All about anodes and cathodes.
- Thread starter want2ride
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Help Support Gold Refining Forum:
I want to put things straight:
Yellow gold is absorbing UV, as well as green
and blue(about 30-50% reflectivity in that range
meaning 70-50% absorbance).This is why it is
yellow. The high reflectivity is toward red, infra red.
However if you would like to filter the whole UV
radiation you'll need several layers. Nanogold is a
semiconductor with thoroughly different gap, that is
why it can be red, pink, blue...
Lino1406,
author of "gold electronic enigma..."
Yellow gold is absorbing UV, as well as green
and blue(about 30-50% reflectivity in that range
meaning 70-50% absorbance).This is why it is
yellow. The high reflectivity is toward red, infra red.
However if you would like to filter the whole UV
radiation you'll need several layers. Nanogold is a
semiconductor with thoroughly different gap, that is
why it can be red, pink, blue...
Lino1406,
author of "gold electronic enigma..."
Eesh I forgot most of what little I knew about band gaps. I just remember the maths got bad quick when geometry changes. All numerical anyways.
VernonBlack
New member
- Joined
- Feb 12, 2012
- Messages
- 2
Interesting banter on this thread but not much info on anodes and cathodes...Perhaps it should be renamed??....Just saying....
NobleMetalWorks
Well-known member
lance1 said:
The best metal for anodes and cathodes depends on what electrolytic solution you are using, the type of material you are attempting to part, the distance from anode to cathode, the amps and volts of your power supply, the availability of the metals in your area, the cost of the metals and many other factors.
Why not search the forum for what it is you wan to do, say remove gold plating. Then read the different types of parting cells and the metals used for anode/cathode. Instead of re-inventing the mouse trap, just simply follow the explicit step by step instructions that have been posted, to build and then operate a parting cell.
Scott
Woodworker1997
Well-known member
Lou said:
I have taken the reflectance spectra of both gold and silver. It depends on what wavelength you are looking at. Gold is a great reflector but, silver is usually better. Silver coated laser mirrors have a down side though. They work great when new but the reflectance degrades over time. They tarnish.
CVD gold mirrors last forever until physically damaged. Or if i turn my laser up too high :roll:
Harold_V said:
ok this is a little off topic but I deplated some jewelry with sulfuric acid (-) stainless and (+) copper and now what i have is black and red powder and gold at the bottom of the dish so now i do see contaminants are high but I"ve look all over the forums and I cant seem to find how to seperate the gold from the mix is AR my only solution?
98ram,
It is not a good idea to put gold into an aqua regia solution with base metals.
I would give the powders a boil in water to wash some of the sulfate.
If there was not tin (or gold fill), you could remove base metals in nitric acid, before going to aqua regia.
If tin is involved, I would wash sulfates, dry, and incinerate the powders, cool, then boil in HCl, rinse with hot water, neutralize with dilute hydroxide and rinse salt well with water, dry, and incinerate again to remove traces of chlorides, before using the nitric acid.
It is not a good idea to put gold into an aqua regia solution with base metals.
I would give the powders a boil in water to wash some of the sulfate.
If there was not tin (or gold fill), you could remove base metals in nitric acid, before going to aqua regia.
If tin is involved, I would wash sulfates, dry, and incinerate the powders, cool, then boil in HCl, rinse with hot water, neutralize with dilute hydroxide and rinse salt well with water, dry, and incinerate again to remove traces of chlorides, before using the nitric acid.
butcher said:
ok i thank you greatly butcher for the help. There was some gold fill jewelry. Now Ihave kind of a dumb question I cant seem to find any nitric, HCl, or hydroxide anywhere in the town I live in is there any household products that would do the same? Or I probably could go to a nearby city chemical store just dont want to buy in big bulk since I'm not doing large scale.
Check the hardware stores, pool chemical supplier, or where they sell brick, for HCL also called Muriatic acid.
95% tin solder to make your stannous chloride can also be found at the hardware store or where they sell lead free fishing sinkers.
There is no need for nitric acid, or aqua regia if you cannot find nitric, I would not normally use it here anyway.
3% H2O2 hydrogen peroxide, can found in the home drug store area.
Fish tank air bubbler, second hand store.
Bleach sodium hypochlorite NaClO can found be where you buy it to wash your clothes groceries store-cleaning isle
SMB sodium metabisulfite, can be found where they sell beer or wine making supplies, or check in the hardware garden supply, as Bonide brand stump remover is also SMB.
Ferrous sulfate can be made with transformer Iron and sulfuric acid., it can also be found in the garden supply (but all I have ever found in the store was oxidized brown to where it was no good to precipitate gold with, you need nice green crystals)
Sodium hydroxide can be found in cleaning supplies (lye), or in drain cleaners, hardware or cleaning supply or grocery stores.
(Copper II chloride leach also called acid peroxide can be used instead of nitric to remove many of the base metals from the powders).
Check in the second hand store for a corning ware dish or amber violet glass skillet, and solid plate electric hot plate, that and your hand held propane torch.
You can incinerate, and almost complete the whole process in the corning ware casserole dish on a hot plate, using a suction tool and a pipette to remove and transfer liquids from above the powders, the valuable powders stay in the dish almost the whole process.
I would give the powders a boil in water to wash some of the sulfate.
Incineration will not only help to remove sulfate, but it will help to oxidize the tin and other base metals in the powders., the boil in HCl will help to remove the tin and some of the other base metal oxides, the boiling hot water washes will help to remove the soluble lead chlorides.
If tin is involved, I would wash sulfates, dry, and incinerate the powders, cool, then boil in HCl, rinse with hot water, neutralize with dilute sodium hydroxide (lye) and rinse salt well with water, dry, now you can use the copper chloride leach to pick up copper and base metals from the powders, wash the powders and dissolve in HCl/NaClO (bleach) to refine the gold.
I am not stating the minor details in these processes such as filtering and other steps in the procedure. So if you’re not familiar with the processes study them first to avoid many troubles.
You mentioned using nitric and aqua regia so I assumed you had these chemicals, if your not familiar with it aqua regia can be very tricky to use to dissolve gold, HCl bleach is much easier if the material in foils or fine powders.
Not knowing how contaminated your powders are, or the details of your cell, which I assume was the concentrated sulfuric acid stripping cell, it is a little difficult giving advice, but it sounds as though the cell was too dilute and left a lot of copper in the powders.
Visiting Laser Steve's web site and reading the early posts on the cell will help with the sulfuric cell and its proper use, also see the general reaction list and the guide to the forum, in the general chat section.
Using the sulfuric cell properly would eliminate the need to remove copper from the powders at this stage).
Also study dealing with waste in the safety section.
Spending a little time studying can save you a heck of a lot of time dealing with messes, and looking for what happened to all of that gold you had, before putting it into chemicals.
95% tin solder to make your stannous chloride can also be found at the hardware store or where they sell lead free fishing sinkers.
There is no need for nitric acid, or aqua regia if you cannot find nitric, I would not normally use it here anyway.
3% H2O2 hydrogen peroxide, can found in the home drug store area.
Fish tank air bubbler, second hand store.
Bleach sodium hypochlorite NaClO can found be where you buy it to wash your clothes groceries store-cleaning isle
SMB sodium metabisulfite, can be found where they sell beer or wine making supplies, or check in the hardware garden supply, as Bonide brand stump remover is also SMB.
Ferrous sulfate can be made with transformer Iron and sulfuric acid., it can also be found in the garden supply (but all I have ever found in the store was oxidized brown to where it was no good to precipitate gold with, you need nice green crystals)
Sodium hydroxide can be found in cleaning supplies (lye), or in drain cleaners, hardware or cleaning supply or grocery stores.
(Copper II chloride leach also called acid peroxide can be used instead of nitric to remove many of the base metals from the powders).
Check in the second hand store for a corning ware dish or amber violet glass skillet, and solid plate electric hot plate, that and your hand held propane torch.
You can incinerate, and almost complete the whole process in the corning ware casserole dish on a hot plate, using a suction tool and a pipette to remove and transfer liquids from above the powders, the valuable powders stay in the dish almost the whole process.
I would give the powders a boil in water to wash some of the sulfate.
Incineration will not only help to remove sulfate, but it will help to oxidize the tin and other base metals in the powders., the boil in HCl will help to remove the tin and some of the other base metal oxides, the boiling hot water washes will help to remove the soluble lead chlorides.
If tin is involved, I would wash sulfates, dry, and incinerate the powders, cool, then boil in HCl, rinse with hot water, neutralize with dilute sodium hydroxide (lye) and rinse salt well with water, dry, now you can use the copper chloride leach to pick up copper and base metals from the powders, wash the powders and dissolve in HCl/NaClO (bleach) to refine the gold.
I am not stating the minor details in these processes such as filtering and other steps in the procedure. So if you’re not familiar with the processes study them first to avoid many troubles.
You mentioned using nitric and aqua regia so I assumed you had these chemicals, if your not familiar with it aqua regia can be very tricky to use to dissolve gold, HCl bleach is much easier if the material in foils or fine powders.
Not knowing how contaminated your powders are, or the details of your cell, which I assume was the concentrated sulfuric acid stripping cell, it is a little difficult giving advice, but it sounds as though the cell was too dilute and left a lot of copper in the powders.
Visiting Laser Steve's web site and reading the early posts on the cell will help with the sulfuric cell and its proper use, also see the general reaction list and the guide to the forum, in the general chat section.
Using the sulfuric cell properly would eliminate the need to remove copper from the powders at this stage).
Also study dealing with waste in the safety section.
Spending a little time studying can save you a heck of a lot of time dealing with messes, and looking for what happened to all of that gold you had, before putting it into chemicals.
I've used platinized Ti and Ta anodes many 100's of times in PM plating processes but have never attempted to coat them myself. I've always heard that the difficult process is quite dangerous and that some trade secrets are involved. The main problem is to activate the Ti so that the plating will adhere. Most of the processes I've read about used HF for activation and that's where the danger lies. There are several patents. I remember an interesting patent that soaked the Ti for 4 days in conc. HCl and then applied 10 separate coatings of Hanovia Pt, with firing between each coat.
Maybe 4metals has experience with this. If not, I doubt if anyone on the forum could help.
Maybe 4metals has experience with this. If not, I doubt if anyone on the forum could help.
Chris, the titanium is etched in H2SO4/ammonium bifluoride, then plated with a P salt bath, then annealed in H2. That's how it's done and I've had good success with it. Using HCl is another method, as HCl will dissolve titanium oxide off the surface. Even sulfuric works quite well, so long as it is air free (SO2 sat'd). Substrate prep, like always with plating anything, is key.
Part of the danger is in the fluoride, the other part in the P salt, which is the platinum version of gun powder when dry. It is made from K2PtCl4 and sodium nitrite quite easily but do not concentrate it down; best to use as is.
Platinized titanium is cheap enough to purchase, and the anodes commercially available the only justification for doing this is if you need something platinum coated that isn't going to be an anode (in my case, a super alloy).
Given that zachy can barely make coherent sentences in English, I really would rather not give him a procedure in it.
Lou
Part of the danger is in the fluoride, the other part in the P salt, which is the platinum version of gun powder when dry. It is made from K2PtCl4 and sodium nitrite quite easily but do not concentrate it down; best to use as is.
Platinized titanium is cheap enough to purchase, and the anodes commercially available the only justification for doing this is if you need something platinum coated that isn't going to be an anode (in my case, a super alloy).
Given that zachy can barely make coherent sentences in English, I really would rather not give him a procedure in it.
Lou
Sorry, Lou. I didn't realize that you had done Pt plating.
I just found this patent, 3357858.
https://www.google.com/patents/US3357858?dq=patent:3357858&hl=en&sa=X&ei=F9nrU6_VNsHB8QG5r4C4BQ&ved=0CB4Q6AEwAA
According to the patent, they got the best adhesion by activating the Ti in boiling 2/1, HCl/HNO3 for 30 minutes. The formula for the mentioned Pfanhauser bath is found on page 195 of this article.
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=9&cad=rja&uact=8&ved=0CEUQFjAI&url=http%3A%2F%2Fwww.technology.matthey.com%2Fpdf%2Fpmr-v32-i4-188-197.pdf&ei=O9zrU8T-LIfLsQT-_gI&usg=AFQjCNEA8ra5IJyKx_SWyeyPpHOM1oCMFw&bvm=bv.72938740,d.cWc
I just found this patent, 3357858.
https://www.google.com/patents/US3357858?dq=patent:3357858&hl=en&sa=X&ei=F9nrU6_VNsHB8QG5r4C4BQ&ved=0CB4Q6AEwAA
According to the patent, they got the best adhesion by activating the Ti in boiling 2/1, HCl/HNO3 for 30 minutes. The formula for the mentioned Pfanhauser bath is found on page 195 of this article.
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=9&cad=rja&uact=8&ved=0CEUQFjAI&url=http%3A%2F%2Fwww.technology.matthey.com%2Fpdf%2Fpmr-v32-i4-188-197.pdf&ei=O9zrU8T-LIfLsQT-_gI&usg=AFQjCNEA8ra5IJyKx_SWyeyPpHOM1oCMFw&bvm=bv.72938740,d.cWc
I did a search for Platinum/Titanium anodes, mainly the expanded metal type. It seems there are many manufacturers and there are also many listings on eBay. The pricing is all over the map, ranging from about $4/in2 to $30/in2 (Amazon). The Pt thickness varies considerably, usually from 20 micro" (0.5 microns) to 150 micro" (3.75 microns). I found one listing offering a Pt thickness of 600 micro" (15 microns) but no pricing was given. The actual Pt metal value runs about $0.66/micron/in2, at a $1461 spot price. Pt coated anodes are also available in Tantalum, Niobium, and Zirconium.
Some of the anodes on eBay are used. Used anodes are a pig in a poke since, through usage, the Pt can get thinner. We used to test the anodes by quickly heating a small spot just to red hot with a small torch. If the Pt coating was sound, there was no discoloration after cooling. All the heat did was make it look cleaner. If the Pt was considerably worn off, there would definitely be discoloration. This discoloration was usually blue, if I remember right.
Platinized anodes are used in many industrial electrolytic processes that require the anode to be totally inert. For example, they are almost always used in acid gold plating (pH about 4) and acid rhodium plating. In both cases, stainless can't be used since it would corrode somewhat and contaminate the baths. Bare Ti can't be used because it would form an oxide layer and become passive. Carbon or graphite can't be used because it would slowly erode into small loose particles which would co-deposit and produce roughness on the plated parts. Beside platinized Ti or Ta, about the only other option for acid gold baths would be pure gold or pure Pt anodes, which would be much more expensive than platinized titanium.
Some of the anodes on eBay are used. Used anodes are a pig in a poke since, through usage, the Pt can get thinner. We used to test the anodes by quickly heating a small spot just to red hot with a small torch. If the Pt coating was sound, there was no discoloration after cooling. All the heat did was make it look cleaner. If the Pt was considerably worn off, there would definitely be discoloration. This discoloration was usually blue, if I remember right.
Platinized anodes are used in many industrial electrolytic processes that require the anode to be totally inert. For example, they are almost always used in acid gold plating (pH about 4) and acid rhodium plating. In both cases, stainless can't be used since it would corrode somewhat and contaminate the baths. Bare Ti can't be used because it would form an oxide layer and become passive. Carbon or graphite can't be used because it would slowly erode into small loose particles which would co-deposit and produce roughness on the plated parts. Beside platinized Ti or Ta, about the only other option for acid gold baths would be pure gold or pure Pt anodes, which would be much more expensive than platinized titanium.
