# Question about lye/sugar method



## Ionita (Aug 12, 2015)

I bought LaserSteve's CD on silver a long time ago. Recently I dissolved several pounds of silver containing scrap in nitric. I precipitated the silver chloride out with brine. My question is, other than being a little wasteful, are there any negative concequences to using a little more lye than necessary? If not, if I rinse thoroughly, are there any negative consequences to using too much sugar, as well? Of course,I would expect that I would also need to rinse the excess sugar out as well. I want to be absolutely certain that everything gets converted. Thanks


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## 4metals (Aug 12, 2015)

I do not prefer the silver chloride conversion process because to get pure silver it takes a lot of rinsing and generates a lot of waste. That said, I use the process with silver chloride residues from aqua regia refining and have produced very high purity silver, but most of the time I just convert it to metallic silver with minimal rinsing and melt it into anodes for silver cell refining. 

Using an excess of the caustic and sugar is not a problem other than being wasteful but the only way you can be sure is to test for complete conversion. 

The way to test for completeness of the reaction (conversion) is based on the fact that silver metal is not soluble in ammonium hydroxide while silver chloride is. Mix your reduced silver well and take a small representative sample (two teaspoons full is fine) and rinse it well. 

Next add about 100 ml of tap water and 5 ml of ammonium hydroxide and stir it well. Let the solids settle and then decant about half of the liquid into a beaker and add 20 ml of Hydrochloric acid. If there was any silver chloride or silver oxide in the sample, the liquid will turn cloudy white meaning your conversion was not complete. If it is clear, you are done.

Be careful using ammonia on silver compounds, always acidify the solution when you are done and never let it dry out. Under the right conditions silver chloride and ammonia can form fulminates, which are explosive. Be careful and never leave the alkaline ammonia silver chloride solutions to dry out. Always acidify the solution when you are done.


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