Greetings fellow refiners and a special greeting to the main guys, namely Harold, Gsp, Manuel, Butcher and Steve to name a few.i have been a member of this outstanding forum for a few years and thank the various guys for their good work.i have been refining gold and silver and other metals for a while and recently I tried x rays.i went ahead with a process documented by the university of turkey mentioning a method using NAOH and proceeded to first sort dryview from the wet film.i prepared a concentration of 1M of NAOH at 80 degress celcius and managed to strip the silver layer from the mylars.i now sit with colloidal silver in solution and would like to hear from the experts here how to proceed in getting my silver precipitated.i have searched the forum since yesterday for sum answers and I know the procedure calls for heating and stirring the solution to get silver from it, but I would really like the advice of Manuel or Gsp or perhaps Steve on this one.thanks again
colloidal silver from x ray process
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Well the report I got the investigation from said that silver would be colloidal in the solution and that heating and stirring would be required to get the silver as bb sized shiny particles.i processed 4kg of x rays and have 8litres of solution that is black as the document described it.
Juan Manuel Arcos Frank
Well-known member
Yazeed:
Colloids are very important in many fields,like Biology ,Physics,Medicine,Chemistry and so for but in PM recovering colloids are our enemies because a PM colloidal solution never ever precipitates(well,by sedimentation or gravity).So you have to learn how to destroy(or discharge) a colloid.Colloids are electric charged solutions so the trick is to discharge them...How?...there are three methods:
-Boiling the colloidal solution
-Modifying its PH (if its acidic turn it into basic or viceversa)
-A combination of the two mentioned.
My advice to you is boiling for half an hour your black solution,let settle down and filtrate the mud.
Why did you form a colloid?...hard to say but probably you are using too much NaOH.
Hope it helps.
Kindest regards.
Manuel
Colloids are very important in many fields,like Biology ,Physics,Medicine,Chemistry and so for but in PM recovering colloids are our enemies because a PM colloidal solution never ever precipitates(well,by sedimentation or gravity).So you have to learn how to destroy(or discharge) a colloid.Colloids are electric charged solutions so the trick is to discharge them...How?...there are three methods:
-Boiling the colloidal solution
-Modifying its PH (if its acidic turn it into basic or viceversa)
-A combination of the two mentioned.
My advice to you is boiling for half an hour your black solution,let settle down and filtrate the mud.
Why did you form a colloid?...hard to say but probably you are using too much NaOH.
Hope it helps.
Kindest regards.
Manuel
rickbb
Well-known member
What you probably have is a slurry that contains the silver AND the residue of the gelatin emulsion on the film that the silver was in. That is what the NaOH did, was break down the silver bearing emulsion and release it from the polyester film.
Next step is to let it settle and decant the liquid off. Then dry and incinerate the black powder to burn off the gelatin.
Next step is to let it settle and decant the liquid off. Then dry and incinerate the black powder to burn off the gelatin.
In my refinery, I stripped film in 10% (100g/l or about 0.8#/gal) caustic soda solution in a 3-5 RPM, 30" dia., SS tumbler (made from an industrial clothes dryer) in a heated (about 120-140F) 360 gal., 5' long tank. The tank was originally a milk storage tank with cooling coils under the tank. I modified this to circulate water in and out of a hot water tank with a pump.
Chopped black or green film took about 10-30 minutes and I did about 1000-1500# (100-150oz of silver if it was black rare earth Medical film) in an 8 hr day. I ran no Dry-View. Most of the film I ran was bought at auction from places like Bendix Corp in Kansas City and various nursing homes that had been saving it for 30-40 years. I probably never paid more than 20 cents on the dollar.
About 5' away from the side of the tank, on one wall, I had a heavy duty shelf about 5' off the floor. On the shelf were 6, open top, plastic, 55gal drums with a bulkhead adaptor mounted about 2" off the bottom of each one. After stripping all day, I stirred the tank well and pumped the solution + solids into the drums. After settling overnight, I attached hoses to the bulkhead adapters, drained the solution back into the tank, and heated it for that days production. I used the same solution over and over. The life of a solution was at least a month or two, although I occasionally analyzed it, using a simple acid-base titration, and added whatever caustic it needed.
I stirred up the 2" of sludge/solution in each drum and poured it into buckets. When it had settled, maybe overnight, I poured the solution off the solids carefully, back into the tank. The sludges were collected all together in an 18" Bel-Art plastic Buchner funnel, vacuum filtered, and rinsed a couple of times. The filtered solutions were returned to the tank.
The de-watered sludge was put into a couple of buckets, covered with about 15-20% H2SO4, stirred, and then allowed to leach for a couple of hours. The sulfuric eliminated about half of the emulsion volume. This sludge was then vacuum filtered (the sulfuric sludge filtered faster than the caustic sludge), rinsed, sucked fairly dry, incinerated, and melted with borax and a little soda ash (1 part incinerated sludge, 0.3 parts borax, and 0.1 parts soda ash - all blended together). The results were at least 999 bars, which were then remelted and cast into 10 or 100 oz bars in a book mold.
Although it didn't happen often, a small fraction of the solids wouldn't completely settle in the drums or buckets and some would be drained or poured back into the tank. No problem. It's not lost and it didn't interfere with the stripping. I would eventually get it all. As my Mom used to say, "Everything comes out in the wash."
Chopped black or green film took about 10-30 minutes and I did about 1000-1500# (100-150oz of silver if it was black rare earth Medical film) in an 8 hr day. I ran no Dry-View. Most of the film I ran was bought at auction from places like Bendix Corp in Kansas City and various nursing homes that had been saving it for 30-40 years. I probably never paid more than 20 cents on the dollar.
About 5' away from the side of the tank, on one wall, I had a heavy duty shelf about 5' off the floor. On the shelf were 6, open top, plastic, 55gal drums with a bulkhead adaptor mounted about 2" off the bottom of each one. After stripping all day, I stirred the tank well and pumped the solution + solids into the drums. After settling overnight, I attached hoses to the bulkhead adapters, drained the solution back into the tank, and heated it for that days production. I used the same solution over and over. The life of a solution was at least a month or two, although I occasionally analyzed it, using a simple acid-base titration, and added whatever caustic it needed.
I stirred up the 2" of sludge/solution in each drum and poured it into buckets. When it had settled, maybe overnight, I poured the solution off the solids carefully, back into the tank. The sludges were collected all together in an 18" Bel-Art plastic Buchner funnel, vacuum filtered, and rinsed a couple of times. The filtered solutions were returned to the tank.
The de-watered sludge was put into a couple of buckets, covered with about 15-20% H2SO4, stirred, and then allowed to leach for a couple of hours. The sulfuric eliminated about half of the emulsion volume. This sludge was then vacuum filtered (the sulfuric sludge filtered faster than the caustic sludge), rinsed, sucked fairly dry, incinerated, and melted with borax and a little soda ash (1 part incinerated sludge, 0.3 parts borax, and 0.1 parts soda ash - all blended together). The results were at least 999 bars, which were then remelted and cast into 10 or 100 oz bars in a book mold.
Although it didn't happen often, a small fraction of the solids wouldn't completely settle in the drums or buckets and some would be drained or poured back into the tank. No problem. It's not lost and it didn't interfere with the stripping. I would eventually get it all. As my Mom used to say, "Everything comes out in the wash."
Thanks guys, I have so far left the solution for two days now will see if anything settled, otherwise I will boil in a water bath as Manuel suggested, I will do that first thing in the morning and will come bavk with feedback and hopefully these results will help sumbody else as well in the x ray field.Manuel, you mentioned that boiling or altering the ph may yield the silver, so I am going to boil as suggested, also how would you propose I adjust the ph? Sulphuric? Or hcl? And also id very much like to know how you would run a batch of x rays if you had to use caustic soda.thanks Gsp for your insight as well.
kind regards
Yazeed
kind regards
Yazeed
Juan Manuel Arcos Frank
Well-known member
Yazeed:
By adding a strong acid,like sulphuric(H2SO4) but be careful about its handling and remember NEVER ADD WATER TO AN ACID.
Many years ago I tried to use NaOH process but I always formed a colloid and silver never settled down because I used very concentrated solutions of NaOH (40%),so do not make the same mistake I did.
If the going gets rough then let me know.
Kindest regards.
Manuel
By adding a strong acid,like sulphuric(H2SO4) but be careful about its handling and remember NEVER ADD WATER TO AN ACID.
Many years ago I tried to use NaOH process but I always formed a colloid and silver never settled down because I used very concentrated solutions of NaOH (40%),so do not make the same mistake I did.
If the going gets rough then let me know.
Kindest regards.
Manuel
Silver is one of the amphoteric metals which can precipitate in a base solution, and go back into solution when an excess of a strong base solution is added.
It may or may not have been a colloid that held the silver in solution, either way adding a little H2SO4 acid to adjust pH and heat would be a good choice.
It may or may not have been a colloid that held the silver in solution, either way adding a little H2SO4 acid to adjust pH and heat would be a good choice.
Thanks guys for the information. I have the mud of silver in the filters and I have incinerated the dryview film and collected the ashes.so tomorrow im going to melt my results.Gsp I read in your reply that you melt the ashes with soda ash and borax according to a recipe you have written down here andvwhich I have noted.today I went to purchase soda ash but could not get borax, question is can I use potassium nitrate intstead of borax to flux the mixture? As I have sum potassium nitrate in my lab.i have read that the alchemists of old used salpetre as a flux.
Thanks again and regards to Manuel as well.
Thanks again and regards to Manuel as well.
You can look in the laundry section of your stores, for 20 mule team borax soap.
Nitrate is an oxidizer, it will not work to replace borax, it has a completely different purpose when used in flux.
Nitrate is an oxidizer, it will not work to replace borax, it has a completely different purpose when used in flux.
