Pyrites roasting is important because of sufates.
Since it is hard to change a sulfate salt (a salt is any metal and acid) to a halogen because SO4 is at the bottom of the list( the only way I know how to discribe it) heating to high temperature needed to break the sulfate bond, sulfuric doesnt boil SO2 at low temperature, 700 degress F would be my minimum goal in air for about an hour,
It is easy to change a chloride to a sulfate but not easy to change a sulfate to a chloride, High temperature will, drive off SO2 gas then we can change to chloride. usually for other chemicals to work, such as chloride or other halogen leach. or leach of your choice.
sorry can not tell you another method besides roasting, unless you can come up with a way to drive off SO2 gas chemically.
there are many leach choices besides cyanide, three halogens,many are forms of the halogen leaches, like nitric and sodium chlorides.
to concentrate floatation has been used, I never tried it, but ole timers used pine pitch here.
Maybe someone with more chemical Knowledge, and an ability to explain what they are trying to say, will help with what I am trying to discribe.