You don't. Forges in Darkness Falls don't "melt", they do craft like a workbench. So you need to have (pure) brass in your inventory and craft stuff directly from that. So you need to scrap the trophies first.
End if you have questions specific to mods, i recommend putting the mod name into the title, or in case of DF, use the DF-thread directly. Especially if you did post there already.
