TCCA (Trichloroisocyanuric acid - pool chlorine tablets)

[haveagojoe]

I'm planning to use the HCl-TCCA (pool chlorine tablets) method to dissolve my next lot of escrap foils over the holidays. Previously I have used Sodium Hypochlorite bleach but I can't find any locally any more which doesn't contain fragrance and other additives. I'm curious to try TCCA as it seems the Chlorine is released into the solution in a more controlled manner, and I've read that it also avoids the potential problem of bleach neutralizing the HCl. When I've done it with bleach, while successful, it seemed like the Chlorine left the solution rapidly and I have been obliged to add more HCl to complete the dissolution, resulting in a large volume and low concentration of gold in solution.

I have read everything I can find on the forum about the method, it seems that the ideal approach is to drip HCl onto the TCCA in a flask and bubble the resulting Chlorine gas into the metal reaction vessel via a tube. I have seen @kadriver Sreetips do it that way some years ago on Youtube and a few other times since.

Unfortunately I don't have the right glassware to do it that way, but it seems that alternatively TCCA can be added directly to the foils in HCl. So I plan to do that; first crushing the tablet to powder and adding it in small doses while stirring, allowing time inbetween additions for the Chlorine to react. I'm wondering if perhaps it would be better to use small chunks rather than crushing the tablet to powder? Maybe that would help to slow down the rate of Chlorine production?

I'm considering possibly covering the beaker and stirrer loosely with clingfilm which I'm thinking might help to keep the gas in the beaker while still allowing me to stir it. After allowing the Chlorine to off-gas I plan to cement the gold out of solution with copper before refining.

Since most of the threads on this topic are several years old I was wondering if anyone had any updates or tips to share regarding this process? I understand @Yggdrasil favours this method, alongside HCl-H2O2- sadly though even H2O2 is becoming more difficult to obtain here in the UK, apparently 12% is the maximum available now and the pharmacy may ask you to complete a questionnaire

I was not able to find any specfic information regarding waste handling for this process but I understand that it produces cyanuric acid, which Wikipedia tells me is classifed as "essentially nontoxic" and "a component of urine" which is somewhat reassuring but I want to maintain caution since this is a new method for me.

Maybe I'm overthinking it but better safe than sorry, so any comments would be much valued.

 

[Yggdrasil]

I'm planning to use the HCl-TCCA (pool chlorine tablets) method to dissolve my next lot of escrap foils over the holidays. Previously I have used Sodium Hypochlorite bleach but I can't find any locally any more which doesn't contain fragrance and other additives. I'm curious to try TCCA as it seems the Chlorine is released into the solution in a more controlled manner, and I've read that it also avoids the potential problem of bleach neutralizing the HCl. When I've done it with bleach, while successful, it seemed like the Chlorine left the solution rapidly and I have been obliged to add more HCl to complete the dissolution, resulting in a large volume and low concentration of gold in solution.

I have read everything I can find on the forum about the method, it seems that the ideal approach is to drip HCl onto the TCCA in a flask and bubble the resulting Chlorine gas into the metal reaction vessel via a tube. I have seen @kadriver Sreetips do it that way some years ago on Youtube and a few other times since.

Unfortunately I don't have the right glassware to do it that way, but it seems that alternatively TCCA can be added directly to the foils in HCl. So I plan to do that; first crushing the tablet to powder and adding it in small doses while stirring, allowing time inbetween additions for the Chlorine to react. I'm wondering if perhaps it would be better to use small chunks rather than crushing the tablet to powder? Maybe that would help to slow down the rate of Chlorine production?

I'm considering possibly covering the beaker and stirrer loosely with clingfilm which I'm thinking might help to keep the gas in the beaker while still allowing me to stir it. After allowing the Chlorine to off-gas I plan to cement the gold out of solution with copper before refining.

Since most of the threads on this topic are several years old I was wondering if anyone had any updates or tips to share regarding this process? I understand @Yggdrasil favours this method, alongside HCl-H2O2- sadly though even H2O2 is becoming more difficult to obtain here in the UK, apparently 12% is the maximum available now and the pharmacy may ask you to complete a questionnaire

I was not able to find any specfic information regarding waste handling for this process but I understand that it produces cyanuric acid, which Wikipedia tells me is classifed as "essentially nontoxic" and "a component of urine" which is somewhat reassuring but I want to maintain caution since this is a new method for me.

Maybe I'm overthinking it but better safe than sorry, so any comments would be much valued.

I favor the use of Peroxide.
I found some old 30% that I used.
I can buy 49% but only in 20L cans.
When I used TCCA I ground it up and drizzled it into the HCl.
Quite effective this way since the Chlorine is released slowly.