austexjwlry
Well-known member
- Joined
- Jun 5, 2007
- Messages
- 116
In my silver cells I use Rooto straight from the bottle, no glycerine. I buy it by the case from Ace hardware. They're glad to order it for us as its a guaranteed sale and they're ordering other items from the same company by the pallet anyway.
I don't add water when deplating silver because I like to slow down the action in the cell so as to not create too many hydrogen bubbles. I deplate up to 40 silver plated - nickel silver - base metal items at a time, and perhaps 6 to 8 silver plated stainless knives depending on how many amps I'm drawing per cell. With fresh acid it takes about an hr, when almost saturated around 2 hrs. I reload these cells usually 3 times a day, taking 3 days to saturate fresh acid before I start drawing too many amps. I run 2- 25 amp rectifiers, one for each cell and don't like to draw more than 15 or 16 amps.
When I empty my cells I use a plastic cup or ladle to remove most of the acid and then pour the last little bit into my container. I then use a rubber cake batter spatula to wipe the heavier sludge gently into the container. So as to not splash even small drops onto any part of me. I keep a box of Arm & Hammer baking soda nearby with a cup of water near it. If it does splash on me, I wipe the drop off with a paper towel, then wet my finger and stick it into the baking soda. Then apply the paste to the spot where the acid was to neutralize it, then rinse repeatedly with fresh water. A sulphuric acid burn left untreated will burn and blister much like a burn from a torch flame.
I let the entire contents of my cells settle for at least 5 days as the silver sulfate is very light compared to silver nitrate from a nitric solution. After it's settled all it will, I scoop off the clear dark green sulphuric for further use in my cell. It's still good; I consider it preloaded with buffers.
The remainder is silver sulphate and silver metal from where silver sulphate contacts the copper cathode and is reduced to metal. The sulphuric will only hold so much silver then it starts to self precipitate. You may also have nickel and copper, chromium and iron from the stainless steel items. Perhaps lead and tin from any silver plated pot metal you deplate. Silver plated zinc items deplate fast and are completely dissolved in the time it takes to deplate silver plated nickel silver or stainless items.
I carefully pour the saturated sulphuric sludge into at least 3 times its volume of water. I use the rinse water I used to rinse the items I deplated etc., I precipitate at this time without allowing anything to settle. I precipitate the silver sulphate in solution with a good amount of table salt dissolved in warm to hot tap water. You just add a good amount and you will see a thin light whitish cloud while precipitating. Much lighter with no curds like when precipitating silver nitrate from a nitric solution. It does not agglomerate, forming larger grains like silver nitrate either. Use a definite excess of table salt to keep the silver sulphate from going back into solution while settling overnight. I let this settle a full day then siphon the dark green clear part into a different container.
I pour the clear solution from this container into a 5 gallon bucket which has around 10 lbs of copper scrap or even the nickel silver scrap you just deplated to cement out any remaining silver from solution. Copper and nickel are slowly dissolved by dilute sulphuric acid allowing it to be used for this purpose. I cement out very little silver in this bucket as amost all of it was precipitated by the sodium chloride (table salt).
I pour the contents of this bucket into another 5 gallon bucket containing copper again with virtually no silver cemented out.
I then pour into a 5 gallon bucket containing mild steel where the dilute sulphuric starts to bubble readily and cements out copper with virtually no silver here either.
Yes, I use a fourth bucket with mild steel and get very little copper cemented out. My cementation buckets follow the same 3 day cycle as my cells.
Getting back to the silver sulphate/silver metal/base metal sludge container. I build this up until I have at least 10 lbs because processing 20 lbs is only a little more work than 10 lbs, and 10 lbs only a little more work than 1 lb, but 20- 1 lb batches is 20 times the work of a 1- 20lb batch.
My nitric now costs $49 a gallon and I use as much as necessary to make my wash water run clear. If you leave items in your cell longer than necessary you'll dissolve much more base metal and it's expensive to remove.
Everytime you add nitric to remove base metals from the silver sulphate it doesn't selectively dissolve the base metals like when used on gold. You'll have to reprecipitate some silver in the form of silver nitrate with each wash using table salt . The last few washes I use hydrochloric acid instead of table salt in hopes of removing any remaining traces of lead etc. For my last acid wash I use sulphuric in hopes of removing any last little traces of tin, etc. Then I rinse several times with clean tap water.
I use the karo syrup/lye method to reduce my mixture of silver metal/ silver sulphate/ silver nitrate to silver metal. I like to add the karo first. Now you have to wash again with clean water 10 to 15 times.
Now melt your metal, it'll be close enough to fine if you worked carefully!
Be aware that when old silverplated knives, for instance, are stamped warranted 15 dwt that doesn't mean 15 dwt of silver per piece but 15 dwt of silver per dozen knives. Some very approx. returns from silverplate are:
old tablespoons and forks and large soup spoons 35 dwt per dozen
old dessert spoons and forks, solid fish eaters and fruit knives & forks 25 dwt per dozen
teaspoons 15 dwt per dozen
coffee spoons 10 dwt per dozen
1 dwt equals approx. 1 1/2 grams
I got these estimates from the book The Sampling and Assay of the Precious Metals by E.A. Smith. Based on my limited experience, I think they are pretty close on old silverplate; newer silverplate items may figure out differently, probably less. Large trays, pitchers, cups, saucers etc in my opinion are best deplated in one piece in a larger cell, as it's really hard to cut them up!
I have not found any appreciable amounts of gold, palladium or platinum in silver plated items even in scrap as far back as 1835, the miners, assayers and manufacturers knew their business!
Best Regards,
Wayne
I don't add water when deplating silver because I like to slow down the action in the cell so as to not create too many hydrogen bubbles. I deplate up to 40 silver plated - nickel silver - base metal items at a time, and perhaps 6 to 8 silver plated stainless knives depending on how many amps I'm drawing per cell. With fresh acid it takes about an hr, when almost saturated around 2 hrs. I reload these cells usually 3 times a day, taking 3 days to saturate fresh acid before I start drawing too many amps. I run 2- 25 amp rectifiers, one for each cell and don't like to draw more than 15 or 16 amps.
When I empty my cells I use a plastic cup or ladle to remove most of the acid and then pour the last little bit into my container. I then use a rubber cake batter spatula to wipe the heavier sludge gently into the container. So as to not splash even small drops onto any part of me. I keep a box of Arm & Hammer baking soda nearby with a cup of water near it. If it does splash on me, I wipe the drop off with a paper towel, then wet my finger and stick it into the baking soda. Then apply the paste to the spot where the acid was to neutralize it, then rinse repeatedly with fresh water. A sulphuric acid burn left untreated will burn and blister much like a burn from a torch flame.
I let the entire contents of my cells settle for at least 5 days as the silver sulfate is very light compared to silver nitrate from a nitric solution. After it's settled all it will, I scoop off the clear dark green sulphuric for further use in my cell. It's still good; I consider it preloaded with buffers.
The remainder is silver sulphate and silver metal from where silver sulphate contacts the copper cathode and is reduced to metal. The sulphuric will only hold so much silver then it starts to self precipitate. You may also have nickel and copper, chromium and iron from the stainless steel items. Perhaps lead and tin from any silver plated pot metal you deplate. Silver plated zinc items deplate fast and are completely dissolved in the time it takes to deplate silver plated nickel silver or stainless items.
I carefully pour the saturated sulphuric sludge into at least 3 times its volume of water. I use the rinse water I used to rinse the items I deplated etc., I precipitate at this time without allowing anything to settle. I precipitate the silver sulphate in solution with a good amount of table salt dissolved in warm to hot tap water. You just add a good amount and you will see a thin light whitish cloud while precipitating. Much lighter with no curds like when precipitating silver nitrate from a nitric solution. It does not agglomerate, forming larger grains like silver nitrate either. Use a definite excess of table salt to keep the silver sulphate from going back into solution while settling overnight. I let this settle a full day then siphon the dark green clear part into a different container.
I pour the clear solution from this container into a 5 gallon bucket which has around 10 lbs of copper scrap or even the nickel silver scrap you just deplated to cement out any remaining silver from solution. Copper and nickel are slowly dissolved by dilute sulphuric acid allowing it to be used for this purpose. I cement out very little silver in this bucket as amost all of it was precipitated by the sodium chloride (table salt).
I pour the contents of this bucket into another 5 gallon bucket containing copper again with virtually no silver cemented out.
I then pour into a 5 gallon bucket containing mild steel where the dilute sulphuric starts to bubble readily and cements out copper with virtually no silver here either.
Yes, I use a fourth bucket with mild steel and get very little copper cemented out. My cementation buckets follow the same 3 day cycle as my cells.
Getting back to the silver sulphate/silver metal/base metal sludge container. I build this up until I have at least 10 lbs because processing 20 lbs is only a little more work than 10 lbs, and 10 lbs only a little more work than 1 lb, but 20- 1 lb batches is 20 times the work of a 1- 20lb batch.
My nitric now costs $49 a gallon and I use as much as necessary to make my wash water run clear. If you leave items in your cell longer than necessary you'll dissolve much more base metal and it's expensive to remove.
Everytime you add nitric to remove base metals from the silver sulphate it doesn't selectively dissolve the base metals like when used on gold. You'll have to reprecipitate some silver in the form of silver nitrate with each wash using table salt . The last few washes I use hydrochloric acid instead of table salt in hopes of removing any remaining traces of lead etc. For my last acid wash I use sulphuric in hopes of removing any last little traces of tin, etc. Then I rinse several times with clean tap water.
I use the karo syrup/lye method to reduce my mixture of silver metal/ silver sulphate/ silver nitrate to silver metal. I like to add the karo first. Now you have to wash again with clean water 10 to 15 times.
Now melt your metal, it'll be close enough to fine if you worked carefully!
Be aware that when old silverplated knives, for instance, are stamped warranted 15 dwt that doesn't mean 15 dwt of silver per piece but 15 dwt of silver per dozen knives. Some very approx. returns from silverplate are:
old tablespoons and forks and large soup spoons 35 dwt per dozen
old dessert spoons and forks, solid fish eaters and fruit knives & forks 25 dwt per dozen
teaspoons 15 dwt per dozen
coffee spoons 10 dwt per dozen
1 dwt equals approx. 1 1/2 grams
I got these estimates from the book The Sampling and Assay of the Precious Metals by E.A. Smith. Based on my limited experience, I think they are pretty close on old silverplate; newer silverplate items may figure out differently, probably less. Large trays, pitchers, cups, saucers etc in my opinion are best deplated in one piece in a larger cell, as it's really hard to cut them up!
I have not found any appreciable amounts of gold, palladium or platinum in silver plated items even in scrap as far back as 1835, the miners, assayers and manufacturers knew their business!
Best Regards,
Wayne
