I've tried it and it does not work as well as I thought. Post a free ad online searching for a electric silver recovery units like metafix, I did and got two of them. These will give you pure silver powder in one step.
and you might get more information from my old thread
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=37&t=7596
Another alternatives are zinc/sulphuric acid process,iron wool process and sodium sulphide process,all of them are here in the Forum,use the search box.