# adding HCl to caustic soda and film release Cl gas



## chandler_P (Aug 29, 2011)

Hi all,

Could somebody explain if adding HCl into (NaOH and black stain from xray film that was stripped off) releases chlorine gas?

NaOH + black stain from xray film (probable Ag and gelatin)+ HCl = NaCl(aq) + H2O + Ag + gelatin --> incorrect? 

The used xray film is silver halide.

Thanks a lot.


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## Imran (Sep 1, 2011)

I think this wont work. You can try bleack or H2O2 instead of NaOH and you will get AgCl.


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## sena (Sep 8, 2011)

chandler_P said:


> Hi all,
> 
> Could somebody explain if adding HCl into (NaOH and black stain from xray film that was stripped off) releases chlorine gas?
> 
> ...


where it forms NAcl , i used Hcl to neutralize the Naoh solution mixed with silver halide, i have recovered silver 4kgs , the process reduces the stickiness and hence the halide settle faster, heating the filtered mud till it turns sandal brown , will allow it for melting easily to recover silver .


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## chandler_P (Sep 8, 2011)

sena said:


> chandler_P said:
> 
> 
> > Hi all,
> ...



Hi Sena,

So you add HCl until the solution has pH of 7 (neutralize). With the 4 kgs of silver? How many kgs of xray film did you use?

Thanks!


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## sena (Sep 8, 2011)

chandler_P said:


> sena said:
> 
> 
> > chandler_P said:
> ...


it was 3.6kgs exactly of silver with 200kgs flim.


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## chandler_P (Sep 9, 2011)

Hi Sena, 

Nice. I think there's something wrong with what i'm doing. I already used 30kg of xray film and just had 15grams. :s

THe process I used was NaOH (1.5M solution), and heat till it boils for around 30mins per 10 liter solution. What do you think went wrong why I only got such amount?

Thanks!


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## goldsilverpro (Sep 9, 2011)

chandler_P said:


> Hi Sena,
> 
> Nice. I think there's something wrong with what i'm doing. I already used 30kg of xray film and just had 15grams. :s
> 
> ...



If it's typical developed rare earth medical x-ray film, you should have gotten about 200g of silver from 30kg. If Dryview, from 80 to 200g, depending on the manufacturer.

After stripping the film, was all of the black removed from it? If so, and if you were able to collect all of the sludge from the liquid, by filtration or whatever, all of the silver was in the sludge. At that point, here's what I would do.

Incinerate the sludge, outside, upwind, until no black carbon remains. Stir occasionally to keep it broken up. The dry sludge will be light gray/brown, as in Sena's photo on another recent thread.

Blend the incinerated sludge (grind it up a bit, first - use a dust mask) well with borax - about a third to one half as much weight of borax as you have incinerated sludge. At the same time, blend in some sodium carbonate (Arm & Hammer super washing soda from the grocery store) - use about 1/15 as much, by weight, sodium carbonate as you have sludge. Only fill the crucible about 1/3 full to allow for the foaming up of the borax. Once the foaming has subsided, you can add more of the incinerated sludge to the crucible with a metal scoop

When everything melts, pour into a carboned (or, slightly oiled - WD40 will work for this), heated mold. If you don't have a mold, you can easily make a v-shaped one by welding a square steel plate on each end of a piece of angle iron - the plates act as legs and seal the ends. The plates should angle in a little at the bottom, so the bar will easily slide out. A 6" piece of 3" x 3" angle iron will hold quite a bit - if needed, make a bigger one. When solid, dump everything out of the mold, let it cool, and break all the slag off with a hammer. Weigh the bar. It should be in the range of what is expected.

Note: the slag will usually come off the bar easier if you quench it in in water while still very hot. However, this can be dangerous since the slag can somewhat explode and fly around. If you try this, use at least a 15 gallon metal container filled with water. Just drop the bar in and get away from it quickly.


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## sena (Sep 9, 2011)

chandler_P said:


> Hi Sena,
> 
> Nice. I think there's something wrong with what i'm doing. I already used 30kg of xray film and just had 15grams. :s
> 
> ...


Hi friend saw your post regarding 30kgs of flim , i need to ask you some question for clarification have you done all by yourself i mean melting the sludge? this is because most people they dont do by themself and there by if they werent giveing it to the right smelter there may be lack in amount expected thats the reason i asked you., secondly dont throw away any liquid ,
i was dealing with industrial flims, is it yours medical xray flim?
even though it would strip silver halide using Naoh process ,the time scale is simple check till the last flim you have droped have been striped , i dont think so not more than 2 hrs , no heating required .just remove flim wash it with water , leaving the solution behind .pour the solution as well as , washing liquid in a large container .mix half ltr hcl stir it well ( you can take a sample in glass container after well stiring keep it aside to know wheather your solution got settled with silver halide )the next day siphon the liquid...then do the same i said you earlier, dont give up i have wasted several kgs and right now answering you.Look for Gsp posting he has mentioned clearly for further clarification Pm me.


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## chandler_P (Sep 9, 2011)

Hi GSP/ Sena,

Thanks for the tips. I know, i have not collected or recover the silver very well.  

I' ll try the HCl you have done Sena. 

Thanks GSP for this information.

Thanks again guys!


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## chandler_P (Sep 9, 2011)

goldsilverpro said:


> chandler_P said:
> 
> 
> > Hi Sena,
> ...



The stripping part was all good. used 10liters of NaOH solution for 4kg of medical x-ray film. heated it and waited for settled sludge. I noticed that doing heating, I did not get all the silver, the solution is bluish black so silver must have been washed away. I will try the HCl to recover the sludge.
Maybe add half a liter of HCl to this solution.

Thanks. i will update on my progress.


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## chandler_P (Sep 18, 2011)

Hi my friend,

Finally getting all of the sludge using different approaches. But the topic here, i guess wasn't answered, if adding the HCl to caustic soda solution release chlorine gas? 

Good day everyone!


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## sena (Sep 18, 2011)

chandler_P said:


> Hi my friend,
> 
> Finally getting all of the sludge using different approaches. But the topic here, i guess wasn't answered, if adding the HCl to caustic soda solution release chlorine gas?
> 
> Good day everyone!


no where it forms nacl, gas released is hydrogen .


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