X-Ray Fixer Sediment Question

[Red Ox]

After having successful results from several projects with AP and the sulfuric cell I felt ready to move ahead. Silver.., I thought, so I located some x-ray fixer solution to experiment with. It tested positive (see img)



and I have dropped what I believe is metallic silver from a couple of liters of the fixer solution via zinc shavings. I did filter the fixer before I attempted to drop the silver content however it retained a minor measure of cloudiness that I could not clear. I have not properly washed either liter's values preferring to collect the entire lot's total before proceeding with that step. Subsequent tests of the processed liquid indicate no silver content remaining after the drop. All seems to be progressing as planned and envisioned however, I am truly curious about the sediment that is in this fixer (see img). I simply cannot identify it nor find an answer.



A bit of background:
Dental x-ray fixer. Appx 5gal/19lt. Manufacturer - unknown.
Probable contents - and this is a guess based on the heavy aromatic, slightly sweet, ammonia like odor -
Kodak Readymatic Dental Fixer, MSDS states the following:
Water, Ammonium thiosulfate, Ammonium sulfite, Acetic acid & Aluminum sulfate. I realize that there are many, many recipes for fixers http://hazard.com/msds/gn.cgi?query=x-ray+fixer&whole=partial&start=0 and this is, at best, a rookie’s guess.
I also have no history on this fixer ie; Is/was it present before use, is/was it dry mix, wet mix or premix, number of films processed, age, storage temps, etc.

The sediment itself has a yellow cast (see img).



It's consistency seems to be that of cottage cheese while in suspension yet a little jostle of the container produces a bloom creating a milky liquid with a distinct 'mother of pearl' or opal look that my image just doesn't convey. (see img)



It appears that I am collecting the metallic silver just fine but, the mystery filtrate and it’s ramifications within the process and it’s disposal is of some concern to me. There is, also, no doubt that some has found it’s way in with the values that I’m collecting and I’ll have to deal with that at some point. At the moment I’m keeping the filtrate I’ve collected wet and not allowing it to dry out.

So, I suppose what I’m asking is, can anyone help me with a ‘probable/possible’ ID on this sediment?

Ken

 

[Juan Manuel Arcos Frank]

Ken:

That fixer is too old...I mean,all compounds have reacted to form a mixer of sulphides,among silver sulphide so my advice to you is:

1.- Verify there is not silver in solution by using copper wire method(posted in this wonderful Forum).

2.-If copper wire test is negative for silver in solution then filter the mud,dry it and you have two alternatives to get metallic silver:
I.- By using my silver sulphide process(posted in this wonderful Forum) which means melting the dry mud with saltpetre.
II.-Adding Aqua Regia to the dry mud(read safety handling of Aqua regia and fumes),all compounds will react to form a chloride mixtures,including silver chloride which is insoluble and will precipitate as a white mud on the bottom,let settle down it,filter and transform silver chloride by using metallic replacement process,zinc/acid process or fusion with Na2CO3 to get metallic silver.

Keep us posted about your progress.

Kindest regards.

Manuel

 

[Lou]

Looks like gelatinous aluminum hydroxide to me!

 

[Red Ox]

Lou,
I thank you for that suggestion and will keep it in mind as I proceed.

=========================================

Juan,
The remaining fixer does test positive for silver.
My plan, unless you change my mind, is to progressively filter smaller all of the particulate from the remaining 4± gallons. Start air drying that mud, in preparation to use your process to convert silver sulphide to metallic silver. Meanwhile as the two or three days drying time ticks, I'll begin dropping the metallic silver from the now filtered and pH 5 adjusted fixer with zinc.


And, okay, since you've asked, I'll keep you posted

Ken