The Al Kharid mining site is located north of Al Kharid and north-west of the Duel Arena. It is infrequently visited since Falador Cave is more convenient to use, because of its location on the dungeon teleport. Silver and iron ores are quite abundant in this mining site and has enough rocks to allow multiple miners to get resources.
On any spellbook, select minigames teleport and choose the duel arena option, then head west through the gate. Continue north-west until you reach the entrance of the mine.