

blogfast25 - 23-3-2011 at 09:57

@ S.C. Wack:

Okay, keep your hair on. No one said you’re inept. Your condescension is uncalled for.

You claim iron prevents chromium from dissolving (if I understand you correctly)? How, prey tell? A this point I don’t know whether (plante’s) dissolution is complete either, of course, as I stated. If the Cr doesn’t dissolve, the separation could be achieved this way. If it can then separation based on amfoterism must be possible. Give me one good reason why it shouldn’t. And better solvents for SS may also be available.

I said that based on half potentials, ClO- isn’t capable of oxidising Cr3+ to chromate in alkaline conditions. Based on tabled reduction potentials. Look it up. But I’ll gladly test it myself.

Oh, I’ve got chromite alright, you bet! How else to explain the Cr(OH)3.nH2O dissolves readily in (actually fairly weak) NaOH? Done it may times before, including addition with H2O2 to get yellow chromate. Also on this forum.

Edit:

On hypochlorite + Cr3+, I seem to have misread a table (http://web.archive.org/web/20070518092613/http://www.northla...), which gives:

Reduction: ClO- + H2O + 2e === > Cl- + OH- …. E = + 0.81 V
Oxidation: Cr(OH)3 + 5 OH- === > CrO4(2-) + 4 H2O + 3e …. E = + 0.13 V

So the cell potential would be + 0.94 V.

I’ll verify that experimentally tomorrow.

[Edited on 23-3-2011 by blogfast25]

S.C. Wack - 23-3-2011 at 14:14

Quote: Originally posted by blogfast25

Oh, I’ve got chromite alright, you bet

My last post did not refer to your post immediately before it in any way. I still speak of the original green solution.

There are other experiments. Not always fact filled but relevant:
http://books.google.com/books?id=erMKAAAAYAAJ&pg=PA334

plante1999 - 23-3-2011 at 14:15

how can i precipitate iron sulfide and chromium sulfide?

ive read that reaction work:

2FeCl3 + FeS -> 3FeCl2 + 1/8S

and

6FeCl3 + Cr2S3 -> 2CrCl3 + 6FeCl2 + 3/8S

this one is not favorable.

[Edited on 23-3-2011 by plante1999]

blogfast25 - 24-3-2011 at 09:47

Two experiments

1. Comparison of H2O2 (3%) with commercial bleach as oxidisers for chromite solutions:

Two tubes with approx. 0.1 M Cr3+:

After adding 4 M NaOH and (left) H2O2 and (right) hypochlorite:

At first the hypochlorite didn’t seem to do anything but after heating some Cr(OH)3.2H2O dropped out and the yellow chromate colour developed in the supernatant liquid.

2. Fe-Cr separation experiment based on chromite formation:

For this a 0.1 M solution of Mohr’s Salt (Fe[+II]) was prepared and an equal volume amount of the 0.1 M Cr3+ solution was added. The resulting solution is thus about 0.05 M Cr3+ and 0.05 M Fe2+. Since as the atomic weights of Fe and Cr aren’t miles apart the weight ratio of both elements is roughly 1.

Three test tubes were filled with this broth:

After treatment:

Left: no treatment.

Middle: treated with 4 M NaOH. Turns emerald green but with precipitate.

Right: same as middle but after filtration (filter not shown). The filtrate runs a perfectly clear emerald green, about as intensive as the middle tube. It filters slowly. I didn’t wash.

The precipitate on the filter: right from the start the greenish precipitate started to discolour to reddish/brown. W/o a shimmer of a doubt this is Fe(OH)2.nH2O oxidising to hydrated rust:

This experiment says nothing much about actual separation percentages, yet shows that separation between Fe and Cr is possible, based on Cr [III]’s ampfoterism.

It says nothing about the solubility of stainless steel in strong HCl either. That will be tested separately.

As an aside:

In at least one case, industrially iron and chromium are separated from each other by fusing Chromite ore, FeCr2O4, with KOH, lime and air, to form potassium chromate, CaCO3 and Fe2O3. Leaching of the ground frit followed by acidification then yields dichromate.

[Edited on 24-3-2011 by blogfast25]

blogfast25 - 26-3-2011 at 10:55

Well, well. Looks like SC Wack may well be right or at least partly right about the difficulty of separation Cr and Fe using chromite to keep Cr in solution...

Here’s are the experiments.

56 g of a stainless steel object (a bathroom beaker) were dissolved in about 27 w% HCl and 300 ml of solution were obtained and filtered. It took about 2 h. Dissolution was near complete with just a little brownish-blackish residue left on the filter (more about that below).

100 ml of that solution was first iced and then neutralised with 3 M NaOH to pH 13 to 14. The precipitate formed was very dark (blackish, really) and was filtered off on a coffee filter. To my surprise, the filtrate ran clear and almost colourless, no green (chromite) to be seen (see photo, RIGHT). The filtrate was then tested for chromium by boiling a 20 ml sample with some twenty ml bleach, with extra NaOH added. No precipitate, no green, no yellow, nothing!

Then two teaspoons of the still very wet precipitate were mixed with some more NaOH and bleach added. Immediately the colour of the precipitate changed to the familiar reddish-brown (of Fe2O3) and this suspension was boiled for about 5 mins, topping up with bleach once. This was filtered and now the chromium showed up as green chromite (see photo, LEFT):

Treating the green solution with H2O2 (9 %) yielded chromate yellow.

From this result I tentatively conclude that on this occasion, in clear contradiction with the previously obtained test tube results, the chromium had co-precipitated in its entirety with the Fe2+, the majority constituent.

Other tests were carried out, some ongoing.

Some of the precipitate was dried in a steel pan on my lab gas cooker and 8 g of this (see photo, MIDDLE) very dark powder was mixed with 8 g KOH and 2 g KClO3 and fused for 15” to a dull red heat. Water was then added after cooling and this will be filtered tomorrow.

Also 2 teaspoons of the still wet precipitate have been mixed with 50 ml water and 25 ml NaOH. This will be left to stand overnight and filtered. No oxidiser (other than air) is present.

Then a test tube test. To a few ml of the SS steel solution was added the same amount of the Cr3+ solution used in the test tube experiments in the post above. 4 M NaOH was then added in excess. Again the filtrate ran clear and colourless, indicating that the Cr had co-precipitated with the iron.

Is it possible that in some conditions something akin to Chromite ore, FeCr2O4 (FeO.Cr2O3), precipitates and that only oxidation of the Fe [II] to [III] ‘breaks’ this ‘complex’ (or ‘double oxide’)?

Finally, a couple of tests on the brownish-blackish filter residue. It dissolves in 50/50 w/w % NaOH, with evolution of gas, which would point to carbon or silicon. With hot, 38 w% nitric acid no dissolution occurs but the residue is ‘bleached’ (??!?) No nitric soluble metals like Ni or Cu (for instance) appear to be present in the HCl insoluble residue.

Final results tomorrow.

[Edited on 26-3-2011 by blogfast25]

blogfast25 - 27-3-2011 at 09:36

The result of the fusion with KOH was leached by adding cold water and standing overnight, it was then filtered. The filtrate is very dark green with potassium chromite:

The result of the test where only a lot of extra alkali was added wasn’t worth filtering: it can be seen that the supernatant liquid is clear and colourless:

Yet another experiment was conducted by oxidising 30 ml of the stainless steel solution with about 5 ml of 38 w% nitric acid:

FeCl2(aq) + 1/3 HNO3(aq) + HCl (aq) === > FeCl3(aq) + 1/3 NO(g) + 2/3 H2O(l)

The oxidation was carried out in a large test tube on steam bath:

The cooled solution was then neutralised to pH 13 - 14 and filtered: much to my surprise the filtrate ran clear and colourless:

Heating the slurry obtained above made no difference but adding bleach to the hot slurry cause the filtrate to run yellow:

Conclusions:

1. It would appear that in some conditions iron and chromium co-precipitate. This wasn’t observed at low concentrations (0.05 M) and low Fe/Cr molar ratios (about 1) but it was observed at high concentrations (about 3 M) and high Fe/Cr molar ratios (8 - 9). Whether a Cr/Fe complex precipitates or whether this is a case of chemisorption, in one instance merely oxidising the Fe [+II] to Fe [+III] wasn’t enough to ‘free’ the chromium.
2. There are various ways to recover chromium from scrap stainless steel but at bench level I’d suggest the following:
• Dissolve scrap in strong HCl, then precipitate with strong alkali as mixed oxide.
• Filter off precipitate (washing is optional) and dry it to a paste or powder.
• Add about the same amount of KOH (this may be overkill but it worked for me) and fuse the mixture. After cooling add water and allow to soak overnight.
• Filter: the filtrate should contain the chromium, in my case as potassium chromite (but oxidation state of the Cr may depend on duration of fusion). No guarantees about the degree of separation can be given.

S.C. Wack - 27-3-2011 at 10:06

Quote: Originally posted by blogfast25

Is it possible that in some conditions something akin to Chromite ore, FeCr2O4 (FeO.Cr2O3), precipitates and that only oxidation of the Fe [II] to [III] ‘breaks’ this ‘complex’ (or ‘double oxide’)?

When using 3-10% H2O2, only a small amount of Cr would extract at once, only on boiling even after the iron looked like it was all oxidized and lots of peroxide had been added (much seemed wastefully decomposed instantly). It took several repetitions to get all the Cr out. And the filtered, clear, chromate/NaOH solution contained unseen iron, which did not all precipitate at once on slow concentration in air.

blogfast25 - 27-3-2011 at 10:26

Quote: Originally posted by S.C. Wack

True, but in all these experiments I've only ever used H2O2 (3% but I've now got 9%) to show the green was due to chromite, never to oxidise anything else. It's far too precious for that, IMHO.

What I also found surprising is that the fusion with KOH seemed to yield chromite only. But it was a very short run (15")...

plante1999 - 29-3-2011 at 08:01

does it will work with impure NaOH containing NaNo3 for making sodium chromite.

the way: disolve the stainless in hot HCl when no acid is present boil the solution in a stainless mud , you will have calcined oxide.
than take sodium hydroxide and melt it in and lets it for a long time . digest it and filter , now you have sodium chromite. (does it will be pur?) if yes
boil it in stainless to get the oxide , if no , i dont have any idee.

thanks!!

blogfast25 - 29-3-2011 at 12:49

1st question: I don't see why not. Using 'toilet drainer', eh?

If you wanted to to purify the chromite, best way would probably to use KOH rather than NaOH, thus obtaining the K chromite. Oxidise this to K chromate, then acidify with H2SO4, this converts the chromate (CrO4(2-)) to potassium dichromate (K2Cr2O7), which is only sparingly soluble in cold water (Wiki: 4.9 g/100 g water @ 0 degrees C). So simmer in your solution, then ice. Recrystallise once for good purity. Na2Cr2O7 could probably be displaced to K2Cr2O7 with KCl and ice.

The dichromate can be converted to Cr3+ salts by reduction with alcohol (methylated spirits, wine, vodka, whatever)

cyanureeves - 29-3-2011 at 13:52

plante1999 what is the make up of that dg spoon?i got a custom belt buckle made for a navy officer and i haven't a clue what its made of.it looks like s.steel with with gold plate outline of an american eagle.with all due respect to servicemen i will boil some of it in hcl acid and electrolyze a portion in sodium carbonate.anyhow what test did you use for nickel test?ammonium hydroxide?

plante1999 - 29-3-2011 at 14:55

i think you must go to the dollar store and buy spoon , it is cheap and you wont scrap something that is interessing. ammonium hydroxide make a good test , if nikel is present a green prec. form and it disolve in exec ammonia , you will get a distinctive pink color. if no nikel is present , you sould see nothing , but befor peforming this test ad small amount of H2O2 for oxidising compound II to III.

plante1999 - 29-3-2011 at 16:35

sorry for the double post.

finnaly no-iron chromium compound.

procedure:
3spoon disolved in 100ml 31%HCl .
than boil the solution to get the calcined oxide.

than take a ss beaker and ad green crystal drano, melt the mixture at 600-800 for 15minute.
disolve the chromite in water , ad small amount of zinc chloride (((catalist)a yellow precipitate form) chrome yellow) than ad HCl and you have green chromium III chloride.

picture for later.....

[Edited on 30-3-2011 by plante1999]

cyanureeves - 29-3-2011 at 17:03

what would they use instead of steel? or iron and make it cheap?zinc? you have to melt the drano?anyway dichromate in solution with a little sulfuric acid and using a lead anode will leave a wonderful yellow crossedge pattern on metal.just like you see on the inside of a new tin can. it's not what i was after but after seeing this i was not dissapointed.next time i'll look you up for metal composite instead of google.this was like c.s.i.

plante1999 - 29-3-2011 at 17:15

finnaly i decided to make a large amount of zinc chromate with my zinc chloride solution. i precipitate it and than wash it with ammonia , i think it is very pure and , can i use zinc chromate to make chromium , via thermite reaction.

it is probably made of aluminium or zinc with a brass plating.

3 ZnCrO4 + 8 Al === > 3 Zn + 3 Cr + 4 Al2O3

i think it will probably need an oxidizer.

no battery for making picture , sorry.

[Edited on 30-3-2011 by plante1999]

[Edited on 30-3-2011 by plante1999]

plante1999 - 29-3-2011 at 17:36

photo!

finally whe have done!!!

first , the beaker with the rust residu . the filter paper with zinc chromate . erlenmeyer with ammonia and chromium hydroxide , my test tube for precipitation and finnaly , the spoon. I think an improuvement is to precipitate lead chromate and than add HCl to the dry product to make nearly insolube lead chloride and chromium III chloride.

check my homemade clamp !!

[Edited on 30-3-2011 by plante1999]

[Edited on 30-3-2011 by plante1999]

[Edited on 30-3-2011 by plante1999]

[Edited on 30-3-2011 by plante1999]

[Edited on 30-3-2011 by plante1999]

[Edited on 30-3-2011 by plante1999]

[Edited on 30-3-2011 by plante1999]

plante1999 - 30-3-2011 at 11:34

Extraction of lead chromate from 18/0 Stainless steel
by plante1999

First this is a guide for extration of a realy pur chromium compond for futur prossesing , the lead chromate produced can be aded to 0 degree celcius 31% hydrochloric acid to precipitate lead chloride and keep in solution chromium III chloride. Picture will be aded later.this is a prepublication of the futur prepublictation that i eill post on prepublication forum.

Warning: Hydrochloric acid is corrosive to the skin , the fume are toxic and corrosive. Molten sodium hydroxide is incredibly corrosive lead chromate is probably a cancerigen.

Part:1 Lead Acetate

For this part you will need:
Lead metal , can be found at the scrap yard
copper acetate , different way of synthesis include : copper carbonate + vinegar (acetic acid) or cleaning vinegar(10% acetic acid) + hydrogen peroxide + copper.
800ml beaker
hot plate
filter paper
funnel
erlenmeyer for filtering

Take an exes of lead and ad it to a 800ml beaker with 500ml of 10% copper acetate solution. After a certain amount of time the lead will react and form lead acetate.

This is the equation:
Pb + Cu(C2H3O2)2 → Pb(C2H3O2)2 + Cu

Filter the solution. You have around 10% solution , boil it to 120ml. Lets the solution hot for one of the last step. Repeat this 3 time.

Part:2 Make the oxide of the 18/0 Stainless

First you need to get Stainless steel spoon from the dollar store. This type of spoon is alway 18/0 stainless steel , 18% chromium , 0% nickel and 82% iron.

I have found 2 way to make the oxide , here a resume of each way:

Way:1 disolve spoons in hot Hcl and boil the solution to get the calcined oxide.
Way:2 electrolisis of the spoon in NaCl solution and boil the solution to get the oxide.

Way:1 Disolving in HCl

You will need:
3x166ml of 31% Hcl
250ml beaker
3 spoon or 105g of 18/0 Stainless
Hot plate

Fist take 166ml of 31% HCl per 35g of Stainless steel (use 105g of stainless) Heat the HCl to boiling in glass beaker and ad the stainless. 2 reaction take place at the same time.

Fe + 2HCl -> FeCl2 + H2

2Cr + 6HCl -> 2CrCl3 + 3H2

After most of the Stainless eacted , boil the solution in a Stainless beaker to get the calcined oxide. Lets it hot for the next step.

Way :2 The electrolisis

You will need:
A 12Volts 15amps power supply
400ml of 5% NaCl solution
3 spoon or 105g of 18/0 Stainless
Hot plate

Take 400ml of 5% NaCl solution and electrolise the spoon as an anode in a steel beaker that is use as an cathode. After certain amount of time the hydroxide will precipitate , this way have an adventage , but falloig this guide you need to disolve 105 g of 18/0 stainless, you could disolve the amount of spoon you want. When it is done boil the solution to get the calcined oxide. Lets it hot for the next step.

Part:3 Make sodium chromate

You will need green crystal drano. Ad 70g drano to the mixed oxide made in the part 2 per 105g of Stainless and heat with a blow torch to melt the hydroxide with the chromium oxide , mix it with a Stainless spoon. Stop after 15-20min the heating.

This reaction take place :

Cr2O3 + 4NaOH + 3NaNO3 -> 2Na2CrO4 + 3NaNO2 + 2H2O

Part:4 Make Lead chromate

You will need :
100ml of distill water
2x500ml beaker
300ml of hot acetate solution
The melt from the part:3
2 filter paper
Buchner funnel
Vacuum pomp
500ml buchner funnel
3-5% ammonia solution

Digest the melt in 100ml of distill water for 12hour. Now filter it in 500ml beaker , you will get yellow sodium chromate solution. Per 105g of Stainless ad 300ml of the hot lead acetate solution.

This is the equation of the reaction :

Pb(C2H3O2)2 + Na2CrO4 -> PbCrO4 + 2Na(C2H3O2)

A heavy yellow precipitate form, vaccum filter it and wash it with dilutew ammonia.

[Edited on 30-3-2011 by plante1999]

[Edited on 30-3-2011 by plante1999]

[Edited on 30-3-2011 by plante1999]

[Edited on 30-3-2011 by plante1999]

[Edited on 30-3-2011 by plante1999]

blogfast25 - 30-3-2011 at 12:58

Quote: Originally posted by plante1999

i think it is very pure and , can i use zinc chromate to make chromium , via thermite reaction.

it is probably made of aluminium or zinc with a brass plating.

4Al + 3ZnCrO4 -> 2Al2O3 + 3Zn + 3Cr

i think it will probably need an oxidizer.

no battery for making picture , sorry.

[Edited on 30-3-2011 by plante1999]

Oxidiser?? What do you think ZnCrO4 is, huh?

But using Zn chromate will mean you’re making an alloy of Zn and Cr, not pure Cr:

ZnCrO4 + 8/3 Al === > Zn + Cr + 4/3 Al2O3 is correctly balanced (yours isn’t). Multiply both sides with 3 if you don’t like fractions (LOL):

3 ZnCrO4 + 8 Al === > 3 Zn + 3 Cr + 4 Al2O3

When you got the sodium chromite, why not carefully neutralise to pH ≈ 7? Cr(OH)3.nH2O drops out. Filter, wash and dry (semi-calcine) to Cr2O3.

Then Cr2O3 + 2 Al === > 2 Cr + Al2O3

Industrially, aluminothermic reduction of Chromite ore is used to produce ferrochomium:

FeCr2O4 + 8/3 Al === > Fe + 2Cr + 4/3 Al2O3.

plante1999 - 30-3-2011 at 13:03

in fact i think the zinc will volatilise. and i already tested the ph 7 but it doesn work for my. Probably because i have no chromite but chromate , because of the 25%NaNO3

[Edited on 30-3-2011 by plante1999]

cyanureeves - 30-3-2011 at 13:36

excuse me plante1999. in step #3 where does the chromate come from? the spoon used to stir or the s.steal container in which you melted it? or did i miss a step? if 18% chromium and 82% iron were 18% nickel and 82% iron,wouldn't that be good quality s.steel? go for chromium metal now!unless you got to do all that dry calcium burning stuff you googled.

plante1999 - 30-3-2011 at 13:47

when drano is added to the beaker it melt and react with the chromium oxide in the mixed oxide of iron and chromium to make the chromate.

This reaction take place :

Cr2O3 + 4NaOH + 3NaNO3 -> 2Na2CrO4 + 3NaNO2 + 2H2O

cheap stainless contain 18% chromium 0%nickel and 82% of iron.

the guide is edited.
[Edited on 30-3-2011 by plante1999]

[Edited on 30-3-2011 by plante1999]

cyanureeves - 31-3-2011 at 06:25

the oxide step is very short in detail and i overlooked it even though its the most important. sorry about the 18% nickel crap i said. i used to work with s.steel sheets alot and all this time i thought nickel was a bigger component than chromium in s.steel. you use the term calcined, does that mean cooked dry after evaporation or will just evaporation do?the term calcined is used alot in chemistry lit and so is dry over and passed through. as passed through a stream of hot charcoals.confusing terms!by the way lead in vinegar will bleed white lead acetate too wont it?but it will take longer i bet. cool work man.

plante1999 - 31-3-2011 at 08:07

when i said calcined i want to said heated on a hotplate to decompose the chloride or the hydroxide tho the oxide , like you said it need to be cooked , evaporation wont decompose the chloride to the oxide and hydroxide will take a long time. Lead in vinegar take so long time that it is not usefull. Thanks!!!

blogfast25 - 31-3-2011 at 12:21

Quote: Originally posted by plante1999

in fact i think the zinc will volatilise. and i already tested the ph 7 but it doesn work for my. Probably because i have no chromite but chromate , because of the 25%NaNO3

[Edited on 30-3-2011 by plante1999]

Yes, my bad, chromate needs to be reduced first to chromite, of course.

ZnCrO4 thermite is likely to near-explosive, possibly flash powder. You MUST use Cr2O3.

By calcining here i mean heatinng to 500 C or more, so not 'proper'calcination (1000 C and above)

[Edited on 31-3-2011 by blogfast25]

Magpie - 31-3-2011 at 19:11

Quote: Originally posted by plante1999

check my homemade clamp !!

I like your clamp. Did you use a coat hanger?

I have just made a nickel crucible/liquid metal bath assembly from a Mr Bartender cocktail shaker. But I'm not ready to show it off yet.

blogfast25 - 1-4-2011 at 07:31

Yeah, the clamp is good, very professionally looking! But I doubt if coat hanger wire would be rigid enough. And how is it attached to the lab stand?

A broad and fairly crude estimate of the reaction enthalpy for the aluminothermic reduction or ZnCrO4 with Al came out as somewhere in the region of - 800 to - 850 kJ/mol of Cr produced. For the reduction of Cr2O3 the value is - 270 kJ/mol of Cr produced. A whopping difference!

[Edited on 1-4-2011 by blogfast25]

blogfast25 - 2-4-2011 at 08:13

About 6 mmol (expressed as [Cr3+]) of blue-green chromium [III] oxide hydrate in a large test tube:

Obtained as a by-product of oxidising K2Cr2O7 with methylated spirits.

3 chromium metal nuggets (11.2 g), obtained from Cr2O3 thermite (and a 1 p coin):

[Edited on 3-4-2011 by blogfast25]

plante1999 - 5-4-2011 at 08:46

Quote: Originally posted by blogfast25

Yeah, the clamp is good, very professionally looking! But I doubt if coat hanger wire would be rigid enough. And how is it attached to the lab stand?

[Edited on 1-4-2011 by blogfast25]

thanks! it is made from large coat hanger plated nickel wire.
it is attached be 2 stainless steel bolt.

nice chromium from the oxide!

plante1999 - 6-4-2011 at 07:56

does methanol work for oxidising ammonium or sodium dichromate?

blogfast25 - 6-4-2011 at 13:51

Quote: Originally posted by plante1999

does methanol work for oxidising ammonium or sodium dichromate?

You mean reducing (Cr [+VI] === > Cr [+III])? Yes. All primary alcohols are oxidised to their carboxylic acids, all secondary alcohols to their ketones... Methanol works to reduce dichromate to Cr [+III].

Strangely enough, in acid conditions dichromate can also oxidise H2O2 to water. So, in alkaline conditions H2O2 is an oxidiser for Cr3+, in acid conditions Cr2O7 (2-) oxidises H2O2 to H2O!

[Edited on 6-4-2011 by blogfast25]

Lambda-Eyde - 6-4-2011 at 13:53

I'd use isopropanol in place of methanol, as both methanol and formic acid are toxic and not exactly fun to handle. Acetone, on the other hand, is a walk in the park.

blogfast25 - 6-4-2011 at 13:59

Quote: Originally posted by Lambda-Eyde

I'd use isopropanol in place of methanol, as both methanol and formic acid are toxic and not exactly fun to handle. Acetone, on the other hand, is a walk in the park.

Both methanol and formic acid really are of quite low toxicity: avoid spills, imgestion and wash your hands on contact. I've seen formic acid being used in kettle descaler sachets.

[Edited on 6-4-2011 by blogfast25]

ScienceSquirrel - 6-4-2011 at 14:05

The standard reagent for making chrome alum from potassium dichromate is sulphuric acid and methylated spirits.
I have done it and it works really well, the other product is mainly acetaldehyde.

plante1999 - 10-4-2011 at 05:17

2 CrCl3 + Cr → 3CrCl2 , does anyone can test if it work? i think the iron cannot react because it is more noble than chromium, some patent said for extract iron from ore to conssentrate the use of FeCl3 is good.

blogfast25 - 10-4-2011 at 09:49

Quote: Originally posted by plante1999

2 CrCl3 + Cr → 3CrCl2 , does anyone can test if it work? i think the iron cannot react because it is more noble than chromium, some patent said for extract iron from ore to conssentrate the use of FeCl3 is good.

Check the reduction potentials for Cr3+ == > Cr2+ and Cr(0) == > Cr3+. Add Ered + Eox. If Ered + Eox > 0 the reaction can proceed...

cyanureeves - 11-4-2011 at 05:13

plante1999 you did very well with chromium extraction and i think you would have been useful in the nickel from cupro-nickel extraction thread. that thread has many methods but i dont know if all were actually done because alot of theory was in place.The belt buckle i dissolved turned out to be cupro-nickel i dont know why i forgot about that s.steel looking alloy.electrolyzing and plating out the copper onto the annode is the best i could do.nichrome wire has a bit of chrome in it,i took some from inside of heating coil. i electrolyzed some in sulfuric acid solution and some in hcl solution and dont understand why i cant seperate nickel solution from chromium by adding sodium hydroxide. i thought i would get insoluble nickel hydroxide and chromium in solution but it all precipitates as a black cloud.both also go into carbonate together and when turned into acetate it turns red(chromium acetate?)by the way nichrome wire made a great nickel anode for nickel plating. i electrolyzed some nichrome wire in sodium carbonate for three solid days i got a yellow solution and a bit of orange precipitate but spilled that solution. all was not lost because the acetate solution mixed well with my homemade nickel watts plating bath. which consists of nickel sulfate, nickel chloride and boric acid and now nickel acetate. i cant believe canadians used solid nickel in coins, so it is common to find these coins in circulation still isnt it?

plante1999 - 11-4-2011 at 08:16

it is very common to find 85% nickel coin in canada but for geting the nickel the best way I find is disolve the alloy in 30%HCl with 3% H2O2, than is precipitating the sulfide , leaching the sulfide with chlorine to solubilise copper but, dont solubilise nickel sulfide , prety hard process but very effective.

for your ''i had NaOH and the precipitate was black'' , this process dont work , this is just theorie , when i test this it was non-worcking.

but , why you dont post that on the nickel extraction post , also i wasn't usefull in the post of the extraction of nickel.

about CrCl3 leaching process , it work good , altoug after a certain amont of time it stop to disolve and whe need to lets it in air with HCl to get again CrCl3. some iron impurity is observed.

i thing for beter inprouvement , ading na2s to solution of ss 18/0 to precipitate sulfide and than leach the crushed sulfide with CrCl3.

but for worcking process i think at this time the best process is the one i explain up ther , (you can replace the lead acetate by satured sol of zinc chloride).

at this time i am in work for making a video about the extraction of Cr.

[Edited on 11-4-2011 by plante1999]

[Edited on 11-4-2011 by plante1999]

[Edited on 11-4-2011 by plante1999]

plante1999 - 13-4-2011 at 15:27

today something very special appen , i made a solution of 4% sodium hydrogen carbonate and i electrolise 18/0 ss and after a certain amont of time i stop the electrolisis and i ad other sodium hydrogen carbonate , at the start nothing but , after 15seconde very vigourus reaction ocured relaching a gas that smell carbon dioxide , wath is this!

also it react with all sodium hydrogen carbonate i ad, over 40g was aded to 70ml of solution , migh the solution is a catalyst for decomposition of sodium hydrogen carbonate.

cyanureeves - 13-4-2011 at 17:47

would not that be a hydroxide?dude i electrolyzed for three days and every day i would add a bunch of sodium carbonate and its like it disappears to nowhere with only a tad of precipitate.carbon dioxide smell?is that like the smell of scentless lye soap?is your solution chromium yellow or ferrous green?

plante1999 - 14-4-2011 at 02:33

my sol is green and when i ad the NaHCO3 lot of buble are producted the same smell as when i make carbon dioxide from NaHCO3 , i suspect something like this:

....................catalyst
2NaHCO3 ---------->Na2CO3 + CO2 + H2O

[Edited on 14-4-2011 by plante1999]

[Edited on 14-4-2011 by plante1999]

[Edited on 14-4-2011 by plante1999]

Arthur Dent - 14-4-2011 at 03:37

Quote: Originally posted by plante1999

it is very common to find 85% nickel coin in canada but for getting the nickel

An even better, from 1955 to 1981, all canadian 5 cent pieces were made out of solid 99.9% nickel! That's how I made myself a small batch of nickel chloride, I dissolved 6 or 7 coins in HCl (took months) until they were nearly completely gone. The resulting solution was a beautiful emerald green color.

Robert

blogfast25 - 14-4-2011 at 04:40

CO2 is odourless.

Measure the pH when the bicarbonate starts fizzing. Electrolysis seems to have rendered your solution aicdic. Your 'catalyst' is H3O+.

cyanureeves - 14-4-2011 at 04:48

wikipedia shows canadian coins made prior to 1999 to be of 99% nickel, 1968 quarters to be of 50% silver and all main streets paved in gold. whoa! nickels were changed in composite in 1981 but not the quarters, canada's money value is backed by nickel?plante1999 maybe your effervesence is just oxide build up on annode or cathode contact and is causing a delay in reaction. cool reaction you got figured out i just thought that and oxygen atom gets pushed out at the annode and hydrogen at the cathode.it will be interesting to see where the chromium will end up.

Zyklon-A - 13-3-2014 at 11:55

After searching through all my "silverware", I found three fork that said: SS, 18CR. So does that mean that it's composition is 18% Cr and 82% Fe? It didn't say: 18/0 or 0 Ni, so should I just assume it contains no nickel?

blogfast25 - 13-3-2014 at 12:30

Stainless steel is supposed to be 10.5 % minimum of Cr. No Ni.

Zyklon-A - 13-3-2014 at 12:41

I don't know if that's what SS is supposed to be. But many kinds of SS silverware contains nickel. 18/10 SS is 72% Fe, 18% Cr and 10% Ni.

Crowfjord - 13-3-2014 at 13:57

There are many different grades of stainless steel with their own specifications on elemental percentages. The most common I've dealt with are 304 and 316, which can contain between 16 to 19 or so percent Cr (the highest I have seen was about 25 percent Cr, I think), 8-10 percent Ni, up to 2 percent Mo and about 1 percent Mn. I rarely see stainless steel without at least a couple weight percent nickel, with 400 series steels like 410 and 416 type steels being an exception.

Zyklon-A - 13-3-2014 at 17:18

This site says that there are two kinds of silverware, 18/10 and 18/0, which the "18" is the Cr and the "10 or 0" is the Ni.