Unarchiver won't unzip .bin files

I downloaded a Playstation 1 emulator last night and tried to set it up, but the BIOS files I downloaded in order for it to function are in a .bin format and the Unarchiver son't unzip them. Every time I try to unzip them, a window pops up and says that "The contents of this file cannot be extracted with this program. But the weird thing is, when I downloaded Final Fantasy VII Disc one, it was able to unzip that .bin file just fine. Help?