kesavan said:
Hye guys...seriously need a piece of advice on Silver Chloride....I just recovered Silver in the form of Silver Chloride two days back..and its still wet..now..i wanna know whether I can straight away melt these Silver Chloride to Silver..or i need to add on any other process before melting it...??pls help me guys...badly need to know about it.TQ
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=50&t=8147&p=76056&hilit=+convert+silver+chloride+Karo+syrup#p75964
For each troy ounce of silver, as silver chloride, well rinsed, just cover with water and add to this 20 grams of sodium hydroxide, dissolved previously, in water, plus about 13.3 ml of Karo light syrup. Stir for about 15 minutes. A power stirrer is the best, since it will chop things up and you will have a better yield. The solution will turn reddish-black but all the silver chloride will be converted to a gray, granular silver powder. Rinse very well and melt the silver.
The sodium hydroxide converts the silver chloride to silver oxide. The silver oxide is converted to silver metal by simply heating and melting it. Also, as HAuCl4 said, you can use H2O2 to convert it to metal. I would imagine the amount of NaOH needed would be about the same - about 20 grams per troy ounce of silver contained in the silver chloride.
It's not easy to get 100% conversion of AgCl to silver metal. If you have unconverted AgCl, it will end up in a layer in between the silver and the slag after melting and cooling. This solid AgCl is very difficult to convert to metal. Also, when molten, AgCl puts off dangerous fumes. It's best to get it all converted before melting it. All of your efforts should be towards this goal.
When the AgCl is chunky, the NaOH or NaOH/Karo solutions only tend to convert the AgCl on the surface of the chunk. The center is still AgCl. When AgCl dries out, it crystallizes and forms hard chunks. Never let the AgCl dry out - keep it wet. To get near 100% conversion, you must pulverize the AgCl. I would do this even if it's been kept wet. This can be easily done by adding water and putting it in a blender for awhile. If the seals will stand up to the NaOH, it would be best to also perform the chemical reactions in the blender - whether you're using NaOH alone or both NaOH and Karo syrup. If you don't have a blender, a flour sieve might work on dry material, but not as well as a blender.
If using NaOH and Karo (corn syrup) or other sugar to get a complete conversion to metal, you are always told to add the NaOH first and, only when it has been converted to the oxide do you add the syrup. I has found that this isn't necessary. You can add both at once, with the same results. I always calculate or estimate how much silver I have and use 10% extra chemicals.
Chris