qst42know
Well-known member
See the Olin alloy at the end of this page. Quite a blend.
http://en.wikipedia.org/wiki/Phosphor_bronze
http://en.wikipedia.org/wiki/Phosphor_bronze
Went against my gut! Grrr...
- Thread starter cnbarr
- Start date
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Hey Chris....We need more schooling. 
Here's why. I follow the teachings of Harold on this tin thing. If I recall correctly, Harold has posted that the incineration and HCL wash was not a cure for tin. It just made it much more filterable. ( If I am misquoting you on this Harold Please correct me). This is my findings using this method.
After incineration and the HCL wash, the solution always tests positive for gold. Everytime I have done it any way. This time I looked at what Geo posted about the tin becoming elemental with incineration so I doubled the incineration time to see if I could effect a change of the tin chloride to metal. Torched it with a mapp gas torch for 20 minutes, Even concentrated on selected areas for an extended time to see if I could make it elemental. Did not happen. Crushed the skin of material to a powder and tried to torch again but it was too fine and I was going to loose some to blowing out with even the lowest flame I had.
Questions....Torching to red hot and keeping it there for 20 minutes and I still get A/R during the HCL wash. How can this happen? Shouldn't the nitrates be long gone?
Does it require more heat or a longer duration to knock off the extra oxygen molecule?
Thats all I can think of for the moment.
Here's why. I follow the teachings of Harold on this tin thing. If I recall correctly, Harold has posted that the incineration and HCL wash was not a cure for tin. It just made it much more filterable. ( If I am misquoting you on this Harold Please correct me). This is my findings using this method. After incineration and the HCL wash, the solution always tests positive for gold. Everytime I have done it any way. This time I looked at what Geo posted about the tin becoming elemental with incineration so I doubled the incineration time to see if I could effect a change of the tin chloride to metal. Torched it with a mapp gas torch for 20 minutes, Even concentrated on selected areas for an extended time to see if I could make it elemental. Did not happen. Crushed the skin of material to a powder and tried to torch again but it was too fine and I was going to loose some to blowing out with even the lowest flame I had.
Questions....Torching to red hot and keeping it there for 20 minutes and I still get A/R during the HCL wash. How can this happen? Shouldn't the nitrates be long gone?
Does it require more heat or a longer duration to knock off the extra oxygen molecule?
Thats all I can think of for the moment.
Geo
Well-known member
this is from wiki.
When heated in an inert atmosphere initially disproportionation occurs giving Sn metal and Sn3O4 which further reacts to give SnO2 and Sn metal.[3]
4SnO → Sn3O4 + Sn
Sn3O4 → 2SnO2 + Sn
if you are heating it in an oxygen rich flame, it may not work. in theory, your trying to remove an oxygen atom, so you may have to use a retort or at least deprive it of oxygen.
When heated in an inert atmosphere initially disproportionation occurs giving Sn metal and Sn3O4 which further reacts to give SnO2 and Sn metal.[3]
4SnO → Sn3O4 + Sn
Sn3O4 → 2SnO2 + Sn
if you are heating it in an oxygen rich flame, it may not work. in theory, your trying to remove an oxygen atom, so you may have to use a retort or at least deprive it of oxygen.
ericrm
Well-known member
information remove due to eroneous content :lol:
ericrm
Well-known member
geo are you sure it is 4 SnO and not Sno2? or am i lost and i dont know it?
Geo
Well-known member
http://en.wikipedia.org/wiki/Tin(II)_oxide
i cant make it link the whole address.
Tin(II) oxide
From Wikipedia, the free encyclopedia
Tin(II) oxide
IUPAC name[hide]
Tin(II) oxide
Other names[hide]
Stannous oxide, tin monoxide
Identifiers
CAS number 21651-19-4
PubChem 88989
EC number 244-499-5
RTECS number XQ3700000
Jmol-3D images Image 1
SMILES
[show]
InChI
[show]
Properties
Molecular formula SnO
Molar mass 134.709 g/mol
Appearance black or red powder when anhydrous, white when hydrated
Density 6.45 g/cm3
Melting point
1080 °C (decomp)[1]
Solubility in water insoluble
Structure
Crystal structure tetragonal
Thermochemistry
Std enthalpy of
formation ΔfHo298 −285 kJ·mol−1[2]
Standard molar
entropy So298 56 J·mol−1·K−1[2]
Hazards
MSDS ICSC 0956
EU Index Not listed
Flash point Non-flammable
Related compounds
Other anions Tin sulfide
Tin selenide
Tin telluride
Other cations Carbon monoxide
Silicon monoxide
Germanium(II) oxide
Lead(II) oxide
Related tin oxides Tin dioxide
(verify) (what is: /?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references
Tin(II) oxide (stannous oxide) is a compound of tin and oxygen where tin has the oxidation state of +2. There are two forms, a stable blue-black form and a metastable red form.
Contents [hide]
1 Preparation and reactions
2 Structure
3 Uses
4 References
[edit]Preparation and reactions
Tin(II) oxide burning
Blue-black SnO can be prepared by heating the tin(II) oxide hydrate, SnO.xH2O (x<1) precipitated when a tin(II) salt is reacted with an alkali hydroxide such as NaOH.[3] Metastable, red SnO can be prepared by gentle heating of the precipitate produced by the action of aqueous ammonia on a tin(II) salt.[3] SnO may be prepared as a pure substance in the laboratory, by controlled heating of tin(II) oxalate (stannous oxalate) in the absence of air.[4]
SnC2O4 → SnO + CO2 + CO
Tin(II) oxide burns in air with a dim green flame to form SnO2.[3]
2 SnO + O2 → 2 SnO2
When heated in an inert atmosphere initially disproportionation occurs giving Sn metal and Sn3O4 which further reacts to give SnO2 and Sn metal.[3]
4SnO → Sn3O4 + Sn
Sn3O4 → 2SnO2 + Sn
SnO is amphoteric, dissolving in strong acid to give tin(II) salts and in strong base to give stannites containing Sn(OH)3−.[3] It also dissolves in strong acid solutions to give the ionic complexes Sn(OH2)32+ and Sn(OH)(OH2)2+, and in less acid solutions to give Sn3(OH)42+.[3] Note that anhydrous stannites, e.g. K2Sn2O3, K2SnO2 are also known.[5][6][7] SnO is a reducing agent and this appears to its role in the manufacture of so-called "copper ruby glass".[8]
[edit]Structure
Black, α-SnO adopts the tetragonal PbO layer structure containing four coordinate square pyramidal tin atoms.[9] This form is found in nature as the rare mineral romarchite.[10] The asymmetry is usually simply ascribed to a sterically active lone pair; however, electron density calculations show that the asymmetry is caused by an antibonding interaction of the Sn(5s) and the O(2p) orbitals.[11]
Non-stoichiometry has been observed in SnO.[12]
The electronic band gap has been measured between 2.5eV and 3eV.[13]
[edit]Uses
The dominant use of stannous oxide is as a precursor in manufacturing of other, typically divalent, tin compounds or salts. Stannous oxide may also be employed as a reducing agent and in the creation of ruby glass. It has a minor use as an esterification catalyst.
Cerium(III) oxide in ceramic form, together with Tin(II) oxide (SnO) is used for illumination with UV light.[14]
[edit]References
^ Tin and Inorganic Tin Compounds: Concise International Chemical Assessment Document 65, (2005), World Health Organization
^ a b Zumdahl, Steven S. (2009). Chemical Principles 6th Ed.. Houghton Mifflin Company. p. A23. ISBN 0-618-94690-X.
^ a b c d e f Egon Wiberg, Arnold Frederick Holleman (2001) Inorganic Chemistry, Elsevier ISBN 0-12-352651-5
^ Satya Prakash (2000),Advanced Inorganic Chemistry: V. 1, S. Chand, ISBN 81-219-0263-0
^ The First Oxostannate(II): K2Sn2O3, M Braun, R. Hoppe, Angewandte Chemie International Edition in English, 17, 6, 449 - 450, doi:10.1002/anie.197804491
^ Über Oxostannate(II). III. K2Sn2O3, Rb2Sn2O3 und Cs2Sn2O3 - ein Vergleich, R. M. Braun, R. Hoppe, Zeitschrift für anorganische und allgemeine Chemie, 485, 1, 15 - 22, doi:10.1002/zaac.19824850103
^ R M Braun R Hoppe Z. Naturforsch. (1982), 37B, 688-694
^ Colour development in copper ruby alkali silicate glasses. Part I: The impact of tin oxide, time and temperature ,Bring, T., Jonson, B., Kloo, L. Rosdahl, J , Wallenberg, R., Glass Technology, Eur. J. Glass Science & Technology, Part A, 48 , 2 , 101-108 ( 2007)
^ Wells A.F. (1984) Structural Inorganic Chemistry 5th edition Oxford Science Publications ISBN 0-19-855370-6
^ On type romarchite and hydroromarchite from Boundary Falls, Ontario, and notes on other occurrences, Robert A. Ramik,, Robert M. Organ, Joseph A. Mandarino, The Canadian Mineralogist; June 2003; v. 41; no. 3;. 649-657; doi:10.2113/gscanmin.41.3.649
^ Electronic structures of rocksalt, litharge, and herzenbergite SnO by density functional theory, A. Walsh, G.W. Watson, Phys. Rev. B 70, 235114 (2004)doi:10.1103/PhysRevB.70.235114
^ Cation nonstoichiometry in tin-monoxide-phase Sn1-δO with tweed microstructure, Moreno, M. S.; Varela, A.; Otero-Díaz, L. C., Physical Review B (Condensed Matter),56, 9,(1997), 5186-5192, doi:10.1103/PhysRevB.56.5186
^ Science and Technology of Chemiresistor Gas Sensors By Dinesh K. Aswal, Shiv K. Gupta (2006), Nova Publishers, ISBN 1-60021-514-9
^ "Spectral Studies of New Luminophors for Dental Porcelain". Jdr.iadrjournals.org. DOI:10.1177/00220345800590090801. Retrieved 2012-04-05.
i cant make it link the whole address.
Tin(II) oxide
From Wikipedia, the free encyclopedia
Tin(II) oxide
IUPAC name[hide]
Tin(II) oxide
Other names[hide]
Stannous oxide, tin monoxide
Identifiers
CAS number 21651-19-4
PubChem 88989
EC number 244-499-5
RTECS number XQ3700000
Jmol-3D images Image 1
SMILES
[show]
InChI
[show]
Properties
Molecular formula SnO
Molar mass 134.709 g/mol
Appearance black or red powder when anhydrous, white when hydrated
Density 6.45 g/cm3
Melting point
1080 °C (decomp)[1]
Solubility in water insoluble
Structure
Crystal structure tetragonal
Thermochemistry
Std enthalpy of
formation ΔfHo298 −285 kJ·mol−1[2]
Standard molar
entropy So298 56 J·mol−1·K−1[2]
Hazards
MSDS ICSC 0956
EU Index Not listed
Flash point Non-flammable
Related compounds
Other anions Tin sulfide
Tin selenide
Tin telluride
Other cations Carbon monoxide
Silicon monoxide
Germanium(II) oxide
Lead(II) oxide
Related tin oxides Tin dioxide
(verify) (what is: /?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references
Tin(II) oxide (stannous oxide) is a compound of tin and oxygen where tin has the oxidation state of +2. There are two forms, a stable blue-black form and a metastable red form.
Contents [hide]
1 Preparation and reactions
2 Structure
3 Uses
4 References
[edit]Preparation and reactions
Tin(II) oxide burning
Blue-black SnO can be prepared by heating the tin(II) oxide hydrate, SnO.xH2O (x<1) precipitated when a tin(II) salt is reacted with an alkali hydroxide such as NaOH.[3] Metastable, red SnO can be prepared by gentle heating of the precipitate produced by the action of aqueous ammonia on a tin(II) salt.[3] SnO may be prepared as a pure substance in the laboratory, by controlled heating of tin(II) oxalate (stannous oxalate) in the absence of air.[4]
SnC2O4 → SnO + CO2 + CO
Tin(II) oxide burns in air with a dim green flame to form SnO2.[3]
2 SnO + O2 → 2 SnO2
When heated in an inert atmosphere initially disproportionation occurs giving Sn metal and Sn3O4 which further reacts to give SnO2 and Sn metal.[3]
4SnO → Sn3O4 + Sn
Sn3O4 → 2SnO2 + Sn
SnO is amphoteric, dissolving in strong acid to give tin(II) salts and in strong base to give stannites containing Sn(OH)3−.[3] It also dissolves in strong acid solutions to give the ionic complexes Sn(OH2)32+ and Sn(OH)(OH2)2+, and in less acid solutions to give Sn3(OH)42+.[3] Note that anhydrous stannites, e.g. K2Sn2O3, K2SnO2 are also known.[5][6][7] SnO is a reducing agent and this appears to its role in the manufacture of so-called "copper ruby glass".[8]
[edit]Structure
Black, α-SnO adopts the tetragonal PbO layer structure containing four coordinate square pyramidal tin atoms.[9] This form is found in nature as the rare mineral romarchite.[10] The asymmetry is usually simply ascribed to a sterically active lone pair; however, electron density calculations show that the asymmetry is caused by an antibonding interaction of the Sn(5s) and the O(2p) orbitals.[11]
Non-stoichiometry has been observed in SnO.[12]
The electronic band gap has been measured between 2.5eV and 3eV.[13]
[edit]Uses
The dominant use of stannous oxide is as a precursor in manufacturing of other, typically divalent, tin compounds or salts. Stannous oxide may also be employed as a reducing agent and in the creation of ruby glass. It has a minor use as an esterification catalyst.
Cerium(III) oxide in ceramic form, together with Tin(II) oxide (SnO) is used for illumination with UV light.[14]
[edit]References
^ Tin and Inorganic Tin Compounds: Concise International Chemical Assessment Document 65, (2005), World Health Organization
^ a b Zumdahl, Steven S. (2009). Chemical Principles 6th Ed.. Houghton Mifflin Company. p. A23. ISBN 0-618-94690-X.
^ a b c d e f Egon Wiberg, Arnold Frederick Holleman (2001) Inorganic Chemistry, Elsevier ISBN 0-12-352651-5
^ Satya Prakash (2000),Advanced Inorganic Chemistry: V. 1, S. Chand, ISBN 81-219-0263-0
^ The First Oxostannate(II): K2Sn2O3, M Braun, R. Hoppe, Angewandte Chemie International Edition in English, 17, 6, 449 - 450, doi:10.1002/anie.197804491
^ Über Oxostannate(II). III. K2Sn2O3, Rb2Sn2O3 und Cs2Sn2O3 - ein Vergleich, R. M. Braun, R. Hoppe, Zeitschrift für anorganische und allgemeine Chemie, 485, 1, 15 - 22, doi:10.1002/zaac.19824850103
^ R M Braun R Hoppe Z. Naturforsch. (1982), 37B, 688-694
^ Colour development in copper ruby alkali silicate glasses. Part I: The impact of tin oxide, time and temperature ,Bring, T., Jonson, B., Kloo, L. Rosdahl, J , Wallenberg, R., Glass Technology, Eur. J. Glass Science & Technology, Part A, 48 , 2 , 101-108 ( 2007)
^ Wells A.F. (1984) Structural Inorganic Chemistry 5th edition Oxford Science Publications ISBN 0-19-855370-6
^ On type romarchite and hydroromarchite from Boundary Falls, Ontario, and notes on other occurrences, Robert A. Ramik,, Robert M. Organ, Joseph A. Mandarino, The Canadian Mineralogist; June 2003; v. 41; no. 3;. 649-657; doi:10.2113/gscanmin.41.3.649
^ Electronic structures of rocksalt, litharge, and herzenbergite SnO by density functional theory, A. Walsh, G.W. Watson, Phys. Rev. B 70, 235114 (2004)doi:10.1103/PhysRevB.70.235114
^ Cation nonstoichiometry in tin-monoxide-phase Sn1-δO with tweed microstructure, Moreno, M. S.; Varela, A.; Otero-Díaz, L. C., Physical Review B (Condensed Matter),56, 9,(1997), 5186-5192, doi:10.1103/PhysRevB.56.5186
^ Science and Technology of Chemiresistor Gas Sensors By Dinesh K. Aswal, Shiv K. Gupta (2006), Nova Publishers, ISBN 1-60021-514-9
^ "Spectral Studies of New Luminophors for Dental Porcelain". Jdr.iadrjournals.org. DOI:10.1177/00220345800590090801. Retrieved 2012-04-05.
ericrm
Well-known member
sorry ,my mistake
ericrm
Well-known member
geo incinerating as we do it is not made in an inert atmosphere ... also SnO is supose to be soluble in strong acid and strong baseGeo said:
im totally lost...............
Geo
Well-known member
inert is a simple way of saying oxygen free. when we incinerate things of organic nature or carbon based, we want oxygen to reach the material to convert the carbon to carbon dioxide.when you want to remove an atom of oxygen the opposite is true. if you heat tin oxide to its boiling point, it will release the extra oxygen atom.what i used as a retort was a 6" threaded steel nipple with a cap on one end and a reducing cap on the other so i could reduce the size down to a manageable size and connect a copper tube to it with a compression fitting.any closed container that can withstand the heat will work, of coarse it has to have a vent so the gases can escape.
also, metastannic acid is a form of tin oxide. when you dissolve tin in nitric acid, metastannic acid is what you get. if i knew of an acid that would break it down, i would be using it.
also, metastannic acid is a form of tin oxide. when you dissolve tin in nitric acid, metastannic acid is what you get. if i knew of an acid that would break it down, i would be using it.
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- Feb 25, 2007
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Not being a chemist, I don't know that the tin has been removed. All I know is incineration, followed by a wash in hot HCl resulted in easier filtration, which was my goal. I do not recall even one instance where that wasn't a cure for bad filtration, so it is definitely a viable way to improve one's process.glondor said:Hey Chris....We need more schooling.
Harold
glondor said:Hey Chris....We need more schooling.
After incineration and the HCL wash, the solution always tests positive for gold. Everytime I have done it any way. This time I looked at what Geo posted about the tin becoming elemental with incineration so I doubled the incineration time to see if I could effect a change of the tin chloride to metal. Torched it with a mapp gas torch for 20 minutes, Even concentrated on selected areas for an extended time to see if I could make it elemental. Did not happen. Crushed the skin of material to a powder and tried to torch again but it was too fine and I was going to loose some to blowing out with even the lowest flame I had.
Questions....Torching to red hot and keeping it there for 20 minutes and I still get A/R during the HCL wash. How can this happen? Shouldn't the nitrates be long gone?
Does it require more heat or a longer duration to knock off the extra oxygen molecule?
Thats all I can think of for the moment.
The same thing has happened to me as well testing positive for gold after incineration.
So if my understanding is correct, from what Geo has posted above, is the conversion of tin chloride to elemental tin, through incineration has to be done in a low or no oxygen environment?
But as glondor said, How is the Hcl wash, after incineration still creating a weak AR? Unless a mapp gas torch doesn't keep it consistently hot enough too burn off the nitrates?
I'm with Harold on this one. I don't know how things work chemistry wise sometimes i just know they work. I've often wondered if it acts as a catalysis of some sort. I know that when you add one metal to another it changes the properties of both metals. Like when you add one metal to another and it lowers the melting point of both metals. Another example is when you add one metal to another so you can get it dissolve into solution like pure palladium or platinum that don't want to dissolve sometimes. Don't know what's happening i just know it happens! Read my thread called " I got robbed but i got pictures " to see what kind of lesson i had to learn the hard way and how expensive that lesson can be.
Geo
Well-known member
cnbarr said:
actually, i was talking about tin oxide. tin chloride can be dealt with in a different way. when tin(II)chloride is formed in AP for instance, and is mixed with your foils, you can incinerate in the normal fashion and then hcl will dissolve it. tin(II)chloride is insoluble in hcl but when you incinerate it, it converts it to tin(I)chloride which is readily soluble in hcl.
Palladium, I read your got robbed post it was a good read. I actually just dealt with something similar, I was refining the cemented values form my stock pot and had the same thing happen (minus the tin), but it would only dissolve a small portion of values in between incineration's, I ended up taking the last 1/4cup of powder to a friends house and had him smelt it with a flux mixture in his kiln. Then ran the resulting 78g nugget through my junk silver cell and collected the slimes for later processing.
Geo, That makes more sense know, cause I didn't think you could reduce a chloride to an elemental. So just to double check, you can reduce tin oxide to elemental tin through incinerating in an inert (no oxygen) environment? And without the need of a flux mixture as well?
Geo said:
Geo, That makes more sense know, cause I didn't think you could reduce a chloride to an elemental. So just to double check, you can reduce tin oxide to elemental tin through incinerating in an inert (no oxygen) environment? And without the need of a flux mixture as well?
I am not positive on all of the chemistry involved in the incineration process to deal with tin.
Here are some of my thoughts on it, tin metal is a base metal, above hydrogen in the reactivity series of metals, the metal I believe would oxidize fairly easily with red heat especially in air or with oxygen, I think carbon in a melt (not an incineration), may reduce tin to metal because it is below carbon in the reactivity series of metals this is if enough carbon was used in a melt and the furnace was deprived of oxygen.
so I do not think we reduce tin to metal in incineration but we do oxidize it making it easier to dissolve in the boiling hot concentrated HCl (which forms SnCL2 in solution, which is just soluble enough to filter), if we dilute this wash with too much water I believe we form Sn(OH)2 in solution and again the solution becomes a bear to filter, or if we dilute with a peroxide we form hydroxides and oxides of tin in solution (same problem with filtering).
Lowering the acidity of tin chloride SnCl2 (stannous chloride in solution can also give us oxides or hydroxides of tin making the filtering problem worse.
I also believe the tin in solution is a good reagent for reducing other metals in solution to elemental metal, like reducing dissolved gold in solution to colloids of gold, or reducing copper in solution to copper metal, the tin seems to hold these reduced metals in solution not letting them precipitate, almost impossible to filter out of solution and the more metals in the mess the worse the problem, the more diluted or less acidic the worse the troubles in dealing with them.
Tin chloride will also reduce silver in solution or reduce some of the silver chloride powder in the bottom of your solution to metal silver, although normally you would not have much silver dissolved in a chloride solution unless it is highly acidic and concentrated (like aqua regia may hold some silver in solution), the silver can be reduced to metal (similar to how they made some types of mirrors).
Tin in the highly acidic and oxidizing environment of nitric acid becomes metastannic acid (acid tin oxide) H2SnO3, this forms a gelatinous solution impossible to filter as the tin acid oxide is not that soluble, but also it will not settle out of solution (and here again I believe reducing some other metals in solution),
Tin metal will dissolve in copper sulfate reducing the copper to metal powder making a water-soluble tin sulfate solution.
CuSO4 (aq) + Sn (s) à Cu (s) + SnSO4 (aq)
Yes you can use copper sulfate to dissolve tin from your scrap (instead of using you new jug of HCl).
If you have volumes of nitric solution with fine gold floating in solution and it will not settle or filter (at least for what would seem like forever), you could try what I proposed earlier in this thread (adding a little copper and some sulfuric acid) and distill off the nitric acid from this mix and leaving the gold in a solution of copper sulfate (and water soluble tin sulfate) the gold foil will separate easily from the copper and tin sulfate solution, the nitric distilled of would be less in volume than the original nitric used but can be reused, you also form some copper sulfates to use for other projects like to dissolve tin from gold plated pins.
Of course there are several other ways to try and deal with tin in solution besides screening or filtering evaporating to powder and incineration, then HCl boil wash method.
However you look at it or choose to deal with it tin can be a major pain.
Although I do not understand all of the chemistry of tin, I do understand it is a monster to deal with and will steal your gold from you if you are not careful.
But then again tin chloride can also be very useful it allows us to see where our gold is at when used properly in the stannous chloride test.
How can this metal be an angel at times and a devil in others?
Here are some of my thoughts on it, tin metal is a base metal, above hydrogen in the reactivity series of metals, the metal I believe would oxidize fairly easily with red heat especially in air or with oxygen, I think carbon in a melt (not an incineration), may reduce tin to metal because it is below carbon in the reactivity series of metals this is if enough carbon was used in a melt and the furnace was deprived of oxygen.
so I do not think we reduce tin to metal in incineration but we do oxidize it making it easier to dissolve in the boiling hot concentrated HCl (which forms SnCL2 in solution, which is just soluble enough to filter), if we dilute this wash with too much water I believe we form Sn(OH)2 in solution and again the solution becomes a bear to filter, or if we dilute with a peroxide we form hydroxides and oxides of tin in solution (same problem with filtering).
Lowering the acidity of tin chloride SnCl2 (stannous chloride in solution can also give us oxides or hydroxides of tin making the filtering problem worse.
I also believe the tin in solution is a good reagent for reducing other metals in solution to elemental metal, like reducing dissolved gold in solution to colloids of gold, or reducing copper in solution to copper metal, the tin seems to hold these reduced metals in solution not letting them precipitate, almost impossible to filter out of solution and the more metals in the mess the worse the problem, the more diluted or less acidic the worse the troubles in dealing with them.
Tin chloride will also reduce silver in solution or reduce some of the silver chloride powder in the bottom of your solution to metal silver, although normally you would not have much silver dissolved in a chloride solution unless it is highly acidic and concentrated (like aqua regia may hold some silver in solution), the silver can be reduced to metal (similar to how they made some types of mirrors).
Tin in the highly acidic and oxidizing environment of nitric acid becomes metastannic acid (acid tin oxide) H2SnO3, this forms a gelatinous solution impossible to filter as the tin acid oxide is not that soluble, but also it will not settle out of solution (and here again I believe reducing some other metals in solution),
Tin metal will dissolve in copper sulfate reducing the copper to metal powder making a water-soluble tin sulfate solution.
CuSO4 (aq) + Sn (s) à Cu (s) + SnSO4 (aq)
Yes you can use copper sulfate to dissolve tin from your scrap (instead of using you new jug of HCl).
If you have volumes of nitric solution with fine gold floating in solution and it will not settle or filter (at least for what would seem like forever), you could try what I proposed earlier in this thread (adding a little copper and some sulfuric acid) and distill off the nitric acid from this mix and leaving the gold in a solution of copper sulfate (and water soluble tin sulfate) the gold foil will separate easily from the copper and tin sulfate solution, the nitric distilled of would be less in volume than the original nitric used but can be reused, you also form some copper sulfates to use for other projects like to dissolve tin from gold plated pins.
Of course there are several other ways to try and deal with tin in solution besides screening or filtering evaporating to powder and incineration, then HCl boil wash method.
However you look at it or choose to deal with it tin can be a major pain.
Although I do not understand all of the chemistry of tin, I do understand it is a monster to deal with and will steal your gold from you if you are not careful.
But then again tin chloride can also be very useful it allows us to see where our gold is at when used properly in the stannous chloride test.
How can this metal be an angel at times and a devil in others?
Just an update, I dried and crushed all the solids, then incinerated for a good 30 minutes, then crushed again and screen out any garbage. Then washed in hot water for 15 minutes, let settle and decanted. Then went to a boiling Hcl wash, let settle and decanted while warm. At this point I realized I am dealing with more then tin chloride, after decanting the Hcl wash I gave two more water washes, and still had a fair amount of chloride powders in my beaker but it settled quite quickly. It's look and texture and how quickly it settle leads me to think it is silver chloride but I could be wrong, any thoughts on if it is silver chloride and where it might have came from???
So after washing I ran it through AR, let settle filtered and dropped gold with ferrous sulfate, this wasn't too difficult after incinerating. I don't have yield data yet, I still need to wash and refine one more time. If I get some positive yes's that my powders might be silver chloride, I'll convert it with NaOH and sugar, then run the resulting button through my silver cell to see if any gold got locked up in it. If this sounds like a bad idea, please tell me???
Thanks again,
Chris
So after washing I ran it through AR, let settle filtered and dropped gold with ferrous sulfate, this wasn't too difficult after incinerating. I don't have yield data yet, I still need to wash and refine one more time. If I get some positive yes's that my powders might be silver chloride, I'll convert it with NaOH and sugar, then run the resulting button through my silver cell to see if any gold got locked up in it. If this sounds like a bad idea, please tell me???
Thanks again,
Chris
Geo
Well-known member
if you incinerated and hcl didnt dissolve it, chances are its silver chloride. take a small sample and add to it some ammonium hydroxide (household ammonia) and see if it dissolves.heat it to be sure. filter out any solids and then add to the solution enough hcl to make it acidic. any silver will precipitate out as silver chloride. dont breath the smoke that comes off as you add the hcl.
this way you will know if it is silver chloride or something else.
this way you will know if it is silver chloride or something else.
White powders (metal chloride salts) what are they and how to seperate them?
HCl will convert copper I chloride insoluble powders to a solution of copper II chloride (brown if lots of copper green if less copper), silver or lead is insoluble in HCl,
To dissolve lead add water and boil, then lower heat and keep solution hot but let powders settle before decanting, (silver chloride will take a little time to settle), the boiling hot water will dissolve lead chloride, leaving silver chloride insoluble, when the lead chloride solution cools the lead will precipitate back out of the water,
Silver chloride when dilute will turn almost purple to black in the sunlight (it can be dissolved in ammonia but must not be dried because can form a thermal or shock sensitive compound, acidify the solution to precipitate the silver and make the solution safe),
Then there is salt NaCl normally more of a clear, salt of course is also water soluble.
There are a couple of more metals that make insoluble chloride salts but these are the ones we will deal with most of the time.
HCl will convert copper I chloride insoluble powders to a solution of copper II chloride (brown if lots of copper green if less copper), silver or lead is insoluble in HCl,
To dissolve lead add water and boil, then lower heat and keep solution hot but let powders settle before decanting, (silver chloride will take a little time to settle), the boiling hot water will dissolve lead chloride, leaving silver chloride insoluble, when the lead chloride solution cools the lead will precipitate back out of the water,
Silver chloride when dilute will turn almost purple to black in the sunlight (it can be dissolved in ammonia but must not be dried because can form a thermal or shock sensitive compound, acidify the solution to precipitate the silver and make the solution safe),
Then there is salt NaCl normally more of a clear, salt of course is also water soluble.
There are a couple of more metals that make insoluble chloride salts but these are the ones we will deal with most of the time.
Okay Geo, I took your advise and a took a small 30ml sample of the unknown chlorides and added ammonium hydroxide to it and this is what happened instantaneously,
Then I added heat and a touch more ammonium hydroxide, I then let it cool a bit and filter out the solids, here is a picture of the solids,
Then I added Hcl to bring the solution back to acidic, Ph of 0.1,
after bring the solution back to acidic with Hcl, there was no precipitation of silver chloride,
So I believe we can rule out silver chloride, and lead chloride, unless it is tin chloride (but it didn't cause settling or filtering issues in my AR last night) I am absolutely befuddled as to what it is and I think it is locking up gold, cause I just washed my powders from what I precipitated last night, and I don't think I have more then 2g from 4 1/2+lbs of these pins. My estimation was a bit higher then that.
This round has definitely been more then a learning experience, thanks you all so much for a wealth of knowledge and more still yet to be gained!!!
Chris
Edit: I just realized my phone takes better pictures then my real camera!!! :shock: :shock: :shock:
Then I added heat and a touch more ammonium hydroxide, I then let it cool a bit and filter out the solids, here is a picture of the solids,
Then I added Hcl to bring the solution back to acidic, Ph of 0.1,
after bring the solution back to acidic with Hcl, there was no precipitation of silver chloride,
So I believe we can rule out silver chloride, and lead chloride, unless it is tin chloride (but it didn't cause settling or filtering issues in my AR last night) I am absolutely befuddled as to what it is and I think it is locking up gold, cause I just washed my powders from what I precipitated last night, and I don't think I have more then 2g from 4 1/2+lbs of these pins. My estimation was a bit higher then that.
This round has definitely been more then a learning experience, thanks you all so much for a wealth of knowledge and more still yet to be gained!!!
Chris
Edit: I just realized my phone takes better pictures then my real camera!!! :shock: :shock: :shock:
