Mark,
Making that kind of shot is a convenient way to have your scrap so that you can weigh out what you might need for a particular casting, but it isn't necessary. When I refine gold or silver scrap, I usually make a smelt with all the potential scrap (grindings, polishing sweeps, filings, used abrasive paper, old polishing wheels, etc.) mixed with a very large amount of flux and flour. During the melt all the junk (mostly carborundum) is trapped in the flux and the mixed metal sinks to the bottom. All the light trash has burned away. I let that all cool down and then brake the crucible to free the button of metal. That button is then remelted and poured into shot so that it is much more finely divided for the next step in the process. The shot is then dissolved chemically, separated into all its individual constituent metals (gold, silver, platinum, palladium, rubidium, etc.) and then those individual metals are re-melted and cast into ingots for further use. Sometimes I make those now pure metals into shot to make alloying more convenient.
